| Abstract |
1. Background
Rice is an important staple crop for billions of people. However, the cultivation usually exposed to drought stress which is the factor that limited plant growth. The previous evidence suggested that the low concentration of hydrogen peroxide (H2O2) plays an important role in abiotic stresses. It regulates the antioxidant system and the other drought tolerance mechanism via ABA signaling (Saxena et al., 2016). Although the studies about the effects of H2O2 on drought tolerance related to physiological characteristics were well-established; however, various concentrations of H2O2 were used and the suitable concentration for rice is not reported. Therefore, this study aimed to investigate the effects of different concentrations of H2O2 on the physiological characteristic related to drought tolerance by foliar spray method.
2. Results
Rice seedlings exposed to drought stress dramatically decreased RWC and total chlorophyll content but increased EL and MDA content compared to the seedlings under well water condition. Foliar spray with H2O2 benefits to rice seedlings by improving several physiological characteristics. It is well-known that H2O2 act as the signaling molecule under drought stress, many mechanisms related to drought tolerance are activated during this condition including enzymatic-antioxidant system and abscisic acid signaling. The main antioxidant enzymes including SOD and CAT were induced under drought stress in order to remove the reactive oxygen species. Foliar spraying with all concentration of H2O2 tended to increase these enzymes activities compared to distilled water spraying. The similar trend was found in MDA content and EL, the results indicated that H2O2 spraying slightly decreased the oxidative damage compared to distilled water treatment. In addition, the advantage in improving total chlorophyll content was found in 1-2 mM of H2O2 spraying compared to distilled water group. In summary, H2O2 plays a vital role during drought stress by enhancing antioxidant system as well as maintaining the water content. H2O2 is involved in ABA signaling which is related to stomatal closure. This may help H2O2 treated seedlings maintaining higher RWC. As a result, higher antioxidant enzymes activities were higher in H2O2 treated group; moreover, the reduction of EL and MDA were observed. The results from this study indicated that the most effective H2O2 concentration in this study was 1 mM.
Keywords: Foliar spray, Drought stress, Hydrogen peroxide
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Publication
Journal Publication
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