RICE (ORYZA-SATIVA L) GERMPLASM SUITABLE FOR DIRECT SOWING UNDER FLOODED SOIL SURFACE

Screening for rice germplasm which can establish seedling from flooded soil was conducted using 256 accessions of conserved germplasm from the International Rice Germplasm Center (IRGC) and 404 accessions from the International Network for Genetic Evaluation for Rice (INGER), IRRI. IRGC germplasm represented broad genetic diversity while INGER germplasm involved desirable agronomic characters. Seeds germinated for 2 d were planted at 25 mm depth in seedling trays. The trays were then submerged to a depth of 30-50 mm. Seedling establishment was evaluated by analyzing leaf development, seedling height, and percentage establishment 15 d after planting. Eight percent and 2% of IRGC and INGER germplasm, respectively, were identified statistically as superior to the control semidwarf IR varieties. Among the superior germplasm were those from Northeast India and Bangladesh which were adapted to deepwater and early summer rainfed lowland cultures. These could be utilized as parents in breeding programs which aim to develop varieties suitable for direct seeding technology (i.e., germinated seeds are sown under the surface of flooded soil).