Effects Of Different Amount Of Base-Tiller Nitrogen Fertilizer On Plant N-Uptaking And Soil Nitrogen Supplying And Yield Formation Of Rice

During 2000 -2001 in the experimental farm of crop cultivation and physiology key laboratory, Yangzhou University, the experiment was conducted with mid-season rice Xiangjing 97-3017 and Indica, cv. Shanyou 63. Under the condition of same spikelet fertilizer, the effects of different amount of base-tiller nitrogen fertilizer on plant N-uptaking and soil nitrogen supplying and yield formation and quality of rice were studied systematically. The results showed as follows:1. Total amount of N-absorption (ANA) and ANA in every stages increased with the amount of base-tiller nitrogen fertilizer increasing. The coefficient of variation of several key stages (the critical leaf age of productive tiller stage, the jointing stage, the heading stage and the maturing stage) showed: the effect of base-tiller fertilizer on ANA before jointing stage was more than that after jointing stage. ANA of plant in maturing stage showed a parabolic curve relationship with yield and the ANA of panicles in maturing stage correlated well with yield. With base-tiller fertilizer increasing, the total ANA of rice increased, but N accumulated ratio in stem increased progressively, and that in ear decreased relatively. The result of this experiment showed: proper quantity of base-tiller fertilizer applied, yield per unit N increased, and the utilization of nitrogen fertilizer was raised.2. With the amount of base-tiller fertilizer increasing, from transplanting to jointing stage the concent of effective N in soil increased but it induced step by step from jointing to maturing stage. In this experiment, the effective N in soil in maturing stage was 11.34kg/mu (11.26-11.41 ng/mu). The amount of nitrogen supplyed by soil averaged 7.85kg/mu (7.57-8.12kg/mu). The nitrogen of grain from the soil was about 67-72%.3. When the amount of spikelet fertilizer fixed, the amount of base-tiller fertilizer was adjusted to make the ratio of base-tiller fertilizer to spikelet fertilizer reasonable. It would do good to the number of panicles per area harmony with that of spikelets per panicle, and then the optimum society was gotten. The total number of glumous flower was enlarged. Dry weight accumulationfrom the heading to maturing stage increased, setting percentage and weight per 1000 grains improved. All those would make the high yield be obtained. The result of this test showed that to obtain yield of 700kg/mu or so, the optimum amount of N application of Xiangjing 97-3017 was 17.8kg/mu and that of Shanyou 63 was 15.1kg/mu. The optimum amount of base-tiller fertilizer of Xiangjing 97-3017 was 10.3kg/mu, and that of Shanyou 63 was 9.0kg/mu. The ratio of base-tiller to spikelet fertilizer was 6:4 or 5.5:4.5.4. The nitrogen requirement per 100kg grain increased with the additional application of base-tiller fertilizer. Nitrogen requirement per 100kg grain showed a parabolic curve relationship with yield. The yield was highest when the nitrogen requirement per 100kg grain increased to a certain value. The utilization of nitrogen in this season showed a parabolic curve relationship with total fertilizer and base-tiller fertilizer, and it correlated well with yield. In this test, when the yield was about 700kg/mu, the nitrogen requirement per 100kg grain of Shanyou 63 was 2.1±0.1kg, that of Xiangjing 97-3017 was 2.2±0.1kg. The utilization of nitrogen of Shanyou 63 and Xiangjing 97-3017 in this season was 41±1% and 41.5±1% respectively. The nitrogen requirement of the target yield can be accounted through the standford equation with three parameters that were the nitrogen requirement per 100kg grain and the amount of N from soil and the utilization of fertilizer in this season.