The Analysis of Nitrogen Uptake and the Study on Fertilization Technique in Two Types of Japonica Rice
Cao Hongs heng Huang Pisheng Miao Baoshan Lu shilong Cheng Jintie
Four cultivars of midseason japonica rice, which belong to multi-ear type or large-ear one, were studied on the law of nitrogen uptake and the fertilization technique. The results are as follows: At the tilling stage, the multi-ear type rice takes up more nitrogen than large-ear type rice does. On the contrary, at ear primordium stage, the nitrogen uptake of large-ear type was more than that of multi-ear type. For all the cultivars, at the tilling stage the relative accumulation rate of nitrogen(RARN), which is used to indicate the nitrogen uptake intensity, is the highest, and at the ear primordium stage the RARN ranks behind the previous one; at the grain filling stage it is the lowest. At each developmental stage, the nitrogen uptake intensity of large-ear type is higher than that of multi-ear type. It is suggested that the total nitrogen uptake of the plant is positively correlated with the fertilizer norm. The relationship between the yield and the total nitrogen uptake of the plant shows a quadratic equation curves. In this experiment, when the yield per mu was about 500kg, the total nitrogen uptake of the plant was 11.6kg per mu, 58-68 per cent of the nitrogen coming from the soil.