Mr Potassium nitrate, Silicon dioxide and Salicylic acid Mediation Increase Seedling Growth, Biochemical Attributes and Protective Enzymes Activities of Rice (Oryza sativa) var. FARO44 Under Drought

Abstract

Application of potassium nitrate, silicon dioxide and salicylic acid to seed are approaches that impart stress tolerance to germinating seeds and seedlings under stressful conditions. This study evaluated the effects of synergistic osmopriming and hormonal priming with 2.5% KNO₃+3.5% SiO₂, 3.5% SiO₂+1 mM SA and 2.5% KNO₃+1 mM SA on seed germination, seedling growth, antioxidant enzymes, protein, proline and malondialdehyde contents in 3-weeks old FARO44 rice seedlings under drought conditions induced by polyethylene glycol (PEG6000). Germination experiments were laid in a completely randomised design (CRD) with each treatment replicated five times. The results revealed that synergistic priming significantly seedling growth, antioxidant enzymes catalase, ascorbate peroxidase and superoxide dismutase activities in rice seedlings by 2 folds compared to unprimed seedlings under drought. Synergistic effect of priming methods improved protein and proline contents in rice seedlings while decreased malondialdehyde content. Osmopriming and hormonal priming with 2.5% KNO₃+3.5% SiO₂, 3.5% SiO₂+1 mM SA and 2.5% KNO₃+1 mM SA showed different responses, however, they were found to be effective in enhancing germination, seedling growth, antioxidant enzymes’ activities and biochemical attributes in rice seedlings under drought. Enhanced antioxidant enzymes’ activities, proline content and decreased malondialdehyde content in rice seedlings correlate with improved drought tolerance. Therefore, pre-soaking of FARO44 in 2.5% KNO₃+3.5% SiO₂, 3.5% SiO₂+1 mM SA or 2.5% KNO₃+1 mM SA is recommended for faster germination, growth of seedlings and drought tolerance in arid ecosystems.