Response of Tomato Quality and Yield to Elevated Temperatures under Controlled Environment

The experiment was carried out during 2020-2021 at the Department of Plant Physiology, College of Agriculture, Vellayani, Kerala Agricultural University. The experiment was carried out with the aim of characterization of contrasting tomato genotypes for high temperature tolerance under high temperature condition and control condition to identify key quality and yield traits controlling high temperature tolerance in tomato. The experiment was designed in completely randomized design (CRD) with 2 treatment levels- control and high temperature conditions (36+/-2oC) wherein 3 tolerant and 3 susceptible genotypes were selected for the study. These genotypes were selected from the summer varietal screening experiment performed during the summer months of 2021 from March to May. The best performing genotypes were selected in terms of pollen viability, leaf membrane thermo-stability, chlorophyll fluorescence, number of fruits, fruit set %. One set of treatment was maintained under ambient condition and the other set with high temperature stress was maintained under polyhouse facility from transplanting stage to the harvesting stage. The quality parameters and yield traits were analysed at the harvesting stage of the crop. From this study it can be understood that many of the quality parameters like lycopene content, total sugars, flavanol content was found decreasing in both tolerant and susceptible genotypes but the extend of this reduction was considerate in tolerant ones. In case of ascorbic acid content and firmness of fruit at the time of ripening these were found to be improved in heat stress (HS) conditions. Yield related qualities like number of fruits, yield per plant, and root-shoot ratio was found decreasing whereas root dry weight, total dry weight and intensity of fruit drop and flower drop was increased under HS. Therefore, this study focused on tomato genotypes reported to be resilient to high-temperature stress, and comparing them to the susceptible cultivars under stress and control settings for analyzing the variations in terms of quality and yield traits in tropical hot climate regions of India. The study performed here highlights the possibility for future breeding programs utilizing the key quality and yield traits enhancing thermo-tolerance in tomato and to develop new genotypes that can combine good yield performances and fruit nutritional quality at high temperatures.