Abstract
Drought stress is a major factor limiting crop growth and yield. Hydrogen peroxide (H2O2) is known as a signalling molecule in the plant cell in which activates multiple physiological changes that play essential roles in tolerance mechanism. This study investigated the effects of seed priming with H2O2 on growth, some physiological characteristics and antioxidant enzyme activities in rice seedling under drought stress. Rice (Oryza sativa L.) cv. Khao Dawk Mali 105 seeds were primed with 0 (distilled water), 1, 5, 10, and 15 mM H2O2 and grown for 21 days. The seedlings were subjected to drought stress by withholding water for 7 days. The results showed that priming with low concentrations of H2O2 improved plant growth and biomass as well as relative water content, malondialdehyde content, electrolyte leakage. Priming with H2O2, however, had no beneficial effect on chlorophyll content, proline and leaf total soluble sugar. Seed priming with appropriate levels of H2O2 also enhanced antioxidant enzyme activities including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase (GPX). It is concluded that seed priming with 2-10 mM H2O2, is beneficial for enhancing drought tolerance in rice seedling by increasing antioxidant capacity, which in turn reduces oxidative stress and damages to the cellular components.
Highlights
Rice (Oryza sativa L.) is a staple crop food for billion people worldwide, and a major export crop of Thailand
The seedlings had higher root and shoot fresh weights when primed with 1, 2 and 5 mM H2O2 compared to unprimed group but were lower in 10 and 15 mM H2O2
Root and shoot dry weights were higher in the seedlings primed with 1, 2 and 5 mM H2O2 but were lower in the seedlings primed with 10 and 15 mM H2O2
Summary
Rice (Oryza sativa L.) is a staple crop food for billion people worldwide, and a major export crop of Thailand. Rice production in Thailand, is primarily affected by drought stress because most of the rice-growing area is under rainfed condition. Drought is abiotic stress limiting growth and productivity of plants. Drought stress affects many physiological processes including growth, photosynthesis, enzyme activity, reactive oxygen species (ROS) production and membrane integrity (Farooq et al, 2009; Li et al, 2011b). It has been known to play a vital role in stress tolerance by acting as a secondary messenger in the plant when its level presents in low concentration (You and Chan, 2015; Farooq et al, 2017). The previous study suggested that H2O2 application in crop plants improve plant performance under stressful condition, such as Cakile maritima, mustard, rice variety ADT (R) 49 and Wheat (He and Gao, 2009; Mohammad and Fujita, 2013; Hameed and Iqbal, 2013; Ellouzi et al, 2017).
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