Effects of Hill Spacing, Number of Plants Per Hill and Nitrogen Supply on Growth and Yield of Rice

Summary

In a factorial experiment with two spacings, four numbers of seedlings per hill, and two levels of nitrogen the highest numbers of shoots were produced in high nitrogen and high plant density plots. Increasing the number of seedlings per hill led to a rise in the number of shoots per plot and this was more pronounced in high than in low plant densities. Significant differences in shoot number between high and low nitrogen plots occurred only at the higher plant density, but high nitrogen and wide spacing led to an increase in the number of shoots per hill and per plant. Increasing the number of seedlings per hill resulted in an increase in the number of shoots per hill but a decrease in the number of shoots per plant. The effects of treatments on leaf blade area at ear emergence and on grain yields were similar to those on shoot number. The percentage increase in the yield of grain per unit area due to increasing the number of seedlings to three and four were 12 and 9 respectively. The percentage shoot mortality was greater in plots with low than with high plant density. Plants were higher in high nitrogen plots, especially at high plant density, while high nitrogen supply and four seedlings per hill increased the number of days from seeding to ear emergence. The former treatment also increased ear length. Low plant density and three seedlings per hill increased the ear to shoot dry weight ratio. The best combination of treatments for high grain yield was high nitrogen, 15 cm x 15 cm spacing, and four seedlings per hill.