【作者】 潘燕；

【导师】 李贤伟；

【作者基本信息】 四川农业大学 ， 森林培育学， 2008， 硕士

【摘要】 本文采用三因素三水平正交试验设计,应用盆栽控制试验,研究不同肥料种类及施肥水平对台湾桤木细根生长及衰老生理的影响,并通过对四川退耕地台湾桤木幼林根系结瘤调查,了解土壤养分与台湾桤木根系结瘤的相互关系。主要研究结果如下:（1）不同肥料种类及施肥水平对台湾桤木细根衰老的影响不同。各施肥处理的台湾桤木根系活力在不同生长季节均呈下降-上升-下降的变化趋势,10月达到最大值。氮肥在4月对根系活力有促进作用,但氮肥处理植株根系活力下降很快,少施或者不施氮有利于根系活力提高;在整个生长期,磷肥对根系活力有促进作用;钾肥对根系活力的影响不明显。各处理台湾桤木根系可溶性蛋白含量在不同生长季节的变化趋势与根系活力相同。4月,施氮处理对可溶性蛋白含量有促进作用,而在10月出现抑制;施磷有利于可溶性蛋白含量的增加,施钾处理在7月表现出对根系可溶性蛋白含量的抑制作用,10月表现促进作用。但磷、钾不同施用量对可溶性蛋白含量的影响不显著。可溶性糖含量在整个生长期都呈上升趋势。氮肥在4月、7月、10月对可溶性糖含量均表现促进作用,翌年1月开始出现抑制作用;上水平(50g·盆^-1)磷肥的施用能促进其含量的增加;钾肥在4月作用不明显,翌年表现促进作用。MDA含量在10月最低,之后出现较大上升。零水平(25g·盆^-1)氮肥的施用在4月抑制MDA含量的增加,到翌年1月促进MDA的生成;施用磷肥在4月对MDA含量影响不明显,10月表现为抑制作用;钾对MDA含量影响不显著。对各衰老指标相关性分析表明,可溶性蛋白含量、可溶性糖含量与MDA含量之间存在着极显著相关关系,但三者与根系活力的相关关系不显著。（2）不同肥料种类及施肥水平对根系保护酶的影响不同。SOD酶活性的总体变化趋势是先上升后下降。氮肥在4月对SOD酶活性有抑制作用,但作用不明显;不同磷肥水平在生长开始阶段（4月）对SOD酶活性的影响差异不显著,但在10月以后,施用磷肥表现出对根系SOD酶活性的促进作用;零水平(5g·盆^-1)钾肥处理对SOD酶活性有促进作用。4月份POD酶活性最高,此后呈下降趋势,到翌年1月,酶活性又有上升,但幅度不大。氮肥对根系POD酶活性有促进作用,不同水平磷肥对POD酶活性的作用差异不大,钾肥在4月对POD酶活性有抑制作用,10月以后零水平(5g·盆^-1)的钾肥对POD酶活性有促进作用。CAT酶活性的变化趋势是7月到10月有大幅度的上升,此后平稳。氮肥处理在4月、7月对CAT酶活性有促进作用,翌年1月表现出抑制,零水平(25g·盆^-1)磷肥处理对CAT酶活性有促进作用;钾肥抑制CAT酶活性的提高。各保护酶之间的相关分析表明SOD活性与POD活性之间存在极显著的正相关关系,而CAT与前两者相关性不显著。（3）不同肥料种类及施肥水平对台湾桤木生长的影响。施肥处理的台湾桤木地径生长量均大于不施肥处理。氮肥对根系体积的增加有抑制作用,磷肥对根系体积的增加又显著促进作用。试验表明零水平(12.5g·盆^-1)氮肥对一级新根的生长和侧根长均有促进作用。上水平(50g·盆^-1)的磷肥促进一级新根生长,零水平(25g·盆^-1)的磷、钾肥(5g·盆^-1)也利于侧根的生长。有效磷对根系体积和根系一级侧根新根数有极显著的促进作用。侧根根长与根系体积(P＜0.01,r=0.76^**)和一级新根生长数(P＜0.01,r=0.43^**)间均有极显著相关关系。根系体积与一级新根数量呈正相关,但相关性不显著。（4）不同肥料及施肥水平对根系结瘤的影响。根系结瘤与土壤养分有一定关系。台湾桤木根瘤主要生长在侧根上,且多生长在小于2mm的细根上。最早出现根瘤的是不施肥处理,随后是施磷肥处理。说明磷肥能促进根系结瘤,而在土壤养分不缺乏的情况下,施肥反而抑制根系的结瘤。单施磷肥的处理根瘤体积较大,数量较多;单施氮肥处理根系结瘤量较少;对照根瘤数量较多,但体积较小。施肥对根瘤体积有较显著的影响。根瘤与土壤水解氮含量存在极显著的负相关(P＜0.01,r=-0.84^**),与有效磷含量存在极显著正相关(P＜0.01,r=0.91^**),与土壤钾素含量相关性不显著。（5）台湾桤木根系与叶片衰老具有同步性。可溶性糖含量在叶片与根系中含量的变化呈极显著正相关关系,二者质膜透性也具有极显著的正相关关系。对根系与叶片的抗衰老保护酶相关分析得到SOD、POD酶活性均呈极显著的正相关。（6）野外调查研究表明,台湾桤木细根在不同土壤层次中生物量分布不同,直径＜2mm细根主要分布在0～20cm土层中,而直径＞2mm根则主要分布20cm土层以下,其生物量大于直径＜2mm细根,主要原因是20cm土层以下粗根较多。台湾桤木根瘤主要分布在土壤表层（0～20cm土层）,多数附着在＜2mm细根上。根瘤的分布与土壤养分关系密切,有机质和全氮对根系结瘤量有着较大的负向作用,有效磷对根瘤生物量有正向促进作用。更多还原

【Abstract】 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.更多还原