Effects Of Different Nitrogen Rate And Density On Lodging Resistance And Yield Formation Of Maize

This paper focuses on the research on the impact of nitrogen application rate and density on the internode characters, the cane stem weight and strength, and production characters during the vegetation process of corns. This research provides both theoretical and practical support on preventing the lodging at different stages of growth and development. The experimental material for this research is Liangyu 99. The split block design is used of the main block nitrogen fertilizer rate and the secondary block is density. To be more specific, the nitrogen application rates are: 150 kg·hm-2(N1), 250 kg·hm-2(N2), and 350 kg·hm-2(N3); the density settings are: 50,000·hm-2(M1), 75,000·hm-2(M2), and 100,000·hm-2(M3). The samples are extracted from jointing stage, bell stage, tasseling stage, mid grain filling stage and maturation stage. And the samples are used to measure the height of the plants and spikes. Different handles on the length and stem diameter of the 1 to 6 nodes of the corns are analyzed, and the rate of the length over the diameter as well as the dry matter between each node and the whole plant is calculated. The 1 to 6 nodes' characters and production of the spikes are measured and analyzed when the corns are harvested. The results have been analyzed systematically. The main research results are as following:1. The impact of the nitrogen application rate and density on the plants' characters of the corns.Given the same nitrogen application rate, the stem length will increase while the stem diameter will decrease if the density is increased, so that the rate of the length over the diameter will increase. The index of plant height, ear height and coefficient of ear height will also increase significantly. At the same level of density, N2 is performing better than N1 and N3. Increasing nitrogen application rate after tasseling stage will increase the stem length and decrease the stem diameter so that the rate of the length over the diameter will increase. Increasing the nitrogen application rate under medium nitrogen fertilizer rate will lower the height of the spikes. The change is significant on the impact of density of the stem characters after tasseling stage. Increasing density will cause the height of spikes increasing gradually. The height of plant will increase first and then decrease and the height of spikes will decrease first and then increase. The rate of stem length and diameter are correlated positively with the density, on the other hand, the stem diameter is correlated negatively. Under the impact of the nitrogen application rate and density, the rate of stem length and diameter of N1M2 and N2M1 is smaller than others, and the diameters of N1M2 and N2M1 larger than others. The index on plant height, ear height, and coefficient of ear height is at the lowest level, and the plant character is at the highest level.2. The impact of the nitrogen application rate and density on the dry matters of the corns.Under the same rate of nitrogen application, increasing density will reduces the dry matter between each nodes and the weight of the whole plant. Under high or low level of density, increasing nitrogen application rate will cause the dry matter between nodes increase first and then decrease. Under medium level of density, increasing nitrogen application rate will decrease the dry matter between each nodes. The impact of nitrogen application rate is not obvious during jointing stage bell stage tasseling stage and maturation stage decrease the nitrogen application rate will increase the dry matter of the first internode. In tasseling stage mid grain filling stage,decrease nitrogen application rate will increase the dry matter of the first?second?sixth and the second ? third internode. Under the impact of nitrogen application rate and density: N3M1>N2M1>N1M1>N2M2>N3M2>N1M2>N3M3>N2M3>N1M3.N3M1 nis 22.9% larger than N1M3 at all stages of the vegetation process. Integrating the dry matter between nodes and the whole plants, N2M1, N3M1 and N1M1 are better than other blocks.3. The impact of the nitrogen application rate and density on the stem strength of the corns.Under the same level of nitrogen application rate, increasing the density will significantly decrease the stem strength. Under high or low density level, increasing the nitrogen application rate will increase the stem strength and then drop down. Under medium density level, increasing the nitrogen application rate will decrease the stem strength. In the tasseling stage and mid grain filling stage, increasing the nitrogen application rate will cause the stem strength of the first and second internode. In tasseling stage medium nitrogen application rate will increase the stem strength of 3rd to 6th nodes. The difference at maturation stage is not obvious in terms of low and medium nitrogen application rate, but they are both higher than the high nitrogen application rate. It is consistent for all three periods increasing density will decrease the stem strength between nodes. Under the impact of nitrogen application rate and density, N2M1 handles better than N2M3.4. The impact of the nitrogen application rate and density on the production and the production factors of the corns under the same nitrogen application rate, increasing the density will decrease the length and diameter of the spikes and kernel weight, and increase the length of bald.Under medium or low density level, increasing the nitrogen application rate will increase the length and diameter of the spikes and kernel weight first and then drop down. Under high density level, increasing the nitrogen application rate will change the characters of the spikes. Increasing the nitrogen application rate and density will affect the characters of the spikes and the production of the corns. In terms of production, N1 and N3 shows not much difference but lower than N2. When increasing density, the effective numbers of spikes is also increased, so in terms of production, M3>M2>M1. In terms of the production and characters, N2M2 is way better than N1M3.Under the impact of nitrogen application rate and density: N2M2>N3M3>N2M3>N1M3>N2M1>N3M2>N1M2>N1M1>N3M1, the differences between the maximum and the minimum is as large as 18.2%.In conclusion, under N2M1 handling, which is 250 kg·hm-2 and 50,000·hm-2, the rate of stem length over stem diameter is the smallest and the stem diameter is the largest. The weight between nodes and the whole plant are higher than others. The index of plant height?ear height and coefficient of ear height advantage over others, and the advantage is obvious in terms of stem strength. In terms of production, N2M2 is better than others in terms of ear length, ear diameter, kernel weight and Kernels per row, moreover, the length of bald is relatively smaller and the production is much better than others.