不同种源乌桕幼苗对干旱胁迫的生理响应

以不同种源1年生乌桕幼苗为材料,采用盆栽控水试验研究了持续干旱条件下其外部形态及主要生理指标的变化,探讨各种源乌桕的抗旱性特性与差异。结果显示:(1)随着干旱持续时间的延长,各种源乌桕幼苗生长均受到不同程度抑制,外形表现出明显的缺水特征;其叶片相对含水量逐渐减小,复水后明显回升。(2)在极度干旱条件下(停水后第12天),幼苗叶片净光合作用速率仍维持一定的强度,而且细胞膜透性的变化不显著;在干旱胁迫条件下,幼苗叶片的过氧化物酶和超氧化物歧化酶活性增强,可溶性糖和可溶性蛋白质质量分数增加,丙二醛含量上升,脯氨酸积累,复水后呈现相反的变化趋势。(3)极度干旱条件下,不同种源乌桕幼苗间除丙二醛和相对电导率外,其它生理指标的变化差异显著或极显著,即不同种源具备比较稳定的抗旱性差异。(4)采用隶属函数法对不同种源幼苗的抗旱性分析发现,安徽黄山、河南商城两种源综合评价指数最大,为抗旱性较强的种源。研究表明,各种源乌桕幼苗能够通过调控自身保护酶活性和渗透调节物质含量来有效缓解干旱胁迫的伤害,从而表现出较强的抗旱性和适应性,但种源间存在稳定的差异,并以安徽黄山和河南商城种源抗旱性较强,可应用推广于季节性干旱区造林。

Physiological Response of Sapium sebiferum Seedlings from Different Provenances to Drought Stress

Changes of external morphology and physiological indexes of one year old seedlings of Sapium sebiferum from different provenances under continuous drought were studied.The results showed that:(1)The growth of S.sebiferum seedlings was negatively influenced by different degree of drought stress,and external morphology characteristics of water shortage were distinct.Relative water content of leaves decreased under drought stress,but that raised again after rewatering;(2)Under extreme drought stress (at the 12th day),net photosynthetic rate of seedlings maintained certain intensity,and the change of relative membrane permeability was not obvious,so resistance of S.sebiferum seedlings to drought stress was stronger;Among drought period both SOD and POD activities enhanced,contents of soluble sugar and soluble protein increased,MDA content climbed,proline accumulated,and the change reversed after rewatering,so seedlings could maintain normal osmotic adjustment ability to drought;(3)At the same time experiment showed that changes of physiological indexes except for MDA and relative conductivity rate of S.sebiferum seedlings from different provenances were significantly different (P<0.05),some was very significantly different (P<0.01).Under extreme drought stress,there were stable genetic variations among them;(4)Through comprehensive analysis of Fuzzy,it was concluded that the tolerating ability to drought of both Huangshan Anhui and Shangcheng Henan provenance were the strongest among 5 provenances,as their synthetic evaluation index were the biggest comparatively,and their cultivation and applying in seasonal arid region should be extended.