Physiological and Biochemical properties of wild pear seedlings (Pyrus biosseriana) in response to different watering regimes

One of the best solutions to overcome drought stress is the use of wild germplasm. We aim to understand how wild pear (Pyrus boisseriana) conserves water and recovers water potential after drought. After 18 days without water، which coincides with leaf rolling، we surveyed physiological and biochemical parameters of pear seedlings and were re-surveyed them again after a week of re-watering. After signs of leaf rolling، the relative water content decreased to a critica level (35%). In contrast to the control، RWC declined by 58% and recovered acceptably. By the end of the experiment، xylem water potential declined -2. 22 Mpa، but increased watering. For osmosis adjustment in the plant cell، free proline and glucose content was increased about 5-6%. The finding showed that increasing carotenoid content is one of the strategies in response to oxidative stress، because active oxygen species could not decrease chlorophyll content. On the other hand، MDA and H2O2 content as lipid peroxidation and oxidative stress indicator respectively narrowly increased. Finally it can be concluded that increasing the carotenoid and proline content are the important mechanism for water limiting stress. It seems that this wild pear germplasm can tolerate lack of water for about 18 days. Moreover، leaf rolling sign is a good indicator of drought resistance potential.