Author : Riyanto

Summary : Field experiment was conducted at the Central Experiment Station (CES) Farm, University of the Philippines, College of Agriculture, Los Baños, Laguna, to determine the interaction of rate and time of nitrogen application and weed control methods in two upland rice varieties, C-22 and IR 2035-242-1, grown under upland culture. IR 2035-242-1, a semi-dwarf IRRI selection, produced more tillers, more panicles and less percentage of unfilled grains than C 22, a tall, College-recommended upland variety. Statistical analysis indicated that among the weed control methods used, pre-emergence application of butachlor at 2 kg a.i./ha followed by handweeding at 25 DARE was comparable to handweeding three times in terms of less weed biomass, taller plants, more tillers and panicles and higher grain yield. Increasing rates of nitrogen application resulted in shorter panicle initiation period and blooming days, taller plants, more tillers and panicles, less in percentage of unfilled grains, and increase in grain yield.