Studies On N Application Rate, Time And Partitioning Of Summer Maize (Zea Mays L.) In HeiLong-gang Region

The research was aimed to provide theory basis of N application and to define the N application rate, time and partitioning of summer maize in HeiLong-gang region. Using summer maize variety Zhengdan 958 as the material, this research detected the effect of the N application rate, time and partitioning on morphological and biological characteristics, photosynthetic characteristics, dry matter accumulated and distribution, N dynamic changing, yield and N fertilizer economic benefit. The study contributed a lot to the improvement of culture with higher yield of summer maize. The results as follows:Different the N application rate, time and partitioning had influenced plant height and root growth of the summer maize. It could increase the plant height and the root growth, increase the root layers and root quantity if additional N supplied in the early period. It became obvious along with increasing the rate of the N fertilizer application.The summer maize leaf area index, photosynthetic rate and the leaf area duration had the same influence trend on the condition of different the N application rate, time and partitioning. In the moderate range of the rate of N fertilizer application, increasing the rate of N fertilizer application could obviously improve the photosynthetic rate of the summer maize. When the rate of N fertilizer application was 300 kg · hm^-2, the green leaf area of the plant was larger;the leaf index was higher;the leaf area duration was larger and the photosynthetic rate was faster. And when the N application time and partitioning was seedling fertilization 30% + twelve-leaf stage fertilization 60% + after silking fertilization 10%, the summer maize maintained larger green leaf area and higher photosynthetic rate so that it could assure that more nutrition matter was transported to the seed in the grouting and lay foundation to the higher yield.Compared the treatments of N fertilizer application rate, time and partitioning, the dry matter accumulation of every organ of the summer maize was different. When the rate of N fertilizer application was 150 kg · hm^-2, additional N supplied in seedling period could get more dry matter accumulation than fertilized in twelve-leaf stage. However, the products of the photosynthates transferred to the seed decreased and N nutrition was insufficient, the dry matter accumulative rate was slower in the late growth period. When the rate of N fertilizer application was 300 kg · hm^-2 and time and partitioning was seedling fertilization30% + twelve-leaf stage fertilization 60% + after silking fertilization 10%, the dry matter accumulation of the single plant and the seed were the biggest and the biggest increasing rate and the average increasing rate were also higher.As the rate of N fertilizer application increasing, the intension of the summer maize absorbing N was bigger, and the time of the peak value of absorbing N emerging was put off. When the amount of N fertilizer was 225 kg ? hm²⁴50 kg ? hm"2, there were two peaks. One was in the silking stage and the other was in the 30th day after silking stage. When the amount of N fertilizer was 0 and 150 kg ? hm"2, there was one peak only in the twelve-leaf stage. For the low N fertilizer treatment, it was in the early period for plant to absorb N, however, for the high N fertilizer treatment, it was in the late period. So it was important to additional N supplied in the late period to gain higher yield.When the rate of N fertilizer application was 300 kg ? hm"2, the N absorbing ratio of the maize plant under additional N supplied after silking fertilization condition was increasing, so it could supply more nutrition to seed grouting. When the rate of N fertilizer application was 300 kg ? hm"2, it can improve the N transportation from the nutrition parts to the seed, so that the offering ratio of the N to the seed could maintain a high level. When it was less than 300 kg ? hm"2, N was insufficient and the transportation of the nutrition apparatus was big so that the leaves were donated earlier. When it was more than 300 kg * hm"2, the N transported to seed was decreased because the vegetative mass was too vigorous.In treatments of N fertilizer, the suitable amount of N fertilizer was 300 kg ? hm" . The time and partitioning of N fertilizer application was seedling fertilization 30% + twelve-leaf stage fertilization 60%+ after silking fertilization 10%. The amount of seeds per ear, the 1000-grain weight and the grain unit weight were all the highest. It showed that chasing after silking fertilization could supply sufficient nutrition to maize grouting, so it could vail to maize grouting and increased yield.In HelLoing-Gang Region, when the rate of N fertilizer application was 300 kg ? hm", the stage and the partitioning was seedling fertilization 30% + twelve-leaf stage fertilization 60% + after silking fertilization 10%, it could obviously improve the photosynthetic rate, improve the dry matter accumulation and the N absorbing, vail to maize grouting, increase the 1000-grain weight and the grain unit weight and finally increase the yield.