黄瓜幼苗内源激素和多胺对NO3-胁迫的适应性变化研究

通过溶液培养试验，研究了黄瓜幼苗内源激素和多胺对NO3-胁迫的适应性变化研究。结果表明，黄瓜幼苗在56~98 mmol/L NO3-浓度范围内培养7 d，根中ZR、GA和IAA含量均比对照显著升高；ABA含量降低。说明在此浓度范围内，根系有关酶活性首先被激活，从而引起促进生长的激素合成加速；而ABA等促进衰老的激素合成受抑，黄瓜生长势增加。叶中激素变化规律与根中正好相反，说明主导黄瓜幼苗生长的关键激素是根中相关激素的变化。当NO3- 浓度达140 mmol/L时，叶片中ZR、GA、ABA和IAA含量比对照极显著升高；而根中ZR、GA和IAA含量开始降低，ABA含量开始升高，幼苗生长受到严重抑制，从而加速了幼苗的衰老。叶片中Spm和Spd及根中Spm含量在一定浓度范围内，均随NO3-浓度的增加而升高，当NO3-浓度高于140 mmol/L时，其含量反而开始降低；叶片中Put含量均明显低于对照。而叶片和根中（Spd+Spm）/Put比值却显著高于对照。结果表明，黄瓜幼苗内各种激素之间通过此消彼长的变化过程，以提高对高浓度NO3- 胁迫的抗性。

Changes of endogenous polyamines and hormone responsing to NO3- stress in cucumber seedling

Changes of endogenous polyamines and hormone under different NO_3~- stress were studied in cucumber seedlings growing by solution culture method.Results showed that,after treating with 56 and 98 mmol/L NO_3~- for 7 days,zeatin fiboside(ZR),gibberellic acid(GA)and auxin(IAA)in cucumber roots were increased significantly,but abscisic acid(ABA)was decreased,which suggested that activating enzymes were related to hormone synthesis and caused the growth and development of cucumber seedlings.However,with the same treatment,ZR and GA were de- creased,but ABA was increased in cucumber leaves,which suggested that the endogenous hormone in roots was the ma- jor cause for the growth of cucumber seedlings.With the treatment of 140 mmol/L NO_3~-,ZR,GA,IAA and ABA in leaves were significantly higher than control,but in roots,ZR,GA and IAA was decreased,while ABA was increased, thus,it might stimulate senescence of cueumber seedlings.With the treatment of NO_3~- concentration between 56 and 98 mmol/L,spermine(Spm)and spermidine (Spd) in leaves and Spm content in roots were increased with concentration of NO_3~-,but decreased when concentration reached 140 mmol/L and higher.Under 140 mmol/L NO_3~- treatment,pu- trescine(Put)in leaves were significantly lower than control,but the ratio of(Spd Spm)/Put in both leaves and roots were remarkably higher than control.Thus,results suggested that changes and interaction of endogenous hormone(in- cluding polyamines)might be responsible for NO_3~- tolerance in cucumber seedlings.