Study of Some Physiological Responses of Different Pomegranate (Punica Granatum L.) Cultivars under Drought Stress to Screen for Drought Tolerance

Pomegranate (Punica granatumL.) is one of the most important Iranian horticultural products, which is usually cultivated in arid and semi-arid regions. Climate change has led to drought stress and it's a threat to the agricultural products as well as pomegranate. This experiment was conducted on two-year-old rooted pomegranates of eight commercial cultivars namely 'Malase Saveh' ('M-Saveh'), 'Malase Isfahan' ('M-Isfahan'), 'Robabe Ghermeze Shiraz' ('Robab'), 'Gabrie Yazd' ('G-Yazd'), Gabrie Torshe Yazd' ('GT-Yazd'), 'Zaghe Sefide Yazd' ('ZS-Yazd'), 'Zaghe Torshe Yazd' ('ZT-Yazd') and 'Malase Torshe Pishva' ('M-Pishva'). Irrigation treatments were 50% of maximum allowable deficiency (without stress) and 80% of maximum allowable deficiency (stress). This research carried out as a factorial experiment based on randomized complete block design. Increased proline content was variable in pomegranate cultivars exposed to stress, so that, the highest increase was observed in the 'M-Saveh' with a 20.27% increase compared to the control treatment. 'Robab' showed the lowest increase in proline content. The highest increase in superoxide dismutase and peroxidase activity was 8.49 and 16.84%, respectively, in 'ZS-Yazd'. The activity of superoxide dismutase in 'Robab', which was exposed to drought stress, decreased. This cultivar showed the highest electrolyte leakage with an average of 83.58%. The lowest electrolyte leakage was belonged to 'ZS-Yazd' (24.1%), and then 'GT-Yazd' (18.66%). Cluster analysis divided the genotypes into four main groups. 'ZS-Yazd' and 'M-Saveh' were in the same group. These two cultivars were more tolerant to drought stress than other cultivars in the physiological aspects.