Effects On Soybean Yield And Quality And Nitrogen Metabolism Under Different Sowing And Ratio Of Nitrogen Basal And Topdressing

Soybean(Glycine max[L.]Merr.),an important oil crop,occupies a pivotal position in agricultural production.In this study,soybean cv.Nannong 99-6 was used to study the effects of sowing date and ratios of base and topdressing of nitrogen levels on dry matter accumulation,yield,quality and nitrogen metabolism with field experiment.Different ratios of base and topdressing were requested during different sowing period,which maintained a high nitrogen metabolism activity,regulated plant vegetative and reproductive growth balance,got better population quality,reduced flower and pod abscission and increased the rate of pod and yield.The results were as follows:1.Sowing date and nitrogen fertilizer had an obvious effect on soybean agronomic traits,yield and quality.Early sowing(B1)improved soybean plant leaf area index and total dry matter accumulation and yield compares with sowing in good time(B2).In early sowing,the highest number of pods per plant,grains,plant weight,grain weight occurred in R1(0:10)treatment,followed by R2(5:5)and R3(10:0)in turn.In addition,B1R1 could maintain a higher leaf area index,chlorophyll content and photosynthetic capacity than B1R2 and B1R3 after filling period.Contrarily,yield and total dry matter accumulation were highest in B2R2,and lowest in B2R3.Soybean nitrogen fertilization management should focus on postponing N application,especially in the treatment of early sowing.Postponing N application maintained a higher leaf area index,chlorophyll content and photosynthetic capacity,and delayed maximum leaf area duration during late growth stage,which,in turn,provided better source supply for grain.R1 treatment was requested in early sowing to achieve high yield,while R2 treatment was suitable for sowing in good time.2.Sowing date and nitrogen treatment have a significant impact on nitrogen metabolism activity,plant nitrogen transport and distribution,and quality in soybean.Plant nitrogen accumulation gradually increased during the whole growth period,and it was higher in early sowing than normal sowing.Flowering fertilizer increased NR and GS activities,and NO3-content during late growth stage,which in turn maintained a high nitrogen content,expressed as B1R1>BIR2>B1R3,B2R2>B2R1>B2R3;a high nitrogen receipt index,showed B1>B2;reduced the rate of pod off the flowers,ultimately yielding.Protein,fat and free amino acid content in early sowing is greater compared with normal sowing.Among fertilization methods,protein and free amino acid content expressed as B1R1>B1R2>B1R3,while their content showed B2R2>B2R1>B2R3.Moreover,the content protein,but not free amino acid,had a positive correlation with yield.Consequently,R1 treatment was requested in early sowing to achieve high quality,while R2 treatment was suitable for sowing in good time...