The Effects On Photosynthetic Characteristics Of Dicranopteris Ichotoma Under The Treatment Of Water Extract From8Kinds Of Eaves With Light Intensity

Dicranopteris dichotoma is an acidity indicator plant widely distributed in the subtropical zone ofChina. It often squeezes out the growth of other plants due to its double propagation mode (sporepropagation and root sucker clonal propagation) and the containment of relatively abundantallelochemicals. As a result, a mono-dominant synusium with Dicranopteris dichotoma as the mainground cover is formed. In the masson pine artificial mono-dominant community in particular, thevegetation type in the lower layer is single with Dicranopteris dichotoma as the main type. There arefew trees, shrubs and sod plants. In the sections with dense growth and distribution, masson pinecommunity features simple structure and relatively poor growth potential. However, when the massonpine community is mixed with some falling leaves or evergreen species, the quantity and distributionarea of Dicranopteris dichotoma are reduced significantly, and the growth condition of masson pine isalso improved. then according to analysed results,there are two reasons that led to decline ondistribution area and quantity of Dicranopteris dichotoma1)It's likely that the masson pine communityis mixed with some falling leaves or evergreen species lead to illumination environment changes.2)Some falling leaves or evergreen species of allelopathy inhibit the growth of Dicranopteris dichotoma.In this study, the transplanted pot cultured Dicranopteris dichotoma is taken as the object of study.Ecological simulation study method is utilized. The luminous environment under forest standard issimulated (undergrowth, forest gap and forest edge), and3shading gradients are set (30%,50%and80%) are set to study the influence of leave leaching liquors of masson pine and7accompanying plants(Loropetalum chinense, China fir, Cyclobalanopsis, Castanopsis sclerophylla, Liquidambar formosanaHance, Cinnamomum camphora Presl and holly) on Photosynthetic Physiological Characteristics ofDicranopteris dichotoma in summer and autumn. The study results indicate:1. Light responses of photosynthetic parameters of Dicranopteris with the Treatment of LeachingLiquors of8Tree Species under Different Illumination IntensitiesIn the summer of2011, it was tested and observed that high temperature and full sunlight explosurewere not beneficial to the growth of Dicranopteris dichotoma. After treatment of masson pine andChina fir leaching liquors, Pn value of Dicranopteris dichotoma is relatively high. Pn value ofDicranopteris dichotoma is lowest with the treatment of Loropetalum chinens Under3shading gradients,Pn (80%)<Pn (30%)<Pn (50%); During30%shading, thephotosynthesis of Dicranopteris dichotoma is inhibited;The influence of different seasons onDicranopteris dichotoma is mainly reflected in the difference of illumination intensity. Compared withsummer, the illumination intensity in autumn is relatively weak, resulting in that the photosyntheticindexes of Dicranopteris dichotoma under different shading rates and treatments are smaller than thosein summer. The influence of leaching liquors of Loropetalum chinense and Liquidambar formosanaHance is significant (p<0.05).2. The effects on chlorophyll fluorescence parameters of Dicranopteris dichotoma with the Treatment ofLeaching Liquors of8Tree Species under Different Illumination IntensitiesIn summer, with the reduction of shading rate, the initial fluorescence (Fo) of Dicranopterisdichotoma continuously increases while Fv/Fm value is continuously reduced; under3shadinggradients, Fo values of leaching liquors of holly, Loropetalum chinense, China fir and Liquidambarformosana Hance are relatively big. If the shading rate is30%, except the treatment of China fir andLoropetalum chinense, Fv/Fm values are relatively small and the difference is significant (p<0.05),Compared with summer, the initial fluorescence (Fo) of Dicranopteris dichotoma is increase under threeshading intensities, The effects on Fv/Fm value with the treatment of Loropetalum chinens is great, andthe difference is significant (p<0.05).3. The effects on chlorophyll content of Dicranopteris with the Treatment of Leaching Liquors of8TreeSpecies under Different Illumination IntensitiesDuring Summer And Autumn, the content of chlorophyll a and b in Dicranopteris which presents anegative correlation with shading rate; the contents of chlorophyll a and chlorophyll b of Dicranopterisdichotoma is higher after treatment of masson pine and China fir leaching liquors, the treatment ofleaching liquor of holly are the lowest. Compared with summer, the contents of chlorophyll a andchlorophyll b of Dicranopteris dichotoma is less in autumn.4. Influences of Seasons (summer and autumn), Shading Intensity, Different Leaching Liquors and TheirInteraction on Dicranopteris dichotomaThe dominant factor influencing the photosynthetic indexes of Dicranopteris dichotoma is shadingin summer. It imposes a significant influence on the dark respiration rate, content of chlorophyll andflorescence parameters Fo and qN of Dicranopteris dichotoma. The order of influencing weights is shown as follows: shading> interaction> leaching liquors of different tree species. However, differentfrom summer, the dominant factor influencing the photosynthetic physiological changes ofDicranopteris dichotoma in autumn is the leaching liquors of different tree species the influence ofwhich on fitting parameters and content of chlorophyll is far greater than that of shading and interaction.Compared with that in summer, the influencing weight increases significantly, and then comes tointeraction. Shading has the minimal influence, indicating a time difference between shading andleaching liquors of different tree species concerning the influence on photosynthetic physiologicalcharacteristics.5. Presumption of Influence of Leaf Litter Composition on Dicranopteris dichotomaWith the combination of the presumption of photosynthetic physiological parameters ofDicranopteris dichotoma, the relatively high contents of phenols and their oxides in Loropetalumchinense and Liquidambar formosana Hance are the main reasons contributing to the weakening ofphotosynthetic physiological parameters of Dicranopteris dichotoma; the leaching liquors of massonpine and China fir can promote the photosynthetic physiological parameters of Dicranopteris dichotoma.The reason may be related to the fact they contain relatively abundant alcohol compounds after analysis.