Effects Of Different Collocation Patteren Of Basic Seedling Number And Fertilizer Application Rate On The Yield Formation Of Machine-transplanted Super Hybrid Rice

Field experiments of the machine transplanting with super hybrid rice varieties(i.e.,Longliangyou Huazhang,LLYHZ and Jongliangyou Huazhang,JLYHZ)were conducted by using different collocation patterns of four basic seedling number and three fertilizer application rates in Ningxiang county of Hunan province in 2016-2017.The tillering patteren,nutrients absorption and utilization,dry matter production and allocation,grain yield and its components were measured.The correlation between the yield and yield of different basic seedling configuration and fertilizer application was also analyzed.The main results are sumarreized as follows:(1)Adding to planting density and/or basic seedling number per hill increased the number of effective panicles,while decreased the spikelet number per panicle and reduced panicle traits(reduction in primary and secondary branches and panicle length).Grain yield between varieties and years was slightly different.The average yield of 2 varieties in 2017was 36.01 percent lower than that of 2016.And the key reason that restricted increase in grain yield in 2016 was the number of effective panicles whereas was the grain filling rate in2017.In general,The single seedling machine-transplanted hybrid rice under dense planting conditions(SMT)had the highest yield,and showed the suitable population,appropriate tillers and higher earbearing tiller percentage,and higher leaf area index(LAI),higher dry matter production and partitioning rate.While DMT could not achieve high yield because of the lower grain filling since it could coordinate the growth of population and individual and had the highest pikelets per m~2.(2)Significant effects of fertilizer application rates on the growth,grain yield and its components of machine-transplanted hybrid rice were abserved.With the increasing of fertilizer application rate,the growth rate of tillering,number of peak tillers,LAI,dry matter production at full heading stage and total dry matter weight at maturity were improved.Similarly,panicle length,the number of primary and secondary branches were also increased,which resulted in more effective panicles,spikelets per panicle and total spikelets per m~2.In addition,different responses of grain yield to fertilizer application were found between 2016and 2017 for two varieties.In 2016,grain yield improved by 7.18%to10.53%with the increasing of fertilizer application,while decreased by 6.73%to 12.65%in 2017.This was because severe bacterial blight happend due to increase of fertilizer applicaiton in 2017,which lead to significant decrease in grain filling rate.Generally,the results suggested that a combination of medium fertilizer application rate(960 kg/hm~2)and SMT(28.6-33.3×10~4 hills/hm~2 with single seedling per hill)can achieve high yield and high fertilizers use efficiency,simultaneously,for machine-transplanted hybrid rice to.