| Under the field conditions,rape(variety Yu You 28),the main oil-bearing crop in Southwest China,was used as the research object.Three different fertilization methods,i.e.broadcast methods(B),furrow methods(F),hole methods(H),combined with three different nitrogen application rates,i.e.180kg/hm~2(N1),144kg/hm~2(N2),108kg/hm~2(N3),were tested to analyze their effects on growth and development,yield,nutrient absorption,soil nutrients,enzymes and soil microbial functional diversity of rape(Brassica chinensis L).It could provide reference for improving fertilization technology and fertilizer utilization rate in rape production.The main results were as follows:(1)Furrow application and hole application of nitrogen fertilizer could promote the growth of rape.Furrow application and hole application of nitrogen fertilizer could promote the rape height in the whole growth period,which showed that furrow methods and hole methods were significantly higher than the spreading application.Furrow application and hole application of nitrogen fertilizer could significantly improve the stem diameter at the bud and flowering stage of rape,especially the advantages of furrow application and hole application under the level of N2.Furrow application and hole application of nitrogen fertilizer could significantly improve the stem diameter at the bud and flowering stage of rape,especially the advantages of furrow methods and hole methods under the level of N2.Furrow application and hole application of nitrogen fertilizer could significantly increase the number of functional leaves,the length of leaves and the area of rape leaves,which was conducive to the progress of rape photosynthesis.Increasing the amount of nitrogen applied on the basis of N3 significantly increased the plant height of the whole growth period of rape,and the stem thickness during the bud period,flowering period,and mature period,which helped to increase the number of functional leaves and increase the leaf area.(2)Furrow application and hole application of nitrogen fertilizer could improve root morphology and promote root growth.The total root length,root surface area,root tip number,total root length,root surface area,total root volume,and total root volume and total root length at flowering stage were significantly increased by furrow application and hole application of nitrogen fertilizer.Increasing the amount of nitrogen applied on the basis of N3 was beneficial to the increase in the number of root tips at the seedling stage and the flowering stage,and promoted the increase of the total root length,total surface area and total root volume at the seedling stage and the bud stage.However,there was no significant effect of nitrogen application rate and fertilization method on root growth at maturity.(3)Furrow application and hole application of nitrogen fertilizer was beneficial to the accumulation of dry matter in rape.The dry matter accumulation of shoot and leaf increased significantly at bud and flower stage.The response of root system to the change of fertilization was not obvious.With increasing nitrogen fertilizer,the dry matter of shoot,shoot and whole plant increased significantly,while that of shoot and whole plant increased significantly at flowering stage.There was no significant effect at maturity stage.Increasing the amount of nitrogen and deep application of nitrogen had no significant effect on the number of seeds per pod and 1000 grain weight,but they could significantly increase the number of pods per plant,and the yield of rape.In addition,the average increase of nitrogen partial productivity(NPP)was 9.12%and11.09%under the treatment of furrow application and hole application respectively.It was indicated that the deep application of nitrogen significantly increased the NPP of rape.(4)Furrow application and hole application of nitrogen fertilizer significantly increased the content of oleic acid,yellow seed and oil in rape seeds,and reduce the content of glucosinolate and erucic acid and improve the quality of seeds.Increasing the amount of nitrogen increased protein content,decreased oil,glucosinolate and yellow seed.Increasing the amount of nitrogen,furrow application and hole application of nitrogen fertilizer furrow application and hole application of nitrogen fertilizer were helpful to the accumulation of nitrogen in all organs of rape.The overall performance was N1>N2>N3,H>F>B.Furrow application and hole application of nitrogen fertilizer could significantly improve the accumulation of nitrogen in the stems and leaves of seedlings,buds,flowering,but it had little effect on the roots.In the mature stage,increasing the amount of nitrogen only increased the accumulation of nitrogen in the seeds,but had no significant effect on the root,stem and pericarp.(5)The effects of furrow application and hole application of nitrogen fertilizer on microbial diversity had both advantages and disadvantages.The effects of different fertilization methods on soil microbial activity were different.After incubation for 48hours,the carbon utilization intensity of N1 and N3 was F>B>H,while N2 had no advantage in furrow application and hole application of nitrogen fertilizer.Increasing the amount of nitrogen was helpful to enhance the utilization of carbon sources by microorganisms.The hole methods could significantly improve Simpson index(D),but reduce evenness index(E),ditch application had no advantage over the application.Increasing the amount of nitrogen was helpful to increase Shannon diversity index(H)and evenness index(E),but not to the increase of richness index(S),and decrease of Simpson index(D).(6)Increasing the amount of nitrogen application on the basis of N3 and furrow application,hole application of nitrogen fertilizer significantly improved soil nutrients.Increasing the amount of nitrogen significantly increased the content of total potassium and alkali-decomposed nitrogen in the soil,and furrow application,hole application of nitrogen fertilizer significantly increased the content of total potassium,organic matter and p H of the soil.Furrow application and hole application of nitrogen fertilizer could improve soil enzyme activity.In the seedling stage,flowering stage and mature stage,the deep application of nitrogen significantly increased protease activity.In the seedling stage and flowering stage,furrow application and hole application of nitrogen fertilizer significantly enhanced urease activity.All invertase and amylase in seedling stage,bud stage and whole growth stage were increased,but not significantly between different fertilization methods.The activities of invertase and amylase,protease and urease in seedling,bolting and flowering stages were significantly increased with increasing nitrogen fertilizer.In summary,increasing the amount of nitrogen was the guarantee for promoting the growth of rapeseed,increasing the yield of rapeseed,and enhancing soil nutrients,microorganisms,and enzyme activity.Furrow application and hole application of nitrogen fertilizer could effectively improve fertilizer efficiency,helped rape production,and improve soil quality. |
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