Estimates of genetic variability and interplay of germination and seedling traits conferring salinity tolerance in rice (Oryza sativa L.)

Abstract

This study estimates genetic variability and correlations among germination and seedling traits conferring salinity tolerance in rice accessions. Five rice accessions were screened under salinity levels of 0, 50, 100, and 200 mM NaCl in a controlled laboratory setting. Traits such as germination energy, capacity, shoot and root length, and biomass were measured. Data were analyzed for variance and correlations to assess variability and trait relationships. Significant genetic variability was found among accessions for all traits. Germination energy showed the highest coefficient of variation (CV) at 22.29% under control conditions, while fresh shoot weight had the highest CV (34.35%) under 200 mM salinity. Accessions ACC2 and ACC5 consistently demonstrated higher performance in germination energy (23.33 to 53.33% and 10.00 to 41.67%), germination capacity (40.00 to 60.00% and 28.33 to 46.67%), and shoot length (0.67 to 2.97 cm and 0.40 to 3.93 cm) under various salinity stress levels. ACC1, ACC3, and ACC4 showed more variability but maintained some consistency in specific traits, with ACC4 generally showing lower performance across most traits. Genetic parameter estimates indicated high heritability (˃60%) for all traits, with the highest in germination capacity (96.88%). High genetic advance (GAM) was observed for all traits (˃20%), with germination energy showing the highest (107.00%). Traits with high heritability and genetic advance, such as germination energy, germination capacity, and root length, suggest strong genetic control and potential for improvement through selective breeding. Significant correlations were found between germination energy and capacity (r= 0.89 to 0.96) and between shoot length and leaf length (r= 0.92) under stress conditions. Stress tolerance indices identified accessions ACC2 and ACC5 as the most tolerant, with ACC1 showing consistent performance across traits. This study underscores the importance of identifying resilient traits and accessions to enhance salinity tolerance in rice, contributing to improved productivity in saline-affected regions.