Effect of Planting Density and Nitrogen Application Rate on Population Quality and Yield Formation of Super High-Yielding Winter Wheat

In order to clarify the effect of planting density and nitrogen fertilization application rate on population quality and yield formation of winter wheat,a field experiment was carried out at Gaocheng county,Hebei province,during 2013-2014,using a winter wheat cultivar,Shimai 18.The experiment was designed as split plot arrangement,with planting density as main plots(150×104,225×104,300×104 and 375×104 plants·hm-2)and nitrogen fertilization rate as split plots(N 180,240 and 300kg·hm-2).The results showed that the amounts of population culms(spikes)of wheat increased with the increase of planting density during all growing stages,but all the four densities got enough spikes.The leaf area index(LAI)and dry matter accumulation during pre-winter to anthesis increased with the increase of density,but the LAI and dry matter accumulation under 150×104 and 225×104 plants·hm-2 were higher than those of 300×104 and 375 ×104 plants·hm-2 during post-anthesis period.The difference of the population culms at all growing stages(except erecting stage)was not significant among the three nitrogen fertilization rates.The dry matter accumulation had a tendency toincrease with the increase of nitrogen rates,and the LAI of wheat with higher nitrogen fertilization rates declined slowly after anthesis.The effect of planting density on yield and its components of wheat were statistically significant(P0.05).And the effect of nitrogen fertilization rate on 1 000 grain weight and grain yield were also statistically significant(P0.05).The interactions of planting density and nitrogen rate on grain weight and grain yield were significant.The highest grain yields of wheat,10 308.65 and 10 221.98kg·hm-2,were achieved in the treatments with the planting density 150×104 plants·hm-2,and the nitrogen fertilization rates 240 and 300kg·hm-2,respectively.According to the results,it is recommended that,nitrogen fertilization should be increased properly under low planting density.Considering saving cost and improving nitrogen use efficiency,nitrogen input should be decreased under high planting density,so as to realize high yield and high efficiency of wheat production.