Dissecting genetic variability and trait interrelationship in open condition under heat stress in tomato (Solanum lycopersicum L.) for fruit yield and seed production

Abstract Tomato is sensitive to high temperature which effects vegetative as well as reproductive behavior. The present study was conducted in 2020 and 2021 using 76-diverse tomato genotypes, during summer months in Ludhiana, Punjab conditions where temperature is persistently high i.e., more than 35 °C which is detrimental for tomato production. The genotypes were evaluated based on 17 traits which included vegetative, reproductive and biochemical traits. Genetic parameters (PCV, GCV, heritability, genetic-advance), and multivariate analysis (correlation and path-analysis) were used to assess the diversity and trait association of the genotypes. Paired-ANOVA showed significant differences among genotypes for all traits, confirming ample genetic variability. High heritability coupled with high genetic-advance for pollen viability, number of fruits, and fruit yield per plant, suggesting additive gene action. Pollen-viability reduced considerably in the susceptible genotypes where the viability reduced to less than 60% contrastingly tolerant genotypes retained more than 80% viability. These findings provide critical insights for breeders to develop heat-resilient genotypes through targeted selection and genetic improvement strategies. Correlation showed that fruit yield and seed yield was strongly and positively associated with number of fruits ( r = 0.35), pollen viability ( r = 0.20) and seed yield ( r = 0.33), while negatively correlated with number of days to anthesis ( r = – 0.25) and dry matter content ( r = – 0.18), indicating the advantage of early flowering during heat stress. Path-analysis showed that number of fruits (0.50) and number of seeds (0.35) had positive association with fruit and seed yield while days to anthesis showed strong negative effects, confirming that reproductive efficiency traits are the most reliable targets for improving yield in heat-stressed tomato.