| In order to identify the differences and change laws of precise and quantitative N(nitrogen) application parameters including soil basal N application, N absorption of 100kg seeds and N use efficiency in different growth duration type rice, a field experiment was conducted in rice varieties with different growth duration type including early ( 125~135d, growth duration)(EMMJ), medium(136~145d) and late-maturing(146~155d) medium Japonica (MMMJ, LMMJ) and early (156~165d) and medium-maturing(166~175 d) late Japonica (EMLJ,MMLJ)rice in yangtze river under 0,low (150 kg/ha),middle (225 kg/ha),high (300 kg/ha) N fertilizer application in 2007 and 2009 on the farm of Yangzhou university, Jiangsu province, China. Yield and the parameters of precise and quantitative N application were studied systematically in different growth duration type rice under different N fertilizer levels, and classified assessment from yield, the dry matter production and N accumulation and N use efficiency in mutil-aspects respectively, so that illuminated the rang of suitable parameters in the different type rice with different growth duration and yield level. That could be provided theoretical and practical basis for guiding large-scale rice high-yield precise and quantitative N application. The main results were as follows:(1) The yield for different growth type rice increased with the growth duration extension and N application rising except for medium-maturing late Japonica rice. Part of the varieties yield for MMLJ showed the highest at middle N level, but second at high N level. The basic characteristics of dry matter accumulation in tested rice with 5 kinds of growth duration types were studied respectively during the jointing, heading and maturity stage. The results showed that the amount of dry matter accumulation in the different growth stage increased distinctly with N fertilizer application rising in different type rice, which illuminated that the amount of N fertilizer application had greater influence effects on rice dry matter production characteristics. The dry matter accumulation of each treatment showed MMLJï¹¥EMLJï¹¥LMMJï¹¥MMMJï¹¥EMMJ comparing among different growth duration type, that was to say dry matter accumulation showed an increasing trend with the extension of rice growth duration.(2) Plant N accumulation at jointing, heading and maturing stage increased significantly with the extension of growth duration in different type rice under different N treatments. For example, plant N accumulation in the MMLJ rice during the maturing stage was 24.2%, 23.74%, 18.43% and 15.42% higher than that of EMMJ, MMMJ, LMMJ and EMLJ respectively under zero N level, 36.96%,34.73%,26.92% and 6.16% higher under low N level, 25.44%,21.89%,11.35% and 1.75% higher under middle N level, and 20.24%,11.66%,8.74% and 0.69% higher under high N level. From the percentage difference of plant N accumulation known that, the differences between types reduced gradually with the extension of growth period.(3) Soil basal N application increased with the rice growth duration prolonging. Under zero N condition, the average yield of 5.24(4.37-6.06)t /ha, N absorption of 100 kg basal yield was 1.75 (1.64-1.92) kg for early-maturing medium Japonica, and was 1.73 (1.17-1.82) kg with the average yield of 5.99 (4.59-6.92)t /ha for medium-maturing late Japonica rice. While, N absorption of 100 kg basal yield was small differences in medium,late-maturing medium Japonica and early-maturing late Japonica rice for appropriate planting in local test area. The average yield of 5.97(4.87-6.58)t /ha, N absorption of 100 kg basal yield was 1.58 (1.50-1.63) kg, and the range of which was small and much more stable. It can be used widely in rice production.(4) The N quantity required of the target yield was expressed by N absorption of 100 kg seeds under N application. It was to be an upward trend with the increase of N application rate, and which of low N level was significantly lower than that of middle and high N levels, and which of high N level was significantly higher than that of middle N level, while the yield differences of the two N fertilizer levels were not significant. Under middle N level, for early-maturing medium Japonica rice, with the average yield of about 7.42 t /ha, N absorption of 100 kg seeds was to be 2.08 (1.92-2.23) kg. N absorption of 100 kg seeds was to be 1.91 (1.9-1.92) kg with the average yield of about 9.65 t/ha for middle-maturing medium Japonica rice, 1.92(1.9-1.93)kg with the average yield of about 9.88 t/ha for late-maturing medium Japonica rice, 1.91(1.90-1.94)kg with the average yield of about 9.89 t/ha for early-maturing late Japonica rice, 2.02 (2.01-2.04) kg with the average yield of about 9.85 t/ha for middle-maturing late Japonica rice. That was to say, N absorption of 100 kg seeds of the other three growth types rice were not significant differences except for early-maturing middle Japonica rice. With the average yield of about 7.5 t/ha, N absorption of 100 kg seeds was to be 1.86(1.85-1.87)kg under middle N level, 2.01(1.98-2.05)kg under high N level. with the average yield of about 9 t/ha, N absorption of 100 kg seeds was to be 1.94(1.91-2.04)kg under middle N level, 2.08(2.01-2.19)kg under high N level. With the average yield of about 10.5 t/ha, N absorption of 100 kg seeds was to be 1.95(1.93-2.01)kg under middle N level, 2.09(2.08-2.1)kg under high N level. Correlation analysis indicated that there existed highly significant positive correlations between yield and N absorption of 100 kg seeds. It was indicated that the proper N absorption of 100 kg seeds was beneficial to the improvement of the rice yield.(5) There were significant differences in N use efficiency under different N treatments. The average N use efficiency raised with N application increasing, while which of middle N level was the highest. N use efficiency of middle and high N levels was not significant differences, but both with low N treatment differences were significant. The comparison between different growth type showed that N use efficiency increased with the growth extension under low N treatment, and declined in middle-maturing Japonica rice under middle and high N levels. That was because of middle-maturing late Japonica rice was not mature safety under high N level. N use efficiency was 31.32%,37.64%,38.5%,41.08% and 38.11% under middle N level , 28.74%,36.13%,37.16%,40.15% and 39.42% under high N level respectively with the extension of the growth duration. It suggested that middle-maturing late Japonica rice planting a large area along the Yangtze river was headed variety attribute to having high yield and high N use efficiency. However , the varieties with the growth duration period being too short or too long would cause the reduction of the N use efficiency.(6)By further study on the stability of the parameters of N application in EMLJ,LMMJ and MMMJ in yangtze river, the results showed that three kinds of yield type with low, medium and high-yielding were divided under middle and high N levels using Min-SSw cluster analysis method based on the yield. Tested varieties were classified and preliminary divided into three types of varieties with low-yielding at middle and high N levels, medium-yielding at middle and high N levels and high-yielding at middle and high N levels, in which MMMJ accounted for 32%, 24% and 12%, 11.1%, 19.4% and 27.8% in LMMJ, and 20.69%, 20.69% and 13.79% in EMLJ, respectively. The varieties sum of the proportion in three yield grade was more than 50%, which indicated that the yield grade of more than half of tested varieties was more stable with N level changed. The amount of N accumulation at high N level was higher than that of low N level, and lower than low N level in N use efficiency at the same yield grade. The difference of parameters of N accumulation of different varieties with the same yield grade at one N level was small and stable relatively, which indicated that the parameters of N accumulation at the same N level in rice varieties with the same yield grade were consistent basically and changed slightly with different N level.In addition, the parameters of N accumulation in prevail and common varieties were studied that these parameters value of prevail varieties (headed varieties) were higher and more stable than those of common varieties.(7) A stability verification experiment was conducted in 2009 by using the N uptake and utilization parameter values obtained in 2007-2008 under middle N level. The results showed that the three parameters of the precise and quantitative N application were consistent well between the actual and target value. Most of the actual yield under middle and high-yield levels was more or close to the target output, and the actual yield was average 2.46 percentage points higher than that of the target. The fitting equation (as opposed to Y (target value) = X (actual value)) of the actual and target value coefficients tested that the fitting coefficients of basal yield , target yield, N absorption of 100kg seeds and N use efficiency were 1.0200, 1.007, 1.011 and 1.008, respectively. It was indicated that the inter-annual parameters of the precise and quantitative N application had a certain stability and the consistent coefficient was fluctuation basically around 1. So it was because of the stability existence and which made it possible using the stanford equation to calculate accurately N quantity required of the target yield in rice production. |
PDF Full Text Request