外源氮素形态对紫花苜蓿不同生育期根系特性的影响  

Effects of exogenous nitrogen forms on root characteristics of alfalfa at different growth stages

作　　者：刘晓静[1,2] 叶芳[1,2] 张晓玲[1,2] 

机构地区：[1]甘肃农业大学草业学院,甘肃兰州730070 [2]草业生态系统教育部重点实验室/中美草地畜牧业可持续发展研究中心,甘肃兰州730070

出　　处：《草业学报》2015年第6期53-63,共11页Acta Prataculturae Sinica

基　　金：国家自然科学基金(31460622);草业生态系统教育部重点实验室(甘肃农业大学)项目(CYZS-2011012);甘肃省财政厅项目资助

摘　　要：在完全营养液的条件下,采用砂培法,研究了3种外源氮素形态配比(NO3--N,NH4+-N以及NO3--N∶NH4+-N为1∶1)和3个氮素水平(0,105,210 mg/L)对"甘农3号"紫花苜蓿整个生育期根系特性的影响。结果表明,不同形态氮素处理下紫花苜蓿的根系生物量、根表面积、根体积、根系活力、根瘤数、根瘤重和固氮酶活性均显著高于CK,NO3--N和NH4+-N混合培养下效果最好,NH4+-N培养下次之,NO3--N培养下最低,但对根系平均直径的影响并不大。随着氮素水平的增加,各形态配比下紫花苜蓿的根系生物量、根表面积、根体积、根系活力、根瘤数、根瘤重和固氮酶活性均呈增加的变化趋势,各指标在NO3--N+NH4+-N的浓度为210 mg/L时,达到最大值。整个生育期,各处理下紫花苜蓿的根系生物量、根表面积、根系活力、根瘤数、根瘤重和固氮酶活性均在苗期、现蕾期、盛花期差异比较明显,结荚期和鼓粒期差异不显著,各指标之间均有不同程度的相关性。This paper reports research on the effect of exogenous nitrogen on the root characteristics of “Gan-nong No.3”Alfalfa at different growth stages.Samples were cultivated for the whole growth period using the sand culture method under the condition of complete nutrient solution.Three exogenous nitrogen forms (ni-trate nitrogen,ammonium nitrogen and nitrate nitrogen)were investigated;with the ammonium nitrogen solu-tion at 1∶1 and the others are three solution levels (CK,105,210 mg/L).Results showed that under different forms of nitrogen treatment,the root biomass,root surface area,root volume,root activity,root nodule num-ber,nodule weight,and nitrogenase activity of alfalfa are significantly higher than that of CK.With increasing nitrogen levels,there were increases in the proportions of alfalfa root biomass,root surface area,root volume, root activity,root nodule number,nodule weight and nitrogenase activity.The effects are in the following or-der:NO3 --N and NH4 +-N mixed culture the highest,followed by NH4 +-N and with NO3 --N the lowest. The impact on root average diameter was not large.The maximum values were reached by NO3 - +NH4 + with a concentration of 210 mg/L.In terms of the whole growth stage,root biomass,root surface area,root activi-ty,root nodule number,nodule weight and nitrogenase activity were significantly different during the seedling, budding and flowering stages.However,differences during seed podding and podding were not significant.

关 键 词：紫花苜蓿 NO3--N NH4+-N 生育期 根系特性 

分 类 号：S541.9[农业科学—作物学]