Study On Biochemical Resistantance To Nitrogen Dioxide Of Cinnamomum Camphora Seedlings

In this paper, potted one-year-old seedings of Cinnamomum camphora were fumigated by nitrogen dioxide (NO2). In this experiment we studied the injured symptoms,and tested the content of MDA, chlorophy, activities of SOD,NRA,Vc,GR with the treatments of different concentrations, or same concentration but different air temperature and different illumination; we tested content of nitrogen in leaves, and analyse the relationship between different treatments. Simultaneously, we placed gas NO2, gas HF, the mixture-gas of NO2 and HF as toxic gases in the experiment, studied the biochemical resistantance of Cinnamomum camphora. The main results are as the followings.1. The injured symptom first appeared in young leaves of Cinnamomum camphora to nitrogen dioxide stress. Then injured degree in young leaves is also higher than other leaves.2. In different NO2 concentration treatment, as the increasing of NO2 concentration, the activity of SOD and the content of Vc are appeared increasing and then decreasing trends, the content of MDA appeared a steady increasing trend and that of Chl appeared a steady decreasing trend, the activity of NRA appeared a decreasing and then an increasing trend, and the activity of GR changed little. The diurnal variation of net photosynthetic rate (Pn) of Cinnamomum camphora from different NO2 concentration is similar to the diurnal variation of stomatal conductance (Gs) of Cinnamomum camphora from different NO2 concentration, both of them have two apexes. As the increasing of NO2 concentration, the chlorophyll fluorescence (Fv/Fm) is appeared decreasing trends.3. In different air temperature treatment, as the increasing of temperature, the activities of SOD,NRA, the content of Vc are appeared decreasing trends; The contents of MDA and Chl are appearing increasing and then decreasing trends; the activity of GR appeared decreasing and then increasing trends.4. The different illumination treatment affected not so remarkable to the indexes, except the activties of SOD and GR, while illumination increased to 5000 lux, both of them appeared the highest activity.5. We also placed gas NO2,gas HF, the mixture-gas of NO2 and HF as toxic gases in fumiagtion to study the correlations of the indexes. Whenαis 0.05, the Pearson Correlation of Chl-NRA is 0.996 which is the highest among them. In gas HF treatment, the Pearson Correlation Chl-NRA is 0.981 as the highest among them. In the mixture-gas of NO2 and HF, the Pearson Correlation of Chl- Vc is 0.999, is significant. The result showed that mixture-gas of NO2 and HF injuried Cinnamomum camphora most.In low concentration (9 mg·kg-1) treatment, Seedings of Cinnamomum camphora have great resistance to and absorbency of gaseous NO2; as the increasing of temperature, the resistance of Cinnamomum camphora appeared decreasing trend;however, the different illumination treatment affected not so remarkable to the seedings of Cinnamomum camphora; injured degree of the seedings in the mixture-gas of NO2 and HF treatment is higher than the ones in single-gas treatments.