Research On The Nitrogen And Phosphorus Nutrition Characteristics And Nutrition Control Technology Of Super-high Yield Maize

Maize plays a very major role in our country's grain production and it has great significance to ensure national food security. However, under the double pressures of food needs and resources shortage, the only way to increase grain yield is to enhance the yield per unit. So the only way to break the limitation of maize yields per unit and develop the sustainable technology for maize super-high yield is to strengthen the basic research of maize super-high yield, enrich the theory and reveal the formation mechanism of maize super high yield, so that the theory can be used to guide maize super-high yield practice and give enough yield with limited resources to ensure national food security. This thesis combined field experiments and lab test, researched the characteristics of maize economic yield, biomass, N, P and tested the effects of nutritional regulation in order to find the nutrition rules of super-high yield maize and authenticate that theory in practice. The results are as follows:1,The three elements of economic yield in super-high maize were higher than those in other yield maize. Spring maize should have more than 87200 ears per hm2, more than 540 grain number per ear and more than 280g per thousand grain weight for super-high yield. The path analysis of yield and its elements showed that the most importance to grain yield is ears number per hectare, then is the grain number per ear and the weight per thousand grains. So for the same kind of maize and same density, spring maize should decrease the rate of empty pole and seedling in order to get the maximum ear number per hectare. At the same time, good nutrition, less abortion and bald tip should be made to enhance the number of ears. And water and fertilizer in the late growth stage should be strengthened to delay leaves aging, enhance weight per thousand grains and get super-high yield.2,The biomass of aboveground plants was the highest in filling-milky stage, whose biomass was 36.3% of total accumulation. The maximum and average accumulation rate of dry matter of super-high yield maize were higher than other yield, and the date of appearing maximum accumulation rate was 86 days after emergence, just during the filling stage. So the obvious advantage of dry matter accumulation rate could be found in the late growth stage of super-high yield, which established matter basis to the formation of economic yield.3,The accumulation of dry matters in different organs of super-high yield spring maize was maximum in the milky stage, the date of appearing peak was 20 days later than low yield spring maize (CK). The transfer amount of dry matters among organs was the highest in super-high yield spring maize, while the transfer rate and contribution rate was the least in super-high yield spring maize. The rate of transfer amount of super-high yield spring maize to dry matter weight in mature stage was 27.5%. And the rate of weight of dry matter in grain which transferred from leaves in photosynthetic products to the weight of grain accounted for 72.5%. So the higher yield we have, the lower of the dependence extent of grain on dry matter of various organs, and the stronger dependence extent on the leaves photosynthesis.4,Characteristics of nitrogen accumulation in super-high yield spring maize lies in a high and continuous need for nitrogen nutrition after jointing stage. Three key stages for N control were jointing,anthesis silking and filling stages. The maximum absorption rate appeared on the third day after bell stage.5,The jointing stage and anthesis silking stage were important to N control for leaves and stems of super-high yield spring maize. The characteristics of N distribution in various organs was that the change of N distribution rate among organs decreased and more balance, which was important to retain proper distribution rate of N among nutrition organs in the late growth stage and delay the organ caducity. Though the transfer amount of N was large, the contribution rate of transferring and grain was small.46.7% N of grain in super-high yield spring maize came from transform among nutrition organs and the other 55.3% came from roots in the late growth stage.6,The rate of P absorption and accumulation for super-high yield spring maize in jointing-bell stage and anthesis silking-filling stage was obviously higher than that in other stages. The max P absorption and accumulation rate of super-high yield spring maize was 45.2%-84.4% higher than that in other yield. The max rate of P absorption appeared on the third day after bell stage.7,The jointing stage is not only the bottleneck for P accumulation of super-high yield spring maize leaves,sheath and stem, but also the key stage for P nutrition control. The distribution rate of P in leaves and stem was high than other organs for super-high yield spring maize, and P in grain was relatively low. The P transfer amount among organs of super-high yield spring maize was the highest, but the transfer rate and the contribution rate to grains were relatively low.50.6% P in super-high yield spring maize came from other nutrition organs, but the other 49.4% came from roots supply directly in the late growth stage.8,According to the characteristics of biomass, N and P in super-high yield spring maize, this thesis showed that the key factor to get super-high yield for spring maize lied in as follows: the first was to pay attention to nutrition control of maize in the late growth stage. The second was to prolong the function stage of nutrition organ, at the same time, enhance the ability of absorb nutrition for roots in the late growth stage to satisfy the need to N and P for super-high yield spring maize in the late growth. The third was to enhance the ability of photosynthesis in the mid and late growth stage and promote the foundation of biomass in the late growth stage to make the basis for super-high yield of spring maize. This thesis also showed that the key stage of N control for super-high yield spring maize was the jointing stage and anthesis silking stage. According to the P transfer amount was low in the soil, the thesis proposed that the key stage of P control was the jointing stage, and it is feasible to fertilizer in this stage in the theory.9,This thesis showed that the nutrition control technology for super-high yield spring maize was as followed:The first was to apply N 360 kg/hm2, in which 30% of N was applied when plowing,10% when seeding,25% when jointing,35% when earring; the second was to apply P (P2O5) 150 kg/hm2, in which 90% when plowing, and 10% when seeding; the third was to apply K (K2O) 225 kg/hm2, in which 40% when plowing,30% when jointing,30% when bell stage. Above the nutrition control could get more than 16000 kg/hm2 with super-high yield. In this experiment, the ratio of N:P2O5:K2O was 1:0.42:0.63, the contribution rate of N, P, K to yield was 27%,14% and 17% respectively. The contribution rate to yield was N>K>P, and we found that yield could be obviously enhanced by increasing K.