EFFECTS OF PLANTING DENSITY AND PLANTING PATTERNS OF YOUNG SEEDLINGS TRANSPLANTING ON THE GROWTH AND YIELD OF RICE PLANTS

This study was carried out to examine the effects of planting density and planting patterns in reference to various characteristics at the panicle formation, heading and maturing stages in rice plants (Oryza sativa L., cv. Nipponbare). In square planting plots, the plant length at the panicle formation stage was the tallest at a 49 hills/m2 plot, at the heading and maturing stages it was taller in lower planting density plots. In row planting plots, the plant length decreased with increasing plant density. The number of culms of square planting plots was the largest at a 100 hills/m2 plot at the panicle formation stage and at a 64 hills/m2 plot at heading time. Those of row planting plots were the largest at the most dense plot (100 hills/m2). Top dry weights in square and row planting plots were maximized at plant densities of 64 and 100 hills/m2 at panicle formation and heading stage, and 49 and 100 hills/m2 at maturing stage. The highest panicle number was obtained at a 81 hills/m2 plot of square planting and at a 100 hills/m2 plot of row planting. The percentage of ripened grains was the highest at a 25 hills/m2 plot of square planting and at a 100 hills/m2 plot of row planting. As a result, the highest yield was obtained at a 49 hills/m2 plot of square planting, and at a 100 hills/m2 plot of row planting. It is suggested that the best planting density to obtain the highest yield in paddy rice may also depend upon planting patterns.