NaCl胁迫对胡杨幼苗叶主要渗透调节物质的影响

Effects of NaCl Stress on Main Osmotic Adjustment Substances in the Seedling Leaves of Populus euphratica

以胡杨幼苗抗盐能力为研究目标,采用盆栽沙培,以2年生胡杨实生苗为试验材料,设置5个NaCl浓度0.3%、0.6%、0.9%、1.2%和2.0%进行盐胁迫试验,在盐处理后的1、5、10d和20d采叶样测定胡杨幼苗叶片中脯氨酸(Pro)、可溶性蛋白、超氧化物歧化酶(SOD)、Na+、K+和Cl-的含量。通过不同NaCl浓度胁迫下胡杨幼苗叶生理生化指标变化,探讨胡杨幼苗的耐盐生理机制,为胡杨造林与资源的合理利用提供理论依据。结果表明:1)盐胁迫下,胡杨幼苗叶片中Pro含量逐渐增加,在2%盐浓度胁迫下迅速积累,同时,胡杨幼苗叶Pro含量受盐浓度与胁迫时间影响非常显著。2)胡杨幼苗在中、低NaCl盐浓度处理下,SOD活性基本趋于降低的趋势,但2%NaCl盐浓度处理,SOD活性增加显著,胁迫时间对胡杨幼苗叶SOD活性的影响大于盐浓度。3)胡杨幼苗叶片中可溶性蛋白含量在不同胁迫时间下总体随盐浓度的增加呈先降低后增加的趋势。4)盐胁迫下,胡杨幼苗叶片中K+含量降低,Na+和Cl-含量增加。从浓度与胁迫时间效应分析,胡杨叶片中K+含量随着胁迫浓度的增加和胁迫时间的延长呈降低趋势,总体K+含量的降低幅度不大。Na+含量在NaCl低浓度胁迫下,随时间效应不显著,在高浓度胁迫下,胁迫时间累积效应显著。盐胁迫下,胡杨叶片中的Cl-含量随着NaCl浓度的增加和胁迫时间的延长而增加,0.3%、0.6%NaCl低盐浓度胁迫时Cl-含量增加幅度较小,2%NaCl盐浓度处理下增加幅度较大。表明胡杨幼苗叶片生理生化过程对盐分具有一定的适应性,通过增加Pro、可溶性蛋白、SOD活性含量,保持较高的K+的吸收水平,增强了胡杨幼苗抵御盐胁迫的能力;在盐胁迫下,胁迫时间的延长会加重盐胁迫程度,具有累积效应。

The two-year seedlings of Populus euphratica planted in sand pots were irrigated by water with different concentrations of NaCl：0.3%,0.6%,0.9%,1.2% and 2.0%,respectively,and the no NaCl treatment as controls.The leaves were collected in day 1,5,10,and 20 after salt treating to measure the proline（Pro）,soluble protein,superoxide dismutase（SOD）,Na^＋,K^＋and Cl^-contents for learning the tolerating-salt mechanism of the seedlings.The results are as follows：1）proline contents in the leaves increased gradually with the increase of salt concentration,and with 2% NaCl treatment,the proline contents increased rapidly.Furthermore,salt concentration was a more important factor than salt-stress timeto affect proline contents.2）The SOD activity in the leaves decreased under 0.3%,0.6%,0.9% NaCl concentration treatments,but it increased significantly under 2% NaCl concentration treatment.Saltstress time affected SOD activity more significant than that of salt concentration.3）The soluble protein contents in the leaves decreased at first and then increased with the increase of NaCl concentration.Salt concentration affected soluble protein contents more significant than that of salt-stress time.4）K^＋content in the leaves decreased gradually with NaCl salinity increasing or salt-stress time prolonging moderately.Otherwise,the Na^＋and Cl^-contents in the leaves increased gradually with NaCl salinity increasing or salt-stress time prolonging moderately.In high salt salinity treatments,the salt stress time was a more important factor affecting Na^＋and Cl^-absorption than that in low concentrations.Therefore,physiological process in the seedling had some ways to adapt to salt stress by increasing proline content,soluble protein content and SOD activity significantly and keeping a high level of K^＋to enhance the seedling ability to enduring salt.Seedlings would be suffered in high salt salinity soil more seriously with salt stress time prolonging.