壳聚糖对蝴蝶兰幼苗耐热性的诱导作用

The inducing effect of chitosan on heat resistance of Phalaenopsis seedlings

为了评价壳聚糖对蝴蝶兰幼苗耐热性的诱导效应,分别采用0(以无壳聚糖为对照)、25、50、100、200和400 mg·L^(-1)壳聚糖溶液处理蝴蝶兰幼苗,并置于42℃下胁迫3 d,测定了蝴蝶兰幼苗的生理指标变化。结果表明:当壳聚糖浓度由25 mg·L^(-1)增大到100mg·L^(-1)时,蝴蝶兰幼苗叶片的SOD、POD、CAT活性、脯氨酸、可溶性糖、叶绿素和类胡萝卜素含量不断增加,而质膜透性和丙二醛含量不断下降,但可溶性蛋白含量没有显著变化;特别是在100 mg·L^(-1)时,SOD、POD和CAT活性、脯氨酸、可溶性糖、叶绿素和类胡萝卜素含量增加到最大值且极显著高于对照,而质膜透性和丙二醛含量下降至最小值且极显著低于对照,蝴蝶兰幼苗遭受了轻微的高温伤害;随着壳聚糖浓度由200 mg·L^(-1)增大至400mg·L^(-1),SOD、POD和CAT活性、脯氨酸、可溶性蛋白、可溶性糖、叶绿素和类胡萝卜素含量极显著下降,而质膜透性和丙二醛含量极显著上升,蝴蝶兰幼苗的受害趋于加重;由此可见,100 mg·L^(-1)壳聚糖处理能显著提高蝴蝶兰幼苗的耐热性。

This study aims to assess the effect of chitosan on heat resistance of Phalaenopsis seed- lings. Phalaenopsis seedlings were treated with chitosan at 0 （without chitosan addition as con- trol）, 25, 50, 100, 200, 400 mg·L^-1 respectively, at 42 ℃ for 3 days, and then the physio- logical changes in Phalaenopsis seedlings were determined. The results showed that with increas- ing the chitosan concentration from 25 to 100 mg ·L^-1, the activities of superoxide dismutases （ SOD）, peroxidases （POD） and catalase （ CAT）, and the contents of proline, soluble sugar, total chlorophyll and carotenoid in Phalaenopsis seedling leaves increased gradually, while the membrane permeability and malondialdehyde （MDA） content of the leaves declined gradually, but no significant change was found in the content of soluble protein. In treatment with 100 mg ·L^-1 chitosan, the activities of SOD, POD and CAT and the contents of proline, soluble sugar, to- tal chlorophyll and carotenoid in Phalaenopsis seedling leaves reached their peak values and were significantly higher than those of the control （ P〈0.01 ） , whereas the membrane permeability and MDA content of the leaves showed the lowest values and were significantly lower than those of the control （P〈0.01）, and the Phalaenopsis seedlings suffered a slight heat injury. With increasing chitosan concentration from 200 to 400 mg·L^-1 , the activities of SOD, POD and CAT, and the contents of proline, soluble protein, soluble sugar, total chlorophyll and carotenoid of the leaves decreased significantly （P〈0.01）, whereas the membrane permeability and MDA content of the leaves increased significantly （P〈0.01）, and Phalaenopsis seedlings tended to suffer more serious heat injury. According to the results obtained, it is concluded that treatment with 100 mg ·L^-1 chitosan can significantly improve heat-resistance of Phalaenopsis seedlings.