干旱胁迫下牛心朴子幼苗的抗旱生理反应和适应性调节机理

Physiological response and adapting mechanism of Cynanchum Komarocii seedlings under drought stress

为探讨牛心朴子抵御干旱的生理反应和适应性调节机理,对其幼苗进行不同PEG(聚乙二醇)浓度和不同胁迫时间的处理。结果表明:各项生理反应主要受PEG浓度的影响,而受胁迫处理时间长短的影响较小;在10%～20%的PEG浓度胁迫下,叶片相对含水量、根系活力、根系及地上部生长量下降的幅度较小,根冠比、可溶性糖、Pro、K+上升的幅度也较小,表现出耐旱的生理特性;在25%的PEG浓度胁迫下,上述指标发生了很显著的变化,叶片相对含水量、根系活力明显下降,可溶性糖最大含量出现的时间较20%浓度胁迫提早3d,且较20%PEG浓度时的最大含量低,并在延长处理3d后进一步下降,根系和地上部的生长受到严重抑制,且地上部影响大于根系,根冠比显著增大,胁迫后期趋于恒定状态,生长几乎完全停止;在PEG浓度为25%的严重干旱胁迫下,处理9d时,其渗透调节物质的累积量开始下降,致使渗透调节效应减弱。研究表明,25%的PEG浓度是牛心朴子抗旱胁迫的最大适应阈值。

The Cynanchum Komarovii seedlings were treated with PEG under different concentration and treated time in order to inquire into their physiological responses and adaptive regulation mechanism to drought resistance. The result showed that the physiological responses were mainly affected by concentration of PEG and less affected by time of PEG treatment. Under 10%~20% PEG treatment, relative water content of leaves, root activity, and growth rate of root and shoot showed a little reduction, and ratio of root/shoot, content of soluble sugar, content of Pro and potassium showed a little increase. But under 25% PEG treatment, all these indexes showed marked changes.Relative water content of leaves and root activity displayed a apparent reduction. The time of highest content of soluble sugar appeared was three days earlier, and the content of soluble sugar was less than that under 20% PEG treatment. After the treatment period were prolonged for three days, the content of sugar reduced again. The growth of root and shoot were retarded severely and the ratio of root/shoot was increased manifestly. The ratio of root/shoot tended to become stable and the growth almost stopped at the later period of PEG treatment. The osmotic regulation capacity of Cynanchum komarovii was weakened when treated for 9 days under severe water stress of 25% PEG, indicating that 25% PEG concentration was the threshold value of Cynanchum komarovii under the drought stress.\;