Effects Of Nitrogen Application Rate And Density On Photosynthetic Production,Yield And Quality Of High Oil Soybean

Soybean is rich in protein and fat and plays an important role in people's dietary structure.As people's living standards improve,so does the need for soybeans.Heilongjiang soybean is famous in the country for its quality and yield,but most of its soybeans are mainly high in protein and relatively high in high oil soybeans.Cultivating high-quality high-oil soybeans is of great significance to the development of soybean industry in Heilongjiang.The experiment was carried out in the Agricultural Education Master's Degree Program for Agricultural Masters of Heilongjiang Academy of Agricultural Sciences in Northeast China Agricultural University in2018.The "Zhonglongdou No.1" high-oil soybean was used as the experimental material.The nitrogen application rate was set at four levels,F0?0 kg/hm²?,F1?90 kg/hm²?,F2?150 kg/hm²?,and F3?210 kg/hm²?.The nitrogen application rate was set at four levels,F0?0 kg/hm²?,F1?90kg/hm²?,F2?150 kg/hm²?,and F3?210 kg/hm²?.The density is set at four levels: D1?240,000plants/hm²?,D2?300,000 plants/hm²?,D3?360,000 plants/hm²?,and D4?420,000 plants/hm²?.The effects of different nitrogen application rates and densities on photosynthetic characteristics,dry matter,dry matter distribution ratio and yield of soybean were studied.Furthermore,a high-yield cultivation mode is obtained,which provides theoretical guidance for the promotion of high-oil soybean cultivation.The main results are as follows:?1?Nitrogen application rate and density had significant effects on soybean photosynthetic rate?Pn?,intercellular CO₂ concentration?Ci?,stomatal conductance?Gs?,and transpiration rate?E??P<0.05?.Soybean photosynthetic rate?Pn?,intercellular CO₂ concentration?Ci?,stomatal conductance?Gs?,and transpiration rate?E?both increased first and then decreased during the R1-R5 period.The R4 period combining rate?Pn?,stomatal conductance?Gs?,and transpiration rate?E?reached a maximum.The photosynthetic rate?Pn?,stomatal conductance?Gs?and transpiration rate?E?increased first and then decreased with the increase of nitrogen application rate and density.The nitrogen application rate was treated with F2?150 kg/hm²?.The highest and the highest density were treated with D3?360,000 plants/hm²?,and the fat combination in each period was the highest with F2D3.The intercellular CO₂ concentration?Ci?decreased first and then increased with the increase of nitrogen application rate and density.?2?The effects of nitrogen application rate and density on soybean leaf surface index?LAI?and chlorophyll?SPAD value?were significant?P<0.05?.Soybean leaf surface index?LAI?and chlorophyll?SPAD value?showed a trend of increasing first and then decreasing during the period of R1-R5.The response of leaf surface index?LAI?and chlorophyll?SPAD value?to the increase of nitrogen application rate increased first and then decreased.Density was positively correlated with leaf surface index?LAI?and negatively correlated with chlorophyll?SPAD value?.Under the same density treatment in each period,the leaf area index?LAI?and chlorophyll?SPAD value?were the highest under the treatment of nitrogen application rate F2?150 kg/hm²?.?3?The effects of nitrogen application rate and density on the dry matter of soybean stem and leaf were significant?P<0.05?.The dry matter of soybean stem and leaf showed an increasing trend during the R1-R5 period.With the increase of density,the stem and leaf dry matter of soybean plants showed a downward trend.Under the same density,with the increase of nitrogen application rate,it increased first and then decreased.Under the treatment of nitrogen application rate F2?150 kg/hm²?,the stem and leaf dry matter of single plant were the highest.?4?The nitrogen application rate and density had significant effects on the dry weight of soybean and the dry weight of the population?P<0.05?.The weight of dry matter per plant and the weight of dry matter of the group showed a trend of increasing first and then decreasing during the period of R1-R8.The weight of dry matter per plant showed a downward trend with the increase of density,while the weight of dry matter of the group showed an upward trend.Under the same density,the dry matter weight was the highest under the treatment of nitrogen application rate F2?150 kg/hm²?.?5?Nitrogen application rate and density had significant effects on grain weight per plant,?5?Nitrogen application rate and density had significant effects on grain weight per plant,number of pods per plant,100-kernel weight,and number of seeds per plant?P<0.05?.The response of soybean weight per plant,number of pods per plant,100-kernel weight,and number of grains per plant decreased with increasing density.Under the same density,the grain weight per plant,the number of pods per plant,the weight of 100 seeds,and the number of seeds per plant were the highest under the treatment of F2?150kg/hm²?.?6?The effect of nitrogen application on soybean protein content and oil content was not significant,and the effect of density on protein content and oil content was significant?P<0.05?.The response of oil content and protein content to the increase of nitrogen application increased first and then decreased.There was a negative correlation between oil content and density,and the response of protein content increased with density increased first and then decreased.?7?Nitrogen application rate and density had significant effects on soybean yield?P<0.05?,and the response of yield to nitrogen application and density increased first and then decreased.The output of the combination room is the highest with F2D3,and the output is 2831.33kg/km².