Climate change determined drought stress profiles in rainfed common bean production systems in Brazil

- We investigate future breeding directions for rainfed common bean in Goiás state for the 2030 s (2020-2045);.
- Four drought stress profiles exist: drought free, reproductive, terminal, and joint reproductive-terminal stress.
- Climate change is projected to substantially increase probability occurrence of reproductive and/or terminal drought.
- Research on which traits (e.g. early maturity and deep rooting) are needed for drought adaptation is warranted.

Reductions in agricultural productivity with consequences for food security associated to climate change are expected in the absence of adaptation. For common beans, across South America, a decrease in climatic suitability has been projected, with heat and drought stresses being the key drivers for such suitability reductions. Breeding programs will play an important role in the adaptation of common beans to the changing climates. However, breeding targets may vary as climate changes during the 21st century. Here, we assess historical and future (2030) probabilities of occurrence, intensity and impact of seasonal variations of drought stress, which is the most important stress for common beans in the Goiás state. We focus on two rainfed (wet and dry) target population environments (TPEs), which encompass ca. 62% of the bean cropped area in the state for 2016, and address potential breeding implications of future projected changes. The analysis revealed two environment groups for both TPEs (highly favorable environment and favorable environment), and four drought stress profiles within these environmental groups (drought stress free, reproductive stress, terminal stress, and joint reproductive-terminal stress) across all climate and management (cultivars and sowing dates) scenarios. Results suggest that, with respect to the historical (1980-2005) period, climate change will make drought more frequent, but less severe, across the region. For the dry TPE, the probability of occurrence of drought stress situations (reproductive and/or terminal) changes from 29.6% (baseline) to ca. 70% (2030, RCP [Representative Concentrations Pathway] 8.5), whereas for the wet TPE, it increases from 16% (baseline) to ca. 43% (2030, RCP 8.5). Results are consistent across RCPs, although benefits from stringent (RCP 2.6) mitigation are evident. We conclude that drought tailoring under climate change is needed for the Embrapa dry bean breeding program.