drought resistance of wild pear (pyrus boisseriana buhse.)

trees are an important source of wild germplasm for sustainable forestry. wild pear germplasm (pyrus boisseriana) was collected from a forest ecosystem and resistance potential to drought stress was surveyed in a greenhouse. in six-month seedlings, signs of leaf rolling appeared after 18 days without water (drought simulation). gas exchange parameters, such as net photosynthesis, stomatal conductance, and transpiration, decreased with increasing drought over the time. decreasing net photosynthesis caused negative effects on growth and leaf expansion and caused the seedlings to drop their leaves. in contrast, however, there was no effect of drought on root and shoot biomass, compared to control plants. mean xylem water potential was -0.66 and -2.22 for control and stressed seedlings respectively. the xylem water potential led to decreasing of rwc (%) and finally electrolyte leakage increased by 45%. we did not observe any negative effect of drought on chlorophylls a and b, but the carotenoid content increased. we found no increase in the proline content of the stressed plants. finally, wild pear are able to tolerate drought for about 18 days, by decreasing some physiological parameters (gas exchange, xylem water potential, and relative water content), and by increasing some antioxidant systems like carotenoid . additional research, but with field populations, and with studies of gene and protein expression, are necessary before wild pear can be used as a source of germplasm.