Eco-physiological screening and genetic diversity analysis of tomato genotypes in response to summer heat.

Abstract

The impact of heat stress on agriculture is severe and negatively impacts crop productivity. In tropical and subtropical tomato-growing regions around the world, poor fruiting of tomato plants caused by heat stress is a major factor in low output. Exceeding optimum temperatures can shorten plant life and greatly accelerate fruit flowering and maturation. Temperatures above the reference temperature cause irregular flower development, reduced pollen production, pollen viability, fruit drop, ovule abortion, and ultimately reduced yield, generates an excess of reactive oxygen species (ROS), oxidative stress, and metabolic mechanism instability. High temperatures severely affect flower shedding, with tomato plants losing 80% of their flowers and reducing fruit set. For the characteristics pollen viability, photosynthetic rate, membrane stability and fruit number, high values of genotypic coefficient of variability, phenotypic coefficient of variability, heritability, and genetic progress were discovered. All nine separate traits demonstrated additive gene action in trait expression and should be given the utmost weight in phenotypic selection. Eigen value > 1 and cumulative variance of 75.04% were shown for the four main components.