Author(s):

M Arumugaperumal and KB Sujatha

Abstract: Tomato (Solanum lycopersicon) is one of the most important and widely grown vegetables crops in both temperate and tropical regions of the world. Global warming leading to high temperature is predicted to be one of the limiting factors for cultivation of tomato and other plants in the future. In this study, plants were grown under two different temperature regimes, one at ambient (30 °C) and other at elevated temperature (38±1ºC) in open top chambers at the Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore. The physiological and biochemical responses of 20 tomato genotypes to heat stress were evaluated. The cell membrane stability was high in IIVR-L thereby preventing the damage to the lipid bilayer of biological membranes as compared to other genotypes under elevated temperature conditions. Proline content increased at a higher rate in IIVR-L that helped in maintaining the tissue water potential under high temperature while nitrate reductase activity (NRA) decreased in all the genotypes by 16-20%, as the enzyme is very sensitive to stress conditions. There was no fruit production in the genotypes like IIHR – 2388 and IIHR – 709 though flowers were produced by these genotypes (100% reduction in fruit set) that might be due to their higher sensitivity of post flowering stage to high temperature The physiological and biochemical changes clearly connotes how the best performed genotypes like IIVR-L were able to overcome the heat stress as compared to the poorly performed genotypes (IIHR-2388 and IIHR–709).

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