Evaluation of some physiological responses of three indigenous watermelon (Citrullus lanatus L.) accessions to drought stress

In view of limitation of water resources in Iran, screening drought-tolerant watermelon genotypes and evaluate their response to drought stress conditions has been a research priority in country. In order to study the physiologic an agronomic response of indigenous accessions of Aliabad, Sistani and Torbat to water stress, a field study was carried out as a randomized complete block design with split plot arrangement of treatments under three water regimes, 100, 70 and 40% of required water, representing non-stress, mild stress and severe stress treatments, respectively, at Jiroft region in the spring and summer of 2017 growing seasons. The highest fruit weight and yield were at 100 and 70% required water whereas the lowest was achieved at 40% treatment. There were no remarkable differences among accessions under non-stress and 70% required water treatments while Sistani accession showed a better physiological and agronomic yield in response to increase water stress level to 40% required water. The increase of water stress led to an increase of proline concentration and activity of antioxidant enzymes of superoxide dismutase and catalase in all accessions, as this increase was higher in Sistani in comparison to other accessions. Based on the results obtained from this research, it could be state that Sistani accession with maintaining its physiological and agronomic yield showed a better tolerant under adverse condition in compared to other accessions. The utilization of indigenous and tolerant watermelon genotypes in breeding programs and irrigation managements might help in overcoming water shortage.