Exploring Adaptative and Susceptible Mechanism in Selected Tomato Genotypes Employing Physiological Modulations and Antioxidative Pathways under Drought Stress

Background: Drought is a critical abiotic stress that affects the productivity, growth and yield of crops. The current study was evaluated to screen six widely grown tomato (Solanum lycopersicum) genotypes viz, Shivam, Siri, Bhagyashree, Arka Samrat, Arka Rakshak, Arka Apeksha, in the south part of India to drought stress. Methods: The studies were performed mostly on leaves in pot experiments using a complete randomized arrangement (CRD), polybags were divided into two sets for each genotype-one set of polybags consist of four bags were given drought treatment by withholding irrigation for 10 days which includes sampling days and another set of polybags consisting of four bags were routinely watered considered as a control for preceding sampling days. The set standard protocols were used for each experiment conducted. Result: This studies on morpho-physiology showed a significant reduction along with oxidative damage in all genotypes including increase in malonaldehyde content (MDA content) and hydrogen Peroxide and superoxide radical localization that led to increase in antioxidative activity such as superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX), as well as their isozymes. Photosynthetic parameters such as the net photosynthesis rate, stomatal conductance and Fv/Fm and other related measurements drastically decreased in drought-stressed plants. Moreover, stomatal structure showed flaccid guard cells and the closure of the stomata in all genotypes of tomatoes, but with fewer variations in ‘Arka Samrat’ and ‘Shivam’.