Performance Evaluation of Seed Coating and Priming Techniques for Rice (<em>Oryza sativa</em> l.) Varieties under Submergence Conditions in the Low Country Wet Zone of Sri Lanka

Flooding often impacts rice farming in Sri Lanka's Low Country Wet Zone. This study explores seed treatments to improve rice submergence tolerance during early growth under flooding conditions. Two experiments were conducted to evaluate the performance of seed treatment techniques under submergence conditions over two different submergence periods. Experiment 01 evaluated three rice varieties and three promising lines coated with Calcium Oxide (CaO), Alginate, Sodium Lauryl Sulphate, and primed with Calcium Chloride (CaCl2) and submerged for 0–12 days. Experiment 02 consisted of three rice varieties and a promising line treated with Alginate, Sodium Lauryl Sulphate, and primed with Gibberellic Acid, Ascorbic Acid, and Calcium Chloride (CaCl2), and five-day-old seedlings submerged for 5 to 19 days. The experimental design was a two-factorial randomized complete block design (RCBD) with three replicates. The interaction between variety and seed treatment significantly (p<0.05) affected the survival percentage in both experiments and the plant height in Experiment 02. The only factor that significantly impacted plant height under submergence in Experiment 01 was variety. The study suggests that priming with CaCl2 and coating with Alginate are promising treatments for alleviating the impact of submergence stress on rice at early growth stages.