CHANGES IN LEAF CHARACTERS OF LOQUAT UNDER REPEATED DROUGHT STRESSES

Two-year-old potted grafted trees of two cultivars of loquat (Eriobotrya japonica Lindl. ‘Jiefangzhong’ and ‘Changhong No.3’ were used for this study. Control plants were watered normally with a soil relative water content from 61 to 64%. Relative soil water content was kept from 49 to 52%, 38 to 41% and 27 to 30%, respectively, in light, moderate and severe drought treatments. The water-stressed plants were watered once after 14 days of water withholding period and then subjected to the same drought stress treatments. Such drought-watering was repeated four times. The results showed that drought stresses caused significant (P<0.01) decrease in leaf expansion rate and in the final leaf area. The decrease was greater under more severe drought. Under the same level of drought stress, the decrease in ‘Changhong No.3’ was less than in ‘Jiefangzhong’. With the increase in drought severity, the density of stomata in the leaves of both cultivars increased significantly (P=0.01), but their size reduced. Under the same level of drought stress, the stomata density increase and their size decrease in ‘Changhong No.3’ were greater than in ‘Jiefangzhong’. Under moderate drought stress, concentrations of chlorophylls and carotenoids in ‘Jiefangzhong’ leaves decreased significantly (P=0.01) compared to the control. The more severe the drought stress, the greater the decrease in the concentrations of photosynthetic pigments. However, in ‘Changhong No.3’ leaves, concentrations of photosynthetic pigments increased significantly (P=0.01）under the light drought stress. Although they decreased with the increase in drought stress severity, they maintained significantly higher (P=0.01）than the control. The results suggested that ‘Changhong No.3’ was more resistant to drought than ‘Jiefangzhong’.