Effect of high day and night temperature regimes on tomato (Solanum lycopersicum) genotypes

Abstract

Five tomato (Solanum lycopersicum L.) genotypes, including heat tolerant (Pusa Sadabahar, Booster, Pusa Sheetal), one F1 combination (Pusa Sheetal × Pusa Sadabahar ) and one susceptible genotype (Pusa Rohini) were grown under phytotron under four temperature regimes, i.e. 20/24, 22/26, 24/32, 27/37°C night (11 hours)/day (13 hours) temperature, respectively. Pusa Sadabahar and Booster recorded high value of relative water content (RWC) and low value of membrane injury index (MII) both at normal and high temperature conditions. High value of chlorophyll a and chlorophyll b ratio was recorded in Pusa Sadabahar and Pusa Sheetal×Pusa Sadabahar under all the temperature regimes showed their tolerance to high temperature. Normal (more than 80 percent) flowering and fruiting was recorded in all the genotypes at 20/24°C & 22/26°C. However at 24/32°C Pusa Sadabahar recorded 65 per cent fruit set and other genotypes 25 to 49 percent fruit setting only. None of the genotypes could record fruit set at 27/37°C, except Pusa Sadabahar which could set few small fruits (19%). Pollen germination was maximum (ranging from 21.8 - 62.9%) in Pusa Sadabahar under all temperature regimes. The susceptible genotype, Pusa Rohini recorded exerted stigma in 100% flowers at 27/37°C temperature whereas it was 75% in tolerant genotype Pusa Sadabahar. Night/day temperature 22/26°C was optimum for fruit set, pollen viability and normal stigma development in tomato. High night temperature (³ 26°C ± 2°C) at flowering was the major factor in reducing fruit set in tomato than the day temperature. The study showed that day temperature of ³ 35°C and night temperature of ³ 26oC may be used for screening tomato against high temperature tolerance.