| As a multi purpose and high yield grain crop,maize plays an increasingly important role in modern agriculture,In recent years, with the development of China’s economy and the increase in population, the demand of maize increased year by year. Increasing application of nitrogen fertilizer is an effective means to increase maize yield, however, unreasonable application of nitrogen not only causes serious waste of resources, but also causes serious damage to the agricultural environment. So it has important practical significance for studying the process of dry matter accumulation and nitrogen metabolism of different maize varieties at different nitrogen levels, analyzing the difference of nitrogen efficiency and electing the maize varieties with high nitrogen efficiency. In this study, 3 different genotypes of maize varieties were tested under different nitrogen application levels,and they were sampled in the key growth stages for field experiments and laboratory test, the results show that:1.The dry matter accumulation efficiency of maize varieties was increased after applying nitrogen fertilizers, but the responses of different maize varieties to nitrogen were different. The experiment showed that TY and XY were more sensitive, the dry matter weight of each part of plant was significantly increased by increasing nitrogen application.,while LY was less sensitive,the difference among different nitrogen levels was small. Reasonable nitrogen fertilization could improve the dry matter weight of maize, but excessive nitrogen fertilization could inhibit the growth and development of the plant.2.The total nitrogen content of all parts of maize plants decreased gradually with the growth and development of plants, and the total nitrogen content in leaves were the highest, followed by grain. As for the nitrogen accumulation, the nitrogen accumulation in grain is increasing, other parts of the nitrogen accumulation was increased first and then decreased, generally in the filling period reaches the maximum, and then began to shift to the nitrogen in grain. the nitrogen accumulation of TY under low nitrogen condition was the lowest, while increased significantly in the condition of high nitrogen, and it was higher than the other two varieties of Maize;the nitrogen accumulation of LY under low nitrogen condition remained at a high level,and it had no obvious changes with the increase of amount of nitrogen fertilizer; the nitrogen accumulation of XY under low nitrogen condition was highest, but the high nitrogen application environment will lead to the decrease of the amount of nitrogen accumulation in the grain. In addition, XY has a strong ability to absorb nitrogen in the late growing period, and it is an important symbol of high efficiency of nitrogen.3.The nitrogen efficiency index of TY and XY increased with the increase of nitrogen rate,they were kept at a high levelu nder the condition of high nitrogen, and XY was slightly higher than that of TY, LY had higher nitrogen use efficiency and nitrogen harvest index under low nitrogen conditions, Increasing nitrogen application levels would reduce the nitrogen partial productivity and agronomic efficiency of nitrogen. The absorption and utilization efficiency of nitrogen would reduce under high nitrogen environment.4.Through the correlation analysis and the path analysis,we got that the grain nitrogen content could play a important role in the yield under the condition of no nitrogen application; In nitrogen condition, corn yield is mainly affected by the nitrogen use efficiency. The nitrogen content of plant and nitrogen harvest index had a negative effect on the yield of maize.5.TY is suitable for planting in high nitrogen conditions,LY has higher economic value in low nitrogen environment. The adaptability of the XY for the environment is higher than the other two varieties, it is suitable for widely cultivated, but reasonable nitrogen fertilization is also very necessary. |
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