间隔干旱胁迫对金钗石斛生理生化特性的影响

Effect of Repeated Drought on Physiological and Biochemical Characteristics in Dendrobium nobile

自然状态金钗石斛常遭受到间隔干旱胁迫,本研究采用聚乙二醇(PEG-6000)模拟间隔干旱(干旱后复水,再干旱),分别选取60%和80%的空气相对湿度下的一年生和两年生的金钗石斛进行培养,测定金钗石斛在间隔干旱条件下膜透性、丙二醛、游离脯氨酸、可溶性糖含量和水势的变化情况。结果表明:两次干旱时,随着PEG-6000浓度增大,一年生金叉石斛在两种空气湿度培养材料的叶片膜透性、丙二醛含量上升,水势下降,游离脯氨酸和可溶性糖含量增加,且60%的空气湿度>80%的空气湿度。轻度干旱(15%PEG-6000)下,与第一次干旱相比较,第二次干旱时,叶片膜透性、丙二醛含量的增长幅度及水势下降幅度较低,游离脯氨酸及可溶性糖含量增长幅度较高。两年生金叉石斛第一次干旱时,60%空气湿度下生理指标>80%空气湿度下生理指标,但是第二次干旱时材料干旱死亡,所以一年生金钗石斛受到一定程度的干旱胁迫后经过恢复可提高其对再次干旱胁迫的耐受性,但是60%相对湿度条件下间隔干旱对两年生金叉石斛影响较大。本研究为进一步阐明金钗石斛对其生长地区间隔干旱环境的响应,为金钗石斛的栽培管理及抗性研究提供理论依据。

Dendrobium nobile in nature are usually subject to repeated drought stress. Repeated drought was simulated by using polyethylene glycol(PEG-6000)(re-watering after drought, drought again) in the study. The project selected and bred 60% and 80% of the air relative humidity of the annual and biennial of D. nobile,respectively, and determined the changes of membrane permeability, malondialdehyde, free proline, soluble sugar content and water potential in D. nobile under repeated drought stress. Results showed that with the increase of PEG-6000 concentration, leaf membrane permeability and MDA content in the annual D. nobile cultured in two kinds of air humidity material increased, and the water potential dropped with two times of droughts. The free proline and soluble sugar content increased, and 60% of the air humidity was greater than 80% of the air humidity.Under mild drought(15% PEG-6000), compared with the first drought, the increasing range of leaf membrane permeability and malonaldehyde content as well as the falling range of water potential were all lower during the second drought, while the content of free proline and soluble sugar increased significantly. It was found that at the first drought of biennial D. nobile, the physiological index under 60% air humidity was higher than that under 80%air humidity. However, D. nobile died in the second drought. Therefore, annual D. nobile could improve its resistance to secondary drought stress after recovering from a certain degree of drought stress, but the repeated drought under the 60% relative humidity condition had relatively significant influence on biannual D. nobile. This study might provide a theoretical basis for further elucidating the response of D. nobile to the intermittent arid environment in other growing regions, as well as providing theoretical basis for the research on the cultivation management and resistance research of D. nobile.