Effect of planting density on growth, yield and yield attributes of rice (Oryza sativa L.)

The study was conducted during 2012 from May to August cropping year at paddy field of Tsukuba International Training Center (TBIC), Japan. The main purpose of the experiment was to investigate the effect of planting density on the growth, yield and yield attributes of rice. The experiment comprised of five planting densities (16.7, 22.2, 25, 33.3 and 50 hills m-2). It was arranged in Randomized Complete Block Design with three replications. The results showed that the effect of planting density was highly significant in influencing panicle number m-2, spikelet number per panicle and ripening percentage. Higher panicle number was obtained in 50 hills m-2 and followed by 33.3 hills m-2 over the standard density. On the other hand, a decrease in density brought a significant increase in spikelet number per panicle over the preceding population density. Spikelet number per panicle increase of 44, 32, 26 and 9% were obtained in 16.7 hills m-2 over 50, 33.3, 25 and 22.2 hills m-2, respectively. Higher grain yield was obtained in 50 hills m-2 and followed by 16.7 hills m-2, but it was not significantly different among density treatments. The paddy yield record obtained due to high planting density over 16.7, 22.2, 25 and 33.3 hills m-2 were 4.0, 9.5, 4.8 and 6.9% respectively. With an increasing plant density from 16.7 to 50 hills m-2 panicle length and stem diameter decreases by 12 and 29.2%, respectively. In most of the evaluated traits, highest values were obtained from 16.7 and 50 hills m-2. Therefore, 16.7 and 50 hills m-2 were more appropriate densities for cultivation of Nerica-4 variety.   Key words: Planting density, rice, growth, yield, yield attributes.