Leaf water potential and photosynthetic characteristics of two Hippophae rhamnoides cultivars with soil drought.
To study the effects of drought stress on the growth of Hippophae rhamnoides in a natural environment, plant water relations and photosynthetic characteristics of two cultivars: H. rhamnoides subsp. sinensis 'Fengning' and H. rhamnoides subsp. mongolia 'Xiangyang' with different degrees of drought were studied by simulating natural soil drought conditions and water recovery processes. Results showed that leaves, experiencing drought treatment, initially shrunk at 22nd (19.40%) for the exotic species 'Xiangyang' and 33rd (11.66%) for the native species 'Fengning'. Also, 'Fengning' had stronger drought resistance compared to 'Xiangyang'. In addition, with increasing drought stress, the leaf water potential of both species decreased (0.77 and 0.45) and the moisture absorption ability increased. The maximum net photosynthetic rate, net photosynthetic rate, transpiration rate, stomatal conductance, light saturation point, and apparent quantum yield decreased with increasing drought stress; whereas, the relative content of chlorophyll and the light compensation point increased. Also, water efficiency rose after falling. The dark respiration rate of 'Fengning' treatment group decreased first and then recovered, but 'Xiangyang' treatment group was unchanged and then increased. After rehydration, the physiological indexes appeared in different degrees of recovery. Therefore, when extreme drought occurred in the process of cultivating a plantation, the leaves shrunk and need timely irrigation to avoid unrecoverable damage with 'Fengning' being more suitable than 'Xiangyang' as a breeding parent.