Analysis of Submergence Tolerance Index in Selected Rice (Oryza sativa l.) Cultivars Grown in Kebbi State, Nigeria

Abstract

Aims: Submergence is a major abiotic stress limiting rice production in flood-prone regions such as Kebbi State, Nigeria. This study evaluated the submergence tolerance of six rice cultivars (MAI HIJABI, CP 60, FARO, FARO 40, SWARNA-SUB1, and IR64) based on survival rate, shoot elongation, elongation rate, and Submergence Tolerance Index (STI). Study Design: The experiment was laid down in a completely randomized design consisting of six cultivars and each replicated three times. Methodology: The experiment was conducted using a completely randomized design in pots under controlled submergence (14 days), followed by a 7-day recovery period. Results: Results showed that SWARNA-SUB1 exhibited the highest survival rate (100%), longest shoot elongation (53.76 cm), highest elongation rate (3.28 cm/day), and superior STI (66.67%), confirming its high tolerance due to the presence of the Sub1A gene. CP 60 and Faro 40 recorded moderate STI values (33.34%) and showed some submergence resilience. Conversely, Mai Hijabi, Faro, and IR64 recorded 0.00% STI and low survival, indicating high susceptibility. While shoot elongation contributed to tolerance, excessive elongation, as seen in Mai Hijabi, did not correlate with survival, suggesting energy depletion. Conclusion: This study highlights the potential of Swarna-Sub1 for cultivation in flood-prone areas and recommends its use in breeding programs to improve rice resilience to submergence stress.