Effects of irrigation on plant growth and nitrogen use characteristics ofCalligonum caput-medusaeSchrenk seedlings

Abstract

Water and nitrogen (N) are two primary factors controlling plant growth in desert ecosystems. Most studies have focused on water stress resulting from the low rainfall and high evaporation rates in arid areas. However, irrigation has become the main strategy for vegetation recovery in the southern rim of Tarim Basin. Many studies have shown that irrigation is most effective when nutrients are not limited, and fertilization is most effective when plants are not water鄄stressed. In addition, N not only affects drought tolerance through changing dry matter partitioning, but also plays an important role in ecosystem functioning and vegetation succession. Therefore, the combined effects of water and N on vegetation recovery and reconstruction in this area should be evaluated. We conducted a pot experiment to study characteristics of N allocation, use, and resorption, and growth of Calligonum caput鄄medusae Schrenk seedlings under different irrigation treatments (4.6, 6.1, 7.7, 9.2, 13.0 kg / plant per irrigation event). The results showed that the amounts of both N and dry matter per whole plant significantly increased with increasing amounts of irrigation. However, C. caput鄄medusae Schrenk seedlings were infected with powdery mildew at the high irrigation level (13.0 kg / plant). During the early growth stage, irrigation promoted dry