Physiological and biochemical response of thermo-sensitive and tolerant tomato genotypes to high temperature stress

High temperature stress induces considerable biochemical and physiological changes in the plants. The aim of the present investigation was to evaluate the physiological response of some selected tomato genotypes to high temperature stress. Twenty one diverse tomato genotypes collected from different sources were field evaluated at the Experimental Farm, Division of Vegetable Science, ICAR-IARI, New Delhi (2013 and 2014). Analysis of variance revealed substantial amount of genetic variability in the genotypes for all the traits. Relative water content (RWC) and membrane stability index (MSI) was recorded maximum in Pusa Sadabahar (83 and 86%, respectively) under heat stress condition. Highest proline content was recorded in wild genotypes, like SPM (S. pimpinellifolium) followed by SPR-1 (S. peruvianum). Tolerant genotypes like SPR-1 and SPM-2 showed the high value of chlorophyll b under heat stress condition as compared to sensitive genotypes. The highest phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) were recorded for yield per plant followed by chlorophyll b, chlorophyll a, lycopene contents and total chlorophyll. High heritability coupled with high genetic advance as per cent over mean was recorded in yield per plant (98.84 and 79.30, respectively) followed by chlorophyll a, chlorophyll b and total chlorophyll content. This indicated the scope for improvement through simple selection for these traits.