The Responses Of Cryptomeria Fortunei To The Disturbance Of Acid Rain And Litter’ Allelopathy On The Photosynthetic Properties And Antioxidant Enzyme Activity

In order to understand the combined effects of acid rain and litter on the seedlings of Cryptomeriafortunei, this study investigated characteristics of the3-year-old seedlings of C. fortunei under the stressof acid rain (pH5.6, pH4.0and pH3.0), litter (40g,50g and60g) and their combination. During the study,we tested pigment contents, reflectance and fluorescence parameters, Pn, antioxidant enzyme activityand the MDA contents. Results were as follows:1. The pigments contents and the value of Chl a/Chl b showed first increasing and then reducingwith the adding of the concentration of acid rain and accumulation quantity of litter. Acid rain enhancedthe inhibitory effect of allelopathy in the litter on chlorophyll a by speeding up the degradation ofchlorophyll a. The reflectance was significantly correlated with the chlorophyll contents. Thereflectance spectral parameters of RR, Dλredand Sredcould be used to evaluate the chlorophyll a,chlorophyll b content and chlorophyll a/b.2. Chlorophyll fluorescence can reflect the photosynthetic characteristics of C. fortunei. Thecombined treatments with pH4.0, pH3.0and litter (60g) encreased the parameters of PIABS, φPo andso on. The results showed the maximum photochemical efficiency in energy transfer was decreasedunder the treatments with acid rain and litter.3. The results showed pH4.0, pH3.0and litter of60g treatments significantly encreased Pnrespectively, and the compound effect of acid rain and litter made significantly changed as well.4. With the adding of the concentration of acid rain, the activity of antioxidant enzyme and thecontent of MDA in the seedlings of C. fortunei showed first increasing and then reduced. In addition,the activity of antioxidant enzyme showed the trends of rising with the adding of accumulation quantityof litter, which indicated C. fortunei could regulate antioxidant enzyme system to remove excessive freeradicals in the body under stress.In a word, the pH4.0, pH3.0and the litter of60g inhibited the growth of the seedlings of C.fortunei. The results showed the litter of60g decreased the inhibitory effect of acid rain. However, acidrain enhanced the inhibitory effect of allelopathy in the litter.