Investigating Water Productivity and some characteristics of Mentha piperita L under Salinity and Drought Stress in the presence of Selenium

Drought and salinity stress are the most important limiting factors for plant growth. Selenium has been introduced as one of the useful elements against the destructive effects of stress. To the investigation of influence salinity and drought stress on water productivity and some characteristics of Mentha piperita L in the presence of selenium, an experiment on the split in time was performed in the Torbat-e Jam region, Iran in 2020, including two levels of cut (cut1 and cut2), three levels of irrigation (including full irrigation (100% of water requirement) = I1, I2=75% I1 and I3= 50% I1), three levels of Salinity (0, 50 and 100 mmol NaCl) and selenium factor in 2 levels (0 and 5 mg/l Na2SeO4). The result showed that fresh and dry weight, plant height, the number of leaves per plant, and the number of nodes decrease under salinity and drought stress. Generally fresh and dry weight, plant height, number of leaves per plant, number of nodes, Essential Oil percentage, and water productivity in the first cut was more than in the second cut. Also, foliar spraying of selenium (5 mgr/lit Na2SeO4) increased the above characteristics and also increased plant resistance against salinity and drought stress. The result showed with increasing salinity and drought stress respectively water productivity increased and decreased. the result showed that the percentage of essential oil increased by applying mild stresses in the form of deficit irrigation and then by applying intense stress, the percentage of essential oil decreased. Also result showed that the use of saline water in the conditions of drought stress caused intensification of reduction in fresh and dry weight, number of nodes and percentage of essential oil.