Effects of Planting Density and Nitrogen Application Rate on Growth and Yield of Rapeseed
To explore the effects of nitrogen fertilizer and planting density on the growth and yield of Brassica napus L,'Yunyouza 28'was used as materials to measure the growth period,agronomic traits,dry weight and yield under different treatments.3 density gradients(D1:150000 plants/hm2,D2:285000 plants/hm2,D3:420000 plants/hm2)and 4 nitrogen application levels(N1:0 kg/hm2,N2:75 kg/hm2,N3:150 kg/hm2,N4:225 kg/hm2)were set for the study.The results showed that under the same planting density,the whole growth period was extended with the increase of nitrogen application,the root neck diameter,leaf area,and total and green leaf numbers increased at the beginning and then decreased with the increase of nitrogen application under D1 density at flowering stage.Dry matter weight and yield both increased firstly,reached the maximum value under D1N2 and then decreased with the increase of nitrogen application under each density.Under the same nitrogen application,the whole growth period was shortened with the increase of planting density.The root neck diameter,total leaf numbers,green leaf numbers and leaf area decreased with the increase of planting density at bolting and flowering stage.The dry matter weight and yield decreased with the increase of planting density in various periods.Planting density and nitrogen fertilizer had little influence on early growth and development,mainly from bolting and flowering stage.Planting density had greater effects on the yield and dry matter weight than nitrogen application,which affected the yield through the number of effective pods per plant.With the interaction of density and nitrogen fertilizer,D11N2 treatment(density of 150000 plants/hm2,nitrogen application amount of 75 kg/hm2)was the best,which had the highest plant height,the highest total number of leaves and green leaves,root neck diameter and leaf area,and the highest yield per plant and per unit area.
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