Effectsof Nitrogen Density Intersction Onbiological Characters Yield And Silage Quality Of Silage Maize

In order to explore the optimum nitrogen application rate and planting density for simultaneous improvement of yield and quality of Silage Maize of different varieties,this experiment took mid-early maturing varieties Zhongyuan Dan32?ZYD32?mid-late maturing varieties Dajingjiu26?DJJ26?and Henan silage 23?YQZ23?as research objects.The Split-split plot design was adopted,with varieties as main plot,density as split plot,nitrogen application level as re-split plot,under field conditions.Three planting densities(67500,90000 and 112500 plants.hm^-2)and four nitrogen application levels(0,150,300 and 450kg.hm^-2)were set up to study the effects of nitrogen density interaction on the growth,yield and quality of silage maize,in order to determine the best nitrogen density treatment combination for different varieties of silage maize,and to provide theoretical basis and technical reference for high-yield and high-quality cultivation of silage maize.The main results are as follows;1.With the increase of nitrogen application,plant height and stem diameter of silage maize increased gradually.Before the powder dispersal stage,the nitrogen application rate of N2 and N3 was significantly higher than that of N0 and N1.The plant height of the three cultivars increased by 10.9%,8.5%,1.2%and 10.8%,9.3%,1.8%and 10.4%,7.8%and 1.3%respectively,and the stem diameter of the three cultivars increased by 14.0%,8.9%,1.4%and 9.3%,8.0%,0.9%and 12.6%,7.6%and 1.2%respectively,compared with other treatments.Under different density treatments,with the increase of planting density,the plant height of silage maize increased gradually,while the stem diameter decreased gradually.In the big mouth stage,when the planting density of ZYD32 was D2,it was significantly higher than that of the other two treatments,which were 15.2%and 11.9%higher than D1 and D3respectively.DJJ26 and YQZ23 were significantly higher than the other two treatments when the planting density of D3 was D1 and D2,which were 12.2%,9.7%,10.4%and 9.4%higher than that of D1 and D2 respectively.The stem diameter of low density D1 treatment was significantly higher than that of D2 and D3 treatment in the period from mouth to powder dispersal.Compared with D2 and D3,the three varieties increased by 6.5%,8.0%and 2.1%,9.8%and 5.2%and 14.0%respectively under D1density treatment.2.In terms of material production,with the increase of nitrogen application,LAI of Silage Maize did not change significantly,and SPAD value gradually increased;LAI of Silage Maize grew rapidly from jointing stage to powder dispersal stage,and reached the maximum value at powder dispersal stage,LAI value was 6.27,8.08,7.69,SPAD value was 57.07,56.21,65.7,respectively,and declined linearly after powder dispersal stage.With the increase of planting density,the LAI of silage maize increased significantly under different density treatments,which showed D3>D2>D1.From jointing stage to powder dispersal stage,LAI increased rapidly,then declined linearly,with the largest decrease in density,which was 26.7%,54.4%and 61.8%respectively.LAI of all three varieties reached the maximum at D3 density of powder dispersal stage,which was 7.73 cm,9.53 cm and 9.58 cm,respectively.The SPAD value of Silage Maize decreased significantly,as follows:D3<D2<D1.SPAD increased rapidly from jointing stage to powder dispersal stage,and the maximum value appeared in powder dispersal stage,which was 56.89,60.17 and 65.74,respectively.In terms of dry matter accumulation,the trend of dry matter accumulation per plant of silage maize was different,and reached the maximum at maturity.Under the same nitrogen application rate,the three varieties showed a Change trend of decreasing first and then rising,specifically 112 500 plants.hm^-2>67500 plants.hm^-2>90 000 plants.hm^-2.Under the same planting density,both ZYD32 and DJJ26 showed an increasing trend with the increase of nitrogen application.YQZ23 showed an increasing and then decreasing trend with the increase of nitrogen application.However,the amount of nitrogen applied to the highest dry matter accumulation of the three varieties was not the same.The amount of dry matter accumulation of ZYD32 and DJJ26 was the highest under the treatment of 450kg.hm^-2 nitrogen application,and the amount of dry matter accumulation of YQZ23 was the highest under the treatment of 300kg.hm^-2 nitrogen application.3.In terms of yield,planting density had a significant effect on Silage Maize yield,especially DJJ26 and YQZ23?p<0.01?.Nitrogen application only had a significant effect on YQZ23?p<0.05?.The interaction between them had a significant effect on the yield of ZYD32 and YQZ23?p<0.01?.This indicated that under nitrogen density treatment,density was the dominant factor affecting silage maize yield,and the interaction between them was the second.Under the same nitrogen application level,the yield of silage maize increased with the increase of planting density,which was D3>D2>D1.Under the same planting density,the yield of silage maize increased first and then decreased with the increase of nitrogen application.The highest nitrogen application rate of three varieties was different.The highest nitrogen application rate of ZYD32 and YQZ23 was 55.67 t.hm^-2 and 70.86 t.hm^-2 at 300kg.hm^-2,respectively.The highest nitrogen application rate of DJ26 was 67.25 t.hm^-2 at 150 kg.hm^-2.The yield of YQZ23 was significantly higher than that of ZYD32 and DJJ26.4.In terms of quality,the content of CP and FAT of different varieties decreased gradually with the increase of density under the same nitrogen application rate.Under the same density,the contents of CP and FAT of different cultivars increased first and then decreased with the increase of nitrogen application.ZYD32 had the highest CP content?9.74%?under D1N1 treatment,followed by YQZ23with 9.45%under D3N2 treatment,and finally DJ26 with 9.18%under D1N1 treatment.ZYD32 had the highest FAT content?3.82%?under D1N2 treatment,followed by DJ26 with 3.25%under D1N1treatment,and finally YQZ23 with 2.98%under D1N2 treatment.The ADF and NDF contents of ZYD32 and DJJ26 increased first and then decreased with the increase of planting density under the treatments of 0 kg.hm-² and 150 kg.hm^-22 of nitrogen application.YQZ23 showed a decreasing trend with the increase of planting density,while N1 treatment was lower than N0 treatment.Under the treatments of 300 kg.hm^-2 and 450 kg.hm^-2 of nitrogen application,the ADF and NDF contents of the three varieties increased with planting density.The increase showed an increasing trend,and N3 treatment was lower than N2 treatment.Among the density treatments,ADF and NDF of the three cultivars decreased with the increase of nitrogen application rate under the treatments of 67500 hm^-2 and 90000 hm^-2.The ADF and NDF contents of ZYD32 were lower than those of the other two varieties under different nitrogen densities.ZYD32 had the lowest content of ADF and NDF under D1N3 treatment,18.8%and 32.69%respectively,followed by DJJ26,23.26%and 35.72%under D1N1 treatment,and finally YQZ23,24.07%and 39.87%under D1N3 treatment.5.In terms of nitrogen use efficiency,the maximum nitrogen accumulation of ZYD32,DJJ26 and YQZ23 appeared in D3N3 treatment,and the maximum NAA values of the three varieties were 997.92kg/hm^-2,1337.07 kg/hm^-2 and 1390.72 kg/hm^-2,respectively.Under the same density,nitrogen application rate was proportional to nitrogen accumulation.Nitrogen accumulation of silage jade increased with the increase of nitrogen fertilizer,while the agronomic and nitrogen uptake efficiency of nitrogen fertilizer were opposite.ZYD32,DJJ26 and YQZ23 could achieve the mutually promoting relationship between yield and nitrogen use efficiency under D3N1,D1N2 and D1N1 treatments,respectively.