The increasing frequency of heat stress due to climate change is posing significant challenges to agricultural crops, particularly mung beans (Vigna radiata), which are integral to food security in Southeast Asia. A recent study conducted by researchers at Kansas State University assessed how ten diverse genotypes of mung beans respond to various high-temperature stress regimes, aiming to identify varieties resilient to heat stress as temperatures continue to rise.
The study found significant genetic variability among the mung bean genotypes, with all tested plants exhibiting differing responses to three specific temperature regimes of 34/25 °C, 39/30 °C, and 42/30 °C. Under high-temperature conditions, severe leaf damage was recorded, marked by high rates of cell membrane injury, decreased chlorophyll index, and diminished chlorophyll fluorescence. Specifically, these detrimental effects were pronounced at the extreme temperatures of 39/30 °C and 42/30 °C, leading to reduced yield components such as effective pods per plant and total seed yields.
Heat stress during the reproductive phase of mung beans can substantially impair key processes, including pod formation and seed filling. The researchers found significant reductions—up to 83%—in seed yield under the most severe heat stress conditions. Notably, the genotypes PI 425243 and PI 425238 demonstrated the least severe yield reductions under heat stress, indicating their potential as candidates for breeding programs seeking to develop climate-resilient cultivars.
"Correlation analysis suggested selecting genotypes with higher chlorophyll index and increased canopy temperature depression could help identify mung bean varieties with enhanced pod and seed yields under heat stress," the authors noted, emphasizing the strategic importance of physiological traits for addressing the challenges posed by extreme climate events.
The study highlights the potential for utilizing the genetic diversity found among mung beans to create more resilient varieties. By focusing on key physiological metrics like chlorophyll content and membrane stability, crop scientists can develop strategies for selecting and breeding heat-tolerant mung beans poised to thrive under changing climatic conditions.
Considering mung beans are cultivated primarily during the humid summer season across Asia, Africa, and Australia, these findings are particularly pertinent. The total global mung bean production stands at around 5.3 million tons, making it one of the leading grain legumes cultivated. India alone contributes over 2 million tons of this yield, reflecting its significance for nutrition and economic development.
A staggering loss of yield potential during these high-temperature periods can lead to food shortages, especially for vulnerable populations relying on this legume for nutrition. The research now paves the way for future studies aimed at improving heat tolerance in mung beans, urging the agricultural community to pay heed to genetic variations as tools for breeding more resilient crop varieties.
With the looming threat of climate change affecting ecosystems worldwide, this study reinforces the urgency to cultivate heat-resistant crop strains. "Genotypes like PI 425243 and PI 379667 may be ideal candidates for developing climate-resilient cultivars," the researchers concluded, providing hope amid the global agricultural challenges posed by rising temperatures.