干旱胁迫与复水对块根紫金牛生理特性的影响

Effects of drought stress and rehydration on physiological characteristics of Ardisia corymbifera var. tuberifera seedlings

以岩溶特有药用植物块根紫金牛为试材,研究土壤水分胁迫及复水条件下其叶片光合参数、相对含水量、质膜透性、渗透调节物质含量的变化特性。结果表明:水分胁迫下,块根紫金牛的叶片净光合速率、气孔导度和蒸腾速率均几乎接近零点,但胞间CO2浓度上升,即非气孔因素限制是光合速率下降的主要原因。水分胁迫不影响块根紫金牛单位面积的总叶绿素和类胡萝卜素含量,但干旱处理的Chl a/b和Car/Chl分别显著低于和高于对照。水分胁迫下,块根紫金牛的叶片相对含水量、相对电导率和丙二醛含量显著增大,即膜系统受到一定的伤害;块根紫金牛叶片脯氨酸含量显著降低,可溶性蛋白含量无显著变化,可溶性糖含量显著增大,但增大幅度不大,说明其在干旱胁迫下的渗透调节能力较弱。复水处理后,块根紫金牛全部指标均能恢复到对照水平,说明其对干旱胁迫较为敏感,主要采取避旱策略。

In order to understand the physiological adaptation mechanism and recovery mechanism of karst plant under drought,this study was conducted with karst endemic medicinal plant Ardisia corymbifera.The physiological charac-teristics,including photosynthetic parameters,leaf relative water content,leaf membrane permeability,and osmotic regulation substances content of A.corymbifera seedlings under drought stress and re-watering conditions were stud-ied.The results showed that under water stress,the leaf net photosynthetic rate,stomatal conductance and transpira-tion rate of A.corymbifera were close to zero,but the intercellular CO2 concentration increased,suggesting that the non stomatal limitation was the main cause of the decline of photosynthetic rate.Water stress did not affect the total chlorophyll and carotenoid content per unit area of A.corymbifera,but the Chl a/b and Car/Chl was significantly lower and higher than that in control,respectively.Under water stress,the leaf relative water content,relative conduc-tivity and MDA content of A.corymbifera increased significantly,while the membrane system was inj ured.Under drought stress,the proline content of A.corymbifera reduced significantly,soluble protein content did not show sig-nificant change,the soluble sugar content increased significantly,but increased marginally,these results suggested that osmotic adj ustment ability of A.corymbifera to drought was weak.After re-watering,all these parameters could re-cover and reach the normal level.This study suggested that A.corymbifera was sensitive to drought stress and mainly employed avoidance strategies.