Effects of Nitrogen and Phosphorus Addition on Agronomic Characters, Photosynthetic Performance and Anatomical Structure of Alfalfa in Northern Xinjiang, China

The productivity of alfalfa is associated with a large amount nitrogen (N) and phosphorus (P); the addition exogenous N P fertilizers can fully exploit growth potential alfalfa. However, there uncertainty about relationship between changes in photosynthetic physiology anatomy. We conducted field fertilization experiments on second third years under drip irrigation, as well measurement physiology, anatomical structure agronomic traits at different levels (0, 120 kg·ha?1) P2O5 50, 100 150 kg·ha?1). results showed that dry matter yield (DMY), crude protein (CP), net rate (Pn) specific leaf weight (SLW) were increased by 2.10~11.82%, 4.95~11.93%, 4.71~7.59% 2.02~7.12% application treatment compared non-N treatment, while DMY, CP, Pn SLW 3.19~17.46%, 1.99~8.42%, 6.15~24.95% 2.16~11.90% non-P treatment. increase thickness spongy tissue (ST) alfalfa, which will facilitate entry exit gas water, further affect indexes, such stomatal conductance (Gs) transpiration (Tr), leaves. Increased palisade (PT) also enhance adaptability plant leaves to strong sunlight, thereby increasing maximum (Pmax) light saturation point (LSP). Fertilization highest utilization efficiency for low better adaptation light, but Rd decreased. comprehensive scores principal component analysis structure, performance N1P2 > N0P2 N1P3 N1P1 N0P3 N0P1 N1P0 N0P0. Therefore, contributed adaptive anatomy improvement capacity, beneficial yield, nutritional quality, most obvious effect obtained kg·ha?1 P2O5.