干旱胁迫对苹果树苗活性氧代谢及渗透调节的影响

Effects of Drought Stress on Active Oxygen Metabolism and Contents of Osmotic Adjustment Substances in the Leaves of Apple Seedling

以1年生"红富士"苹果苗为试验材料,采用盆栽控水的方法,研究了土壤干旱和复水过程中苹果树苗叶片活性氧代谢及渗透调节物质含量的变化,探讨苹果树苗适应逆境干旱的可能生理机制。结果表明:干旱胁迫条件,果叶片产生速率、H2O2和MDA含量随胁迫时间和程度而逐步增加,证明干旱胁迫导致活性氧积累,引膜脂过氧化作用;产生速率与MDA含量呈显著相关,H2O2含量与MDA含量呈极显著相关。在干旱处理过程中,SOD、POD和APX 3种保护酶活性呈现一定规律的变化。在干旱的初期(轻度干旱)其活性呈轻微升高或降低趋势,经短暂的适应后,其活性明显上升,通常在接近严重干旱时活性随之降低。这表明适度干旱条件下保护酶活性的提高能有效清除植株体内过多的活性氧,提高了苗木适应干旱胁迫的能力。干旱条件下脯氨酸、可溶性糖含量显著升高,是主要渗透调节物质。经过一定时期的干旱处理后恢复水分供应(复水处理),几种保护酶活性和渗透调节物质的含量均降低,但总体仍然明显高于对照,这说明经适度的干旱胁迫能提高或增强相关抗逆生理基础,对树苗以后的生长和适应逆境是有利的。

One-year-old potted apple（Malus domestica Borkh.CV.Red Fuji） seedlings were used to investigate active oxygen metabolism and the changes of the contents of osmotic adjustment substances in the leaves under the drought stress,and to explore the possible mechanism of adapting draught stress of the seedlings.The results indicated that with the increase of time duration and stress intensity,the generating rate of superoxide anion,the contents of H2O2 and MDA gradually increased,indicating that the drought stress results in the accumulation of active of active oxygen,and leads to the lipid peroxidation of the membrane.Most significant correlations were observed between the generating rate of supper oxygen anion and MDA content,and between the contents of H2O2 and MDA.The contents of MDA,H2O2,proline,soluble sugar,and the generating rate of super oxygen anion increased under draught stress,and decreased after rewatering.The content of soluble protein had the maximum value at the 7th day under drought stress,then decreased after rewatering.It was concluded that under moderate drought stress could protect the plasma membrane stability by increasing the activities of protective enzymes and promoting the contents of organic osmotic adjustment substances.