| The experiment was conducted from 2015 to 2016,in Kangcheng village Shundian township of Yuzhou city,Henan Province.The low density and large panicle type Weike702 was selected to study the relationship between the growth and dry matter accumulation,nutrient use and yield of maize.The aim of this study was to explore the suitable amount of Nitrogen Application on the basis of the increase of density,so as to obtain higher yield of maize,and enhance the absorption and utilization of nitrogen,phosphorus and potassium.A total of four densities(45000,60000,75000,90000 plant·hm-2)and three nitrogen levels(0,180,360 kg·hm-2)were designed to find the suitable density and nitrogen fertilizer combination and to provide technical and theoretical support for high yield and efficient use of nutrient resources.The main results are as follows:1.The interaction of density and nitrogen fertilizer could significantly increase grain number per spike and 1000-grain weight.The 1000-grain weight and grain number per spike of two maize varieties showed a decreasing trend with the increase of density.Under the same density,nitrogen application could increase the value of1000 grain weight and grain number per spike,but excessive application of nitrogen inhibited the increase of 1000-grain weight t and grain number per spike,especially in high-density conditions have reached a significant level of decline.Nitrogen application had no significant difference in pike number,only affected by planting density.The yield of two varieties of maize was significantly different on the influence of nitrogen or density.The yield of two varieties increased firstly and then decreased with the increase of density when the nitrogen application rate was 0 and180 kg·hm-2.The yield of WK702 increased firstly and then decreased with the increase of the density at the amount of nitrogen application of 360 kg·hm-2,but the yield of ZD909 was increased with the increase of density.During the whole study,the yield of the two varieties reached the maximum at the density of 75000 plant·hm-2and the nitrogen of 180 kg·hm-2.The density of high yielding combinations is similarto it,but the amount of nitrogen application was relatively less 30% than 11.5 t· hm-2yield levels.2.The ear of maize was affected by density and nitrogen application rate.The ear length,ear diameter,row number and kernel number of two varieties were gradually decreased in the process of increasing density.The nitrogen application was beneficial to the increase of ear length,ear diameter,row number,and number of rows,under the same density.The bald tip length decreased with the increase of density,under the same density condition: N1>N3>N2.Under the condition of low density,the effect of density on yield is higher than that of row number and grain number.The effect of row number and row number was higher than that of density,at the density of 75000 plant·hm-2.3.During the growth period,the accumulation of dry matter increased with the increase of density and the same law was observed for the accumulation of dry matter after anthesis.Fertilization could promote the accumulation of dry matter at the time of pre anthesis and post anthesis,but excessive fertilization inhibited the growth of dry matter accumulation.Under low density,with the increase of amount of nitrogen application,maize harvest index was improved,whereas the higher nitrogen application restrained the growth of harvest index after a certain density.Under the condition of maximum density,the contribution rate of dry matter accumulation after anthesis was the lowest.4.The accumulation of nitrogen,phosphorus and potassium in the growth period of maize increased with the growth process of maize,the crop growth rate was slow in the early stage then faster in late process.The accumulation of N,P and K was increased with the increase of density at the mature stage,and the order was followed by N2>N3>N1.Nitrogen application could promote the absorption and accumulation of nitrogen,phosphorus and potassium,but the excessive application of nitrogen fertilizer decreased the nitrogen use efficiency,nitrogen partial productivity,agronomic efficiency,and P,K uptake efficiency.The results also suggested that the application of nitrogen could decrease the harvest index of nitrogen and potassium,but increased the harvest index of phosphorus.According to the results of the experiment,our results showed that the utilization rate of nitrogen fertilizer,nitrogen partial productivity,agronomic utilization rate and phosphorus and potassium absorption efficiency were better than the rest,under the condition of D3N2.5.The plant height and ear position were increased with the increase of density,and the length of the stem base decreased with the increase of density.The suitable nitrogen application rate could be used to coordinate the relationship among plant height,ear position and the length of the stem base,which led to reduce the lodging condition of crop.When the rain was plentiful,the lodging rate was higher under the condition of low density and low N application rate or high density and high N application rate. |
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