Study On Adaptation Of Light And Air Humidity Of Dayaoshania Cotinifolia

Dayaoshania cotinifolia is a perennial herb of the Gesneriaceae family,which is critically endangered due to its narrow distribution range,poor weak wild reproduction ability,habitat specificity and human activities.In this study,the cutting propagation seedlings of D.cotinifolia as test materials,artificial simulation of the growth needed to light intensity and air humidity environment factors,and explore the D.cotinifolia on adaptive characteristics of light intensity and air humidity,clarify its optimal grow light intensity and air humidity conditions,and based on the D.cotinifolia the research results of light intensity and air humidity,carried out a preliminary introduction regression study,the study of conservation in the D.cotinifolia and introduction to return to provide scientific theoretical basis.The main results of this study are as follows:1)After 16 weeks of light intensity treatment with 5 gradients,it was found that the optimal light intensity condition for growth of D.cotinifolia was 20%light transmittance,and its light intensity was about 8?18 klux.With the decrease of light intensity,the leaf area,the number of leaves and the water content of leaves of D.cotinifolia tended to increase.The chlorophyll content increased with the decrease of light intensity,while chlorophyll a/b decreased.With the decrease of light intensity,the net photosynthetic rate(Pn),transpiration rate(Tr)and stomatal conductance(Cond)of D.cotinifolia increased significantly,while the intercellular CO₂concentration(Ci)decreased slowly with the decrease of light intensity.The maximum net photosynthetic rate(Pmax),dark respiration rate(Rd),light compensation point(LCP)and light saturation point(LSP)of each treatment all decreased accordingly,while the AQY value of the apparent light quantum efficiency showed an upward trend.The anatomical structure of the treated leaves showed that:with the decrease of light intensity,the leaves of D.cotinifolia became thinner,the leaf area became larger,and the thickness of palisade tissue and sponge tissue cells decreased.2)After the treatment of air humidity in 4 gradients for 60d,it was found that the optimum air humidity for the growth of D.cotinifolia was 80%-90%.With the decrease of air humidity,the leaf length,leaf width,leaf area,leaf survival rate,leaf number and leaf moisture content of D.cotinifolia showed a decreasing trend.Chlorophyll content showed an upward trend with the increase of air humidity.Chlorophyll content was the highest when air humidity was 80%-90%,and the lowest when air humidity was 50%-60%.The malondialdehyde(MDA)content of D.cotinifolia decreased with the decrease of air humidity,but it could adapt to the stress of low air humidity to a certain extent by increasing the enzyme activities of protective enzymes(SOD),peroxidase(POD)and ascorbic acid catalase(CAT).The study on the anatomical structure showed that the change of air humidity had a significant effect on the structure of the leaves of D.cotinifolia,with the decrease of air humidity,leaf thickness,palisade tissue thickness,sponge tissue thickness and palisade sea ratio all showed a downward trend.3)The preliminary regression experiment showed that the survival rate of all the five sites could reach above 96%,and the survival rate of Chufangchong and Shangbajiaodi was as high as 100%.The size of the regressive plants and the number of leaves also had a significant impact on the regression location.The number of leaves in Chufangchong and Shangbajiaodi can reach more than 6,and the size of plants is also significantly better than Chachongkou,indicating that the regressive environment with high humidity and low light intensity is more conducive to the growth of the regressive plants than that with low air humidity and high light intensity,and the growth state of D.cotinifolia also presents the best state.