RCUK-CIAT Newton Fund: Physiological characterization of heat-tolerant bean genotypes in simulated future environments

3.4 million Colombians are employed in primary agricultural production in rural areas on typical wages of less than four dollars per day. Common beans are a major source of protein and mineral nutrition in the diets of the rural poor, but climate vulnerabilities and the post-conflict transition from illicit to food crops mean that rapid introduction of climate-resilient bean varieties to new areas and growers are required.

This study will focus on heat tolerance, as rising temperatures have been predicted to impact very significantly on the areas of Colombia suitable for bean cultivation. A small number of highly heat tolerant bean genotypes have been identified in previous breeding work, and it is proposed to breed the heat tolerance trait from these primary sources into varieties with all the other characteristics needed for widespread acceptance and uptake. At present, the principal means to combine heat tolerance with other traits is via selection of breeding lines in field sites where stressful heat thresholds are normally reached. This process takes years and heat tolerance can be masked by other environmental factors simultaneously at play in the selection environment. The research proposed here involves detailed assessments of the growth and development of existing heat tolerant and susceptible beans under controlled conditions simulating future climates in target regions of Colombia including elevated carbon dioxide levels. By pinpointing in detail the vulnerabilities of susceptible lines and demonstrating mechanisms of tolerance that avoid yield losses, it will be possible in the future to breed for heat tolerance using better targeted selection criteria that will result in shorter breeding cycles and more rapid delivery of climate-smart bean varieties.

As the technologies for breeding new heat-tolerant varieties is developed, the study will also examine the potential economic impact of adoption of beans as a crop in new areas and by new growers, using socio-economic data on current and projected land use, food supply and price in a number of scenarios. It will further appraise the potential economic value of heat-tolerant bean varieties and the rate of return on the underpinning research under a range of adoption scenarios.

The alignment of climate and crop science aimed at more effective breeding for future climates with a socio-economic study of the conditions under which climate-resilient bean varieties can reap significant societal return on investment affords opportunities for the research agenda to be refined to maximise its real-world impact.

The main intended impact of this project is to improve economic welfare and food security of Colombian bean growers in a changing climate, particularly ex-combattants and displaced populations. In order to make such an impact, technologies which have the potential to speed up bean breeding need to be adopted by the breeding community, and varieties which embody the most climate-resilient and marketable qualities must be adopted by traditional and new bean growers alike.

Therefore the impact-oriented activities in this proposal relate to initiating those critical technology transfer and adoption steps.

We expect the "simulated climate change" controlled environment experiments (at Reading) to provide a wealth of metabolomics and physiological data, which will be curated at searchable, publicly accessible database at the University of Reading. These data will be made available within 6 months of the end of the project, allowing sufficient time for the researchers to produce an integrative (open access) research paper. Beyond informing the academic community, this new knowledge of the timing (and value) of different markers of heat stress tolerance will be actively disseminated throughout the CIAT physiology and breeding community so that no opportunities to adopt an deploy new protocols is lost. This should accelerate the breeding process by decreasing the reliance on long-term, multi-genotype field trials in the target environments.

Since high temperature events are often accompanied by significant soil drying, understanding the regulation of crop water use in response to changing soil water status and evaporative demand (determined using Lancaster's water use phenotyping platform) will be valuable to discriminate genetic variation in these traits. More conservative water use may exacerbate the impacts of high temperature stress (due to decreased transpirational cooling). These data will provide complementary data to the "simulated climate change" experiments at Reading.

Informing farmers in lowland tropical regions of Colombia of the genetic resources available to enhance heat tolerance, and thus grain yields, is likely to change farmer attitudes to crop selection. CIAT staff will work with local producers associations to disseminate varietal recommendations, and understand the factors incentivizing (or not) the adoption of specific varieties.
Ex ante evaluation will provide estimates of societal benefit or costs to intervention. When coupled with a participatory workshop, the most pertinent factors within assessment can be derived to maximise economic benefit. Moreover, it provides a framework for justifying the on-going capacity towards plant breeding in developing states, which tend to be low on infrastructure and demonstrate fragility in the long-term. Applying a robust framework and deriving these values which support government decision making and reduce transaction costs in supporting the identification of these benefits.