Effects Of Nitrogen Application On Tiller Characteristics And Yield Of Mechanical Transplanted Rice In Jianghan Plain

To research the appropriate nitrogen application rate of machined-transplanted rice at Jianghan Plain in Hubei.the hybrid rice Cliangyouhuazhan,Quanliangyou681 and conventional rice Huanghuazhan were used as experimental materials to study the effect of tillering,panicle formation,population growth,nitrogen use efficiency and yield formation under different nitrogen application rates(135?180?225 kg/hm~2)in 2017-2018 useing split-zone design.The results shows:1.The tillering of single transplanted into machine-transplanted rice takes advantage of the 4/0-8/0 primary tillering of 3-9 leaf position and 4/1,5/1,6/1 secondary tillering of4-6 leaf position,as the dominant tillers,in which4/0,5/0,6/0 leaf position is primary tiller and 4/1,5/1,6/1 leaf position is the main tiller position;With the nitrogen fertilizer added,low leaf position 3/0 and high leaf position 8/0 increased;and the increase of nitrogen fertilizer application rate furthermore,the incidence of tillering rice increased,and the rate of ear formation decreased;The three transplanted tillers occurred in the 4/0-6/0 primary tiller of 4-6 leaf position at 3-7 leaf position and the 1/4,1/5,2/5 secondary tiller of 4-5 leaf position.The dominant tillers,in which the 5/0 and 6/0 leaf positions are once divided and the 1/4 and 1/5 leaf positions are the main tillers.2.In terms of population growth and light energy utilization under nitrogen application rate on machine-transplanted rice,the accumulation of dry matter increased with the increase of nitrogen application rate;except for the maturity period,the relationship between leaf area index and nitrogen application rate was positively correlated;the high leaf area rate at the heading stage increased first and then decreased with the increase of nitrogen application rate.The effective leaf area rate increased with the increase of nitrogen application rate,and there was a positive correlation between the effective leaf area rate under nitrogen application rate.The canopy light energy interception rate and transmittance increased with the increase of nitrogen application rate,and the reflectance increased with the application.The amount of nitrogen increases and decreases.3.In terms of production completion,the amount of nitrogen applied mainly affected the effective panicle,grain number and seed setting rate of machine-transplanted rice.The yield of machine-transplanted rice increased with the increase of nitrogen application rate,but there were differences among different varieties.Among them,conventional rice Huanghuazhan was a low-nitrogen high-efficiency variety.The yield difference between135-225 kg/hm~2 was not significant.Cliangyouhuazhan was a high-yield medium-nitrogen variety,the nitrogen application rate was the highest at 180 kg/hm~2,and the quanliangyou681 was a high-nitrogen high-efficiency variety.The highest nitrogen application rate was 225 kg/hm~2.4.In terms of nitrogen use efficiency,.with the increase of nitrogen application rate,the nitrogen content in leaves,stem sheaths and panicles of Machine-transplanted rice at the heading stage and mature stage decreased,and the carbon to nitrogen ratio decreased.The135kg/hm~2 was the highest in nitrogen agronomic utilization rate,and the 180kg/hm~2nitrogen application rate was the highest in nitrogen physiological utilization rate and apparent nitrogen utilization rate.5.The brown rice rate,the whole milled rice rate,the protein content and the chalky grain rate increased with the increase of nitrogen application rate.In summary,the machine-transplanted rice in this region can promote the occurrence of low leaf position 3/0 and high leaf position 8/0 and the ear formation through appropriate nitrogen application rate,increase the effective ear area per unit area,and construct a suitable population structure to enhance light.It can use efficiency and improve the yield structure to increase rice yield.For low-nitrogen high-efficiency varieties such as Huanghuazhan,the nitrogen application rate is 135 kg/hm~2,and for the medium-nitrogen high-efficiency varieties such as Cliangyouhua,the nitrogen application rate is 180kg/hm~2,and the high nitrogen high-efficiency variety such as Quanliangyou 681 The nitrogen application rate is preferably 225 kg/hm~2 or more.