CONTEXT

Brazil is one of the main producers of common beans (Phaseolus vulgaris L.), which have high nutritional value as human food. The climate changes predicted in the 21st century might be a possible threat to the planet’s food security, given the expected population increase, and hence, increased demand for food.

OBJECTIVE

This study aimed to project the impact of climate change on common bean cropping systems using an upscaling climate approach and crop modeling to represent the Brazilian production regions.

METHODS

We considered the representative CO₂ concentration pathway scenarios (RCPs) 4.5 and 8.5 presented by the 5th IPCC Assessment Report from 20 atmospheric global circulation models covering the main bean-producing region in Brazil. The well-calibrated CROPGRO-Drybean crop model simulated two representative cultivars of the “black” and “colors” types and three cropping seasons applied by Brazilian farmers.

RESULTS AND CONCLUSIONS

On average, we found that yield increased by 5.56% and 9.12% for the RCP 4.5 and 8.5 scenarios, respectively. Increased photosynthetic efficiency due to the increased atmospheric CO₂ concentration was identified as the main cause of this yield increase. Crop respiration rates increased due to the raised air temperature, and were responsible for increasing the probability (production risk) of not meeting the future domestic demands for grains to 10.13% and 8.34% for the RCP 4.5 and 8.5 scenarios, respectively. For the national supply of grains, estimates pointed to a future in which crop production will probably rely more on area expansion than yield gains by crop intensification.

SIGNIFICANCE

Our findings emphasize the need for new policies for land utilization and investments in scientific research programs aimed towards genetic adaptation in all main Brazilian crops in the face of potential climate change.

中文翻译：

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气候变化情景下巴西普通豆供应的影响评估

语境

巴西是普通豆（Phaseolus vulgaris L.）的主要生产国之一，这些豆作为人类食品具有很高的营养价值。鉴于预期的人口增加，因此对食物的需求增加，在21世纪预测的气候变化可能对地球的粮食安全构成威胁。

客观的

这项研究的目的是通过使用递增的气候方法和作物模型来代表巴西的生产区域，来预测气候变化对普通豆类作物种植系统的影响。

方法

我们考虑了由IPCC第五次评估报告提出的具有代表性的CO ₂浓度途径情景4.5和8.5，该情景来自覆盖巴西主要豆类产区的20个大气全球环流模型。经过良好校准的CROPGRO-Drybean作物模型模拟了两个具有代表性的“黑色”和“颜色”类型的栽培品种，以及巴西农民采用的三个种植季节。

结果与结论

平均而言，我们发现RCP 4.5和8.5方案的产量分别提高了5.56％和9.12％。大气CO ₂浓度增加引起的光合作用效率提高被认为是产量增加的主要原因。由于气温升高，农作物呼吸速率增加，导致RCP 4.5和8.5情景中无法满足未来国内谷物需求的可能性（生产风险）分别增加到10.13％和8.34％。对于国家的谷物供应，估计指出了未来的作物产量将更多地依赖于面积扩大而不是集约化的增产。

意义

我们的研究结果强调，面对潜在的气候变化，有必要制定新的土地利用政策和对科学研究计划进行投资，以期对巴西所有主要农作物进行遗传适应。