不同氮素形态及其比例对菘蓝生物学特性的影响

采用砂培法栽培菘蓝，以菘蓝叶与根的干重、 主根长度与直径、 叶绿素含量和光合参数为指标，研究三种氮素形态，即硝态氮（NO-3-N）、 铵态氮（NH+4-N）和酰胺态氮［CO(NH2)2-N］四种不同浓度对菘蓝生物学性质的影响，为菘蓝栽培生产中高效利用氮肥提供理论依据。结果表明，氮素处理能增加菘蓝叶与根的干重，铵态氮对菘蓝主根长度及侧根数的影响最显著，而酰胺态氮与硝态氮对主根直径的影响相近，硝态氮对菘蓝的叶干重、 根干重与根冠比的影响最为显著；不同形态氮素处理能显著提高叶绿素含量与净光合速率，硝态氮对叶绿素和净光合速率有显著影响，酰胺态氮对气孔导度与蒸腾速率的影响最显著，铵态氮对叶片的胞间二氧化碳浓度有显著影响。不同形态氮素通过对菘蓝叶片的叶绿素含量和光合参数的影响实现对其生长状况的影响，其中硝态氮对菘蓝生长的影响最为显著。

Effect of different nitrogen forms and their proportion on biological characteristics of Isatis indigotica Fort

 To provide a theoretical basis of efficient utilization of nitrogen fertilizer for cultivation and production of Isatis indigotica,  effects of different nitrogen forms and their proportion on biological characteristics of I. indigotica were studied by using sand culture. There were four different concentrations of three nitrogen forms,  NH⁺₄-N,  NO^-₃-N and ［CO(NH₂)₂-N］. The dry weights of leaves and roots,  lengths and diameter of taproots,  chlorophyll content and photosynthetic parameters were used as indicators. The results show that the nitrogen treatments could increase the dry weights of leaves and roots,  the effect of NH4+\|N  on taproot length and number of lateral root is the most significant,  the effect of amide nitrogen and nitrate nitrogen on taproot diameters  is similar,  and the effect  of NO^-₃-N  on dry weights of leaves and roots and root/shoot ratio is the most significant. The nitrogen treatments could significantly improve the chlorophyll content and net photosynthetic rate which affect chlorophyll and net photosynthetic rate of nitrate nitrogen,  stomatal conductance and transpiration rate of amide nitrogen,  and the concentration of carbon dioxide in the intercellular of ammonium nitrogen,  respectively. Different nitrogen forms affect the growth through the effects of chlorophyll content and photosynthetic parameters,  and in which nitrate nitrogen is the most significant nitrogen form.