Comparative Physiology and Antioxidant Response of Grasspea (Lathyrus sativus L.) Seedlings under the Iso-osmotic Potential of Salinity and Drought Stress

Aims: This study's objective was to determine how early-stage grass pea seedlings will respond to salinity and drought stress with iso-osmotic potential, emphasising ROS-scavenging enzymes.

Study Design: Completely randomized design.

Place and Duration of Study: Laboratory studies on the grass pea varieties BK-14 and Pratik were carried out in the academic years 2017–2018 and 2018–2019 at the Department of Plant Physiology, Bidhan Chandra Krishi Viswavidyalaya, Kalyani, Nadia, West Bengal, India.

Methodology: Sodium chloride and PEG 6000 solutions with iso-osmotic potentials of -0.2, -0.4, and -0.8 MPa were used to study salinity's effects and drought stress. The experiment was conducted in sand culture using modified Hoagland solution under diffused light, at a temperature of 22°C and an approximate relative humidity (R.H.) of 80±1%.

Results: Results indicated that drought stress was found to produce more adverse effects on seedling dry weight and lipid peroxidation in comparison with iso-osmotic potential of salinity stress. Variety BK-14 was found to be more tolerant than Pratik for seedling dry weight at the highest intensity of drought stress. The data further indicated that drought- induced more accumulation of phenol in the leaf as well than iso-osmotic salinity stress. The activities of four ROS scavenging enzymes (viz, superoxide dismutase, guaiacol peroxidase, ascorbate peroxidase and catalase) in leaves mostly showed a sigmoidal pattern of changes under varying levels of both stresses. Comparative analysis indicated that Pratik registered higher activities of two peroxidases, viz, GPOX and APX, under higher levels of drought stress while BK 14 registered higher activities under salinity stress. However, BK-14 was found to register a higher increase in SOD activity at the most intense level of salinity and drought stress as compared to Pratik.

Conclusion: In the present experiment, it was discovered that BK-14 was generally more tolerant than Pratik for seedling growth under the utmost level of stress. This may be explained by the stronger antioxidative mechanism it exhibited in the present experiment under the conditions of the maximum stress, as generated by both enzymatic and non-enzymatic components.