Agricultural Horizons: Research, Technology and Sustainable Development Vol. 5

Salinity stress restricts rice seedling establishment by impairing growth, disturbing ionic balance, and increasing oxidative stress. This study assessed associations among morphological, physiological, biochemical, and ionic traits in 20 rice genotypes screened under hydroponic salinity stress. The experiment followed a completely randomised design with two replications, and salinity was increased from 6 to 12 dS m⁻¹ during seedling growth. Salt injury score, seedling vigour index, root and shoot length, root and shoot weight, catalase activity, superoxide dismutase activity, proline content, and the Na⁺/K⁺ ratio were evaluated. At 12 dS m⁻¹, MCM151-3-2-1-1, MCM253-8-2-2, IR04A115, and the tolerant check FL478 recorded a salt injury score of 3, whereas BPT5204 and PUSA44 recorded a score of 9. Salt injury score was negatively associated with superoxide dismutase activity (r = −0.50), catalase activity (r = −0.51), and proline content (r = −0.48), but positively associated with the Na⁺/K⁺ ratio (r = 0.56). Shoot length was strongly associated with seedling vigour index (r = 0.83) and was positively related to several growth and biochemical traits. Catalase and superoxide dismutase activities were also positively associated with proline content. Overall, lower salt injury coincided with better seedling growth, stronger antioxidant activity, greater proline accumulation, and a lower Na⁺/K⁺ ratio under the tested hydroponic conditions, indicating that these traits may be useful for identifying salt-tolerant rice genotypes at the seedling stage.