Quantifying enzyme activities under anaerobic germination in traditional rice landraces to identify donors for direct seeded rice cultivation

Abstract

Climate change has increased environmental risks globally having an adverse effect on agriculture productivity. Among the abiotic stresses, anaerobic germination stress has been identified as a major stress for seed emergence, plant growth and food production. By understanding the manipulation of germination, antioxidant and fermentation enzymes, adaptations to anaerobic conditions can be improved. The ability of rice to emerge under oxygen deprivation is a determinant of anaerobic germination tolerance, critical for successful direct seeding. There is an urge to identify novel rice genotypes associated with better germination and higher enzymatic activities under anaerobic conditions in order to improve seedling establishment. In the present study, twenty-two rice genotypes were characterized for their anaerobic germination potential by assessing the activities of α- amylase, antioxidant enzymes viz., catalase and peroxidase, and fermentative enzyme viz., alcohol dehydrogenase and pyruvate decarboxylase under anoxic stress. α- amylase, catalase, peroxidase, alcohol dehydrogenase and pyruvate decarboxylase activities showed a significant positive association with seed germination under anaerobic conditions. Higher expression of five enzymatic activities confirms anaerobic germination stress tolerance in rice genotypes. This study identified four tolerant genotypes namely Karuppukavuni, Kalanamak, CBMAS 14065, and Kodavilayan, and two moderately tolerant genotypes namely TKM13 and Anna R4 based on principal component analysis and correlation analysis.