Effects Of Habitat Light Intensities On Photosynthesis And Adaptation Strategies Research Of [Polystichum Tsus-simense (Hook.) J.Smith]

In this study, a typical understory shade plant [Polystichum tsus-simense (Hook.) J. Smith] as materials, by comparative the photosynthetic characteristics of shady shed and full sunlight P. tsus-simense, the photosynthetic characteristics of gametophyte'different development periods, the light utilization and light response difference of P. tsus-simense gametophyte and sporophyte, and exogenous flavonoids treatment simulated stress to relieve the photoinhibition on shade P. tsus-simense, to evaluate the affects of deforestation on photosynthesis of P. tsus-simense life history, To investigate its adaptation strategies to exposed habitat light, providing theoretical basis for managing and protection strategies of ferms, at the same time, testify the Resource Availability Hypothesis and Photodamage Protection Hypothesis of environmental induction of secondary metabolites production mechanism, discuss the relationship between the environment and the secondary metabolites.The results showed that:1,The spore germination of P. tsus-simense is typical Vittaria-type, belong requirement light type. From spore germination period, Filament period, Prothallial period, to Prothallus period of gametophyte development, the content of chlorophyll, maximal PSâ…¡efficiency, PSâ…¡activity,photosynthetic capacity and heat dissipation capacity as the development process significantly increased, the light adaptation capacity enhanced. However, the whole process needed 70 days, even more, The longer of development time, the easier would be stressed by environment factors. Finally, it will be decide whether the life history can develop successfully.2,Under the shading and full sunlight light treatment, by lowering the content of chlorophyll, maximal PSâ…¡efficiency, PSâ…¡activity, by increasing photosynthetic capacity and heat dissipation capacity and others adaptation strategies, it could adapt high light environment. Compared to shady shed P. tsus-simense, the carotenoids and total flavonoids contents significant increased, and full sunlight P. tsus-simense, photoinhibition capacity was strength, it showed that high light stress induced the flavonoids of secondary metabolites accumulation, it is useful to clear the oxyradical, which were consistent with the Resource Availability Hypothesis and Photodamage Protection Hypothesis.3,Compared to Sporophyte, gametophyte showed lower content of chlorophyll,Fv/Fm,Fv/Fo and rETR value, but gametophyte has high qP value, it was weak to recover when it was stressed by high light. When Sporophyte and gametophyte were under same high light environment, the gametophyte was easier to be stressed and photodamage. It showed that true leaf formed increased the light utilization and water on plants evolution, so the ability to adapt environment enhanced, made the P. tsus-simense could occupy relatively drought,high light habitat. But exposed habitat is extreme harmful to gametophyte.4,Exogenous flavonoids couldn't relieve photoinhibition of P. tsus-simense, on the contrary, it increased the risk of photoinhibition. Exogenous flavonoids on reducing the shade plants of photosynthesis photoinhibition and wok mechanism are still to research.