Morphological And Chemometrics Of Schima Superb Seeding Fine Root In Response Of Nitrogen Deposition

During July 2011 to July 2015 period,we weighted a certain quality of NH4NO3 to make four nitrogen deposition treatments:Control group(CK,0 kg N hm-2 a-1),low N(LN,50 kg N hm-2 a-1),medium N(MN,100 kg N hm-2a-1)and high N(HN,150 kg N hm-2 a-1).In this study,Schima superba of fine root was selected to study the response of morphological traits,stoichiometry characteristics,nutrient resorption efficiency,four phosphorus fractions in April 2014 to July 2015,The results showed that:(1)Nitrogen deposition significantly promoted specific root length(SRL),specific root area(SRA),special root tips(SRT)and special root forks(SRF)of fine root(P<0.05).Fine root diameter(FRD)with levels of nitrogen deposition decreased firstly to MN and then increased,CK and nitrogen treatment had significantly difference(P<0.05).Root tissue density(RTD)had not significantly difference between different treatment.Being nutrient capacity enhancement of fine root under nitrogen deposition,but fine root water absorption capacity had no significant impact.(2)In the spring and summer,nitrogen deposition significantly promote the uptake and accumulation of fine root of the C content and N(P<0.05).For fine root P content,in October 2014 with the levels of nitrogen deposition first increased and then decreased,other months nitrogen deposition compared with the control treatment significantly reduced(P<0.05).Nitrogen deposition on fine root C/N reduced only in the summer.Low nitrogen deposition promoted fine root C/P while high levels of nitrogen deposition have a negative impact on the fine root C/P.N/P of fine root was increased under nitrogen deposition,a significant reduction in the fall when under low nitrogen treatment and did not reach the level of P limit.We concluded nitrogen deposition reduced fine root P uptake,but at high nitrogen treatment fine root promoted the absorption and accumulation of C and N in spring and summer.It is aimed to promoted capacity ability accumulation of C and reduced the N utilization efficiency to promote the fine root growth and nutrient transport.It also eased restriction N on fine root to a certain extent.(3)N resorption efficiency had no significant on nitrogen deposition.P resorption efficiency of fine root with the levels of nitrogen deposition down then up trend in the process of nitrogen released in MN.Schima superb of fine root N of luxury to use without re-absorption and utilization.Reduce nitrogen deposition fine root P resorption efficiency in order to speed up the P element in the ecosystem of the circulation rate.(4)Nitrogen deposition significantly decreased in the fine root metabolic P concentration and percentage,and the structure of P,nucleic acid P and residual P percentage increased significantly(P<0.05).In October 2014,structure of P concentration reduced and metabolic P rise in low nitrogen deposition.Schima superb of fine root had a reasonable balance of four kinds of P component to adapt the impacts nitrogen deposition,it means that Schima superb of fine root sacrificed metabolic P to build the structure and P nucleic acid to maintain the fine roots the ability to obtain nutrients and growth.The study found that:nitrogen deposition to promote fine root growth nutrient acquisition ability.In spring and summer,fine root promoted C,N accumulation in HN.Nitrogen deposition reduced the P content of the absorption and had no significantly effects on N use efficiency and absorption efficiency.Nitrogen deposition promoted P use efficiency and reduced P absorption efficiency of fine root.By increasing structure P and nucleic acid reduced metabolic P of fine root ways to adapt to nitrogen deposition.