Physiological and Biochemical Mechanisms of Improving Salt and Drought Tolerance in Okra Plants Based on Applied Attapulgite Clay

Abstract

Attapulgite clay (AC), which is rich in good adsorption, catalysis, rheology and heat resistance, is an important mineral resource. However, the roles of AC in regulating stress tolerance of plants have not been investigated. In this study, culture pot experiment was used to analyze the effects of AC applied into the soil on growth and physiological metabolism of okra plants. The applied AC significantly enhanced salt and drought tolerance of okra plants. Component analyses showed that the significant increases of ABA, proline, soluble protein, soluble sugar and photosynthetic pigment content, as well as the significant decreases of hydrogen peroxide, superoxide anion radical and malondialdehyde content were observed in okra plants grown in the soil with applied 30 g/kg AC under salt and drought stresses. Enzymatic analyses indicated the activities of 9-cis-epoxycarotenoid dioxygenase, pyrroline-5-carboxylate synthase, superoxide dismutase and peroxidase were also significantly increased under salt and drought stresses. These results demonstrate that the applied AC can alleviate damage caused by salt and drought stresses, leading to the enhanced salt tolerance and drought tolerance of okra plants. The AC has the potential to be used to develop plant growth regulators to enhance the tolerance to abiotic stresses in plants.