| In recent years,with the change of global climate,the change of precipitation pattern and the increase of atmospheric nitrogen deposition are increasingly obvious.Water and nitrogen are the key limiting factors in arid and semi-arid ecosystems,and their changes will inevitably affect plants.At the same time for xinjiang’s livestock production,the spring forage shortage is an important problem to be solved urgently E.orientale,desert ephemeral plant,widely distributed in northern Xinjiang,timely germination in spring season,is the spring livestock and wild herbivores to eat the object.In this study,the effects of precipitation and nitrogen deposition on growth and forage nutritional value of E.orientale were investigated.Three precipitation levels were set:W1（70 mm）,W2（105 mm）and W3（210 mm）.Three nitrogen deposition levels were set:N0(0 kg·ha-1·yr-1),N1(30 kg·ha-1·yr-1)and N2(60 kg·ha-1·yr-1).Two harvest times:30 days after seeding（jointing and booting stage）and 45 days after seeding（flowering stage）.The main results are as follows:（1）Suitable water and nitrogen supply can significantly promote the growth of E.orientale.Under W3N1 and W3N2 treatment,the plant height,leaf length,leaf width,stem diameter and tiller of E.orientale reach the maximum,and there is no significant difference between N1 and N2 treatment.At the same time,with the extension of harvest period,plant height,leaf width and tiller increased,while stem diameter and leaf length decreased.（2）Suitable water and nitrogen supply can promote the biomass accumulation of E.orientale.The total aboveground biomass,aboveground biomass of individual,total underground biomass and underground biomass of individual reach the maximum under W3N1 and W3N2 treatment,and there is no significant difference between N1 and N2treatment;Increasing precipitation decreased the root shoot ratio of E.orientale.There was little difference in water content among treatments,especially the water content of aboveground part could be maintained within a certain range.With the extension of harvest period,biomass,root shoot ratio and water content had no significant changes as a whole.（3）The addition of nitrogen and water promoted the contents of crude protein and amino acids（except proline）.The crude protein content was the highest under W3N2 treatment in two harvest periods.Under the condition of W2N2 in the first harvest,the content of amino acids reached the maximum,and it could also maintain a high level under the treatment groups of W3N1 and W3N2,and there was no significant difference between the two treatment groups;In the second harvest period,the content of amino acids reached the maximum under W3N2 and maintained a high level under W3N1 treatment group.The contents of crude protein and amino acids in the second harvest were lower than those in the first harvest.（4）The addition of nitrogen decreased the contents of NDF,ADF and soluble sugar of E.orientale;Promoted the increase of tannin content.The increase of precipitation promoted the accumulation of soluble sugar content to a certain extent,and the soluble sugar content was the highest under W3 condition.NDF and ADF in the second harvest were higher than those in the first harvest;The contents of soluble sugar and tannin were lower than those in the first harvest.（5）The addition of nitrogen promoted the absorption and accumulation of K,Ca,Fe and Mn and inhibited the absorption and accumulation of B.Under the condition of W3N2,the K content of E.orientale was the lowest;Under the condition of W3,the Ca content of each nitrogen application level was generally lower than W1 and W2.The content of P and Mg fluctuated little in each treatment group,but the content was the lowest in W3N2 treatment.The content of mineral elements in the first harvest was higher than that in the second harvest.In conclusion,considering the growth and nutritional value,E.orientale can obtain higher forage yield and nutritional value under the condition of W3N1 in the first harvest period（jointing and booting stage）. |
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