Dissecting genetic variability and character associations of physiological, biochemical, agronomic, and yield traits in rice genotypes under salinity stress

Salinity stress poses an increasing threat to global rice production, particularly under climate change. Enhancing salinity tolerance is crucial to sustain rice production and food security. This study aimed to assess genetic variation among rice parental genotypes and their derived crosses under salinity stress by evaluating physiological, biochemical, agronomic, and yield-related traits. Seven diverse rice genotypes were used to develop 21 crosses using a half-diallel mating design in the summer of 2023. The parental genotypes and their derived crosses were evaluated in the summer of 2024 under controlled greenhouse lysimeter conditions. Salinity stress was induced by irrigation with water containing 10.60 dS/m, and soil salinity was maintained at 9.60 dS/m through controlled irrigation and drainage. Twenty key traits were studied, including phenological and agronomic attributes, yield traits, and physiological and biochemical markers such as relative water content, leaf CO2 assimilation, proline accumulation, malondialdehyde content, and antioxidant enzyme activities, to assess salinity tolerance in rice genotypes. The results demonstrated highly significant variation among the evaluated parental genotypes and their derived crosses across physiological, biochemical, agronomic, and yield-related traits, indicating considerable genetic variability in the studied plant materials. The genotypes C9, R8, and R6 were identified as superior combiners contributing favourable alleles for salinity tolerance. Eleven promising F1 crosses exhibited enhanced growth, improved antioxidant enzyme activities, osmotic adjustment, reduced oxidative damage, and higher grain yield under salinity stress. Exploiting these plant materials can improve the development of novel rice genotypes tolerant of salt-affected environments, addressing the current challenges posed by climate change. Strong associations were observed among physiological, biochemical, agronomic, and yield-related traits, indicating an integrated network of responses that collectively contribute to enhanced salinity tolerance in rice.