Effects Of Light Intensity And Simulated Acid Rain Treatments On Photosynthetic Physiological Characteristics Of Dicranopteris Dichotoma

Dicranopteris dichotoma-oriented fern is distributed under Pinus massoniana Lamb,Cunninghamia lanceolata and other artificial monodominant communities. When Dicranopterisdichotoma synusium is distributed densely, the seeds of forest community update difficultly, so thegrowth of Masson pine decreases obviously, it means the distribution of Dicranopteris dichotomasynusium may hinder the community renewal of forest tree species. The overgrowth ofDicranopteris dichotoma synusium may be associated with forest community arbor and shrubsynusium, such as the shading effect of Masson pine and Cunninghamia lanceolatamonodominant community and acid soil under the forest may both have impact on the growth anddevelopment of Dicranopteris dichotoma. Therefore, to analyze adaptability of Dicranopterisdichotoma to light intensity and acid rain, different light intensity and different acid rain controlexperiment was constructed, then photosynthetic, chlorophyll fluorescence parameters andpigment contents of Dicranopteris dichotoma were measured with Chlorophyll FluorescenceAnalyzer, Li-6400Photosynthesis Analyzer and UV-2550UV-Visible Spectrophotometer underdifferent light intensity treatments and acid rain treatments, it reveals the growing mechanism ofDicranopteris dichotoma, at the same time, it also provides the theoretical basis for biologicalcontrol measures that can promote progressive succession of forest community.Treatment of experiment: set full light,30%shading,50%shading and80%shading,4kindsof light intensity levels, and set pH3.0, pH4.0, pH5.6and pH7.0,4kinds of acid rain treatmentsin each light condition. The results showed that:1） The leaves of potted Dicranopteris dichotoma burned deeply, all of the parts on the grounddried, and even the whole plant died under full light from May to July in hot summer. Itmeans full light condition is not suitable for the growth of potted Dicranopteris dichotoma insummer.2） The maximum net photosynthetic rate (Pmax), pigment contents (Chl a, Chl b, Chl (a+b) andCar), chlorophyll fluorescence photopia parameter (Yield) and dark adaptation parameters(Fv/Fo and Fv/Fm) of Dicranopteris dichotoma have different rules with the change of lightintensity in3months. The maximum net photosynthetic rate of Dicranopteris dichotoma presents descending trend with the increased shadings, while pigment contents andchlorophyll fluorescence parameters present ascending trend. It means that high shading is notgood for accumulating organic compound, but can improve the pigment content and PSIIactivity center.3） The pH5.6acid rain treatment is suitable for Dicranopteris dichotoma, while pH3.0acid rainstress treatment inhibits its growth. The maximumin net photosynthetic rate (Pmax), pigmentcontents (Chl a, Chl b, Chl (a+b) and Car), chlorophyll fluorescence photopia parameter(Yield) and dark adaptation parameters (Fv/Fo and Fv/Fm) of Dicranopteris dichotoma havethe consistent change law under the condition of the same light intensity and different acidrain treatments in3months, namely they reach maximum under the pH5.6treatment, whilereach minimum under the pH3.0acid rain stress treatment.4） According to measuring the index of photosynthetic fluorescence parameters and pigmentcontents of Dicranopteris dichotoma under different light intensity treatments and differentacid rain conditions in3months, we discovery that the maximum net photosynthetic rate(Pmax), pigment content (Chl a, Chl b, Chl (a+b) and Car), chlorophyll fluorescence photopiaparameter (Yield)and dark adaptation parameters (Fv/Fo and Fv/Fm) of Dicranopterisdichotoma have consistent month variation, namely: July＞October＞December.5） Light intensity has significant influence on Fv/Fm, and has very significant influence on theremaining; acid rain has very significant influence on fluorescence parameters, maximumphotosynthetic rate and pigment contents; the interaction between the light intensity and acidrain have significant influence on chlorophyll b, but have no significant influence on theremaining.To sum up, high shading is not good for accumulating organic compound, but can increasePSII activity center and pigment contents, pH5.6acid rain treatment is suitable for Dicranopterisdichotoma, while pH3.0acid rain stress inhibits its growth. Therefore, it initially reveals theadaptability of Dicranopteris dichotoma to light intensity and acid rain, and it has importantsignificance to promote progressive succession of forest community.