Characterization and identification of potential restorer lines for anaerobic stress tolerance during germination stage in rice Oryza sativa L

Abstract

newline Direct-seeded rice (DSR) is a cost-effective and sustainable alternative to conventional transplanted rice, offering reduced input requirements for farmers. However, its widespread adoption remains limited due to challenges like anaerobic germination stress caused by waterlogging and erratic rainfall during the early growth stages. To address this, the present study titled Characterization and identification of potential restorer lines for anaerobic stress tolerance during germination stage in rice (Oryza sativa L.) was conducted during Kharif 2024 at ANDUAandT, Kumarganj, Ayodhya, Uttar Pradesh, with complementary research during the 2024 25 off-season at ICAR Indian Institute of Rice Research (IIRR), Hyderabad. A total of 217 restorer lines along with three check varieties (FR13A, Swarna Sub1, and BPT-5204) were evaluated under both stress and control conditions. Significant genotypic variation was observed for traits such as germination percentage, shoot length, root length, and biomass of shoots and roots. Correlation analysis revealed a strong positive relationship between shoot length and shoot fresh weight. Genetic divergence analysis grouped the genotypes into three distinct clusters, with germination percentage contributing the most to variability (73.37%). Principal component analysis (PCA) identified seven components, of which three were significant (eigenvalue gt 1), with PC1 accounting for the highest variance. Phenotypic screening identified nine elite restorer lines (RR-63, RR-45, RR-62, RR-55, RR-72, RR-118, RR-2, RR-73, and RR-58) exhibiting superior performance for germination percentage, shoot and root length, and shoot biomass, with moderate root biomass. Biochemical assays for antioxidant enzymes catalase, peroxidase (POD), and superoxide dismutase (SOD) highlighted elevated activity under stress, confirming their role in reactive oxygen species (ROS) detoxification. POD showed a strong positive correlation with germination percentage, while SOD correlated significantly with fres