Effect Of Density Nitrogen Application On Population Quality And Yield Of Replanted Fodder Rape

In this experiment,the effects of different planting densities（200,000 plants/hm2,300,000 plants/hm2,400,000 plants/hm2）and nitrogen application rates（140 kg/hm²,170 kg/hm²,200 kg/hm²）on morphological indicators,dry matter accumulation,canopy indicators,economic traits and yield components,canopy structure and photosynthetic characteristics of fodder oilseed rape were investigated by means of field experiments using high-quality fodder oilseed rape Huayouza 62 as material.The effects of different N applications（140kg/hm²,170kg/hm²and 200kg/hm²）on morphological index,dry matter accumulation,canopy index,economic traits and yield components,canopy structure and photosynthetic characteristics of fodder rape.The aim is to provide a theoretical basis for the rational cultivation of fodder rape production to improve yield and achieve high yield and quality.The results of the study showed that.1.Density and nitrogen application had significant effects on agronomic traits of rapeseed,and the number of main stem leaves,primary branches,main inflorescence length and effective length of main axis tended to decrease and then increase with increasing density,while the number of branching sites,secondary branches and effective branching height tended to increase and then decrease.The dry matter accumulation per plant increased with the increase of N application,and the ratio of dry matter accumulation in the bud and first flowering period to the whole reproductive period increased with the increase of density;the ratio of dry matter accumulation in the post-flowering period to the whole reproductive period increased with the increase of N application.The best overall agronomic traits,the highest number of primary branches,and the highest amount of dry matter accumulation from leaves to horn fruits were obtained under the treatment of 300,000 plants/hm²density and 200 kg/hm²N application.2.With the increase of density,each leaf without interception scattering are decreasing trend,leaf inclination gradually decreased,tends to horizontal,high density of rape more easily collapse,light distribution is"V"shape.With the increase of nitrogen application,the larger the leaf area index,the more depressed the rape bottom branches and leaves,the smaller the amount of light incidence.3.As the density increased,the net photosynthetic rate of leaves gradually increased,the smaller the intercellular CO₂concentration,and the initial fluorescence showed a trend of increasing and then decreasing.At a density of 200,000 plants/hm²,stomatal conductance,chlorophyll content and PS II receptor pool size increased with increasing nitrogen application.The electron transfer efficiency reached its maximum at low densities and high nitrogen,and the electron transfer quantum yield,maximum photochemical quantum yield and potential PSⅡactivity were maximum at high densities and low nitrogen.Net photosynthetic rate,stomatal conductance and transpiration rate all reached their maximum at around 14:00 noon,and intercellular CO₂concentration showed a minimum at around 16:00 pm.4.Density and nitrogen fertilization had significant effects on the number of angular fruits,angular fruit weight,number of kernels,kernel skin area,and biological and seed yields of rapeseed.Under the interaction of density and N fertilizer,there was a positive correlation between main inflorescence length and effective length of main axis,a positive correlation between number of secondary branches and seed yield,a positive correlation between number of angular fruits and angular fruit weight,thickness of angular layer and density of angular layer,and a significant positive correlation between fruit length and angular fruit width.The different treatments increased the biological yield by 53%and the seed yield by 90%,with the highest biological yield of 62,692 kg/hm²at a density of 300,000 plants/hm²and 200 kg/hm²of nitrogen application,and the best overall evaluation.