苜蓿-无芒雀麦混播方式和比例对禾草叶片碳氮代谢的影响

Effects of the Pattern and Proportion of Mixed Sowing Alfalfa to Smooth Brome on the Carbon and Nitrogen Metabolism in Its Leaves

以紫花苜蓿(Medicago sativa)与无芒雀麦(Bromus inermis)间行(A_(1))和交叉(A_(2))混播两种方式和8个紫花苜蓿密度(5,15,25,35,45,55,65和75株·m^(-2),分别记为B_(1),B_(2),B_(3),B_(4),B_(5),B_(6),B_(7)和B_(8))建植混播草地,通过测定头茬禾草碳氮代谢产物含量和关键酶活性,探究混播方式和苜蓿密度对混播禾草碳氮代谢的影响。结果表明:混播方式对禾草可溶性糖(Soluble sugar,SS)、淀粉(Starch,S)、总糖(Total sugar,TS)、可溶性蛋白(Soluble protein,SP)含量具有显著性影响,A_(2)处理高于A_(1)(P<0.05)。苜蓿混播比例对禾草SS、S、TS、SP、游离氨基酸(Free amino acid,FAA)含量和硝酸还原酶(Nitrate reductase,NR)、谷氨酸草酰乙酸转氨酶(Glutamic oxaloacetic transaminase,GOT)活性有显著影响。随着苜蓿密度增加,禾草SS、S、TS含量呈下降-增加-下降趋势,FAA含量呈增长趋势。B_(3)处理禾草SS和TS含量最高,B_(6)处理禾草SP、FAA含量和NR、GOT活性最高。可见,禾豆交叉混播,当苜蓿比例为25株·m^(-2)时禾草碳代谢能力较高,当苜蓿比例达到55株·m^(-2)时禾草氮代谢能力较高。

A grassland was established by interrow(A_(1))and cross-row(A_(2))seeding of alfalfa(Medicago sativa)and brome(Bromus inermis)with eight different alfalfa densities(5,15,25,35,45,55,65 and 75 plants·m^(-2),denoted as B_(1),B_(2),B_(3),B_(4),B_(5),B_(6),B_(7)and B_(8),respectively).The contents of carbon and nitrogen metabolites and activities of key enzymes of the first stubble grass were measured to study the effect of the mixed sowing patterns and alfalfa density on the carbon and nitrogen metabolism of mixed grass.The results showed that the mixed sowing pattern had a significant impact on the content of soluble sugar(SS),starch(S),total sugar(TS),and soluble protein(SP)of brome,and those of brome in A_(2)was significantly higher than the counterparts in A_(1)(P<0.05).The mixed sowing ratio of alfalfa significantly affected the contents of SS,S,TS,SP,free amino acid(FAA)and the activities of nitrate reductase(NR)and glutamic oxaloacetic acid transaminase(GOT)of brome.As the mixed ratios of alfalfa increased,the contents of SS,S and TS of brome showed a decreasing-increasing-decreasing trend;while the content of FAA showed an ascended trend.The contents of SS and TS of brome were higher under B_(3)treatment;while the contents of SP and FAA,and activities of NR and GOT of brome were higher under B_(6)treatment.In conclusion,the brome had a higher ability of carbon metabolism when the mixed ration of alfalfa was 25 plants·m^(-2);and the nitrogen metabolism level of the brome was higher when the mixed ration of alfalfa was 55 plants·m^(-2)in the cross-sowing between grass and legume.