Résumé
Solanum lycopersicum L., an important vegetable crop (Tomato) in most regions of the world, is affected by high temperature stress at various stages of its growth. Likely increase in periodicity of high temperature episodes under climate change conditions would further affect the tomato production. To sustain productivity and yields under climate change situations, there is an urgent need to develop suitable cultivars as an adaptation strategy. For this endeavour, identification of high temperature tolerant lines for crop improvement is a prerequisite. Hence in the present study, temperature induction response (TIR) technique was employed to evaluate thermotolerance in 52 tomato genotypes. Two day old seedlings were subjected to an initial induction treatment i.e., gradual temperature increase from 33-43°C for 3 h followed by 50°C for 3 h as challenging temperature. Wide variability was seen for seedling survival and vigour. In genotypes IIHR-2202, IIHR-2836 and IIHR-2841 seedling survival was as high as 90%, while H-329, H-371, IIHR-2745 and H-335 showed least reduction in growth and also had better seedling vigour index. Of the 52 genotypes, 21 were identified as tolerant, 12 moderately tolerant and 19 susceptible. This TIR technique is simple, quick and less expensive than whole plant screening. Hence, it could be used by plant physiologists and plant breeders for screening seedlings at an early stage in the phenotyping and crop improvement programmes.