干旱胁迫和复水对梨幼树生理特性的影响

为了解植物干旱生理适应机制和恢复机制,以梨品种‘翠冠’和‘黄冠’幼树为试材,研究土壤干旱胁迫及复水条件下叶片光合参数、叶片相对含水量、叶片质膜透性、超氧化物歧化酶活性及脯氨酸含量的变化特性.结果显示:1)随着干旱胁迫的加剧,两品种的叶片净光合速率、气孔导度和蒸腾速率均呈下降趋势;‘翠冠’叶片胞间CO2浓度呈先降后升的趋势,而‘黄冠’呈持续下降趋势,但‘黄冠’光合作用的4项指标明显高于‘翠冠’;复水后,两品种的光合指标恢复显著,但均未超过对照水平.2)干旱胁迫引起两品种的叶片相对含水量急剧下降,叶片质膜透性和脯氨酸含量显著升高,超氧化物歧化酶活性呈先升后降趋势;复水后,两品种的4项指标不同程度地得以恢复,但大部分指标没有恢复到对照水平,其中‘黄冠’各项指标在复水前后的变化幅度比‘翠冠’更小.综合分析表明,‘翠冠’和‘黄冠’对干旱胁迫的响应存在差异,‘黄冠’对干旱逆境具有更强的适应能力.

Effects of Drought Stress and Rewatering on Physiological Characteristics of Pear Seedling

In order to understand the physiological adaptation mechanism and recovery mechanism of plant to drought,the physiological characteristics,including photosynthetic parameters,leaf relative water content,leaf membrane permeability,SOD activity and proline content of pear seedling under drought stress and rewatering conditions were investigated with the varieties ‘Cuiguan’ and ‘Huangguan’ as materials.The results showed that: 1) In the process of drought stress,leaf net photosynthetic rate,stomatal conductance and transpiration rate of the two varieties were decreased.Intercellular CO2 concentration was initially reduced and then increased in ‘Cuiguan’ leaf,while it showed a consistent downward trend in ‘Huangguan’.The four parameters of ‘Huangguan’ were significantly higher than those of ‘Cuiguan’,and the photosynthetic parameters of both varieties were significantly recovered after rewatering,however they could not recover to the normal level.2) Drought stress resulted in a sharp decrease of the relative water content and increase of the membrane permeability and proline content.And the superoxide dismutase activity in the leaves of both varieties was initially increased and decreased afterwards.Although these parameters could more or less recover after rewatering,they could not reach the normal level.This study suggested that the drought stress tolerance of ‘Huangguan’ was better than that of ‘Cuiguan’.