Multiple physiological mechanisms involved in reproduction could be targeted for breeding heat tolerance in lima bean

Abstract

With global warming, the impact of high‐temperature stress on crop production is one of the major issues facing agriculture. Combining a series of field and controlled environment experiments, the current study aimed at understanding causes of yield loss due to heat stress in lima bean (Phaseolus lunatus L.) in order to guide breeding for heat tolerance. A growth‐stage analysis of multi‐year field trials suggested that yields were reduced by sensitivity to heat during floral transition. High nighttime temperatures during this period were also associated with delayed pod set and subsequent harvest. These effects were validated in controlled environments, with additional tests revealing how nighttime heat stress generally reduces seeds per pod but can also reduce the number of pods set. Using an intra‐plant dual temperature treatment design for vegetative and reproductive organs, it was determined that effects on pollen viability and release are primary factors underlying heat stress‐associated yield losses in lima bean. Elevated nighttime temperatures did not reduce aboveground biomass, indicating the physiological basis for temperature sensitivity was not driven by a photosynthate deficit, but instead could be attributed to changes in source–sink dynamics. Still, the basis for sensitivity to heat differed among genotypes, opening new targets for a multi‐mechanistic breeding approach for heat tolerance.

Andean Lima Bean Ecology and Its Potential Contribution to Food Security

“…Based on the results, these species demonstrate significant potential for future breeding programs due to their early maturation and high yield. On the other hand, Ernest and Wisser (2024) evaluated data from 8 years of testing of lima bean genotypes from the United States planted annually to understand the cause of yield loss due to heat stress in lima bean (P. lunatus L.), suggesting through environmental validations that yields were reduced due to sensitivity to heat during the floral transition. High nighttime temperatures during these study periods were also associated with a delay in pod formation and subsequent harvest.…”

“…Many countries and the Food and Agriculture Organization of the United Nations (FAO) do not keep separate statistics on lima bean production. FAO legume crop reports group lima bean with eight other species of the genera Phaseolus and Vigna, which are collectively classified as dry beans (Ernest and Wisser 2024). In Peru, it is marketed as a fresh legume in pods and as a dry bean for human consumption, as it is rich in protein and other nutrients beneficial to human nutrition (Sandoval-Peraza et al 2020).…”