| Nitrogen nutrient has a very important role in the rice growth and development process. In agricultural production, especially rice, to application of excess nitrogen fertilizer to increase rice yield. However, the utilization efficiency of N in agricultural production has continuously decreased. At the same time, the cost of agricultural production was increased by N fertilizer and this lead to serious environmental pollution. In this paper, the methods of combining field plot experiments, micro zone experiments, pot experiments and indoor analysis were conducted, combining isotope 15N tracer technique, to quantitatively describe the accumulation of 15N in rice, the proportion of 15N uptake, the distribution of in plant and the utilization of nitrogen fertilizer. The results show. The results are as follows.1、The response ability of different rice varieties to N was different, and These results ultimately reflect the rice output. he main reason is that the level of N fertilizer applied directly affects the number of effective spikes per unit area of rice and the number of grains per spike. When the level of N input in the field increased, the amount of N between the rice plant and the organs increased, but it reduces the efficiency of the plant N. Compared with the rice variety Kongyu 131, Longjing 31 has higher throughput and efficiency in N operation.2、The accumulation of N in the vegetative organs is an important source of N in the harvest organs, and accounts for about 70% of the total accumulation of N in the grain. When fertilizer N level increased, distribution rate of different rice varieties labeled 15N isotope in the harvesting of organs decreased, but increased in the stalk and leaf organ root changes is not obvious. This indicates that the increase of N fertilizer application level in rice field can promote the absorption and utilization of N by the nutrition organs.3、In different organs of rice, the proportion of 15N accounted for the largest grain, higher than that of stems and leaves. The percentage of 15N in root system was the least.15N in grain accounts for the proportion, from different varieties of Longjing 31 was higher than empty Kongyu 131, and in the stems and leaves of this trend is opposite. The operation and redistribution of N in rice was influenced by the variety of genetic characters, and this was the important reason for the difference of rice yield.4、There were differences in the utilization efficiency of different rice varieties to N, and this experiment is in the form of Longjing 31 higher than Kongyu 131. To compare the efficiency of the crop N using the 15N isotope tracing method, N use efficiency results is higher by difference method.5、During the rice reproductive stage(from flowering to maturity), the 15N isotope transport of fertilizer was the highest in fertilizer application during spike formation stage. Secondly, as a basic fertilizer. While the tillering fertilizer as top dressing is the lowest. Performance efficiency of basic fertilizer 15N fertilizer was the highest. The other two periods were not significantly different.6、The leaves of rice were the main storage organ of 15N in the nutrition stage of rice. Second is the sheath. In the growth stage, storage in the stem for 15N performance is lower than the first two parts. After entering the reproductive stage, The fertilizer 15N in the vegetative organs is transported to the harvesting organ. Thus the proportion of 15N in the vegetative organs was decreased. The performance of the harvesting organs is increasing.7、In the case of soil N low background, the application of basal fertilizer N on rice growth and development of the whole process has an important role. To improve the basic N level can greatly promote the tillering of rice, and construct robust rice field plant population. During the formation stage of panicle, N was beneficial to the accumulation of the expansion and contents of the organs at the later stage of the reproductive growth. Increasing the level of N input in this period can increase the nitrogen harvest index. There was a lot of loss in the N element during the tillering stage of rice, and this is detrimental to the uptake and utilization of rice. So we can consider increasing the investment in production. At the same time to reduce the tillering stage topdressing fertilizer, or increase tillering stage after fertilizer input. This can improve the utilization efficiency ofN.8、Excessive nitrogen fertilizer can lead to the accumulation of soluble sugar content of the stem and the formation of the yield.. The activity of NR, GS and GOGAT increased with the increase of nitrogen fertilizer, and the activity of EP was decreased, and it was not good for the degradation and transport of protein in the leaves and plants during the growth of the late growth, so the formation of the yield was affected. |
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