Correlation of Morphological and Biochemical Parameters in Rice Genotypes under Hydroponic Salinity Stress
M. Srikanth *
Department of Crop Physiology, Acharya NG Ranga Agricultural University (ANGRAU), Agricultural College, Bapatla-522 101, India.
S. Ratna Kumari
Department of Crop Physiology, Acharya NG Ranga Agricultural University (ANGRAU), Agricultural College, Bapatla-522 101, India.
M. Girija Rani
Department of Genetics and Plant Breeding, RARS, Maruteru-534 122, India.
K. Suneetha
Department of Genetics and Plant Breeding, ICAR- IIRR, Hyderabad- 500 030, India.
G. Vijaya Kumar
Department of Crop Physiology, Agricultural College, Bapatla-522 101, India.
I. Usha Rani
RRU (Soil Chemistry) RARS, Lam, Guntur-522 03, India.
*Author to whom correspondence should be addressed.
Abstract
Salinity is a major abiotic constraint on rice productivity, particularly during the seedling stage. This study evaluated associations among morphological, biochemical, and ionic traits in 20 rice genotypes exposed to hydroponic salinity stress. The experiment was conducted at Agricultural College, Bapatla, using a completely randomised design with two replications and an electrical conductivity of 12 dS m⁻¹. Seedling vigour index, root length, shoot length, root weight, shoot weight, catalase activity, superoxide dismutase activity, proline content, Na⁺/K⁺ ratio, and salt injury score were evaluated. Based on the standard evaluation score, FL478, MCM151-3-2-1-1, MCM253-8-2-2, and IR04A115 recorded a score of 3 and were classified as tolerant. Correlation analysis showed that salt injury score was negatively associated with superoxide dismutase activity, catalase activity, and proline content, but positively associated with the Na⁺/K⁺ ratio. Shoot length was strongly and positively correlated with seedling vigour index and was also positively related to proline content, catalase activity, root length, root weight, and superoxide dismutase activity. Catalase and superoxide dismutase activities were positively correlated with proline content. These findings indicate that improved seedling growth, enhanced antioxidant enzyme activity, greater proline accumulation, and maintenance of a lower Na⁺/K⁺ ratio were associated with reduced salt injury. The identified tolerant genotypes may therefore be useful for further evaluation under saline conditions.
Keywords: Oryza sativa L., salinity stress, hydroponic screening, seedling stage, salt injury score, seedling vigour, superoxide dismutase, catalase, proline, Na⁺/K⁺ ratio, Pearson correlation