Development of Screening Methods for Anaerobic Germination and Seedling Vigor in Direct Wet-Seeded Rice Culture

The development of rice varieties for direct wet-seeded system is one of the major areas of concern in lice research today Recent trend in rice production is marked with the shift from transplanting to direct seeding because the latter benefits the farmers by reducing the cost and time of production. Direct wet-seeded rice (DWSR) should be improved for anaerobic germination, very good seedling vigor, lodging resistance and on top of yield contributing traits that are important to irrigated lowland rice. Series of experiments were conducted at the Philippine Rice Research Institute (PhilRice), Nueva Ecija, Philippines to meet the following objectives: i) to evaluate different anaerobic screening methods and develop a fast and reliable selection of DWSR lines for anaerobic germination; ii) to determine seedling vigor under anoxia (i.e. low or absence of 0) through seedling biomass; and iii) to identify rice varieties and advanced breeding populations with anaerobic germination and seedling vigor for direct wet-seeded rice. Combination of flooding and subsurface seeding in puddled soil using plastic cups indicated that rice genotypes could be selected possessing anaerobic germination and seedling vigor. This method could be used to quantify seedling vigor under anaerobic condition in amass screening program. PR33176-1-3 was identified tolerant to continuous submergence for 14 days in puddled soil. NSIC Rc146, PR32220-16-1-B-1-2, PR32749-10-1-B-B and PR32750-2-9-2 were intermediate to anaerobic germination. PR33176-1-3 and PR30536-B-48-1 have better seedling vigor than the check varieties which are known with good seedling vigor. Other breeding lines were identified to have good anaerobic germination and seedling vigor which could be used for breeding work in direct wet-seeded rice culture.