Author : Akwut Thasanasongchan

Summary : Field experiments were conducted at the International Rice Research Institute, Los Banos, Laguna and at Cuenca, Batangas, Philippines, to determine the effect of methods, sources and time of nitrogen application on yield and yield components of C 22 and IR 1529-430-3 grown under upland culture. In both locations, IR1529-430-3, a semi-dwarf selection, produced higher grain yields, more tillers, more panicles and heavier grains than C 22, a tall recommended rice variety for rainfed upland. Addition of nitrogen markedly increased the grain yield of both varieties, but the yield increment of IR1529-430-3 was higher than that of C 22 in both locations, indicating that the farmer was more responsive to applied nitrogen. SCU was a better source of nitrogen than urea and ammonium sulfate when applied all at planting, either broadcast and incorporated or placed in band.