The Response Mechanism Of4Kinds Of Tree Seedlings Under Shading And The Leaf Of Dicranopteris Dichotoma Extract

Dicranopteris dichotoma have strong growth and interspecific competitive due to its doublepropagation mode (spore propagation and root sucker clonal propagation), it’s exclusion of otherplant species growth and distribution, therefore continuous distribution in the lower layer of Pinusmassoniana and its associated plant and form a single layer. When Dicranopteris dichotomasynusium is distributed densely, the seeds of forest community update difficultly, so the growth ofPinus massoniana decreases obviously. Thus speculated that growth and distribution ofDicranopteris dichotoma is the key layer of impeding Pinus massoniana forest community update,it means the distribution of Dicranopteris dichotoma synusium may hinder the communityrenewal of forest tree species. Then make assumptions:1）The slices distribution of Dicranopterisdichotoma led to the tree seedlings were unable to get enough lighting, so does not grow very well;2）Dicranopteris dichotoma with strong allelopathy, the allelochemicals may inhibit the growth ofsome tree seedlings.In this study, the transplanted pot cultured Castanopsis sclerophylla、Pinus massoniana、Cyclobalanopsis glauca、Liquidambar formosana is taken as the object of study.3shadinggradients (30%,50%and80%) and2extract concentrations (0.1g/ml, and0.05g/ml) be set tostudy the influence of physiological parameters and morphological index on4kinds of treeseedlings by Dicranopteris dichotoma extract water under different light intensity, and both infull light and distilled water as a check test, revealing the mechanism of Allelopathy ofDicranopteris dichotoma and the internal relations of Dicranopteris dichotoma layer and theupdate of tree species. The study results indicate:1. Shading&Extract concentration effect on the light response characteristics of four kinds oftree seedlingsThe light response of four kinds of trees was different. The photosynthesis effects on theneeds to different degrees of lights. The Pn of Castanopsis sclerophylla、Liquidambar formosanaand Cyclobalanopsis glauca was reduced by the shading. Four kinds of trees had diffirent affectsby diffirent extract concentration under the diffirent shading. The photosynthesis of Pinusmassoniana was promoted by the extract, and other trees was promoted by low concentrationand inhibited by high concentration. 2. Shading&Extract concentration effect on the fluorescence parameters of four kinds of treeseedlingsOverall, Fv/Fm、qP value of the four kinds of trees seedlings was increased and qN value wasdecreased under the shading, which mean the PSⅡ photosynthetic electron transport of theleaves of four trees are promoted, and the fluorescence parameters had more impacting. The PSⅡreaction was damaged a lot when the extract concentration was0.1g/ml, and the growth of thefour kinds of trees was inhibited. The influence of shading of the four kinds of trees wassignifican（tp<0.05）. The relation could be: shading>extract concentration>interaction of shading&extract concentration.3. Shading&Extract concentration effect on the chlorophyll content of four types of treeseedlingsFor the four kinds of trees, the content of chlorophyll a and b was increased by the shading&extract, but chlorophyll a/b had changes do not obvious. Compared with July, the contents ofchlorophyll a、chlorophyll b and chlorophyll a/b of the four kinds of trees was less in October.The influence of the four kinds of trees by shading was significant（p<0.05）than extractconcentration and interaction of shading&extract concentration.4. Shading&Extract concentration effect on the spectral characteristics of four types of treeseedlingsThe spectral reflectance and first order derivative spectrum of the four kinds of trees hadalmost the same trendency. The content of chlorophyll was increased by the shading, lead to theabsorption range of the red light was widens, so the “red shift” was accurred.5. Shading&Extract concentration effect on the growth index of four types of tree seedlingsThe growth of the four kinds of trees was inhibited by all light conditions, the growth waspromoted by moderate shading, and was inhibited by over-shading, the growth was worse by80%shading. When the extract concentration is0.1g/ml, the growth of tree seedlings wasinhibited, and irregular by0.05g/ml.6.Presumption of Influence of Extract Composition on four kinds of tree seedlingsWith the combination of the presumption of photosynthetic physiological parameters of4kinds of trees, the growth of four kinds of tree seedlings was influenced by phenolic andterpenoid compounds that were contained in the extract of Dicranopteris dichotoma.