Grain Filling Characteristics And Carbon Nitrogen Metabolism Of Maize Under Different Nitrogen Applications

Corn is an important crop of food and economy, the average amount of corn is regarded as an important symbol of measuring the people’s living standards and the development of animal husbandry. Under the premise that the cultivated land area of our country is limited and the corn acreage is difficult to increase greatly, the only way to increase the total output is to increase the unit area output of maize. In present corn production, increasing planting density and fertilizer (nitrogen) input is the basic measure to increase production, but inevitably taking to two problems:one is planting density increased in groups lead to microclimate conditions deteriorate, individual development inhibited, grain dysplasia, abortion increased, affecting the final yield; second, with the increasing of nitrogen fertilizer application, the nitrogen fertilizer utilization efficiency decreased, a serious loss and environmental pollution has intensified. Coordinating the relationship between grain development and nitrogen utilization efficiency is the key to achieve high yield and high efficiency of maize production, reduce the input of nitrogen fertilizer and reduce the pollution of the environment. In modern maize production, fully exploit the genetic potential of the corn itself, breeding grain well developed in low nitrogen conditions, and obtain high yield new varieties of nitrogen efficiency type is the foundation of improving nitrogen utilization efficiency, ensuring the corn high and stable yield.In the early stage of the experiment, selecting represent high nitrogen use efficiency type and low nitrogen use efficiency type and double efficient type of maize grain, respectively in 2014 and 2015 set four and three levels of nitrogen application, the level of nitrogen fertilizer was mainly treated, and the variety was the secondary treatment, two years to repeat the test. On the field test as the basis, through the determination of physiological and biochemical indexes of indoor, to study the effects of nitrogen efficiency types of different parts of maize grain filling dynamics and internal metabolism, To reveal the different nitrogen efficiency types of maize especially between apical kernel development, and found the relationship between grain growth and nitrogen efficiency of maize types under different nitrogen efficiency.Analysis of test data, combined with the two years of studying found that: the development of maize types with different nitrogen use efficiency are showed as follows:the lower part> top grain, nitrogen> no nitrogen; different nitrogen efficiency type maize kernel dry weight with the number of days after pollination can be used to fit the logistic growth equation, the dry weight changed with "S" curve growth; The percentage of maize grain moisture with different nitrogen efficiency showed a trend to decrease continuously, and the development time could be introduced by percentage of maize grain moisture, and the field management could be more effective. The grain filling rate of maize with different nitrogen use efficiency was fitted with two single peak curve, and the fitting degree is well. The best nitrogen application rate of grain filling rate was consistent with the rate of nitrogen application, and the change of grain filling rate effect the change of yield; different nitrogen efficiency types of maize grain total sugar with the changing of time after pollination showed increasing trend, sucrose during the whole growth period showing a’increase decrease-increase’trend, starch over time with a logistic growth curve growth; the correlation coefficient of starch and sucrose in different nitrogen efficiency types appeared peak value in 20d-25d; this date is the period of sucrose reduction, the accumulation of sucrose provides the raw material for the synthesis of starch; the total nitrogen accumulation of different nitrogen efficiency types showed a trend of increasing after pollination, the rate of total nitrogen accumulation in grain filling stage was large, and the total nitrogen accumulation rate of maize was decreased; The grain volume of maize with different nitrogen efficiency increased linearly with the passage of time after pollination, the changes of maize grain volume and the total amount of accumulation showed a strong positive correlation. Excessive nitrogen application would lead to a decrease in the volume of the top and the amount of total nitrogen accumulation, which could inhibit the growth of the top of the grain; corn grain with different nitrogen efficiency in different nitrogen application levels of the growth development advantages are showed as follows: the Tunyu N2> N1> N0; Luyu N1> N2> N0; Xianyu N2> N1> N0, the Luyu grain in 80kg/hm2 nitrogen application levels growth obviously.