PROSPECTIVA TECNOLÓGICA AAPRESID · Prospectiva Tecnológica AAPRESID – Abril 2014 4 case of Argentinean soybean and Spanish rapeseed El presente trabajo corresponde a una búsqueda

Prospectiva Tecnológica AAPRESID – Abril 2014

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PROSPECTIVA TECNOLÓGICA

AAPRESID

Abril de 2014

Hugo Permingeat


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Temario

AGRICULTURA GENERAL SUELOS - Materia orgánica, Nutrientes y Fertilizantes, Labranzas Background nitrous oxide emissions in agricultural and natural lands: a meta-analysis 5 Agronomic Responses of Continuous Corn to Stover, Tillage, and Nitrogen Management 5 Transgenic Corn Rootworm Protection Enhances Uptake and Post-Flowering Mineral Nutrient Accumulation

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Macrofauna Activity Density in Contrasting Tillage Systems in Buenos Aires Province, Argentina

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Soil profile carbon and nitrogen in prairie, perennial grass–legume mixture and wheat-fallow production in the central High Plains, USA

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Soil respiration, N2O, and CH4 emissions from an Andisol under conventional-tillage and no-tillage cultivation for 4 years

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Continued No-Till and Subsoiling Improved Soil Organic Carbon and Soil Aggregation Levels

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INTERACCIÓN PLANTA-MICROORGANISMOS

- Microbiología de suelos, fijación de nitrógeno, micorrizas.

Back to the basics: The need for ecophysiological insights to enhance our understanding of microbial behaviour in the rhizosphere

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Reconstructing the Microbial Diversity and Function of Pre-Agricultural Tallgrass Prairie Soils in the United States

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PRODUCCION VEGETAL - Ecofisiología de Cultivos Physiological Dynamics of Maize Nitrogen Uptake and Partitioning in Response to Plant Density and Nitrogen Stress Factors: II. Reproductive Phase

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miR172 Regulates Soybean Nodulation 11

- Genética y Mejoramiento Genetics and mapping of quantitative traits for nodule number, weight, and size in soybean (Glycine max L. [Merr.])

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Accelerating plant breeding 12 Field high-throughput phenotyping the new crop breeding frontier 13

- Tecnologías de Cultivos Apparent Red Clover Nitrogen Credit to Corn: Evaluating Cover Crop Introduction 13 A framework for evaluating ecosystem services provided by cover crops in agroecosystems

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Long-term fate of nitrate fertilizer in agricultural soils 15

PROTECCIÓN VEGETAL - Malezas y herbicidas Assessing innovative sowing patterns for integrated weed management with a 3D 16


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crop:weed competition model Factors affecting seed germination and emergence of Gomphrena perennis 16 Biologia e manejo da planta daninha Borreria densiflora DC 17

- Plagas e insecticidas A proteomic approach to study the mechanism of tolerance to Bt toxins in Ostrinia furnacalis larvae selected for resistance to Cry1Ab

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Relationships between soybean shoot nitrogen components and soybean aphid populations

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Natural occurrence of entomophthoroid fungi (Entomophthoromycota) of aphids (Hemiptera: Aphididae) on cereal crops in Argentina

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Occurrence, distribution, and ear damage of Helicoverpa zea (Lepidptera: Noctuidae) in mixed plantings of non-Bt and Bt corn containing Genuity SmartStax traits

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- Enfermedades y su control Peptides as triggers of plant defence 20 Systemic Acquired Resistance (50 Years after Discovery): Moving from the Lab to the Field

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Threats and opportunities of plant pathogenic bacteria 21

AGRICULTURA DE PRECISION YIELDSTAT – A spatial yeld model for agricultural crops 22

AGRICULTURA Y AMBIENTE Sustainable agriculture: possible trajectories from mutualistic symbiosis and plant neodomestication

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Integrated ecotoxicological assessment of bottom sediments from the Paraná basin, Argentina

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In-farm diversity stabilizes return on capital in Argentine agro-ecosystems 24 Land-use land-cover change and ecosystem loss in the Espinalecoregion, Argentina 24

AGRO-BIOTECNOLOGIA Multigene engineering of starch biosynthesis in maize endosperm increases the total starch content and the proportion of amylase

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Genetically modified (GM) crops: European and transatlantic divisions 26 Genomic Misconception: a fresh look at the biosafety of transgenic and conventional crops. A plea for a process agnostic regulation

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Engineering nucleases for gene targeting: safety and regulatory considerations 27 Transgenic Soybeans and Soybean Protein Analysis: An Overview 27

BIOENERGIA Environmental sustainability of advanced biofuels 28 Dedicated crops for advanced biofuels: Consistent and diverging agronomic points of view between the USA and the EU-27

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A methodological proposal for Life Cycle Inventory of fertilization in energy crops: The 29


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case of Argentinean soybean and Spanish rapeseed

El presente trabajo corresponde a una búsqueda bibliográfica de diferentes revistas

científicas especializadas en áreas temáticas de interés agropecuario y biológico. Cada título está vinculado al artículo original, se incluyó el resumen y se hizo una pequeña descripción del mismo.

La Sección Suelos incluye una serie de artículos relacionados con la emisión de gases de

efecto invernadero, la labranza, la nutrición vegetal y la absorción de nitrógeno. Algunos de estos trabajos fueron realizados en Argentina.

En la Sección Interacción Planta-Microorganismos se presentan dos trabajos que enfocan

interacciones bióticas rizosféricas y estudios de diversidad en suelos de praderas y cultivados. En Producción Vegetal, Sección Ecofisiología de Cultivos se incluyen dos artículos, uno sobre

la distribución de N durante la etapa reproductiva de maíz y otros sobre la regulación de la nodulación en soja por microRNAs. En la Sección de Mejoramiento Genético se incluyen tres artículos, uno sobre el mapeo genético de caracteres relacionados con la nodulación de soja durante la simbiosis con Rizhobium, otro que plantea métodos de acelerar el mejoramiento genético de cultivos y uno tercero que muestra la importancia del fenotipado en la frontera del mejoramiento. En la Sección Tecnologías de Cultivo, dos artículos discuten diferentes aspectos de los cultivos de cobertura y uno tercero enfoca la fertilización nitrogenada en suelos agrícolas.

En Protección Vegetal, Sección de Malezas y Herbicidas se incluye tres artículos, uno que discute aspectos del manejo integrado de malezas, otros dos que analizan la biología y manejo de dos malezas importantes: Gomphrena y Borreria. En la Sección Plagas e insecticidas, varios artículos enfocan la eficiencia del uso de proteínas Bt en versiones transgénicas de cultivos para el control de plagas claves, otros enfocan los hongos entomopatógenos como medios de control y otros discuten aspectos relacionados con los áfidos de la soja. En la Sección Enfermedades y su Control se incluyen tres artículos relacionados con los péptidos antimicrobianos, la resistencia sistémica adquirida y las oportunidades y amenazas de las bacterias fitopatógenas. En la Sección Agricultura de Precisión se presenta un modelo de simulación de rendimiento para cultivos agrícolas. En la Sección Agricultura y Ambiente se incluyen varios artículos sobre agricultura sustentable y evaluación de agroecosistemas, trabajos desarrollados en Argentina. En la Sección Agrobiotecnología se discuten desarrollos tales como la modificación de almidón en cereales, análisis proteómicos de sojas transgénicas y también se incluyen artículos que discuten aspectos regulatorios.

En la Sección Bioenergía se presentan artículos que analizan la sustentabilidad de cultivos bioenergéticos, hacia dónde va la producción de biocombustibles en Estados Unidos y Europa y uno último que enfoca el caso argentino de la soja como materia prima del biodiesel.


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AGRICULTURA GENERAL

- Materia orgánica, Nutrientes y Fertilizantes, Labranzas

Background nitrous oxide emissions in agricultural and natural lands: a meta-analysis

Dong-Gill Kim, Donna Giltrap, Guillermo Hernandez-Ramirez Plant Soil, 373: 17–30 (2013)

This study aimed at better characterising background nitrous oxide (N2O) emissions (BNE) in agricultural and natural lands. We compiled and analysed field-measured data for annual background N2O emission in agricultural (BNEA) and natural (BNEN) lands from 600 and 307 independent experimental studies, respectively. There were no significant differences between BNEA (median: 0.70 & mean: 1.52 kg N2O−N ha

−1 yr

−1) and BNEN (median: 0.31 & mean: 1.75 kg

N2O−N ha−1

yr−1

) (P>0.05). A simultaneous comparison across all BNEA and BNEN indicated that BNEs from riparian, vegetable crop fields and intentional fallow areas were significantly higher than from boreal forests (P< 0.05). Correlation and regression analyses supported the underlying associations of soil organic carbon (C), nitrogen (N), pH, bulk density (BD),and/or air temperature (AT) with BNEs to a varying degree as a function of land-use or ecosystem type (Ps<0.05). Although overall BNEN tended to be lower than BNEA on median basis, results in general suggest that land-use shifts between natural and managed production systems would not result in consistent changes in BNE. Keywords: emisión de gases de efecto invernadero, óxido nitroso, meta-análisis

Los objetivos de este estudio fueron determinar y comparar el background de óxido nitroso (BNE) por tipo de uso del suelo en las tierras agrícolas, según el tipo de ecosistema en tierras naturales, y por país, así como para examinar los factores que controlan biofísicos de la BNE a través de un meta-análisis de los datos disponibles en todo el mundo.

Agronomic Responses of Continuous Corn to Stover, Tillage, and Nitrogen Management

A. J. Sindelar, J. A. Coulter, J. A. Lamb, and J. A. Vetsch Agron. J. 105:1498–1506 (2013)

Corn (Zea mays L.) stover removal for biofuel production is expected to increase in the near future. Previous research suggests stover removal is best suited to continuous corn (CC) cropping systems with reduced tillage. However, grain yields in reduced tillage CC systems in the Upper Midwest can be reduced because of cool soil temperatures restricting early-season growth. Field experiments were conducted over 3 yr at two locations in southern Minnesota with medium- and fine-textured soils to assess the agronomic responses of CC to stover removal, tillage system, and fertilizer N rate. Stover removal and/or tillage increased soil temperature by as much as 4°C, and differences among treatments generally existed until canopy closure. Corn emergence was 6% greater with stover removal in no-tillage (NT), but was not affected by stover removal in chisel-tillage (CT) and strip-tillage (ST). Stover removal increased normalized difference vegetative index (NDVI) at the eight leaf collar stage (V8) by 20 and 13% in NT and ST, respectively, but had no effect on NDVI in CT. Stover removal decreased the economically optimum N rate (EONR) by >12 and >19 kg N ha

–1 in NT and ST, respectively, and increased grain yield at the EONR by 7, 9, and 6% in CT, NT, and

ST, respectively. These results indicate stover removal can improve short-term agronomic productivity of moderate- to high-yielding CC on productive soils in the Upper Midwest. Keywords: monocultivo, labranza, manejo del nitrógeno, maíz

Los objetivos de este estudio fueron determinar los efectos del manejo del rastrojo, los sistemas de labranza reducida y la tasa de fertilizante nitrogenado en las respuestas agronómicas de cultivo continuo de maíz en dos localidades del MedioOeste americano. Los resultados demuestran que el rendimiento de grano del cultivo continuo de maíz


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puede aumentar con la eliminación del rastrojo en ambientes donde las temperaturas del suelo de principios de temporada son frescas y asociadas con el rastrojo en el crecimiento de la planta.

Transgenic Corn Rootworm Protection Enhances Uptake and Post-Flowering Mineral Nutrient Accumulation

Ross R. Bender, Jason W. Haegele, Matias L. Ruffo, and Frederick E. Below Agron. J., 105: 1626–1634 (2013)

Although modern maize (Zea mays L.) hybrids with transgenic insect protection from corn rootworm (CRW) (Diabrotica spp.) demonstrate improved yield and insect control compared to their non-protected (refuge) counterparts, no comprehensive studies have documented the impact of transgenic insect protection on nutrient uptake and partitioning. The objective of this study was to investigate the effect of transgenic protection from CRW on the timing and quantity of uptake for key nutrients such as N, P, K, S, and Zn. Results from two similar experiments across 5 site-years were analyzed and summarized. In the first experiment, transgenic hybrids averaged greater grain yield (10%; 0.9 Mg ha

–1), total biomass (7%; 1.2 Mg ha

–1), and grain nutrient accumulation of N (8%), P (12%), K (9%), S

(9%), and Zn (12%) compared to non-protected hybrids (P ≤ 0.05). In the second experiment, the yield response associated with transgenic insect protection varied among hybrids. Those hybrids which exhibited a yield response compared to their non-protected counterparts resulted in greater post-flowering acquisition of N (31%), P (24%), and K (38%) (P ≤ 0.05). The results indicate that in favorable environments, transgenic CRW protected hybrids not only produce more total biomass and yield, but also maintain greater rates of nutrient acquisition during grain-filling. Keywords: nutrición vegetal, maíz transgénico

El objetivo de esta investigación fue cuantificar la absorción total de nutrientes y la partición a través de varias comparaciones entre híbridos Bt y no Bt. Un objetivo adicional fue medir la biomasa y la acumulación de nutrientes entre las comparaciones Bt seleccionados para entender más a fondo las diferencias en los patrones de absorción y de la partición de nutrientes que pudieran derivarse de la protección transgénica de la agresión insectil en las raíces. La hipótesis inicial del trabajo era que la protección transgénica contra los insectos se traduciría en una mayor rentabilidad y una acumulación total de nutrientes, y que no produciría ninguna diferencia durante el llenado de grano para satisfacer las demandas del destino.

Macrofauna Activity Density in Contrasting Tillage Systems in Buenos Aires Province, Argentina

Pablo L. Manetti, Ariel J. Faberi, Natalia L. Clemente, and Alicia N. López Agron. J. 105: 1780–1786 (2013)

In Argentina, two tillage systems are used, conventional tillage (CT) and no-till (NT). The aim was to determine the ground-dwelling macrofauna taxa and compare the impacts of both NT and CT on their activity density. Samples were taken within wheat (Triticum aestivum L.) (August–December) and maize (Zea mays L.) (November–April) crop fields under CT and NT during three cropping seasons (Cycles 1, 2, and 3). Ten pitfall traps 10 m apart were placed in each field. Traps were collected every 15 d throughout the crop cycles to determine activity density (individuals plot–1) of soil macrofauna. Invertebrates were counted and identified to the class level; Insecta were further identified to order, family, or species levels. Higher mean total macrofauna activity density was found under NT than CT for Cycle 1 in wheat and Cycles 1 and 3 in maize. Arachnida activity density was higher under NT than CT in only a few crop cycles. Carabidae showed no preference for any tillage system. Orthoptera showed more activity density under NT than CT. The activity density of the Lepidoptera and Hymenoptera specimens were higher under CT than NT in some wheat and maize seasons. Diplopoda and Crustacea had higher activity density under NT than CT. In conclusion, the total activity density was consistently greater under NT, but there were differences within taxonomic groups. Keywords: siembra directa, macrofauna, labranza


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El objetivo de este trabajo realizado en Argentina fue determinar la taxonomía de la macrofauna del suelo y comparar el impacto de la labranza (convencional y siembra directa) sobre la densidad de su actividad. El total de densidad de actividad fue consistentemente mayor en condiciones de siembra directa, pero no hubo diferencias dentro de los grupos taxonómicos entre los sistemas de labranza contrastantes. Este hallazgo indica que la calidad del suelo es potencialmente similar entre los sistemas de labranza en el sureste de la provincia de Buenos Aires, si la composición de la macrofauna del suelo y la densidad de la actividad se considera como un indicador. La selección del mejor sistema de labranza dependerá de otros factores, tales como la protección del suelo contra la erosión del agua o la recuperación de las propiedades físicas o químicas.

Soil profile carbon and nitrogen in prairie, perennial grass–legume mixture and wheat-fallow production in the central High Plains, USA

Tunsisa T. Hurisso, Jay B. Norton, Urszula Norton Agriculture, Ecosystems and Environment, 181: 179– 187 (2013)

Conversion of native prairie land for agricultural production has resulted in significant loss and redistribution of soil organic matter (SOM) in the soil profile ultimately leading to declining soil fertility in a low-productivity semiarid agroecosystem. Improved understanding of such losses can lead to development of sustainable land management practices that maintain soil fertility and enhance soil quality. This study was conducted to determine whether conservation practices impact soil profile carbon (C) and nitrogen (N) accumulation in central High Plains. Soil samples were taken at four-depth increments to 1.2 m in July of 2011 from five unfertilized fields under long-term management with varying degrees of soil disturbance: (1) historic wheat (Triticum aestivum)-fallow (HT) – managed with tillage alone, (2) conventional wheat-fallow (CT) – input of herbicides for weed control and fewer tillage operation than historic wheat-fallow, (3) no-till wheat-fallow (NT) – not plowed since 2000 and herbicides used for weed control, (4) grass–legume mixture – established in 2005 as in the Conservation Reserve Program (CRP), and (5) native mixed grass prairie (NP) – representing a relatively undisturbed reference location. Cumulative soil organic C (SOC) was not significantly different among the three wheat-fallow systems when the whole profile (0–120 cm) was analyzed. However, SOC, dissolved organic C (DOC), and total soil N contents decreased in the direction NP > CRP ≥ NT > HT ≥ CT in the surface 0–30 cm depth. In the surface 0–30 cm depth, estimated annual SOC storage rate averaged 0.28 Mg C ha

−1 year

−1 since the cessation of tillage in 2000 and 0.58 Mg C ha

−1 year

−1 since the establishment of CRP

grass–legume mixture in 2005. Cumulative soil inorganic C (SIC) accumulation ranged between 8.1 and 24.9 Mg ha−1

and was greatest under wheat-fallow systems, particularly at deeper soil layers, relative to the perennial systems (NP and CRP). Results from this study suggest that repeated soil disturbance induced by cropping and fallow favored large accumulation of SIC which presence may result in decline in soil fertility and productivity; whereas conversion from tilled wheat-fallow to CRP grass–legume mixture offers great SOC storage potential relative to NT wheat-fallow practices.

Keywords: material orgánica del suelo, agricultura de conservación, praderas

El objetivo de este estudio fue cuantificar el carbono orgánico del suelo y su distribución vertical en los perfiles del suelo a través de un gradiente de perturbación, de las rotaciones trigo-barbecho intensamente labrados a praderas mixtas con gramíneas sin laboreo. El estudio se basa en el supuesto de que el suelo de la pradera nativa representa las condiciones pre-cultivo y que cada sistema de gestión de la conservación representa un nivel de recuperación con respecto a los históricos intensamente cultivados. Los resultados sugieren que hay poco carbono orgánico ganado once años después de la conversión de la producción de trigo-barbecho con labranza hacia sistemas sin labranzas. Esto sugiere que los efectos de la conversión a la siembra directa para mejorar la fertilidad del suelo son más lentos en materializarse en sistemas de cultivo de las tierras secas marginalmente productivas.


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Soil respiration, N2O, and CH4 emissions from an Andisol under conventional-tillage and no-tillage cultivation for 4 years

Seiichiro Yonemura, Isamu Nouchi, Seiichi Nishimura, Gen Sakurai, Kazuki Togami, Kazuyuki Yagi Biol Fertil Soils, 50: 63–74 (2014)

No-tillage (NT) management is a promising method to sequester soil C and mitigate global warming caused by agricultural activities. Here, we report 4 years of continuous soil respiration rates and weekly nitrous oxide (N2O) and methane (CH4) emissions in NT and conventional-tillage (CT) plots in a typical Japanese volcanic soil. Overall, the soil respiration, N2O emission, and CH4 uptake decreased significantly in the NT plot. A difference in soil respiration and N2O emission between the two plots began after the tillage treatment and the incorporation of crop residues and fertilizers, whereas the CH4 uptake did not vary significantly during the fallow period after the treatments. The N2O emission was higher from the CT than from the NT plot during the fall. The overall lower CH4 uptake in the NT than in the CT plot likely resulted from a combination of decreased soil gas diffusivity and higher mineral N content at the soil surface. Higher soil respiration and N2O emission occurred in the NT plot in the summer of 2003 and were plausibly caused by an increase in the soil moisture content that resulted from lower temperatures during July and August; the higher soil moisture must have accelerated the decomposition of organic matter accumulated in the topsoil. These results indicate that NT management is generally effective for the mitigation of the total GWP by reducing soil respiration and N2O emission in temperate regions; however, NT management may increase rather than decrease these emissions when fields experience cool summers with frequent rainfall. Keywords: emission de gases de efecto invernadero, soja, labranzas

Se necesita un estudio de largo plazo para obtener datos consistentes sobre la emisión de gases de efecto invernadero, como resultado de la gestión de siembra directa en un clima templado húmedo como el de Japón, debido a las variaciones en las condiciones meteorológicas de año en año. Aquí, se presenta la respiración del suelo y las emisiones de N2O y CH4 medidas en en parcelas de siembra directa y de labranza convencional durante 4 años. Estos resultados indican que la siembra directa es generalmente eficaz para la mitigación del total gases de efecto invernadero, reduciendo la respiración del suelo y las emisiones de N2O en las regiones templadas; sin embargo, la gestión de siembra directa puede aumentar en lugar de disminuir estas emisiones cuando los campos experimentan veranos frescos con lluvias frecuentes.

Continued No-Till and Subsoiling Improved Soil Organic Carbon and Soil

Aggregation Levels Shenzhong Tian, Yu Wang, Tangyuan Ning, Na Li, Hongxiang Zhao, Bingwen Wang, Zengjia Li,

and Shuyun Chi Agron. J. 106: 212–218 (2014)

Tillage and crop residue inputs are important factors that impact soil aggregation and soil organic C (SOC) decomposition. This study evaluated the impacts of tillage and 10 yr of crop residue removal on aggregate stability, distribution, and associated C. The research was conducted in North China between 2002 and 2011. The treatments were five tillage systems that included conventional tillage (CT), subsoiling (ST), harrow tillage (HT), rotary tillage (RT), and no-till (NT) in combination with crop residue retention (P) or residue removal (A). The results indicate that 74 to 82% of aggregates were macroaggregates (0.25–5 mm) and that these aggregates contained from 53 to 87% of the SOC in the 0- to 30-cm depth. Tillage and residue removal reduced macroaggregates and SOC levels, especially under the RT treatment, but residue inputs slowed down the rate of SOC depletion in the soil. The treatments of no-till with residue retention (NTP) and subsoiling with residue retention (STP), accumulated more C in stable macroaggregates and significantly increased SOC levels, which increased 13.37 and 9.59 Mg C ha

–1, respectively, in 10 yr. Crop residue

input combined with an appropriate tillage system is an effective method for maintaining and improving low-quality soil and SOC levels in the widespread wheat (Triticum aestivum L.)–maize (Zea mays L.) cropping system of North China. Keywords: siembra directa, carbono orgánico del suelo, agregados del suelo


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El objetivo de este estudio fue investigar cómo la distribución, estabilidad, C asociado de los agregados del suelo, y el pool de carbono orgánico respondió a largo plazo y a la gestión de residuos, ya sea solo o en combinación, cuando se comparan situaciones de labranza en un período de de 10 años en un sistema de cultivo de trigo y maíz en el norte de China. La eliminación de residuos de cultivos a largo plazo resultó en una disminución de la estabilidad de los agregados del suelo y condujo a un bajo nivel de carbono orgánico. Por otra parte, algunos sistemas de labranza, como la labranza rotatoria, se utilizan con frecuencia en esta región y no son una buena opción para mejorar los niveles de calidad del suelo y del carbono orgánico, lo que lleva a un riesgo regional de la degradación del suelo y al agotamiento del mismo sin entradas de residuos a largo plazo.

- Interacción planta-microorganismos (microbiología de suelos, fijación de nitrógeno, micorrizas…)

Back to the basics: The need for ecophysiological insights to enhance our understanding of microbial behaviour in the rhizosphere

Francisco Dini-Andreote and Jan Dirk van Elsas Plant Soil, 373: 1–15 (2013)

Microorganisms exhibit an astonishing diversity and wide genetic variability even within species, in particular with respect to their metabolic pathways and host-interactive capabilities. The mosaic genomes that encode these capacities are accountable for the abilities of environmental microbes to survive and thrive in highly complex systems such as soil and the rhizosphere. Whereas credits are to be given to traditional microbiology studies, e.g. with rhizobia and their interaction with the plant, an explosive enhancement of our understanding of the plant-microorganism interactive system has been recently achieved by the broad application of the molecular toolbox, in particular high-throughput sequencing (HTS) technologies. The latter have allowed to access thousands to millions of microbial phylotypes and functions at relatively low cost and effort. While such techniques have improved the accessibility of the taxonomic and functional diversity of rhizosphere and soil microbial communities, detailed insights into organismal ecology and physiology (reflecting the behaviour of populations of cells) within the community in the natural environment are still required. In this review, we first examine the current ‘state-of-the-art’ of rhizosphere ecology studies and what HTS strategies have added to our understanding of the system. We posit that our capacity to develop and test refined ecological hypotheses is hindered if we solely depend on deep-sequencing methods. Plant-soil microorganism systems represent one of the most intriguing ‘playgrounds’ for assessments of ecological theories, since they offer a myriad of ways to investigate ecological interactions (i.e. intra- and inter-specifically), physiological and behavioural traits. In addition, the evolutionary processes that lead to innovation in the microbiota are likely prominent in the rhizosphere. Thus, there is a perceived need to shift our attention from the HTS studies, that extensively map the local microbiota in an overall fashion, to studies focusing on as-yet-unaddressed fundamental questions about the plant-soil microbiota system. Such a paradigm shift will certainly assist us in the unravelling of the building blocks of rhizosphere (and soil) microbial communities, as well as form a basis for targeted manipulation of these in their natural settings. Keywords: interacción planta-microorganismo, ecología microbiana, rizosfera.

La presente revisión examina los recientes avances en la aplicación de herramientas moleculares para el estudio de la rizosfera. Se discuten los puntos fuertes y las advertencias de la amplia utilización de las metodologías moleculares actuales, que determinan de qué manera se pueden aplicar de forma fiable para evaluar las cuestiones fundamentales sobre las interacciones de la rizosfera. Se concluye que los límites están alcanzados con los métodos de secuenciación en términos del nivel de resolución que se


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puede alcanzar. Una cuestión clave es la falta de comprensión del comportamiento ecofisiológico de microorganismos específicos en la rizosfera, así como del suelo.

Reconstructing the Microbial Diversity and Function of Pre-Agricultural Tallgrass Prairie Soils in the United States

Noah Fierer, Joshua Ladau, Jose C. Clemente, Jonathan W. Leff, Sarah M. Owens, Katherine S. Pollard, Rob Knight, Jack A. Gilbert, Rebecca L. McCulley

SCIENCE, 342: 622-625 (2013)

Native tallgrass prairie once dominated much of the midwestern United States, but this biome and the soil microbial diversity that once sustained this highly productive system have been almost completely eradicated by decades of agricultural practices. We reconstructed the soil microbial diversity that once existed in this biome by analyzing relict prairie soils and found that the biogeographical patterns were largely driven by changes in the relative abundance of Verrucomicrobia, a poorly studied bacterial phylum that appears to dominate many prairie soils. Shotgun metagenomic data suggested that these spatial patterns were associated with strong shifts in carbon dynamics. We show that metagenomic approaches can be used to reconstruct below-ground biogeochemical and diversity gradients in endangered ecosystems; such information could be used to improve restoration efforts, given that even small changes in below-ground microbial diversity can have important impacts on ecosystem processes. Keywords: diversidad microbiana, praderas

A excepción de unos pocos relictos de las praderas que nunca han sido cultivadas, los terrenos que actualmente se encuentran en toda la región se parecen muy poco a su estado pre-agrícola. Se confirmó el efecto de los cultivos en las comunidades microbianas del suelo, comparando directamente las comunidades bacterianas en suelos cultivados en suelos no cultivados duplicadas, tomadas de todo el rango de las praderas de pastos altos nativos, y se encontró que los suelos cultivados albergaban comunidades bacterianas que fueron significativamente distintos en la composición de las encontradas en los correspondientes suelos de pradera nativa.

PRODUCCION VEGETAL

- Ecofisiología de Cultivos

Physiological Dynamics of Maize Nitrogen Uptake and Partitioning in Response to Plant Density and Nitrogen Stress Factors: II. Reproductive

Phase Ignacio A. Ciampitti, Scott T. Murrell, James J. Camberato, Mitch Tuinstra, Yanbing Xia, Peter Friedemann,

and Tony J. Vyn Crop Sci. 53:2588–2602 (2013)

Improved plant N utilization and partitioning is critical for future improvements in maize (Zea mays L.) grain yield (GY). The overall research objective was to gain understanding of the physiological mechanisms underpinning biomass (BM), N uptake partitioning, and GY processes during the reproductive period for two maize hybrids grown at varying plant density (PD) (low is 54,000 plant ha

-1, medium is 79,000 plants ha

-1, and high is 104,000 plants ha

-1) and N inputs

(low is 0 kg N ha-1

, medium is 112 kg N ha-1

, and high is 224 kg N ha-1

) over four site– years. At the community level, maize GY was maximized in both genotypes at the medium PD and highest N rate. At maturity, grain harvest index improved as the whole-plant N uptake increased following a linear-plateau model and, for N allocation, both grain and shoot N concentrations increased similarly as BM increased. Around flowering (±15 d), dry mass and N partitioning rates were unmodified by treatment factors. Treatment factors only marginally influenced potential kernel number


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near flowering. Allometric analyses confirmed a lack of treatment impact on whole-plant N uptake and N remobilization coefficients. Greater reproductive-stage N uptake was associated with superior ear strength (kernel number and weight) and late shoot N remobilization, but GY was also positively related to vegetative-stage N uptake. Future research should identify genotypic variation for overcoming the documented N uptake trade-off mechanisms (vegetative-stage N uptake vs. shoot N remobilization) as related to the maize GY improvement process. Keywords: densidad de plantas, maíz, eficiencia en el uso de nitrógeno

En el presente trabajo se estudió la dinámica fisiológica de la absorción de N en maíz y la distribución por la planta en la fase reproductivoa en función de la densidad de individuos en el cultivo. Una mayor absorción de N en la etapa reproductiva se asoció con la fuerza de la espeiga (número de granos y el peso) y el recilaje tardío del N, pero el rendimiento de grano también se relaciona positivamente con la absorción de N en la etapa vegetativa.

miR172 Regulates Soybean Nodulation Zhe Yan, Md Shakhawat Hossain, Jun Wang, Oswaldo Valdés-López, Yan Liang, Marc Libault,

Lijuan Qiu, and Gary Stacey MPMI, 26 (12): 1371–1377 (2013)

Micro-RNAs (miRNAs) play a pivotal role in the control of gene expression and regulate plant developmental processes. miRNA 172 (miR172) is a conserved miRNA in plants reported to control the expression of genes involved in developmental phase transition, floral organ identity, and flowering time. However, the specific role of miR172 in legume nodulation is undefined. Ectopic expression of soybean miR172 resulted in an increase in nodule numbers in transgenic roots and an increase in the expression of both symbiotic leghemoglobin and nonsymbiotic hemoglobin. These nodules showed higher levels of nitrogenase activity. Further analysis revealed a complex regulatory circuit in which miR156 regulates miR172 expression and controls the level of an AP2 transcription factor. The latter, either directly or indirectly, controls the expression of nonsymbiotic hemoglobin, which is essential for regulating the levels of nodulation. Keywords: microRNAs, nodulación de soja, fijación nitrogenada

Los microRNA o pequenos RNA de interferencia (siRNA) cumplen un rol central en la expresión génica de los organismos vivos. Se los llama con un número y así se los asocia con los genes que controlan. En este artículo se informan los datos de soja que sugieren un circuito de regulación complejo vinculado con la nodulación durante la simbiosis con Rhizobium. En este circuito, los niveles de miR156 controlan negativamente la expresión de miR172, que se dirige al ARNm del factor de transcripción AP2-2. Este último, ya sea directamente o indirectamente, regula la expresión de la Hb, que es esencial para la regulación de los niveles de nodulación. El efecto neto es que el nivel de nodulación se controla por la interacción de miR156 y miR172, lo que afecta la expresión de sus genes blancos.

- Genética y Fitomejoramiento

Genetics and mapping of quantitative traits for nodule number, weight, and size in soybean (Glycine max L. [Merr.])

Sadal Hwang, Jeffery D. Ray, Perry B. Cregan, C. Andy King, Marilynn K. Davies, Larry C. Purcell Euphytica, 195: 419–434 (2014)

Soybean research has found that nodule traits, especially nodule biomass, are associated with N2 fixation ability. Two genotypes, differing in nodule number per plant and individual nodule weight, KS4895 and Jackson, were mated to


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create 17 F3- and 80 F5-derived RILs. The population was mapped with 664 informative markers with an average distance of less than 20 cM between adjacent markers. Nodule traits were evaluated in 3-year field trials. Broad-sense heritability for nodule number (no. plant-1), individual nodule dry weight (mg nodule-1), individual nodule size (mm nodule-1), and total nodule dry weight (g plant-1) was 0.41, 0.42, 0.45, and 0.27, respectively. Nodule number was negatively correlated with individual nodule weight and size. Nodule number, individual nodule weight, and size are major components which likely contributed to increased total nodule weight per plant. Composite interval mapping (CIM) identified eight QTLs for nodule number with R2 values ranging from 0.14 to 0.20. Multiple interval mapping (MIM) identified two QTLs for nodule number, one of which was located close to the QTL identified with CIM. Six QTLs for individual nodule weight were detected with CIM, and one QTL was identified with MIM. For nodule size, CIM identified seven QTLs with R2 values ranging from 0.14 to 0.27. Five QTLs for total nodule weight were detected with CIM, one of which was located close to a QTL identified with MIM. These results document the first QTL information on nodule traits in soybean from field experiments utilizing a dense, complete linkage map. Keywords: fijación nitrogenada, soja, nódulos simbiosis, QTLs

El propósito de esta investigación fue determinar la herencia del número de nódulos, peso de nódulos, el tamaño del nódulo, y el peso de nódulos individuales de una población de soja segregante en condiciones de campo. Un segundo objetivo fue determinar QTL para estos rasgos. Se identificaron QTL para el número de nódulos, peso promedio de nódulos, el tamaño del nódulo, y el peso total de nódulos en condiciones de campo. Estos resultados representan la primera información de QTL en los rasgos de nódulos en la soja a partir de experimentos de campo con un denso y completo mapa de ligamiento. Dado que el peso de nódulos individuales y peso total de nódulos están estrechamente relacionados con la fijación de N2, se espera que este estudio sea útil en la selección de genotipos con mayor capacidad de fijación de N2.

Accelerating plant breeding Gerald N. De La Fuente, Ursula K. Frei, and Thomas Lübberstedt

Trends in Plant Science, 18 (12): 667-672 (2013)

The growing demand for food with limited arable land available necessitates that the yield of major food crops continues to increase over time. Advances in marker technology, predictive statistics, and breeding methodology have allowed for continued increases in crop performance through genetic improvement. However, one major bottleneck is the generation time of plants, which is biologically limited and has not been improved since the introduction of doubled haploid technology. In this opinion article, we propose to implement in vitro nurseries, which could substantially shorten generation time through rapid cycles of meiosis and mitosis. This could prove a useful tool for speeding up future breeding programs with the aim of sustainable food production.

Keywords: fitomejoramiento

En este artículo de opinión se propone una idea beneficiando la velocidad de mejora genética a través de la puesta en práctica del ciclo de generación rápida por el uso de la cultivo in vitro. A través de ciclos rápidos de meiosis y mitosis realizados en sistemas de cultivo de tejidos, los tiempos de generación de especies de cultivo pueden reducirse permitiendo más oportunidades para la recombinación y la selección en una unidad de tiempo dado.


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Field high-throughput phenotyping: the new crop breeding frontier José Luis Araus and Jill E. Cairns

Trends in Plant Science, 19 (1): 52-61 (2014)

Constraints in field phenotyping capability limit our ability to dissect the genetics of quantitative traits, particularly those related to yield and stress tolerance (e.g., yield potential as well as increased drought, heat tolerance, and nutrient efficiency, etc.). The development of effective field-based high-throughput phenotyping platforms (HTPPs) remains a bottleneck for future breeding advances. However, progress in sensors, aeronautics, and high-performance computing are paving the way. Here, we review recent advances in field HTPPs, which should combine at an affordable cost, high capacity for data recording, scoring and processing, and non-invasive remote sensing methods, together with automated environmental data collection. Laboratory analyses of key plant parts may complement direct phenotyping under field conditions. Improvements in user-friendly data management together with a more powerful interpretation of results should increase the use of field HTPPs, therefore increasing the efficiency of crop genetic improvement to meet the needs of future generations.

Keywords: fenotipado, fitomejoramiento

El presente artículo de revisión enfoca la importancia de los avances en el fenotipazo, como hecho esencial para capitalizar la evolución de la reproducción convencional, molecular y transgénica y asegurar la mejora genética de los cultivos para la seguridad alimentaria futura. La capacidad para llevar a cabo el fenotipado de precisión, sobre todo en condiciones repetibles y representativos que crecen en el campo, se está quedando muy por detrás de la capacidad de generación de la información genómica. Esto está limitando los avances de mejoramiento. La evolución (por ejemplo, sensores, plataformas, y la capacidad analítica) en fenotipazo ha permitido que estas mediciones se realicen in situ; sin embargo, la integración de los datos se está retrasando.

- Tecnología de Cultivos

Apparent Red Clover Nitrogen Credit to Corn: Evaluating Cover Crop

Introduction Lowell E. Gentry, Sieglinde S. Snapp, Richard F. Price, and Laura F. Gentry

Agron. J. 105: 1658–1664 (2013)

Corn (Zea mays L.) production systems can benefit from introducing a leguminous winter cover crop into the rotation, especially with regard to increased N availability (i.e., legume N credit); however, it is not known if the full agronomic benefit is realized in the first year of cover crop introduction or if the benefit is cumulative with time. The objective of this study was to determine the apparent red clover (Trifolium pratense L.) N credit to corn in a conventional system where red clover was introduced for the first time compared with three agricultural systems that had a 14-yr history of using cover crops. The apparent red clover N credit was calculated by the difference in unfertilized corn N accumulation between cover and no-cover split-split plots. These data suggest that corn growers can realize the full benefits of a red clover cover crop in the first year of introduction. Keywords: maíz, trébol rojo, cultivos de cobertura

El objetivo de este estudio fue determinar el crédito de N del trébol rojo evidente para el maíz en un estudio de la rotación de cultivos a largo plazo en la que un cultivo de cobertura (trébol rojo mamut) se introdujo en la rotación por primera vez, en comparación con los tres sistemas agrícolas que tuvieron una historia de 14 años de uso de cultivos de


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cobertura. Un hallazgo único de este estudio fue que los productores pueden obtener el beneficio agronómico completo (es decir, de fertilidad con N) de intersiembra con trébol rojo para el maíz en el primer año de introducción del cultivo de cobertura. Como promedio entre los sistemas, el crédito de N por el trébol rojo aparente fue de 30 y 48 kg N ha-1. El trébol rojo sembrado antes de maíz aumentó la acumulación de N en la biomasa aérea de maíz entre un 32 y 38%. Sin embargo, el el rendimiento de grano de maíz fue significativamente mayor sólo en una campana.

A framework for evaluating ecosystem services provided by cover crops in agroecosystems

Meagan E. Schipanski, Mary Barbercheck, Margaret R. Douglas, Denise M. Finney, Kristin Haider, Jason P. Kaye, Armen R. Kemanian, David A. Mortensen, Matthew R. Ryan, John Tooker, Charlie White

Agricultural Systems, 125: 12–22 (2014)

Cropping systems that provide ecosystem services beyond crop production are gaining interest from farmers, policy makers and society at large, yet we lack frameworks to evaluate and manage for multiple ecosystem services. Using the example of integrating cover crops into annual crop rotations, we present an assessment framework that: (1) estimates the temporal dynamics of a suite of ecosystem services; (2) illustrates ecosystem multifunctionality using spider plots; and (3) identifies key time points for optimizing ecosystem service benefits and minimizing trade-offs. Using quantitative models and semi-quantitative estimates, we applied the framework to analyze the temporal dynamics of 11 ecosystem services and two economic metrics when cover crops are introduced into a 3-year soybean (Glycine max)–wheat (Triticum aestivum)–corn (Zea mays) rotation in a typical Mid-Atlantic climate. We estimated that cover crops could increase 8 of 11 ecosystem services without negatively influencing crop yields. We demonstrate that when we measure ecosystem services matters and cumulative assessments can be misleading due to the episodic nature of some services and the time sensitivity of management windows. For example, nutrient retention benefits koccurred primarily during cover crop growth, weed suppression benefits occurred during cash crop growth through a cover crop legacy effect, and soil carbon benefits accrued slowly over decades. Uncertainties exist in estimating cover crop effects on several services, such as pest dynamics. Trade-offs occurred between cover crop ecosystem benefits, production costs, and management risks. Differences in production costs with and without cover crops varied 3-fold over 10 years, largely due to changes in fertilizer prices, and thus cover crop use will become more economical with increasing fertilizer prices or if modest cost-sharing programs are established. Frameworks such as that presented here provide the means to quantify ecosystem services and facilitate the transition to more multifunctional agricultural systems. Keywords: abonos verdes, servicios del ecosistema, sistemas de cultivo, cultivos de cobertura

Mediante la integración de un conjunto de servicios de los ecosistemas en un marco analítico unificado, en el presente artículo se destaca el potencial de los cultivos de cobertura para influir aumentando en una amplia gama de esos servicios ecosistémicos. Además, se demuestra la importancia de considerar la dinámica temporal en la evaluación de los efectos del sistema de gestión de servicios de los ecosistemas. Las compensaciones se producen entre las medidas económicas y los beneficios ambientales. Los obstáculos económicos a corto plazo que limitan la adopción de cultivos de cobertura podrían reducirse si los precios de los fertilizantes aumentan o mediante la implementación de programas de participación en los gastos o incentivos. En el largo plazo, muchos de los servicios de los ecosistemas que cubren estos cultivos proporcionan mejoras en la capacidad de recuperación (con una retroalimentación positiva) y la estabilidad de los rendimientos, la reducción de las necesidades de insumos externos y la rentabilidad. Un marco de evaluación como el que aquí se presenta puede mejorar la comprensión de la dinámica temporal de los diferentes servicios, guiar la investigación futura e informar la política en beneficio de los sistemas agrícolas en términos económicos, ambientales y socialmente sostenibles.


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Long-term fate of nitrate fertilizer in agricultural soils Mathieu Sebilo, Bernhard Mayer, Bernard Nicolardot, Gilles Pinay, and André Mariotti

PNAS, 110 (45): 18185–18189 (2013)

Increasing diffuse nitrate loading of surface waters and groundwater has emerged as a major problem in many agricultural areas of the world, resulting in contamination of drinking water resources in aquifers as well as eutrophication of freshwaters and coastal marine ecosystems. Although empirical correlations between application rates of N fertilizers to agricultural soils and nitrate contamination of adjacent hydrological systems have been demonstrated, the transit times of fertilizer N in the pedosphere–hydrosphere system are poorly understood. We investigated the fate of isotopically labeled nitrogen fertilizers in a three–decade-long in situ tracer experiment that quantified not only fertilizer N uptake by plants and retention in soils, but also determined to which extent and over which time periods fertilizer N stored in soil organic matter is rereleased for either uptake in crops or export into the hydrosphere. We found that 61–65% of the applied fertilizers N were taken up by plants, whereas 12–15% of the labeled fertilizer N were still residing in the soil organic matter more than a quarter century after tracer application. Between 8–12% of the applied fertilizer had leaked toward the hydrosphere during the 30-y observation period. We predict that additional exports of

15N-labeled nitrate from the tracer application in 1982 toward the hydrosphere will

continue for at least another five decades. Therefore, attempts to reduce agricultural nitrate contamination of aquatic systems must consider the long-term legacy of past applications of synthetic fertilizers in agricultural systems and the nitrogen retention capacity of agricultural soils. Keywords: ciclo del nitrógeno, fertilizantes químicos, lixiviación de nitratros

En el presente artículo se describe una investigación sobre el destino a largo plazo de los fertilizantes nitrogenados (isótopo 15N) en el sistema suelo-agua planta de dos lisímetros intactos bajo rotación de remolacha azucarera y de trigo inviernal en Francia, durante un período de tres décadas (1982-2012). Los objetivos fueron: i) determinar el grado en que los fertilizantes nitrogenados fueron tomados por los cultivos, ii) evaluar el tiempo de residencia medio del fertilizante nitrogenado en la materia orgánica del suelo, y iii) medir las tasas a las que se exportó el nitrógeno a la hidrosfera en las tres décadas después de la aplicación de fertilizantes marcados isotópicamente. El objetivo fue establecer un balance completo de masa de 30 años sobre el destino de fertilizante N en un sistema agrícola y cuantificar en qué medida y durante qué periodo de tiempo el fertilizante N almacenado en la materia orgánica del suelo se ha reciclado, ya sea para la captación de los cultivos o la exportación hacia la hidrosfera. Los resultados destacan la importancia del manejo de la materia orgánica de los suelos agrícolas como un buffer para mitigar las contaminaciones con N en las aguas superficiales y subterráneas. Estos datos también indican que las tendencias actuales de aumento de concentración de nitratos observadas en los sistemas hidrológicos asociados con muchas zonas agrícolas del mundo son el resultado de las actividades actuales y pasadas a lo largo de las últimas décadas. Por lo tanto, las medidas de mitigación o restauración deben tener en cuenta los retrasos que ocasionen los legados de aplicaciones anteriores de fertilizantes sintéticos en los sistemas agrícolas.


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PROTECCIÓN VEGETAL

- Malezas y Herbicidas Assessing innovative sowing patterns for integrated weed management

with a 3D crop:weed competition model Nathalie Colbach, Alban Collard, Sébastien H.M. Guyot, Delphine Mézière, Nicolas Munier-Jolain

Europ. J. Agronomy, 53: 74– 89 (2014)

Weed dynamics models are needed to design innovative weed management strategies. Here, we devel-oped a 3D individual-based model called FlorSys predicting growth and development of annual weeds and crops as a function of daily weather and cropping practices: (1) crop emergence is driven by temperature, and emerged plants are placed onto the 3D field map, depending on sowing pattern, density, and emergence rate; plants are described as cylinders with their leaf area distributed according to height; (2) weed emergence is predicted by an existing submodel, emerged weed seedlings are placed randomly; (3) plant phenology depends on temperature; (4) a previously developed submodel predicts available light in each voxel of the canopy; after emergence, plant growth is driven by temperature; when shaded, biomass accumulation results from the difference between photosynthesis and respiration; shading causes etiolation; (5) frost reduces biomass and destroys plants, (6) at plant maturity, the newly produced seeds are added to the soil seed bank. The model was used to test different sowing scenarios in an oilseed rape/winter wheat/winter barley rotation with sixteen weed annuals, showing that (1) crop yield loss was negatively correlated to weed biomass averaged over the cropping season; (2) weed biomass was decreased by scenarios allowing early and homogenous crop canopy closure (e.g. reduced interrows, increased sowing density, associated or undersown crops), increased summer fatal weed seed germination (e.g. delayed sowing) or, to a lesser degree, cleaner fields at cash crop sowing (e.g. sowing a temporary cover crop for “catching” nitrogen); (3) the scenario effect depended on weedspecies (e.g. climbing species were little affected by increased crop competition), and the result thus varied with the initial weed community (e.g. communities dominated by small weed species were hinderedby the faster emergence of broadcast-sown crops whereas taller species profited by the more frequent gap canopies); (4) the effect on weed biomass of sowing scenarios applied to one year was still visible upto ten years later, and the beneficial effect during the test year could be followed by detrimental effects later (e.g. the changed tillage dates accompanying catch crops reduced weed emergence in the immediately following cash crop but increased seed survival and thus infestation of the subsequent crops). This simulation showed FlorSys to predict realistic potential crop yields, and the simulated impact of crop scenarios was consistent with literature reports. Keywords:malezas, canopeo, modelo de simulación, manejo integrado de malezas

El objetivo del presente trabajo es completar una primera etapa de modelado para predecir el crecimiento de malezas y desarrollo posterior de emergencia de las plántulas para la producción de semillas en función de la competencia por la luz en el canopeo del cultivo y de malezas.

Factors affecting seed germination and emergence of Gomphrena perennis

J M Acosta, D J Bentivegna, E S Panigo, I Dellaferrera & M G Perreta Weed Research 53, 69–75 (2013)

Controlled growth chamber experiments were conducted to determine factors affecting seed germination and emergence of the troublesome weed Gomphrena perennis. The objective of this research was to examine the effects of temperature, light, moist chilling, osmotic potential, dry storage and depth of seed burial on G. perennis

germination and emergence. The optimum temperature for germination was around 15–20C. Seeds showed

germination rates above 90% under 20 ⁄ 10 and 25 ⁄ 15C temperature regimes. The minimum exposure to light needed to stimulate germination was 1 min. However, the light requirement was reduced after a long storage period. Furthermore, germination was high (>90%) in all moist-chilling treatments tested. Germination was highly sensitive to increasing osmotic stress. The highest germination percentage (94%) was achieved at 0 MPa, and decreasing osmotic potential from 0 to -0.3 MPa reduced germination to 11%. The highest seedling emergence occurred for seeds placed


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from 0 to 1 cm deep, and no seedlings emerged from a 5-cm burial depth. Gomphrena perennis has a suitable environment in a no-till soybean field, where seeds remaining on the surface have the required temperature, light and depth needed for germination. Keywords: Gomphrena, malezas

El objetivo de esta investigación (realizado en Rafaela, Argentina) fue determinar el efecto de la temperatura, la luz, el potencial osmótico, húmedad de almacenamiento frío y seco en la germinación de semillas y el efecto de profundidad de enterramiento para la emergencia de las plántulas de Gomphrena perennis. Este estudio ha demostrado que G. perennis se adapta a germinar en el momento de la dispersión en un amplio rango de condiciones ambientales que se encuentran comúnmente en los trópicos y subtrópicos, lo que explica en parte su infestación con éxito en campos de soja argentinos. Los Regímenes de temperatura alterna intermedios han proporcionado mejores condiciones para la germinación que los regímenes más fríos y más cálidos. Debido al efecto del estrés osmótico, la germinación puede ser principalmente relacionada con las épocas del año, cuando la humedad es alta, es decir, la primavera y el otoño, momento en que se producen regímenes de temperatura alterna intermedios. Debido a que las semillas de G. perennis podrían germinar muy temprano en la temporada, son posibles las ventajas competitivas frente a otras especies de malezas en regiones similares.

Biologia e manejo da planta daninha Borreria densiflora DC Bianca Assis Barbosa Martins

Tesis de Maestría en Agronomía, Universidad de Sao Paulo, Brazil, 170 pp

A planta daninha vassourinha-de-botão (Borreria densiflora DC.) está apresentando aumento na sua infestação em áreas cultivadas com cana-de-açúcar e soja, respectivamente nos estados do Maranhão, Goiás e Tocantins. Observações de campo têm relatado a deficiência de controle químico sobre esta espécie, quando ocorre em estádio de crescimento avançado. Sendo assim, este trabalho objetivou classificar botanicamente B. densiflora DC., analisar a influência da luz e da temperatura na germinação desta espécie, seu crescimento, desenvolvimento e estruturas reprodutivas, sua susceptibilidade a herbicidas em condições de pré e pósemergência, e a influência da interação entre a profundidade de enterrio e a presença de palha em diferentes quantidades sobre a superfície do solo sobre a emergência desta planta daninha. A classificação botânica foi realizada na Facultad de Ciencias Exactas y Naturales y Agrimensura – UNNE / IBONE, Argentina; o experimento que analisou a germinação sob diferentes condições foi realizado no Laboratório de Análise de Sementes, do Departamento de Produção Vegetal da USP / ESALQ, e todos os demais experimentos foram conduzidos em casa-de-vegetação, do mesmo departamento. Todos os trabalhos foram conduzidos entre 2006 e 2007. Constatou-se que a planta daninha vassourinha-de-botão se trata da espécie Borreria densiflora DC., pertencente à família Rubiaceae. Com relação à germinação, constatou-se que a vassourinha-de-botão é fotoblástica positiva preferencial, uma vez que sua germinação é favorecida na presença de luz, respondendo diferentemente às condições de luz e temperatura estudadas. As maiores taxas de germinação e índices de velocidade de germinação foram alcançados em condição de fotoperíodo (12h) sob as temperaturas constantes de 30ºC - 35ºC e alternada de 20-30ºC. Praticamente, não houve germinação no escuro constante. Sobre o crescimento e desenvolvimento, observou-se que a planta daninha Borreria densiflora DC. é uma espécie com desenvolvimento inicial lento, de ciclo de vida perene simples, apresentado grande incremento nas variáveis massa seca total, taxa de crescimento relativo e de assimilação líquida entre os 26 e 36 dias após transplante (DAT). Ao final do experimento, os ramos se mostram como os compartimentos mais participativos na partição de fotoassimilados pela vassourinha-de-botão. Esta espécie é capaz de produzir, em média, 93.090 sementes por planta. Com relação ao manejo químico de Borreria densiflora DC., a maioria dos herbicidas promoveram controles considerados adequados, com exceção ao clomazone e MSMA, em condições de pré e pós-emergência, respectivamente. Sendo assim, várias opções de herbicidas e de misturas destes podem ser recomendadas para o manejo da planta daninha B. densiflora DC., tanto em condições de pré-semeadura quanto pré e pós-emergência. O estudo sobre a influência da interação entre profundidade da semente no solo e presença de palha de cana-de-açúcar na superfície do solo sobre a emergência desta espécie demonstrou haver interação entre os dois fatores testados, sendo que quanto maior a profundidade da semente no solo e a quantidade de palha sobre a superfície, menor é a porcentagem de emergência e biomassa fresca


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de B. densiflora DC. Tais resultados são importante na medida em que favorecem o entendimento da dinâmica populacional da B. densiflora DC., auxiliando o manejo integrado desta espécie. Keywords: malezas, manejo de malezas, emergência de malezas, Borreria densilora

El presente trabajo corresponde a una tesis de maestría presentada en la Universidad de Sao Paulo, Brasil, que enfoca a la malezas Borreria densiflora como blanco de estudio. En la misma se analiza la biología de la maleza y su manejo, considerando los aspectos relevantes en el estudio de malas hierbas.

- Plagas e Insecticidas

A proteomic approach to study the mechanism of tolerance to Bt toxins in Ostrinia furnacalis larvae selected for resistance to Cry1Ab

Lina Xu, Natalie Ferry, Zhenying Wang, Jie Zhang, Martin G. Edwards, Angharad M. R. Gatehouse, Kanglai He

Transgenic Res, 22: 1155–1166 (2013)

A Cry1Ab-resistant population of Asian corn borer (ACB-AbR) exhibiting approximately 100 times greater resistance to activated Cry1Ab than a susceptible population (Ostrinia furnacalis; ACB-BtS), was previously shown to exhibit high levels of crossresistance to Cry1Ah (131-fold), but no cross-resistance to Cry1Ie. It was suggested that the proposed mechanism of resistance was due to the alteration of specific receptors for Cry toxins in the midgut brush border membrane. In the present study a proteomic-based approach was used to identify proteins from brush border membrane vesicles (isolated from both resistant and susceptible Ostrinia furnacalis larvae) interacting with biotinylated Cry1Ab, Cry1Ah, and Cry1Ie. 2D-Electrophoresis in combination with ligand blots were employed and putative protein identities obtained using MALDI-ToF/ToF mass spectrometry. The V-type proton ATPase catalytic subunit A and heat shock 70 kDa proteins were identified as interacting with the Cry toxins tested in the ACB-AbR and ACBBtS larvae. The biotinylated Cry toxins showed markedly stronger interactions with proteins in the resistant compared to the susceptible larvae, suggesting an upregulation of the V-type proton ATPase catalytic subunit A and heat shock 70 kDa proteins in the resistant (ACB-AbR) larvae. Interestingly, Cry1Ie interactions with the V-type proton ATPase catalytic subunit A in the ACB-BtS larvae appeared to be absent. Keywords: Bacillus thuringiensis, Ostrinia furnacalis, proteómica maíz Bt

Ya existen preocupaciones sobre el potencial de insectos (como el barrendador del tallo) que evolucionen resistencia de campo a los genes Bt (particularmente el gen Cry1Ab). Los objetivos del presente estudio fueron investigar los mecanismos de resistencia y resistencia cruzada en Ostrinia furnacalis a diferentes toxinas Cry de Bt, como requisito previo a la liberación comercial del maíz transgénico Bt en China. En segundo lugar se evalúa la utilidad de los enfoques basados en proteómica para la identificación de las interacciones de la proteína Cry de Bt.

Relationships between soybean shoot nitrogen components and soybean aphid populations

Walter E. Riedell, Eric A. Beckendorf, Michael A. Catangui Arthropod-Plant Interactions, 7: 667–676 (2013)

Defining the relationships between soybean (Glycine max [L.] merr.) shoot nitrogen (N) components and soybean aphid (Aphis glycines Matsumura) populations will increase understanding of the biology of this important insect pest. In this 2-year field study, caged soybean plants were infested with soybean aphids (initial infestation of 0, 10, 50, or 100 aphids plant

-1) at the fifth node developmental stage. Soybean aphid populations, soybean shoot dry weight, and

shoot concentrations of nitrate-N, ureide- N, and total N were measured starting at full bloom through full seed


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soybean development stages. Soybean aphid population as well as shoot concentration of ureide-N increased rapidly starting at full bloom, peaked at beginning seed, and dramatically decreased by full seed soybean reproductive stages. Regression analysis indicated significant relationships (P = 0.01; r = 0.71) between soybean aphid populations and shoot ureide-N concentration. Thus, soybean aphid population levels appear to coincide with shoot ureide-N concentrations in the soybean plant. Keywords: soja, áfidos, pulgones, nitrógeno,

El presente trabajo se plantea la hipótesis que las concentraciones de N presentes en los brotes/vástagos de la planta de soja (en diferentes etapas del desarrollo) está en relación con las poblaciones de áfidos que se encuentran en esas plantas. Los datos permiten especular que los niveles de población de áfidos de soja coinciden con las concentraciones de los brotes de N-ureido en la planta de soja huésped. Estos datos son de carácter circunstancial; sin embargo, se presentan las correlaciones significativas entre N-ureidos y las poblaciones de áfidos, pero no permiten concluir que los cambios en las poblaciones de áfidos fueron causadas directamente por los cambios en las concentraciones de N-ureidos.

Natural occurrence of entomophthoroid fungi (Entomophthoromycota) of aphids (Hemiptera: Aphididae) on cereal crops in Argentina

R.G. Manfrino, J.L. Hatting, R. Humber, C.E. Salto & C.C. Lopez Lastra Ann Appl Biol, 164: 151–158 (2014)

The spectrum of entomophthoroid fungal species parasitising aphids on cereal crops and a study of the phenology and prevalence of these pathogens were investigated in Argentina. The studies were conducted at six different sites cultivated with crops of Triticum aestivum (wheat), Avena sativa (oats) and Sorghum bicolor (sorghum) during two consecutive years. Entomopathogenic fungi from the new phylum Entomophthoromycota were recorded from six aphid species on cereals in Argentina: Rhopalosiphum maidis, Rhopalosiphum padi, Rhopalosiphum rufiabdominalis, Schizaphis graminum, Sitobion avenae and Sipha maydis. Three species of entomophthoroid fungi were found infecting these aphid species: Pandora neoaphidis, Zoophthora radicans (Entomophthorales: Entomophthoraceae) and Neozygites fresenii (Neozygitales: Neozygitaceae). Entomophthoroid fungal infections occurred mostly in autumn–winter seasons (March–August), and coincided with periods of high relative humidity and comparatively low temperatures. This study represents the first base-line characterisation of entomophthoroid fungi infecting aphids on cereal crops in Argentina. Keywords: áfidos, cereales, control biológico, hongos entomopatógenos

El objetivo general de este estudio fue investigar e identificar hongos entomopatógenos para los pulgones de cereales, centrándose en la fenología y la prevalencia de estos hongos en la Región Pampeana de la provincia de Santa Fe, Argentina. Los resultados de este estudio realizado indican claramente que los hongos entomopatógenos tienen potencial para reducir las poblaciones de áfidos en condiciones de campo no controlados. Este estudio amplía aún más el conocimiento de los hongos entomopatógenos de pulgones en cultivos de cereales y su potencial como agentes de control biológico

Occurrence, distribution, and ear damage of Helicoverpa zea (Lepidoptera: Noctuidae) in mixed plantings of non-Bt and Bt corn

containing Genuity SmartStax traits Fei Yang, David L. Kerns, Graham P. Head, B. Rogers Leonard, Ying Niu, Fangneng Huang

Crop Protection, 55: 127-132 (2014) Protein contamination on refuge kernels due to cross-pollination from Bt corn to non-Bt corn ears is a major concern in the use of a seed mixture refuge strategy (“RIB”) for resistance management of earfeeding pests. In this study,


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occurrence, distribution, and ear damage of the corn earworm, Helicoverpa zea (Boddie), were evaluated in three planting patterns of non-Bt and Bt corn plants containing Genuity SmartStax traits. The three planting patterns were 1) pure stands of 27 Bt plants; 2) pure stands of 27 non-Bt plants; and 3) one non-Bt plant in the center surrounded by 26 Bt plants. A total of six trials were conducted in open field conditions with natural infestations in 2011 and 2012. Egg populations of H. zea were distributed randomly or uniformly, and the number of eggs laid was similar between Bt and non-Bt corn ears regardless of the planting patterns, suggesting that females of H. zea have no egg-laying preference between Bt and non-Bt plants. Bt corn plants containing Genuity SmartStax traits were equally effective in the control of H. zea in pure stands of Bt corn and “RIB” plantings. Occurrence of larvae and ear damage on Bt corn were significantly lower than on non-Bt plants and there were no significant differences between pure stands of Bt and “RIB” plantings across all trials. However, the limited numbers of live larvae in the pure stands of Bt plants were distributed non-randomly, suggesting a possibility of uneven expression of Bt proteins or elevated larval movement in the pure stands of Bt plants. Larval occurrence (3

rd - 5

th instars) and ear damage on the refuge ears in “RIB” plantings

were similar to or greater than found on ears of pure stands of non-Bt plants. However, more studies are needed to understand the effect of pollen movement on the full life cycle of H. zea before a final conclusion on the refuge function of RIB planting can be made. Keywords: maíz bt, cultivos transgénicos, Helicoverpa zea, manejo de la resistencia a insectos, refugios

En este estudio, se llevaron a cabo varios ensayos de campo para evaluar la ocurrencia y el daño en la espiga por la isoca de la espiga (Helicoverpa zea) en diferentes patrones de siembra de maíces Bt (eventos Genuity y SmartStax) y maíz convencional (no-Bt). Los objetivos del estudio fueron determinar 1) la preferencia de postura de H. zea entre plantas Bt y no Bt, 2) la eficacia de maíz Bt piramidado para el control de H. zea en la plantación mixta de Bt y no Bt de maíz y 3) si las plantas no Bt en la plantación "RIB" podrían desempeñar una función de refugio equivalente a plantaciones de refugio estructurados para H. zea. Los resultados sugieren que las hembras del insecto no tienen una preferencia de postura entre plantas de maíz Bt y no Bt. Esta característica biológica es de importancia crítica en el manejo de plagas, ya las poblaciones de plagas naturales de una especie objetivo se podrían reducir en gran medida cuando el maíz Bt es ampliamente plantado en una región, lo que resulta en menos daño a las plantas de maíz no Bt en esa región. También, los datos de este estudio demuestran que piramidando genes Bt en maíz (SmartStax y Genuity) se logra eficacia en el control de H. zea y protege de daños a la espiga.

- Enfermedades y su contol

Peptides as triggers of plant defence Markus Albert

Journal of Experimental Botany, 64 (17): 5269-5279 (2013)

Plants are confronted with several biotic stresses such as microbial pathogens and other herbivores. To defend against such attackers, plants possess an array of pattern recognition receptors (PRRs) that sense the danger and consequently initiate a defence programme that prevents further damage and spreading of the pest. Characteristic pathogenic structures, so-called microbe-associated molecular patterns (MAMPs), serve as signals that allow the plant to sense invaders. Additionally, pathogens wound or damage the plant and the resulting release of damage associated molecular patterns (DAMPs) serves as a warning signal. This review focuses on peptides that serve as triggers or amplifiers of plant defence and thus follow the definition of a MAMP or a DAMP. Keywords: inmunidad vegetal, péptidos antimicrobianos, defense vegetal

Este artículo de opinión se refiere a las moléculas que señalan e indican un peligro para una planta, por lo que sirven como desencadenantes iniciales de las respuestas de


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defensa de las plantas. Un enfoque especial se coloca en los péptidos que sirven como mediadores, amplificadores, o desencadenantes iniciales de la inmunidad planta.

Systemic Acquired Resistance (50 Years after Discovery): Moving from the Lab to the Field

Franco Gozzo and Franco Faoro J. Agric. Food Chem., 61: 12473−12491 (2013)

Induction of plant defense(s) against pathogen challenge(s) has been the object of progressively more intense research in the past two decades. Insights on mechanisms of systemic acquired resistance (SAR) and similar, alternative processes, as well as on problems encountered on moving to their practical application in open field, have been carefully pursued and, as far as possible, defined. In reviewing the number of research works published in metabolomic, genetic, biochemical, and crop protection correlated disciplines, the following outline has been adopted: 1, introduction to the processes currently considered as models of the innate immunity; 2, primary signals, such as salicylic acid (SA), jasmonic acid (JA), and abscisic acid (ABA), involved with different roles in the above-mentioned processes; 3, long-distance signals, identified from petiole exudates as mobile signaling metabolites during expressed resistance; 4, exogenous inducers, including the most significant chemicals known to stimulate the plant resistance induction and originated from both synthetic and natural sources; 5, fungicides shown to act as stimulators of SAR in addition to their biocidal action; 6, elusive mechanism of priming, reporting on the most recent working hypotheses on the pretranscriptional ways through which treated plants may express resistance upon pathogen attack and how this resistance can be transmitted to the next generation; 7, fitness costs and benefits of SAR so far reported from field application of induced resistance; 8, factors affecting efficacy of induced resistance in the open field, indicating that forces, unrevealed under controlled conditions, may be operative in the field; 9, concluding remarks address the efforts required to apply the strategy of crop resistance induction according to the rules of integrated pest management. Keywords: resistencia sistémica inducida, manejo de enfermedades, fitopatología

El método químico para inducir y activar la resistencia sistémica adquirida representa una forma sostenible para el control de enfermedades de las plantas mediante la explotación de un fenómeno natural. Como tal, se puede considerar como una estrategia alternativa, o complementaria, para el uso de fungicidas. Se ofrece como una tecnología ambientalmente segura y amigable. Sin embargo, aún no ha tenido éxito en la aplicación debido a algunos casos de fitotoxicidad, de costos biológicos asociados (rendimiento, por ejemplo) y de condiciones particulares del producto (dependencia de genotipos, condiciones climáticas, etc).

Threats and opportunities of plant pathogenic bacteria Petr Tarkowski, Danny Vereecke

Biotechnology Advances, 32: 215–229 (2014) Plant pathogenic bacteria can have devastating effects on plant productivity and yield. Nevertheless, because these often soil-dwelling bacteria have evolved to interact with eukaryotes, they generally exhibit a strong adaptivity, a versatile metabolism, and ingenious mechanisms tailored to modify the development of their hosts. Consequently, besides being a threat for agricultural practices, phytopathogens may also represent opportunities for plant production or be useful for specific biotechnological applications. Here, we illustrate this idea by reviewing the pathogenic strategies and the (potential) uses of five very different (hemi)biotrophic plant pathogenic bacteria: Agrobacterium tumefaciens, A. rhizogenes, Rhodococcus fascians, scab-inducing Streptomyces spp., and Pseudomonas syringae. Keywords: bacterias fitopatógenas, ingeniería genética, cultivo de tejidos

Para esta revisión, se seleccionaron cinco diversos (hemi) patógenos de plantas biotróficos bacterianos, y se hace una breve descripción de los síntomas que causan en las


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enfermedades y rendimiento de la planta de impacto. Al mismo tiempo, se destacan diferentes aspectos de estas bacterias y se demuestra que son o tienen el potencial para ser de utilidad para una producción más productiva, respetuosa del medio ambiente y sostenible de plantas o para otras aplicaciones biotecnológicas interesantes.

AGRICULTURA DE PRECISIÓN

YIELDSTAT – A spatial yield model for agricultural crops Wilfried Mirschel, Ralf Wieland, Karl-Otto Wenkel, Claas Nendel, Christian Guddat

Europ. J. Agronomy, 52: 33–46 (2014)

The YIELDSTAT model for crop yields, an advanced hybrid of traditional non-linear regression approaches and expert knowledge databases, was developed to predict the spatial distribution of yields for a range of arable crops (winter wheat, winter barley, winter rye, winter triticale, spring barley, oats, potato, sugar beet, winter oil-seedrape, silage maize, clover, clover/grassmix, lucerne, lucerne/grassmix, fodder grass) and two grassland types (intensive, extensive) in eastern Germany across different scales up to the regional scale. YIELDSTAT accounts for a wide range of yield-influencing factors derived from weather, soil, relief and management data, as well as for the long-term changing atmospheric CO2 concentration and for the trend owing to progress in breeding and agro-technology. YIELDSTAT regression modules were derived from several hundred farm datasets from 1975 to 1990 and tested again strecent yield observations from the Federal State of Thuringia, Germany. The model test was performed at three different spatial scales. YIELDSTAT successfully reproduced the observed data a tall three scales, with a normalised mean bias error of 3.02% across all crops and scales. Model testing also revealed a number of weaknesses in the model, identifying yield-reducing factors that had not been considered previously. All in all, the model proved fitness-for-purpose for simulating spatial yields, also under assumed future climate conditions. Keywords: modelo de simulación, predicción de rendimiento, validación de modelos, manejo de cultivos, agricultura de precisión

En el presente artículo se presenta un modelo de rendimiento regional que también explica el progreso en la mejora vegetal y agrotecnológica, algunas decisiones importantes de gestión del agro tales como la rotación de cultivos, la labranza del suelo y el riego, y otros factores que pueden afectar el nivel y la distribución espacial de los rendimientos de los cultivos, incluida la contribución detallada de los factores relacionados con el sitio o lugar específico. Además, este modelo, llamado YIELDSTAT, calcula el rendimiento para una amplia gama de cultivos agrícolas, por lo que es una herramienta adecuada para operar dentro de un software interactivo y espacial de soporte de decisiones.

AGRICULTURA Y AMBIENTE

Sustainable agriculture: possible trajectories from mutualistic symbiosis and plant neodomestication

Marie Duhamel and Philippe Vandenkoornhuyse Trends in Plant Science, 18 (11): 597-600 (2013)

Food demand will increase concomitantly with human population. Food production therefore needs to be high enough and, at the same time, minimize damage to the environment. This equation cannot be solved with current strategies. Based on recent findings, new trajectories for agriculture and plant breeding which take into account the belowground compartment and evolution of mutualistic strategy, are proposed in this opinion article. In this context, we argue that plant breeders have the opportunity to make use of native arbuscular mycorrhizal (AM) symbiosis in an innovative ecologically intensive agriculture.


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Keywords: agricultura sustentable, agricultura intensive, agricultura extensiva

En este documento se desarrollan nuevas ideas y se sugieren mecanismos para un desarrollo agrícola más sostenible en base a los hallazgos recientes sobre las estrategias en el mutualismo y la selección de plantas, desarrollamos nuevas ideas en este documento y sugerir trayectorias. Se discuten y comparan las ventajas y limitaciones de una agricultura intensiva y extensiva, el rol de las micorrizas en la producción agropecuaria, las estrategias mutualísticas en la agricultura. Una agricultura más sostenible y una neodomestication de plantas tiene que surgir para garantizar el suministro de alimentos en los próximos 50 años. Una forma de lograr una agricultura más ecológica intensiva sería considerar y proteger a las funciones ecológicas mostradas por los hongos micorríticos, que han sido efectivos para los más de 400 millones de años, sea cual sea el ecosistema. Esto no sólo mejorará la nutrición mineral de plantas naturales, sino también el suministro de agua y otras funciones ecológicas que ya han sido claramente documentadas. Los esfuerzos de investigación deben también estimular y acompañar esta posible neodomestication de las plantas.

Integrated ecotoxicological assessment of bottom sediments from the Paraná basin, Argentina

Leticia Peluso, Mariana Abelando, Carina D. Apartín, Pablo Almada, Alicia E. Ronco Ecotoxicology and Environmental Safety, 98: 179–186 (2013)

Paraná River, the six largest in the world, is receptor of pollution loads from tributaries traversing urban and industrializad areas, and extensive agriculture, particularly in its middle and low stretch along the Argentinean sector, where most of the productive activities of the country develop. Within the frame of monitoring surveys, the quality of bottom sediments from distal positions of twenty tributaries and three of the main course was evaluated. The assessment covered testing lethal and sublethal effects with the Hyalella curvispina based toxicity test, a benthic macrofauna survey and physicochemical variables of sediment matrix composition. A multivariate statistical analysis approach permitted integratingt he obtained data from the different survey lines of evidence, explaining potential causes of the measured biological effects. The main perturbations detected were associated to tributaries in the middle sector of the basin, where anoxic conditions with high sulfide contents prevail mostly related to organic matter inputs of diverse combined activities, where sediments induce high lethality, and a consequent strong reduction of the benthic community population and diversity. The integrated survey approach proved being a robust tool in the assessment of causative—adverse effects relationships. Keywords: sedimentos, río Paraná, toxicidad, contaminación

El objetivo del presente estudio fue analizar y discutir los resultados de la evaluación de la calidad de los sedimentos del fondo de las posiciones distantes de los principales afluentes y el curso principal del río Paraná (Argentina), poniendo a prueba los efectos letales y subletales con un ensayo de toxicidad anfípodo basado en la correlación con las variables fisicoquímicas medidas por medio de análisis multivariado, y finalmente la integración de la información con la proyección de la comunidad bentónica. Los resultados indican que las principales perturbaciones detectadas se originan a partir de las áreas urbanizadas e industrializadas asociadas a afluentes en el sector medio de la cuenca. Otros pasos de la investigación futura en la cuenca deberán incluir la influencia de grandes áreas bajo uso agrícola intensivo y extensivo, la introducción de otros factores de estrés, como los plaguicidas asociados a la lucha química contra las plagas, estrategias utilizadas en la producción agrícola de la región.


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In-farm diversity stabilizes return on capital in Argentine agro-ecosystems

Fernando Pacín, Martín Oesterheld Agricultural Systems, 124: 51–59 (2014)

Agricultural production faces risks of various kinds caused by weather, pests, markets, and policy changes. Minimizing these risks is an ongoing objective of farmers. The diversification of activities and the selection of the most stable activities are frequently mentioned as potential stabilizing factors. The aim of this study is to determine the impact of diversification and selection of activities on economic stability over time in a set of farms located in the southwest of the Pampa Region, Argentina. We use the coefficient of variation of return on capital as indicator of economic stability. These farms routinely evaluate their economic performance through a shared methodology. We compiled a data set that included 366 annual productive and economic results for 82 farms in 7 years between 2000 and 2008. We analyzed the economic and yield results of these farms and of a set of simulated farms that differentially combined various activities. We found that a greater diversification of activities was associated with an increase of stability, measured by a reduction of the coefficient of variation of return on capital as diversification increased. This effect resulted from a significant increase of mean return on capital without changing the standard deviation as diversification increased. We also found significant differences in this indicator of economic stability of individual activities as a result of different combinations of variability in yields, prices and costs. Birth to slaughter livestock operation was much more economically stable than either cow-calf or fattening operations. Wheat was the most stable crop, corn was the least stable crop, and sunflower and soybean showed intermediate stability. Overall, livestock activities were more stable than agricultural crops. Simulated farms showed that more diversified combinations were economically more stable. The stability of the average real farm was very similar to the most stable farm simulation. This suggests that farmers in the study area have found in the diversification and selection of activities useful tools to reduce the economic risks they face.

Keywords: riesgo, pastoreo, ganadería, singergia, agroecosistemas

El objetivo de este estudio fue determinar el impacto de la diversificación y la selección de actividades en materia de estabilidad económica con el tiempo en un conjunto de empresas agropecuarias ubicadas en el sudoeste de la región de la Pampa, en Argentina. Los resultados ofrecen pruebas de la existencia de dos herramientas diferentes, de gran alcance y no exclusivas, para reducir la variabilidad de los ingresos agrícolas en la región estudiada: la producción y la diversificación de las actividades de ganadería. Ambos parecen ser frecuentes entre las presentes agricultores. La combinación de las actividades que se asemejaba a la granja real promedio tuvo una rentabilidad sobre el capital y la estabilidad similar a la mejor de las combinaciones hipotéticas propuestas. El modelo de producción seguido por estos agricultores parece surgir de un compromiso entre el rendimiento del capital, la estabilidad, y los requisitos de capital de trabajo. Esto se puede interpretar como el resultado de una exitosa adaptación a un entorno inestable, en la que las explotaciones han descubierto un mecanismo de supervivencia en la producción ganadera y la implantación de un sistema de cultivo complejo con varios cultivos en rotación con pasturas. Este proceso es la antítesis de lo que ha sucedido en las últimas décadas en las zonas del país con condiciones ambientales más favorables para los cultivos, donde la producción de ganado ha desaparecido y el cultivo de soja ocupa más del 70% de la superficie total.

Land-use land-cover change and ecosystem loss in the Espinal ecoregion, Argentina

Bárbara Guida Johnson, Gustavo A. Zuleta Agriculture, Ecosystems and Environment, 181: 31– 40 (2013)

Land-use land-cover (LULC) changes are one of the major threats to biodiversity worldwide, since their principal consequences are the loss, fragmentation or degradation of the habitat available for most species. Therefore, in order


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to provide guidelines for environmental management at the regional scale and thus reverse the trend in degradation, transformations of natural remnants into anthropogenic land uses must be identified and quantified. This study examines LULC transitions from 1987 to 2001 and from 2001 to 2009 in two adjacent water sheds located in the Espinal, one of the least protected ecoregions of Argentina. We detected a 20% loss in ecosystems for the period analyzed and, in particular, 60% of native forests were lost. Changes were mainly driven by the expansion of croplands, which directly transformed wetlands and also acted as an underlying cause of the displacement of ranching activities, which in turn replaced Espinal forests. We developed a conceptual model of observed LULC changes for the study area, which we then complemented by proposing an alternative scenario that reconciles agriculture and biodiversity conservation. These results have implications for provincial land use planning and could contribute to the participatory processes demanded by the recent national legislation sanctioned for the protection of native forests Keywords: uso de la tierra, deforestaciónm, agroecosistemas, El Espinal

El presente artículo estudia el cambio en el uso de la tierra y la transición desde 1987 a 2009 en la ecorregión de Argentina conocida como El Espinal, en las provincias de Entre Ríos y Corrientes. Se estima que el 20% de los remanentes de hábitats naturales presentes en el inicio del período de estudio fueron reemplazados. En cuanto a la pérdida de bosques del Espinal, se encontró que ellos fueron reemplazados por pastizales, que se utilizan principalmente para pastoreo del ganado en esta región. Se presume que las tierras de cultivo están degradadas. También se encontró evidencia de los humedales que se convirtieron en tierras de cultivo, hasta cierto punto. Durante el período de estudio 2001-2009, la sustitución de bosques del Espinal fue menos intensa y otra fuerza está en la dinámica, como las tierras de cultivo también fueron transformadas en plantaciones forestales. Estos resultados conducen a definir políticas que promuevan la conservación de los bosques y la restauración de la flora en regiones sensibles ambientalmente.

AGRO-BIOTECNOLOGÍA

Multigene engineering of starch biosynthesis in maize endosperm increases the total starch content and the proportion of amylose Lili Jiang, Xiaoming Yu, Xin Qi, Qian Yu, Sen Deng, Bing Bai, Ning Li, Ai Zhang, Changfu Zhu,

Bao Liu, Jinsong Pang Transgenic Res, 22: 1133–1142 (2013)

Maize (Zea mays spp. mays) is a staple crop for more than 900 million people. The seeds or kernels provide a rich

source of calories because 70 % of the weight is carbohydrate, mostly in the form of starch. The content and composition of starch are complex traits controlled by many genes, offering multiple potential targets for intervention. We used a multigene engineering approach combining the overexpression of Bt2, Sh2, Sh1 and GbssIIa (to enhance the activity of sucrose synthase, AGPase and granulebound starch synthase) with the suppression of SbeI and SbeIIb by RNA interference (to reduce the activity of starch branching enzyme). Maize plants expressing all six genes plus the selectable marker showed a 2.8–7.7 % increase in the endosperm starch content and a 37.8–43.7 % increase in the proportion of amylose, which was significant compared to untransformed control plants. We also observed improvements in other agronomic traits, such as a 20.1–34.7 % increase in 100-grain weight, a 13.9–19.0 % increase in ear weight, and larger kernels with a better appearance, presumably reflecting the modified starch structure within the kernels. Our results confirm that multigene engineering applied to the starch biosynthesis pathway can not only modulate the quality and quantity of starch but can also improve starch dependent agronomic traits. Keywords: maíz, almidón, amilosa, ingeniería genética, maíz transgénico, transformación multigénica

En el presente artículo se describe el desarrollo de un maíz transgénico al que se aumentó el contenido de almidón en el endosperma y también la proporción de amilasa en el


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almidón. Esto se logró mediante la introducción de varios genes y el silenciamiento de otros.

Genetically modified (GM) crops: European and transatlantic divisions Jim M. Dunwell

Molecular Plant Pathology, 15(2): 119–121 (2014)

‘It seems doubtful to me whether this idea (i.e. transformation) is ever going to be practicable’. These words were included in a report prepared by Ralph Riley (Director of the Plant Breeding Institute in Cambridge) following a Rockefeller Foundation conference that took place in the Villa Sebelloni, Bellagio, Italy, in May 1969. The conference was entitled, ‘Crop Improvement through Techniques of Plant Cell and Tissue Culture’, and its declared aim was ‘to evaluate the present status of cell and tissue culture methods in plants, and to consider what prospects these procedures offer for crop improvement’. Of the 14 international participants, Lou Nickell from the USA was apparently the only one who, at that time, was conducting serious experiments to investigate the possibility of gene transfer to higher plants. However, the philosophy and pace of research changed dramatically during the subsequent decade and, by January 1983, four groups were able to announce at the Miami Winter Symposium that they had successfully used molecular techniques to transfer a gene into a plant. Thirty years later, it is instructive to look back at the application of such technology and, in particular, to assess the present and future commercial status of genetically modified (GM) crops. This brief review pays special attention to the dichotomy of experiences, attitudes and opportunities represented on the two sides of the Atlantic. Keywords: OGMs, agrobiotecnología

Este breve resumen ha explorado algunas de las áreas de la inconsistencia y la variación en los enfoques públicos, políticos y comerciales a las tecnologías de modificación genética dentro y entre los EE.UU. y Europa. Se ha demostrado que 30 años de experiencia no ha simplificado o aliviado estas divisiones internacionales. Debido al estancamiento de la Unión Europea en el sistema de aprobación, generada en parte por conveniencia política, las decisiones comerciales se han hecho por las grandes empresas y las inversiones se han hecho en el mundo en desarrollo, donde la demanda futura es más segura.

Genomic Misconception: a fresh look at the biosafety of transgenic and conventional crops. A plea for a process agnostic regulation

Klaus Ammann New Biotechnology, 31 (1): 1-17 (2014)

The regulation of genetically engineered crops, in Europe and within the legislation of the Cartagena biosafety protocol is built on false premises: The claim was (and unfortunately still is) that there is a basic difference between conventional and transgenic crops, this despite the fact that this has been rejected on scientifically solid grounds since many years. This contribution collects some major arguments for a fresh look at regulation of transgenic crops, they are in their molecular processes of creation not basically different from conventional crops, which are based in their breeding methods on natural, sometimes enhanced mutation. But the fascination and euphoria of the discoveries in molecular biology and the new perspectives in plant breeding in the sixties and seventies led to the wrong focus on transgenic plants alone. In a collective framing process the initial biosafety debates focused on the novelty of the process of transgenesis. When early debates on the risk assessment merged into legislative decisions, this wrong focus on transgenesis alone seemed uncontested. The process-focused view was also fostered by a conglomerate of concerned scientists and biotechnology companies, both with a vested interest to at least tolerate the rise of the safety threshold to secure research money and to discourage competitors of all kinds. Policy minded people and opponent activists without deeper insight in the molecular science agreed to those efforts without much resistance. It is interesting to realize, that the focus on processes was uncontested by a majority of regulators, this despite of serious early warnings from important authorities in science, mainly of US origin. It is time to change the regulation of genetically modified (GM) crops toward a more science based process — agnostic legislation. Although this article concentrates on the critique of the process-oriented regulation, including some details about the history behind, there should be no misunderstanding that there are other important factors responsible for the failure of this kind of


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process-oriented regulation, most importantly: the predominance of politics in the decision making processes combined with the lack of serious scientific debates on regulatory matters within the European Union and also in the Cartagena system, the obscure and much too complex decision making structures within the EU, and the active, professional, negative and intimidating role of fundamental opposition against GM crops on all levels dealing with flawed science, often declared as better parallel science published by ‘independent’ scientists. Keywords: OGMs, aspectos regulatorios

En este extensor artículo de revisión, Klaus Ammann (un pionero académico suizo de la biotecnología de plantas) analiza y compara la bioseguridad genómica de los cultivos convencionales y transgénicos, evaluando críticamente los errores de conceptos que existen como credos en los sistemas regulatorios. Más allá de situaciones ideológicas y políticas, el sistema académico debe plantear los riesgos del uso de transgénicos basándose en antecedentes científicos.

Engineering nucleases for gene targeting: safety and regulatory considerations

Katia Pauwels, Nancy Podevin, Didier Breyer, Dana Carroll and Philippe Herman New Biotechnology, 31 (1): 18-27 (2014)

Nuclease-based gene targeting (NBGT) represents a significant breakthrough in targeted genome editing since it is applicable from single-celled protozoa to human, including several species of economic importance. Along with the fast progress in NBGT and the increasing availability of customized nucleases, more data are available about off-target effects associated with the use of this approach. We discuss how NBGT may offer a new perspective for genetic modification, we address some aspects crucial for a safety improvement of the corresponding techniques and we also briefly relate the use of NBGT applications and products to the regulatory oversight. Keywords: nuevas tecnologías de mejoramiento (NBTs), nucleasas, agrobiotecnología

Entre las nuevas tecnologías de mejoramientos (conocidas como NBT, New Breeding Technologies por sus siglas en inglés) se encuentran las nucleasas. Tres tipos de nucleasas son actualmente las más utilizadas: las nucleasas de dedos de zinc (ZFNs), Transcripción Activador-Like Efector nucleasas (Talens) y meganucleasas. Por otra parte, un nuevo sistema, llamado CRISPR (por repeticiones palindrómicas cortas intercaladas regularmente agrupadas) / Cas, fue recientemente desarrollado como un método adicional. Estas herramientas constituyen, en ciertos casos del mejoramiento, una alternativa a la transgénesis, menos agresiva desde el punto de vista que no conduce a inserción de nuevos genes, sino a reparación o generación de mutaciones específicas en ciertos genes ya presentes en el genoma de los cultivos.

Transgenic Soybeans and Soybean Protein Analysis: An Overview Savithiry Natarajan, Devanand Luthria, Hanhong Bae, Dilip Lakshman, and Amitava Mitra

J. Agric. Food Chem., 61: 11736−11743 (2013)

To meet the increasing global demand for soybeans for food and feed consumption, new high-yield varieties with improved quality traits are needed. To ensure the safety of the crop, it is important to determine the variation in seed proteins along with unintended changes that may occur in the crop as a result various stress stimuli, breeding, and genetic modification. Understanding the variation of seed proteins in the wild and cultivated soybean cultivars is useful for determining unintended protein expression in new varieties of soybeans. Proteomic technology is useful to analyze protein variation due to various stimuli. This short review discusses transgenic soybeans, different soybean proteins, and the approaches used for protein analysis. The characterization of soybean protein will be useful for researchers, nutrition professionals, and regulatory agencies dealing with soy-derived food products.


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KEYWORDS: soja, proteínas, transgénesis

Esta revisión ofrece una visión general de los beneficios de la soja transgénica y el análisis de las diferentes proteínas de soja utilizando una metodología específica (2D-PAGE y MS). La identificación, caracterización y posterior cuantificación de las distintas clases de proteínas de soja son de utilidad para investigadores, profesionales de la nutrición y las agencias reguladoras para investigar los cambios en los perfiles de proteínas y su impacto en la salud. En el artículo se analizan perfiles proteicos de las semillas de varios eventos de soja transgénica y se discuten los beneficios de los mismos cuando esos eventos fueron pensados para lograr una mejora nutricional del grano.

BIOENERGIA

Environmental sustainability of advanced biofuels Sarah C. Davis, Christopher J. Kucharik, Simone Fazio and Andrea Monti

Biofuels, Bioprod. Bioref., 7: 638–646 (2013) Economic and policy incentives for biofuel development differ in the USA and the EU, but indicators of environmental sustainability that have emerged from recent scientific literature transcend political boundaries. We classified these indicators according to six dimensions of environmental sustainability that have been previously identified, providing a description of each, and relating them to proposed international standards for advanced biofuels. Advanced biofuel development can be a step toward environmentally sustainable energy if optimal standards for feedstock selection, management, production, and fuel conversion are explicitly targeted. Tools for assessing environmental sustainability exist, but have not yet been put to task in a standardized way for advanced biofuels. Keywords: biocombustibles de segunda generación, bioenergía, ecología, bioetanol, biomasa

En este artículo se revisa la base para definiciones de sostenibilidad ambiental y se describen los indicadores de sostenibilidad ambiental que se aplican a los sistemas de producción de bioenergía avanzados. El grado en que los indicadores de la bioenergía sostenible con el medio ambiente han sido reconocidos y evaluados a nivel internacional, y también se describen con ejemplos de herramientas que pueden utilizarse para la evaluación.

Dedicated crops for advanced biofuels: Consistent and diverging agronomic points of view between the USA and the EU-27

Walter Zegada-Lizarazu, David Parrish, Marisol Berti, Andrea Monti Biofuels, Bioproducts and Biorefining, 7: 715–731 (2013)

A concise and up-to-date review has been undertaken to summarize consistent or diverging agronomic points of view on dedicated energy crops for advanced biofuels in the USA and the EU-27. The main purpose of this review is to discuss those crops where many agronomic constraints have been resolved, bringing them closer to large-scale production and commercialization. Where possible, examples of crop management practices that would enhance sustainability and energy yields are provided. The most promising crops and agronomic strategies for their production in the EU-27 and the USA are discussed. We also provide discussion of what the theoretically ideal characteristics of advanced biofuel crops might be. On both continents, understanding of management practices for switchgrass (Panicum virgatum L.) and miscanthus (Miscanthus x giganteus) as energy crops appears to be at an advanced stage. Two other widely considered energy crop candidates – sorghum (Sorghum bicolor (L.) Moench) and reed canary grass (Phalaris arundinacea L.) – have production and management guidelines that were developed for forage uses, but can be easily applied to biomass feedstock production. Giant reed (Arundo donax L.) has been developed as a bioenergy crop mainly in Europe. In the USA, giant reed is considered a noxious weed in many states, and its planting is


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prohibited. Establishing crop management practices that will be successful at a large scale and for the long term will help attract growers and investors to produce advanced biofuels, i.e. second-generation biofuels, which can help reduce our dependence on fossil energy sources. Keywords: Miscanthus, Panicum virgatum, sorgo, cultivos energéticos, biocombustibles, bioenergía

En este artículo se discuten los aspectos agronómicos (consistencias y divergencias) de los principales (denominados) cultivos energéticos de Estados Unidos y Europa, analizando la potencialidad de los mismos para generar una energía (de manera sustentable) en sendas regiones.

A methodological proposal for Life Cycle Inventory of fertilization in

energy crops: The case of Argentinean soybean and Spanish rapeseed Francisca Fernández-Tirado, Carlos Parra-López, Javier Calatrava-Requena

Biomass and Bioenergy, 58: 104-116 (2013) Fertilization is one of the agronomic practices that generates the highest environmental burdens in energy crops. However, this practice is essential, since its omission could entail long term processes of soil degradation, endangering the environmental sustainability of agricultural systems. In most of the Life Cycle Assessment (LCA) of energy crops found in the scientific literature, the inputs and outputs of nutrients are not calculated and the environmental impacts of nutrient loss are ignored as well. In this paper, a methodological approach to calculate the balance of nutrients that occurs during annual crop production in the context of the Life Cycle Inventory phase of LCA is proposed and applied to two study cases of energy crops: rapeseed (Brassica napus) in Cádiz, Spain, and soybean (Glycine max) in Buenos Aires, Argentina. The results show that when rational fertilization is carried out, rapeseed fertilization in Spain generates more severe environmental impacts than soybean in the Argentinean Pampas when 1 ha of crop per year is used as the functional unit. Keywords: inventario del ciclo de vida, fertilización, balance nutricional, soja, colza

El objetivo de esta investigación fue proponer un enfoque metodológico en el análisis del inventario del ciclo de vida para determinar las entradas y salidas de nutrientes que se producen en los cultivos energéticos y evaluar los impactos ambientales causados por la fertilización racional, es decir, el mantenimiento de la fertilidad de los suelos. Por lo tanto, se propuso el equilibrio de nutrientes como indicador de la fertilidad del suelo y se presenta una nueva metodología para la evaluación de la fertilidad del suelo en la evaluación del ciclo de vida agrícola basada en este indicador. La metodología desarrollada se aplicó para evaluar los dos cultivos energéticos: colza en las inmediaciones de Jerez en la provincia de Cádiz (España) y la soja en el departamento de Pergamino, provincia de Buenos Aires (Argentina). Los resultados muestran que cuando se hace una fertilización racional en la colza de España, ésta genera impactos ambientales más graves que los de la soja en la Pampa argentina.

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PROSPECTIVA TECNOLÓGICA AAPRESID · Prospectiva Tecnológica AAPRESID – Abril 2014 4 case of Argentinean soybean and Spanish rapeseed El presente trabajo corresponde a una búsqueda