| The effects of nitrogen addition on nitrogen metabolism of desert areae plants were studied.The experiment was conducted at the xerophytes breeding center of Inner Mongolia Mengcao Drought Resistant Co.,Ltd.from the beginning of july to the beginning of august in 2017.Endangered plants like Prunus mongolica and its related species P.pedunculata,P.triloba and Ammopiptanthus mongolicus and its related specie Hedysarum scoparium were selected as experimental plants,foliar sprayed 25 g N·m-2·a-1 and 50gN·m-2·a-1 urea?AR?solution,and the control group was sprayed with the same amount of water.The results were as follows:1)Nitrogen addition increased the total nitrogen content of the experimental plants.The total nitrogen content of Hedysarum scoparium increased by a maximum of 25.34%,and the total nitrogen content of Prunus mongolica increased by a minimum of 6.67%.After treated with urea,each experimental plant of nitrate nitrogen was increased.It was showed that urea was not fully assimilated after being absorbed,and some was oxidized to nitrate nitrogen;The ammonia nitrogen content of 3 species of Rosaceae increased rapidly after nitrogen addition,only after the first three days of treatment there was a significant difference between the control group and the treatment group?p<0.01?,but the difference between the treatment group and the control group of Fabaceae Ammopiptanthus mongolicus was significant on the 6th day?p<0.01?,but the increase was not significant.2)Nitrogen addition significantly increased the relative content of chlorophyll in experimental plants.Among them,the chlorophyll relative content of the Prunus mongolica increased maximum in the treatment groups.At the end?August 4th?,the measured treatment group was 41.20%higher than that of the control group,followed by the Hedysarum scoparium,with an increased 28.00%,the P.pedunculata was 21.35%,P.triloba was 17.27%and Ammopiptanthus mongolicus was 5.07%.3)Nitrogen addlication significantly increased the free amino acid content of the experimental plants,among them the 3 species of the Rosaceae were more sensitive to nitrogen addition,and the treatment group had extremely significant differences with the control group on the 3rd day?p<0.01?,while the 2 species of the Fabaceae were relatively Slow to add nitrogen,Ammopiptanthus mongolicus showed a significant difference from the control group on the third day of treatment?p<0.05?,while the Hedysarum scoparium had a significant difference from the control group on the sixth day of treatment?p<0.01?.Nitrogen addition had a certain degree influence on the proline content of the experimental plants,but due to the experimental base had a irrigation conditions,the experimental plants did not went through substantial drought stress,so the main osmotic adjustment substance,the proline content remained relatively stable.The effect of nitrogen addlication on the soluble protein content of the experimental plants was significant,with the increase ranged from 8.91%to 34.30%.The largest increment was34.30%of Ammopiptanthus mongolicus.The lowest increment was 8.91%of P.triloba.4)Nitrogen addlication had different effects on the activities of key enzymes in nitrogen metabolism of experimental plants.Nitrogen addition results showed that the activity of transaminase increased and the activity of endopeptidase decreased in each experimental plant,while the effect on glutamine synthetase activity was not significant.5)As endangered plants,Prunus mongolica and Ammopiptanthus mongolicus were relatively sensitive to nitrogen addition.Except for the activity of endopeptidase and glutamine synthetase,the tested indicators increased,and the increased rang was larger. |
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