Climate change-induced heat stress poses a significant threat to agricultural productivity, particularly in heat-sensitive crops like tomato (Solanum lycopersicum). This study evaluates the phenotypic and agronomic responses of tomato plants to varying heat stress conditions, specifically focusing on key physiological traits such as photosynthetic efficiency, chlorophyll content, membrane stability, and pollen viability. The research further explores the impact of heat stress on fruit set, plant height, stem diameter, leaf number, days to flowering, and fruit yield. Tomato plants exposed to elevated temperatures exhibited a decline in photosynthetic efficiency, chlorophyll content, and membrane stability, while pollen viability and fruit set were adversely affected under high heat conditions. Agronomic traits such as plant height, stem diameter, and fruit yield were also significantly reduced under heat stress. The study highlights the variability in stress tolerance among genotypes, indicating potential avenues for selecting heat-tolerant cultivars. The findings underscore the importance of developing strategies to mitigate the impacts of heat stress on tomato production, thereby contributing to food security and climate resilience in future agricultural systems.

Tomato (Solanum lycopersicum), Heat stress tolerance, Photosynthetic efficiency, Chlorophyll content, Membrane stability index

The evaluation of 65 tomato genotypes under normal and high-temperature stress conditions revealed significant phenotypic and agronomic variability, highlighting the differential responses of genotypes to heat stress. Under stress, most genotypes exhibited elevated leaf temperature, reduced photosynthetic efficiency, decreased chlorophyll content, impaired membrane stability, lower pollen viability, delayed flowering, and reduced fruit yield. However, specific genotypes demonstrated resilience by maintaining physiological integrity and yield stability. Notably, T65 consistently outperformed others across multiple traits, including photosynthetic efficiency (79%), chlorophyll content (90 SPAD), membrane stability (89%), and fruit yield (45 t/h). Genotypes T34, T28, and T37 also displayed heat-tolerant characteristics, particularly in terms of pollen viability, leaf number, and fruit set. The strong association between physiological stability and reproductive success underscores the importance of integrated trait evaluation for identifying thermotolerant germplasm. These findings confirm that targeted screening of physiological and reproductive traits can effectively discriminate tolerant genotypes with potential for sustained productivity under climate stress.

Sandeep Kumar, Deepak Dubey, Priyanka Dubey and Syed Kulsoom Fatima Jafri (2025). Physiological and Agronomic Responses of Tomato (Solanum lycopersicum) Under Heat Stress: Implications for Climate Resilience and Yield Performance. Biological Forum, 17(9): 62-68.