外源氮对盐胁迫条件下长春花生长和氮代谢途径的影响1）

以药用植物长春花（ Catharanthus roseus （ L．） G．Don）为对象，研究不同形态外源氮供应条件下，长春花生长发育与体内氮代谢响应盐胁迫的变化特点。结果表明，无盐胁迫条件下，不同形态氮源供应对长春花生长影响不显著，但硝态氮与氨态氮混合供应的情况下，硝酸还原酶（ NR）和谷氨酰胺合成酶（ GS）的活性及游离氨基酸总质量分数显著高于其他氮源条件下的；在盐胁迫条件下，硝态氮和氨态氮混合供应显著增加了叶片生物量积累，同时，NR活性也显著提高。总体上，混合氮源供应可以减少盐胁迫对长春花的伤害。这种作用可能与氮代谢过程中关键酶活性的增加有关，特别是与氨代谢有关的酶有关，适量的氨离子可以节省植物代谢硝态氮的能量。

Effects of Exogenously Supplied Nitrogen on Growth and Nitrogen Metabolism of Periwinkle (Catharanthus roseus (l.) g.Don) under Salt Stress

With the periwinkle (Catharanthus roseus (L.) G.Don), we studied the growth characteristics and nitrogen metabolismof plant under exogenous nitrogen in different forms of exogenous nitrogen under salt stress.The effect of nitrogensource in different forms on the periwinkle plants upon non-salt stress was not significant.But nitrate reductase (NR) andsynthetase (GS) activity and total free amino acid amount were significantly higher when nitrate nitrogen and ammoniumnitrogen were mixed to be supplied.Under salt stress, the leaf biomass accumulation was significantly increased in mixtureof nitrate nitrogen and ammonium nitrogen.NR activity was improved significantly .Overall, when the nitrogen source wasmixed to be supplied, plant damage of salt stress was reduced on periwinkle.The key enzyme activity increased was relatedto ammonium metabolism enzymes in nitrogen metabolism.The right amount of ammonium ion can save the energy of thenitrate nitrogen from plant metabolism.