Response of Water Status of Populus bolleana Lauche to the Amount of Irrigation Water in the Southern Edge of Taklimakan Desert, China

AbstractMoisture is a primary limiting factor that affects plant growth. To determine the ideal amount of irrigation water for the growth of individual Populus bolleana Lauche, the major protective species around Qira oasis in southern edge of Taklimakan Desert in Xinjiang, China, we studied the moisture of soil layers with depth between 0-80cm and the response of P. bolleana's water status such as moisture content, stomatal characteristics, leaf water potential, stem sapflow and stem diameter to different irrigation based on the field monitoring data. The results showed that the moisture content of soil layers with depth of 0-80cm gradually increased with irrigation increasing, especially when irrigation was more than 30 liters. When irrigation was 30 and 40 liters, the daily leaf water potential presented an obvious unimodal trend: the predawn and midday leaf water potential increased significantly. Along with the irrigation increased from 10 to 40 liters, sapflow and stomatal conductance followed a trend of first decreases and then increases. When irrigation was 30 liters, the daily mean stem diameter and contraction of P. bolleana reached their peaks, indicating that irrigating more than 30 liters of water could improve the water status of P. bolleana and prevent it from drought stress. Thus, we concluded that the ideal irrigation amount for the normal growth of individual P. bolleana should be 30 liters per year