Morphological Diversity and Genetic Variability of Selected Rice Accessions (Oryza Sativa L.) Cultivated Across Different Seasons in the Low Country Wet Zone of Sri Lanka

Rice (Oryza sativa L.) is cultivated throughout Sri Lanka under diverse environmental conditions, including the wet zone.  Enhancing rice production in this region requires identifying suitable genetic materials with adaptable characteristics. The present study was conducted at the Rice Research Station, Bentota, to evaluate the extent and patterns of morphological diversity among 20 selected rice varieties. The experiment was carried out across two cropping seasons using a Randomized Complete Block Design (RCBD) with five replicates. Morphological variation was assessed using six quantitative traits and fifteen qualitative traits. Results revealed significant seasonal variation in quantitative traits, with leaf length ranging from 25.32 cm -57.20 cm in Maha and 24.14 cm -56.94 cm in Yala, and culm length ranging from 57.74 cm -116.90 cm and 60.44 cm -117.50 cm, respectively, indicating strong genotype × environment interaction. Notably, panicle length, a key determinant of grain number was found to be positively and significantly correlated with leaf length and width, culm length, and culm number, indicating the potential of these traits for indirect selection in breeding programs. Principal Component Analysis identified culm length, leaf length, and panicle length as key traits contributing to variation among genotypes. Therefore, these traits are closely related and contribute similarly to PC1, implying a strong correlation among them. In addition, two diverse major clusters were identified. Overall, considerable morphological variation was observed among the tested rice varieties. The identified diverse genotypes can be utilized in hybridization programme. These, findings are valuable for developing rice varieties adapted to low country wet zone conditions.