外源氮素形态及水平对紫花苜蓿幼苗各部位氮含量的影响

在完全营养液条件下,采用砂培法,研究了2种氮素形态(NO-3-N,NH+4-N)和5个氮素水平(0、105、210、315、420mg/L)对紫花苜蓿品种"甘农3号"和"陇东苜蓿"幼苗各部位氮含量的影响。结果表明:施氮处理下各部位NO-3-N含量、NH+4-N含量和全氮含量均显著高于CK(P0.05)。"甘农3号"和"陇东苜蓿"2个品种的各部位氮含量变化一致,均随施氮水平的升高呈先增加后降低的趋势,但峰值表现不一。同一氮素形态及水平下,不同部位NO-3-N、NH+4-N及全氮含量表现为:叶根茎。"甘农3号"在NO-3-210处理下叶、茎、根中NO-3-N含量最优,分别为490,385和463μg/g;"陇东苜蓿"分别为473,355和447μg/g。"甘农3号"在NH+4-210处理下叶、茎、根中NH+4-N含量最优,分别为212,182和194μg/g;"陇东苜蓿"茎和根中含量分别为177μg/g、178μg/g,叶却在NH+4-315处理最大,为189μg/g。"甘农3号"在NH+4-315处理下叶、茎、根中全氮含量最优,分别为4.25%,1.7%和3.47%;"陇东苜蓿"叶和根中含量分别为4.01%、3.08%,茎却在NH+4-210处理最大,为2.33%。对于同一部位除"陇东苜蓿"茎全氮含量高于"甘农3号"外,其他部位的NO-3-N、NH+4-N和全氮含量均表现为"甘农3号"优于"陇东苜蓿"。

Effects of exogenous nitrogen forms and levels on nitrogen content in different parts of alfalfa seedlings

Under the condition of complete nutrient solution,the effect of two kinds of nitrogen forms (ni-trate nitrogen and ammonium nitrogen)and five nitrogen levels (0,105,210,315,420 mg/L)on content of ni-trogen in different parts of Medicago sativa L.cv.Gannong No.3 and Medicago sativa L.cv.Longdong were studied at seedling stage by sand culture method.The results showed that the content of NO-3 -N,the content of NH +4 -N and total nitrogen content in different parts of alfalfa under nitrogen treatments were significantly high-er than that of CK(P <0.05).Gannong No.3 and Longdong had same variation of nitrogen content in different parts.The variation showed a trend of increased first and then decreased with the increase of nitrogen level,but the maximum were not the same.Under the same nitrogen form and level,the content of NO-3 -N,the content of NH +4 -N and total nitrogen content in different parts of alfalfa showed:leaf > root > stem.Under the best treatment with NO-3 -210 to ‘Gannon No.3’,the content of NO-3 -N in leave,stem,root were 490 μg/g,385 μg/g,463 μg/g,respectively.they were 473 μg/g,355 μg/g,447 μg/g in alfalfa of ‘Longdong’.Under the best treatment with NH +4 -210 to ‘Gannon No.3’,the content of NH +4 -N in leave,stem,root were 212 μg/g,182 μg/g,1 94 μg/g.The content of NH +4 -N in stem and root of ‘Longdong’were 177 μg/g and 178 μg/g,but the best treatment in leaf was NH +4 -315,it was 189 μg/g.Besides,under the best treatment with NH +4 -315 to ‘Gannon No.3’,the total nitrogen content in leave,stem,root were 4.25%,1.7%,3.47%,repectively.The total nitrogen content in leaf and root of ‘Longdong’were 4.01% and 3.08%,but the best treatment in stem was NH +4 -210, it was 2.33%.For the same part,the nitrogen content of ‘Longdong’was higher than ‘Gannon No.3’in stem, but the content of NO-3 -N,NH +4 -N and total nitrogen in the other parts of ‘Gannon No.3’were higher than that of ‘Longdong’.