| Rape is an important oil crop in my country,accounting for about 60%of the national edible vegetable oil.Therefore,the development of the rape industry is closely related to national life.In recent years,in the practice of rapeseed production,there have been problems such as excessive input of fertilizers(especially nitrogen fertilizers),low utilization efficiency,low level of mechanization,and low farmers’enthusiasm for planting.Studying the suitable nitrogen fertilizer application rate and planting density of rape hybrids is of great significance for increasing the income of rapeseed planting and generating income for farmers.In this paper,three-line rapeseed hybrids Shanyou 21,Shanyou 52,and Shanyou1617 independently cultivated were used as experimental materials,and three nitrogen application levels were set at 108 kg/hm~2,144 kg/hm~2,180 kg/hm~2,and three plantings.The density levels LD(15×10?~4plants/hm~2),MD(30×10?~4 plants/hm~2),HD(45×10?~4plants/hm~2)were subjected to a three-factor split area test to study and analyze the effects of nitrogen application and planting density on the growth and development of rape,The impact of nitrogen transfer and utilization and yield,the main results are as follows:1.The number of green leaves and root neck diameter of Shanyou 21,Shanyou 52,and Shanyou 1617 all had the maximum value under MD(30×10?~4plants/hm~2)treatment,and the medium density was more suitable for plant growth and development.In general,Shanyou21 has a better growth and development,and its chlorophyll content is higher than Shanyou52 and Shanyou 1617;increasing nitrogen application increases the dry matter accumulation of roots and shoots of the three rapeseeds at seedling stage,and the influence of planting density The law is inconsistent.2.Under the treatments of LD(15×10?~4plants/hm~2)and HD(45×10?~4 plants/hm~2),the three cultivars had moderate nitrogen application rate and the largest silique area index.The144kg/hm~2 nitrogen treatment promoted the growth and development of siliques.Densification increases the silique area index.The effect of planting density and nitrogen application rate on the light transmittance of the three varieties showed inconsistent changes.Densification decreased the light transmittance of rape during the filling stage.3.Increasing nitrogen application can promote the accumulation and utilization of dry matter in leaves,siliques and stems.Under high density,increasing nitrogen application can reduce the accumulation of dry matter in leaves,siliques and stems of Shanyou 1617.The nitrogen application rate increased from 108 kg/hm~2 to 180 kg/hm~2,the nitrogen content of grains was significantly higher than that of other organs,followed by the nitrogen content of leaves,and the nitrogen content of stems and siliques were less.Density had an effect on the nitrogen content of various organs.The influence law of the amount of nitrogen is inconsistent.Increasing the amount of nitrogen applied will generally increase the total nitrogen accumulation of plants.As the planting density increases from LD(15×10?~4plants/hm~2)to MD(30×10?~4 plants/hm~2),the total plant nitrogen The accumulation is increasing,and the planting density continues to increase to HD(45×10?~4plants/hm~2),the total nitrogen accumulation of plants decreases,and the density increases reduces the nitrogen harvest index,and the partial productivity of nitrogen fertilizer is under LD(15×10?~4 plants/hm~2)It will increase with the increase of the nitrogen application rate.If the density is too high,the nitrogen application rate will decrease the partial productivity of nitrogen fertilizer,which is not conducive to increasing the economic output.Increasing the planting density will reduce the partial productivity of nitrogen fertilizer,and the intensity of individual competition will be high,and individual plant will absorb less nitrogen.Under HD(45×10?~4plants/hm~2),increasing nitrogen fertilizer will transport nitrogen to non-economic parts and make it Biomass increases,while grain yield decreases,resulting in a waste of resources.4.Plant height increases with the increase of nitrogen application rate,but decreases with the increase of density.The effective branch height decreases with the increase of nitrogen application rate,and increases with the increase of planting density.Planting density has a significant effect on the number of branches.There was a decreasing trend with the increase of density,while the amount of nitrogen applied had no significant effect on the number of branches;the length of the main inflorescence increased with the increase of the amount of nitrogen,and decreased with the increase of the density,and the number of effective siliques of the main inflorescence increased with the increase of the amount of nitrogen.The number of siliques in the whole plant decreases with the increase of density,and the number of siliques per horn decreases with the increase of nitrogen application rate.The number of siliques per horn decreases with the increase of nitrogen application rate,and decreases with the increase of density.Thousand-seed weight increases with the increase of nitrogen application rate and increases with the increase of density.Increase the amount of nitrogen applied to improve the agronomic characteristics of rapeseed,which is conducive to the growth and development of siliques,and promotes the increase in yield.There is no significant difference between the density and the amount of nitrogen applied to the yield of three varieties of rapeseed per unit area.The application is carried out according to the characteristics of the varieties.Combination of nitrogen density,higher output.The rapeseed yield per unit area of Shanyou 21 was the highest under the treatment of LD(15×10?~4plants/hm~2)and 180 kg/hm~2,and its value was 3133.33 kg/hm~2.The yield of rapeseed per unit area of Shanyou 52 was the highest Under the treatment of LD(15×10?~4 plants/hm~2)and 180 kg/hm~2,the value was 3362.50 kg/hm~2.The yield of rapeseed per unit area of Shanyou 1617 was the highest under the treatment of MD(15×10?~4plants/hm~2)and 108kg/hm~2,and the value was 3366.67 kg/hm~2.5.The disease index has a very significant positive correlation with the variety.For the three varieties,the order of antibacterial nuclear diseases is:Shanyou 52>Shanyou1617>Shanyou 21.The disease index and nitrogen are also very significantly positively correlated.Increased nitrogen application increased the incidence of sclerotium disease to a certain extent,and increased density increased the occurrence of sclerotium disease.The lodging index was significantly positively correlated with density.Lodging under high-density conditions was significantly higher than that under low-density conditions.Increasing the amount of nitrogen application increased the protein content of the three varieties and decreased the oil content.The effects of nitrogen application rate and planting density on the content of erucic acid and glucosinolate in grains were inconsistent. |
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