Abstract:
Flash flooding during germination limits direct-seeded rice in rainfed
lowlands. Twenty-two rice genotypes were evaluated for submergence tolerance
during germination stage. Materials included improved varieties from Rice Research
and Development Institute, Bathalagoda; traditional varieties collected from local
farmers; and six genotypes selected from previous studies, representing both red- and
white-pericarp genotypes. The experiment was conducted from July to August 2025 at
the Crop Farm, Ariviyal Nagar, Kilinochchi District, Agro Ecological Zone DL3 on lowhumic
gley soils using Completely Randomized Design with three replicates. Seeds
were sown in plastic containers filled with puddled soil at the depth of 5 cm and
subjected to controlled submergence for 3(T2), 7(T3), 10(T4), and 14(T5) days, with
non-submerged seeds as control(T1). Germination percentage, shoot length (cm), root
length (cm), and seedling vigor index were recorded 7 days after submergence. Data
were analyzed using analysis of variance (ANOVA) with mean comparisons by
Duncan’s Multiple Range Test (DMRT) at 5% significance level in SAS 9.4. Rice
genotypes were classified as tolerant, moderately tolerant, or susceptible based on
germination percentage using the IRRI (2013) descriptor, and cluster analysis. Under
seven days of submergence (T3), Pachaiperumal, Bw 372 (red pericarp) showed >75%
germination and were identified as tolerant; Mottaikaruppan karainagar,
Mottaikaruppan Ariyalai, At 362, Pachaiperumal, Analvariyan, At 307, Mottaikaruppan
Karainagar, Bg 379/2 exhibited as moderately tolerant under seven days of
submergence (T3) compared to < 25% germination in susceptible genotypes.
Mottaikaruppan Ariyalai, Mottaikaruppan Karaiainagar, Bg 400-6, Pachaiperumal, Bw
372 showed >50% germination and identified as moderately tolerant even under
fourteen days of submergence (T5). Bw 372, Pachaiperumal and Bg 400-6 were
identified as superior submergence tolerant genotypes at germination. Tolerant
genotypes exhibited shoot elongation and seedling vigor, enabling better
establishment in anaerobic conditions. These are valuable genetic resources for floodprone
direct-seeded rice systems and require multi-location validation.
