Effect of Salinity Variation on the Quantity of Antioxidant Enzymes in Some Rice Cultivars of North Kerala, India

Rice (Oryza sativa L.) is one of the most popular and important cereal crops, providing the staple food for more than half of the world's population, especially those living in developing countries. Salinity is one of the prominent abiotic constraints for crop plants worldwide. It affects their growth, development, productivity and ultimately the yield. It also triggers a series of morphological, physiological, biochemical and molecular changes in plants. Various abiotic stresses lead to the overproduction of reactive oxygen species (ROS) in plants which are highly reactive and toxic and may cause severe damage to proteins, lipids, carbohydrates and DNA which ultimately results in oxidative stress. Plants possess very efficient enzymatic and non-enzymatic antioxidant defense systems which work together to control uncontrolled oxidation and protect plant cells from oxidative damage by the scavenging of ROS. The major antioxidant enzymes include catalase, peroxidase, super oxide dismutase, glutathione reductase, glutathione peroxidase, ascorbate peroxidase, etc. Production of antiaoxidant enzymes by some native rice genotypes collected both from saline and non-saline rice tracts of Kerala State of Inda was studied presently in relation to relative induction of salt stress. All the genotypes showed significant upregulation in the production of antioxidant enzymes in response to increase in salt stress applied.