Variation and impact of drought-stress patterns across upland rice target population of environments in Brazil.

The upland rice (UR) cropped area in Brazil has decreased in the last decade. Importantly, a portion of this decrease can be attributed to the current UR breeding programme strategy, according to which direct grain yield selection is targeted primarily to the most favourable areas. New strategies for more-efficient crop breeding under non-optimal conditions are needed for Brazil's UR regions. Such strategies should include a classification of spatio-temporal yield variations in environmental groups, as well as a determination of prevalent drought types and their characteristics (duration, intensity, phenological timing, and physiological effects) within those environmental groups. This study used a process-based crop model to support the Brazilian UR breeding programme in their efforts to adopt a new strategy that accounts for the varying range of environments where UR is currently cultivated. Crop simulations based on a commonly grown cultivar (BRS Primavera) and statistical analyses of simulated yield suggested that the target population of environments can be divided into three groups of environments: a highly favorable environment (HFE, 19% of area), a favorable environment (FE, 44%), and least favourable environment (LFE, 37%). Stress-free conditions dominated the HFE group (69% likelihood) and reproductive stress dominated the LFE group (68% likelihood), whereas reproductive and terminal drought stress were found to be almost equally likely to occur in the FE group. For the best and worst environments, we propose specific adaptation focused on the representative stress, while for the FE, wide adaptation to drought is suggested. 'Weighted selection' is also a possible strategy for the FE and LFE environment groups.

Sustainable intensification for a larger global rice bowl.

Future rice systems must produce more grain while minimizing the negative environmental impacts. A key question is how to orient agricultural research & development (R&D) programs at national to global scales to maximize the return on investment. Here we assess yield gap and resource-use efficiency (including water, pesticides, nitrogen, labor, energy, and associated global warming potential) across 32 rice cropping systems covering half of global rice harvested area. We show that achieving high yields and high resource-use efficiencies are not conflicting goals. Most cropping systems have room for increasing yield, resource-use efficiency, or both. In aggregate, current total rice production could be increased by 32%, and excess nitrogen almost eliminated, by focusing on a relatively small number of cropping systems with either large yield gaps or poor resource-use efficiencies. This study provides essential strategic insight on yield gap and resource-use efficiency for prioritizing national and global agricultural R&D investments to ensure adequate rice supply while minimizing negative environmental impact in coming decades.

Asian soybean rust: modeling the impact on soybean grain yield in the Triângulo Mineiro/Alto Paranaíba region, Minas Gerais, Brazil / Ferrugem asiática da soja: modelagem do impacto na produtividade da soja na região do Triângulo Mineiro/Alto Paranaíba, Minas Gerais, Brasil

Understanding the impact of Asian soybean rust on soybean yield is of great importance in the crop simulation model for this crop become it is possible to predict yield using different sowing dates and growth conditions. The goal of this study were to evaluate the performance of two soybean cultivars in Triângulo Mineiro/Alto Paranaíba, MG, Brazil and the effects of soybean rust on the yield of these cultivars using the CSM-CROPGRO Soybean model. Two soybean cultivars "NK 7074" (early) and "UFUS-Impacta" (medium late), which differ in their development cycles, were growing in Uberaba city during the 2009/2010 growing season. The validation for cultivar "UFUS-Impacta" was conducted comparing the measured and simulated yield data considering three different sowing dates in the "Uberlândia" city during the 2002/2003 growing season. Daily meteorological data obtained from six meteorological stations of the National Institute of Meteorology (INMET). To determine the performance of the soybean cultivars and the effect of soybean rust on yield, three different scenarios were used: no occurrence of rust (NOR) and occurrence of rust with inoculum concentrations of U5.000 and U10.000 urediniospores/mL. For all environments studied, the early cultivar had the best performance than the medium late cultivar. Soybean rust had the most effect on yield for the U10.000 scenario than for the U5.000 scenario. The best soybean performance occurred for "Araxá" and "Uberaba" cities. The SouthSoutheast area of the "Triângulo Mineiro/Alto Paranaíba" region was the most sensitive to the effect of rust on yield compared to the North region.

Compreender o impacto da ferrugem asiática na produtividade da soja é de grande importância para os modelos de simulação dessa cultura, pois pode-se prever a produtividade utilizando-se diferentes datas de semeadura e condições de crescimento. O objetivo deste estudo foi analisar a performance de duas cultivares de soja na região do Triângulo Mineiro/Alto Paranaíba, MG, Brasil e os efeitos da ferrugem asiática da soja na produtividade desses cultivares utilizando o modelo CSM-CROPGRO Soybean. Duas cultivares de soja NK 7074 (precoce) e UFUS-Impacta (semitardia), as quais diferem nos seus ciclos de desenvolvimento, foram cultivadas em Uberaba na safra 2009/2010. A validação para a cultivar UFUS-Impacta foi conduzida comparando os dados observados e simulados de produtividade considerando três diferentes datas de semeadura na safra 2002/2003 em Uberlândia, MG. Foram utilizados dados meteorológicos diários de seis estações meteorológicas do Instituto Nacional de Meteorologia (INMET). Para determinar o desempenho das cultivares de soja e o efeito da ferrugem na produtividade, utilizou-se três diferentes cenários denominados de: não ocorrência de ferrugem (NOR) e ocorrência de ferrugem nas concentrações de inóculo de U5.000 e U10.000 urediniósporos/mL. Para todos os ambientes estudados, a cultivar precoce teve o melhor desempenho em relação a cultivar semi-tardia. A ferrugem da soja teve maior impacto na produção para o cenário U10.000 do que para o cenário U5.000. O melhor desempenho das cultivares de soja foram para as cidades de Araxá e Uberaba. A área Sul-Sudeste do Triângulo Mineiro/Alto Paranaíba foi a mais sensível ao efeito da ferrugem na produtividade em comparação com a região norte.

Caracterização dos padrões de estresse hídrico para a cultura do arroz (ciclo curto e médio) no estado de Goiás e suas conseqüências para o melhoramento genético / Characterization of water stress patterns for rice (short and medium cycle) in Goiás State and their consequences for the plant breeding program

O estresse por deficiência hídrica é considerado como a maior restrição na produção e estabilidade da produtividade de culturas em muitas regiões do mundo. No Estado de Goiás predomina a produção de arroz de terras altas em sequeiro, sendo comum essa cultura sofrer períodos de deficiência hídrica ao longo do ciclo, que podem reduzir a produtividade. No processo de desenvolvimento de novas variedades, genótipos são selecionados em função de sua adaptabilidade em um determinado ambiente alvo. Assim, programas de melhoramento vegetal requerem informações sob a probabilidade de ocorrência e intensidade dos padrões de deficiência hídrica, associada as diferentes fases de desenvolvimento da cultura. Um modelo de simulação de culturas foi utilizado para determinar os padrões de deficiência hídrica no Estado de Goiás, considerando 12 locais e seis diferentes datas de semeadura para o arroz de ciclo curto e médio. Para ambos, as variedades estudadas, arroz ciclo curto e médio, quando semeados nas épocas favoráveis e sem impedimento ao desenvolvimento do sistema radicular, o estresse por deficiência hídrica não é uma restrição ao desenvolvimento da cultura no Estado de Goiás.

Drought stress is a major constraint to crop production and yield stability in many regions of the world. In the state of Goiás, most of the rice crop system is rainfed. In a plant breeding program, new genotypes are selected as a result of their adaptability for a determined environment. Therefore, a plant breeding program needs information about drought frequency as well as its characteristics, intensity, and time during crop development. A crop simulation model was used to determine patterns of drought stress for 12 locations and six different planting dates for short and medium cycle rice. For upland rice, short and medium cycle, in favourable conditions (no soil impediment), drought stress is not a main constraint for the rice development in the state of Goiás.