Reactions Of Different Rice Varieties On N-application Rate

The experiment was conducted in experimental farmland of Yangzhou university in 2000~2001. The soil was sandy loam. The soil fertilizer was middle level and the pre-planted crop was wheat. There were 24 experiment materials, that respectively were eleven conventional middle Japonica rice varieties, seven conventional late Japonica rice varieties, two hybrid Japonica rice varieties, two conventional Indica rice varieties and two hybrid Indica rice varieties. Zero, low, middle and high N level were designed for every rice variety, and Okg N/mu, 6.67kg N/mu, 13.34kg N/mu, 20kg N/mu were respectively applied for every rice over life. The experiment results of the two years were same as below:(1) The heading stage and the mature stage of the different varieties were delayed and all days over life increased with the N-application rate. The order of effects of N-application rate on growth period of different rice varieties was medium-maturing late Japonica rice > early-maturing late Japonica rice hybrid Japonica rice > late-maturing middle Japonica rice > medium-mature middle Japonica rice early-maturing middle Japonica rice >conventional Indica rice hybrid Indica rice.(2) All rice varieties didn't lodged at zero and low N level, but at middle and high N level, some rice lodged and some inclined. In the experiment, the general lodging trend of different rice varieties showed that the Indica rice lodged more easily than Japonica rice, middle rice lodged more easily than late rice, conventional Japonica rice lodge more easily man hybrid Japonica rice.(3) The yield of the most conventional middle and late Japonica rice varieties and hybrid Japonica rice increased with N-application rate, but the yield of the conventional Indica rice, hybrid Indica rice and some conventional Japonica rice increased with N-application rate, amounted to the greatest level at middle N level, then descended dramatically at high N level. Comparing with middle N level, the conventional Indica rice reduced 9.9% and the hybrid Indica reduced 11.1%. At every N treatment, the yieldof conventional middle Japonica rice among the rice varieties was the lowest. At zero, low and middle N level, the yield of hybrid Indica rice was highest and at high N level, the yield of hybrid Japonica rice was highest.(4) The head rice ratio, chalkiness, amylose content and the protein content increased with N-application rate. Gel consistency became longer with N-application rate. The effects of N-application rate on pasting traits showed that with N-application rate, the breakdown of different rice varieties descended, but the setback increased. The pasting temperature had no obviously varied trend with N-application rate. The experiment results showed the paste traits of conventional middle Japonica rice and hybrid Japonica rice were better, and that of conventional Indica rice and hybrid Indica rice were worse.(5) Biomass accumulation of some conventional Japonica rice and hybrid Japonica rice increased with N-application rate. While the biomass accumulation of conventional Indica rice, hybrid Indica rice and some conventional Japonica rice increased with N-application rate, amounted to the greatest level, then descended at high N level, and conventional Indica rice, hybrid Indica rice respectively reduced 3.8% and 6.2%. The biomass accumulation increased with the growth period delaying, and got to the highest value at the period of jointing stage to heading stage. The ratios of biomass accumulation from jointing stage to heading stage to total biomass accumulation were more than 40%. The differences of biomass accumulation were significant among varieties. The total biomass accumulation of conventional middle Japonica rice was the lowest under the four N level. Under zero, low, high N level, the total biomass accumulation of hybrid Japonica rice was the highest.(6) The N-uptake amount of different rice varieties increased with the N-application rate and the growth period delaying. The N-uptake amount got to t...