Enhancement of Germination, Seedling Growth, and Oxidative Metabolism of Barley under Simulated Acid Rain Stress by Exogenous Trehalose

This study investigated the effects of simulated acid rain on germination, seedling growth, and oxidative metabolism in barley (Hordeum vulgare L.). Barley seeds were separately soaked in trehalose solutions of 5, 10, and 15 mM concentration or distilled water (the control). Results showed inhibited seed germination, increased foliar damage, decreased chlorophyll content, damaged roots, and delayed seedlings growth in barley when exposed to acid rain at pH 3.0. Although the treatment with acid rain increased the activities of peroxidase, catalase, and plasma membrane H+-ATPase, membrane permeability and malondialdehyde content still increased significantly. However, the addition of exogenous trehalose significantly alleviated the negative effect of acid rain on growth inhibition of barley and increased total leaf chlorophyll due to an increase of chlorophyll a content. Trehalose also increased catalase and peroxidase activity, which led to an increase in the antioxidant capacity and a balance in production and scavenging of free radicals. Plasma membrane H+-ATPase activities of roots and leaves also increased with trehalose and maintained stable pH of the cytoplasm of roots and leaf cells under low pH. The 10 mM trehalose pretreatment was enough to alleviative the negative effects of acid rain in barley.