The physiological responses of various pomegranate cultivars to drought stress and recovery in order to screen for drought tolerance

- Drought tolerance of various pomegranate cultivars was investigated with some rapid and reliable methods.
- Physiological responses of pomegranate to drought stress and recovery were studied.
- Water stress cause to increase the intrinsic water use efficiency in young pomegranate plants.
- Compared with the stem water potential, the relative water content showed a smaller decrease during the water stress period.
- 'Ghojagh' was more drought tolerant than other cultivars.

In order to screen pomegranate cultivars for drought tolerance, few rapid, less expensive and reliable methods were used. Two-year-old pomegranate (Punica granatum L.) plants of various commercial cultivars namely 'Rabab-e-Neyriz' ('Rabab'), 'Shishe-cap-e-Ferdows' ('Shishecap'), 'Malas-e-Saveh' ('M-Saveh'), 'Malas-e-Yazdi' ('M-Yazdi'), and 'Ghojagh-e-Qom' ('Ghojagh') were grown in large containers filled with a mixture of leaf mould, sand, and soil (1:1:1, by volume) in greenhouse. The plants were subjected to 14-day drought stress by withholding irrigation, followed by re-watering for 7 days. Midday stem water potential (Ψstem), leaf relative water content (RWC), membrane stability index (MSI), leaf dry mass per area (LMA), rapid test for drought tolerance (DTI), gas exchange parameters including net photosynthesis (An), leaf scale transpiration (Tr), and stomatal conductance (gs), and intrinsic water use efficiency (IWUE) were determined in well-watered and drought-stressed plants. All cultivars showed an ability to tolerate drought stress, but 'Ghojagh' exhibited more tolerance, with a higher RWC and Ψstem and a greater osmotic adjustment. 'Ghojagh' also revealed higher cell membrane stability and IWUE and a lower reduction in net CO2 assimilation rate. This study found that 'M-Yazdi' was more vulnerable to severe water stress, and displayed the lowest degree of cell membrane stability as compared to the other examined cultivars and showed no recovery for RWC at the end of recovery period.