The Effect Of Different Fertiliztion Treatments On Fine Roots Growth And Senescence Physiology Of Alnus Formosana

Fine root senescence is important to study fine root longevity and turnover.Orthogonal experimental design with three factors and three levels was used in this research in order to explain the effect of different levels of N,P,K treatments on fine roots physiology and growth by pot experiment,and Root nodules,soil nutrition and their relationship were analyzed in different young Alnus Formosana plantations in Forest Lands Converted from Agricultural Lands in Sichuan province.The main conclusions of investigation as follows:(1)The results showed that different fertilizing treatment had different effects on root senescence.In the whole growth process,root vigor came down firstly,then went up and then came down again.It arrived maximun in October.N fertilizer showed positive promotion effect on root vigor in initial stage(April),and then appeared restrained.P has promotion impact to root vigor in whole process.The effect of K fertilizer on root vigor was not obvious.As for soluble protein content,the change trend was the same as root vigor.N fertilizer showed promotion effect firstly and then retained.But there was not significant difference between P and K fertilizer.Soluble sugar went up in the whole process,N,P fertilizer showed promotion effects on it in initial stage but N fertilizer restrained soluble sugar.The effect of K fertilizer was not obvious.MDA content reached minimum in October and then went up.N restrained MDA content in early stage and then showed promotion effects.P and K fertilizer has no markedness effect on it.Correlation analysis indicated that there were highly markedness between soluble protein,soluble sugar and MDA content, but not obviously with root vigor.(2)It were different effects on root protection enzyme of Different fertilizer and fertilizer level.The whole trends of SOD enzyme activity were went up firstly and then came down.N fertilizer treatment showed no obvious effect on SOD.P and moderate K showed promotion impact to root SOD activity anaphase.As for POD enzyme activity,it was upper first and then come down and went up a little in January next year.N fertilizer showed promotion effect on root POD enzyme activity,different level of P fertilizer were no obvious effect on POD enzyme activity,K appeared restrained effect firstly(April) and then promote function.As for CAT enzyme activity,the vertiginous phase was form July to October.N showed promotion effect on CAT enzyme activity in firstly and then restrained. Moderate(25g per pot) P fertilizer improved CAT enzyme activity but K restrained it. Correlation analysis showed that there was highly markedness between SOD and POD activity,but nonsignificant with CAT activity.(3)Effect on growth in different fertilizer and level.The growth of caudex with fertilizer was faster than unfertilized.N fertilizer has restrained effect on root vol.but P showed promotion effect.Moderated(12.5g per pot) N and abundance(50g per pot) P fertilizer showed promotion effect on 1^st order new root growth and the lateral root growth. Correlation analysis showed that there were highly markedness between lateral root,root vol.and 1^st order new roots.(4)Root nodules in different fertilized.Most root nodules of Alnus formosana were accreted on lateral fine roots(d＜2mm),there were relationship between root nodule and soil nutrition.In this experiment,the root nodule appeared earliest in antitheses treat with.Then appeared in P fertilized treat with,which showed that when soil nutrition was enough, fertilized would restrained root nodules growth.Different nodulation trait corresponding different fertilized.The treatment with abundance fertilized corresponding large number and large root vol.,especially P fertilized treatment.N fertilized treatment corresponding small number.The trait of root nodules in CK were large number and small vol..Correlation analysis showed that there root nodule were highly negative with soil hydrolysis N(P＜0.01, r=-0.84^**) and highly positive markedness with available P(P＜0.01.r=0.91^**).(5)It was synchronous of Alnus formosana root and shoot senescence process.Some physiology index showed that the changes of soluble sugar contents and relative conductance in root and in shoot appeared highly positive marekedness.SOD and POD enzyme activity in root and shoot also appeared highly positive markedenss.(6) fine root,root nodules,soil nutrition and their relationship were analyzed in different young Alnus Formosana plantations in four areas in Forest Lands Converted from Agricultural Lands in Sichuan province.The results showed that the vertical distribution of fine root(d≤2mm) was concentrated in the soil layer of 0～20cm and d＞2mm roots were concentrated in the deeper soil layer(under soil layer of 20cm).The vertical distribution of root nodules of young A.Formosana were concentrated in the soil layer of 0～20 mm,most of which were accreted to fine root(d≤2 mm).The principal component regression analysis showed that root nodule biomass was significantly negative correlative with soil hydrolytic N and soil organic matter,and significantly positive correlative with soil available P.