干旱胁迫下胡杨生理适应机制的研究

Physiological adapting mechanism of Populus euphratica under drought stress

胡杨具有很强的抗旱能力,是生长在沙漠地区少有的乔木树种,在我国主要分布于新疆的塔克拉玛干沙漠.为了更深入阐明胡杨的抗旱机制,我们对生长在新疆塔克拉玛干沙漠的天然胡杨林进行了实地调查、现场采样和室内相关实验.结果表明,在干旱胁迫下,胡杨叶片的蒸腾作用减少,气孔阻力增加.严重干旱胁迫后,叶片中的K+和Ca2+含量增加,分别为对照的1·43倍和2·99倍,而Mg2+和Na+变化不明显.和对照相比,中度干旱胁迫下胡杨叶片质膜H+--ATPase的质子转运活性没有差别,但严重干旱胁迫则使其活性降低,质膜H+--ATPase转运质子的能力下降.以上结果表明,胡杨可通过增加气孔阻力来降低胡杨叶片的蒸腾作用,选择性的吸收无机离子以及降低ATP消耗来适应干旱环境的胁迫.

Populus euphratica is well known for its high drought tolerance. It is one of the few tree species in establishing natural forests in the semiarid area and it mainly distributes in Takaramakan Desert of Xinjiang, China. In order to study the mechanism of drought tolerance of P. euphratica, the authors investigated, sampled and analyzed trees in Takaramakan Desert of Xinjiang. The results showed that the stomatic resistance increased as well as transpiration decreased in leaves of P. euphratica under drought stress. Compared with the control, under serious drought stress, the content of K^+ and Ca~ 2+ increased by 0.43 and 1.99 times, but there were no changes in the content of Mg~ 2+ and Na^+. The proton_pumping activity of plasma membrane bound H^+-ATPases hardly differed between the leaves of the control and P. euphratica plants under middle drought stress. However, under serious drought stress, the proton-pumping activity decreased. These results indicate that P. euphratica adapts to drought stress by various ways, such as decreasing transpiration of its leaves, absorbing inorganic ions selectively and reducing ATP consuming.