Abstract
Drought is an important environmental constraint limiting the productivity of many crops worldwide. Seedling tolerance to drought is crucial for crop growth and development through the whole season under water-limited condition. Experiments were conducted to investigate the effects of seed pretreatment by hydrogen peroxide (H2O2) on drought tolerance in wheat (Triticum aestivum L.) seedlings. H2O2-pretreated seeds exhibited 56% higher in germination rate than the water-pretreated seeds (control) under PGE-induced drought condition. Level of H2O2 in seedlings arising from H2O2-treated seeds grown under drought stress was markedly lower than the controls, indicating the operation of antioxidant system in them. These seedlings exhibited increased growth characteristics including higher net photosynthetic rate, leaf area and dry weight. Moreover, H2O2 treatment improved water use efficiency (WUE) and proline level. H2O2 pretreatment enhanced the membrane stability, as revealed from greatly reduced membrane damage rate (MDA) and malondialdehyde (MDA) content. The seedlings showed the higher expression of antioxidative enzyme such as catalase (CAT) and ascorbate peroxidase (APX). The present data suggest that H2O2, a stress signal, could trigger the activation of antioxidants in seeds, which persists in the seedlings to alleviate the oxidative damage, leading to improvements in physiological attributes for the seedling growth under drought. Key words: wheat (Triticum aestivum L.), seed pretreatment, H2O2, signaling, drought tolerance, membrane permeability, antioxidative system.
Highlights
Water shortage is increasingly becoming a major constraint for crop productivity worldwide (Wollenweber et al, 2003)
Healthy seeds were surface sterilized with 75% ethanol for 2 min followed by repeated washings with ddH2O. 200 clean-healthy seeds per replicate were transferred to H2O2 solution at different concentrations (20, 40, 60, 80, 100, 120 and 140 mM)
In order to detect the optimized concentration of H2O2 for enhancing wheat seedling growth, the seeds were treated with different levels of H2O2 and subsequently, the characteristics of seedling growth were recorded
Summary
Water shortage is increasingly becoming a major constraint for crop productivity worldwide (Wollenweber et al, 2003). Pre-sowing treatment and priming of plant seeds are easy, low cost, low risk and effective approaches to enhance plant tolerance to the stressful environments (Wahid and Shabbir, 2005; Ashraf and Foolad, 2005). A number of priming strategies include seed treatments with osmotica, inorganic salts, hormones or water, respectively. These seed pretreatments are reported to induce pre-germination changes, which usually have beneficial effects on seed germination rate and uniformity, seedling growth and development, under stressful conditions (Parera and Cantliffe, 1991; Ashraf and Foolad, 2005)
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