Effect Of Nitrogen Addition On Physiological Characteristic Of Desert Endangered Plants And Their Relative Species

In this study,the effects of foliar spraying of 25gN·m^-2·a^-1 and50gN·m^-2·a^-1 nitrogen on photosynthetic pigment content,photosynthetic rate,water physiology,mineral nutrition and flowering physiology of endangered plants including Prunus mongolica and Ammopiptanthus mongolicus and Prunus pedunculata?Prunus trilobal and Hedysarum scoparium in desert area were studied.The experiment result shows that:?1?Nitrogen addition significantly increased the chlorophyll content of the plant.Among them,the content of chlorophyll in the P.mongolica and the Hedysarum scoparium was increased significantly in the 3rd day compared with the control group?p<0.05?.The chlorophyll content of P.pedunculata,P.triloba and Ammopiptanthus mongolicus was significantly different in late time,and it didn't begin to show significant differences until the 9^th-15^th days.?2?The net photosynthetic rate of plant was increased compared with that in the control group after nitrogen addition.The P.mongolica increased significantly?p<0.01?than the control group.The concentration of intercellular CO2 in the plant was increased,and there were significant differences?p<0.05?with the control group.The photosynthetic parameters,such as maximum net photosynthetic rate(P_max),apparent quantum yeild?AQY?,light saturation point?LSP?,light compensation points?LCP?and dark respiration rate?R_d?,were not significantly affected by nitrogen treatment.?3?After the addition of nitrogen,the physiological indices of plant water were changed.The transpiration rate and porosity conductance of P.mongolica and P.pedunculata and Ammopiptanthus mongolicus and the leaf water potential of P.mongolica and P.trilobal and Ammopiptanthus mongolicus improved compared with control group,while the transpiration rate and porosity conductance of P.trilobal and Hedysarum scoparium and the leaf water potential of P.pedunculata and Hedysarum scoparium decreased compared with control group.?4?Copper,iron,zinc,calcium,magnesium,manganese,nitrogen,phosphorus and potassium are the components of plant chlorophyll and many kinds of oxidase in plant.Nitrogen addition is beneficial to photosynthesis and chlorophyll synthesis of leaves,which promotes drought resistance and absorption of these elements.The content of the plant elements was significantly changed by nitrogen addition treatment.The content of these elements was significantly increased?p<0.05?in the treatment in the 3^rd-9^thh days than in the control group.?5?After nitrogen addition,the pollen vigor of 5 plants was determined by using the method of benzotriazole and iodine-potassium iodide in laboratory.The results show that:The pollen vigor of 3 different flowering periods of P.mongolica and P.pedunculata were significantly increased compared with that in control group,while the pollen vigor of P.triloba,Ammopiptanthus mongolicus and Hedysarum scoparium was not changed.