氮素形态对半夏生长及生物碱和总有机酸累积的影响

研究氮素形态对半夏光合特性、相关酶活性、总生物碱及总有机酸累积的影响，为半夏氮肥的合理施用提供依据。采用无土栽培方法栽培半夏，测定同一氮素水平不同氮素形态处理下，半夏叶片叶绿素含量、相关光合参数、硝酸还原酶（NR）活性、硝态氮含量、块茎中总生物碱及总有机酸含量。结果表明:半夏叶片光合色素含量随铵硝比增大呈先升后降趋势；铵硝比为75∶25时，叶绿素a和类胡萝卜素含量最高；铵硝比为25∶75，叶绿素b含量最高，同时，净光合速率、气孔导度和蒸腾速率达最大值；随着NO3--N比例降低，NR活性整体呈现下降趋势；块茎总生物碱含量，全硝营养下含量最高，随着NO3--N比例降低，呈现降低趋势；而随着NH4+-N比例增加，半夏块茎中总有机酸呈现上升的趋势。结论:铵态氮、硝态氮复合施用有利于半夏的生长，较高硝态氮比例有利于总生物碱的积累，较高铵态氮比例有利于总有机酸的累积。

Effects of nitrogen form on the growth and accumulation of total alkaloid and free total organic acids of Pinellia ternata

To study the effect of nitrogen form on photosynthetic characteristics,nitrogen metabolism related enzymes activity,accumulation of total alkaloid and free total organic acids of Pinellia ternata.A sand culture experiment was conducted and the content of chlorophyll,photosynthesis parameters,nitrate reductase(NR) activity,the content of nitrate in the leaves as well as the accumulation of total alkaloid and free total organic acids in the tuber were determined.Results: The content of photosynthetic pigment in the leaves of Pinellia ternata increased with the NH+4-N/NO-3-N ratio increasing initially,then decreased.The contents of chlorophyll-a and carotenoid were the highest at the NH+4-N/NO-3-N ratio of 75 ∶ 25;The content of chlorophyll-b,net photosynthetic rate,stomatic conductance and transpiration rate were the highest at the NH+4-N/NO-3-N ratio of 25 ∶ 75.The activity of nitrate reductase decreased with the increase NO-3-N ratio.The accumulation of total alkaloid in the tuber was the highest with the NH+4-N/NO-3-N ratio of 0 ∶ 100,and declined with the decrease of NO-3-N ratio.The content of free total organic acids increased with the enhancement of NH+4-N ratio.Proper ratio nitrogen fertilization is propitious to the growth of Pinellia ternata.A higher proportion of NO-3-N is beneficial to the accumulation of total alkaloid;while a higher proportion of NH+4-N is beneficial to the accumulation of total free organic acids.