| Zingiber Officinale is an important spice crop, and has been used as traditional Chinese medicine. Drought is considered to be one of the most an important environmental factor that causes sharp decrease in crop productivity and thus pose a serious problem for agriculture.Abscisic acid (ABA) is necessary for adaptation of plants to Various environmental stresses including drought stress. However, effect of exogenous ABA application on growth, physiological indices of ginger has not been investigated so far. In particular, the responses of rhizospheric soil of plant under drought stress to exogenous ABA remain uncertain. Thus, there is urgent need to study the mechanism of drought tolerance of Zingiber Officinale plants. In addition, it is also of great necessity and significance to increase Zingiber Officinale productivity through taking all sorts of effective measures to enhance its drought tolerance. In the present study, the effects of different concentration exogenous ABA (50μM and 100μM ) on plant growth, physiological indices and rhizospheric soil of Zingiber Officinale under drought stress have systematically studied in details. The main results showed that: 1. Drought significantly decreased the biomass of leaf, stem, and root compared with those of well watered plants. Low concentration ABA(50μM) improved growth parameters while high exogenous ABA(100μM) further suppressed growth of ginger under drought stress.2 Drought depressed the activities of SOD, CAT, POD, the content of AsA and chlorophyll while increased APX activity, contents of MDA and proline and soluble sugar content. Low ABA concentration (50μM) application significantly increased the antioxidant enzyme activity and AsA level, and decreased MDA content, which indicate that low concentration of exogenous ABA ameliorated the growth and oxidative damage of ginger under drought stress.3 Drought increased the contents of total acids, total amino acids and phenolic acid substances while decreased total sugar content compared with those of well watered plants. Low concentration ABA increased the total sugar content and decreased the content of total acids, total amino acids and phenolic acid substances of root exudates. However, high concentration ABA has little effect on root exudates of ginger.4 Drought decreased bacteria and fungi number while increased the actinomycetes number in rhizosphere soil of ginger. 50μmol/LABA application increased actinomycetes and fungi number while 100μmol/L ABA lightly decreased actinomycetes number.5 Drought depressed the activities of sucrase, protease, urease, neural phosphatase and increased polyphenol activity of rhizosphere soil of ginger. 50μmol/LABA application increased actinomycetes and fungi number, the activities of sucrase, protease, urease, neural phosphatase and polyphenol oxidase activity. High concentration ABA decreased acid phosphatase, sucrase activity, protease activity and increased polyphenol oxidase activity.6 There were significant correlations between physiological indices, root exudates and biomass, microbe number in rhizomspheric soil. The varieties of growth and physiological processes induced by drought and exogenous ABA application affect microbe number and activities of soil enzymes. These suggested that the changes in microbe number and activities of soil enzymes might affect nutrient avialblity and growth of the plants.
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