氮素水平对科尔沁沙地羊草叶片氮代谢及产量的影响

Effects of nitrogen rates on yield and leaf nitrogen metabolism of Leymus chinensis grown in Horqin sand land

合理的施氮量可以提高羊草氮素代谢关键酶活性,促进羊草氮素积累和利用,进而获得高产。为确定科尔沁沙地羊草适宜施氮量及其促高产的生理机制,采用随机区组设计,选取两块样地分别追施0、50、100、150、200 kg/hm2氮肥(纯N),分别用N0、N1、N2、N3、N4表示,5月20日测定羊草叶片氮代谢相关酶活性及含氮物质含量,7月10日测定羊草产量。结果表明:羊草产量、硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、谷氨酸草酰乙酸转氨酶(GOT)、谷氨酸丙酮酸转氨酶(GPT)活性和游离氨基酸(AA)、可溶性蛋白(SP)含量均随施氮量的增加而呈现先增加后降低的变化趋势,其中NR、GS、GOT、GPT活性和AA含量在N3水平下达到最大值;羊草产量和可溶性蛋白含量在N2水平下达到最大值。结论:在科尔沁沙地生境下追施150 kg/hm2氮肥(纯N)羊草叶片的氮素代谢能力最强,最有利于羊草干物质产量的积累。

The application of reasonable amount of nitrogen fertilizer could increase the activity of key enzymes in nitrogen(N)metabolism,promote N accumulation and utilization and achieve high yield for Leymus chinensis.This study aimed to determine the appropriate level of nitrogen for L.chinensis in the Horqin sand land and its physiological mechanisms for high yield.Two sample plots were selected and topdressed with different levels of N fertilizer(pure N)at 0,50,100,150,200 kg/ha(denoted by N0,N1,N2,N3,and N4,respectively),using a randomized block design.The enzyme activities related to N metabolism and N content of the leaves were measured on 20th May,and the yield was measured on July 10.The results showed that L.chinensis yield,nitrate reductase(NR),glutamine synthetase(GS),glutamate oxaloacetate transaminase(GOT),glutamate pyruvate transaminase(GPT)activity and free amino acid(AA),and soluble protein(SP)content initially increased,followed by a decrease in response to the increasing N rates.Among them,NR,GS,GOT,GPT enzyme activity and AA content reached the maximum at the N3 level;the yield and SP content reaches its maximum at the N2 level.When topdressed with 150 kg/ha pure N fertilizer,L.chinensis grown in the Horqin sandy habitat had the strongest leaf N metabolism capacity,which was most beneficial to its dry matter accumulation.