Genetic variability for heat tolerance in tomato (Solanum lycopersicon) genotypes at seedling stage
2016
Arshad, M.S.
Tomato (Solanum lycopersicum) is an important vegetable crop of Pakistan. Its fruit is used directly or processed in various forms. Tomato yield is challenged by various biotic and abiotic factors. Among abiotic stresses, heat stress is critical in reducing the yield potential of tomato. Rise in temperature is also one of the factors, promoting climate change in coming years. This experiment was conducted to evaluate 50 genotypes of tomato for their tolerance against heat stress. Seeds were sown in plastic cups in completely randomized design with split plot structure and three replications. After 45 days of sowing one set of genotypes was kept at normal 22 plus minus degree C temperature and other exposed to heat shock treatment at 44 degree C for 4 hours. After 24 hours of heat shock treatment data was noted on plant height, fresh and dry plant biomass, fresh and dry weight of root and shoot, chlorophyll contents and cell membrane thermo-stability. Tolerant genotypes indicated less cell membrane injury and relatively reduced loss of biomass than susceptible genotypes. All seedling growth parameters displayed strong, significant and positive correlation. Cell membrane thermostability at seedling stage indicated weak yet significant correlation with growth parameters. Genotypes CLN-2001A, CLN-2366, LA-2711 and CLN-1691L were marked as heat tolerant genotypes whereas, BL-1175, BL-1176 and 017902 were noted to be heat susceptible. It was concluded that among studied genotypes CLN-2001A and CLN-2366, LA-2711 could be used for further breeding program aiming induction of heat tolerance in tomato.
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