Studies On Physiological Response Of Two Species Of Woody Plants To Different Shading

This thesis is mainly focusing on the morphological and physiological responses Illicium henryi and Ardisia crenata to different light treatments. In order to have a profoundly understand of the adaptive and responsive physiology of plants under shading conditions, we designed the experiment with five different shading treatments (100%,52%,33%,15%,6% light intensity), and measured morphological and physiological indices of plants among treatments and treatment times. Furthermore, we analyzed the plasticity of form, nutrition distribution and photosynthetic attributes. The results were as follows:1.Morphological variation:For I.henryi and A. crenata, the shading treatments didn't significantly affact height and basal stem diameter of the plants, however had significant effects on leaf lengthening and broadening.2. Biomass variation:The shading treatments significantly enhanced the biomass in branches, stem, roots and plants of I. henryi,. The 52% illumination treatment markedly increased the biomass in leaves, roots, and plants of A. crenata,.3.Cntents of chlorophyll:The contents of chlorophyll in I. henryi increased and this tendency would continue with the elongation of time until reach its peak value in the latter growing period. The ratio of content of chlorophyll a to chlorophyll b of each illumination controlled treatment reach its summit at the latter growing period; The content of chlorophyll a, chlorophyll b and a+b of the sunlight controlled treatments in A. crenata have been increased compared to the full illumination treatment. During the latter growing period, the ratio of value of chlorophyll a to chlorophyll b of each illumination controlled treatment is smaller than that of full illumination treatment, what is more, the stronger the degree of controlling illumination, the smaller the ratio of value of chlorophyll a to chlorophyll b.4.Physiological indices:the contents of soluble sugar in I. Henryi and A. crenata decreased by the decline of illumination; also the content of starch reached the summit at the latter growing period; meanwhile the contents of soluble protein in all treatments are significant smaller than that in the full illumination treatment; furthermore, there is no difference of the SOD among each treatments; moreover, NR and contents of Nitrate of the 52% and 33% sunlight controlled treatments in I. Henryi are significant smaller than the full illumination treatment, while it is the opposite case in the content of leaf nitrogen. In A. crenata NR and contents of Nitrate increased by the decline of illumination; besides, contents of leaf nitrogen increased by the degree of withholding exposure to the sunlight.。5.Parameters of photosynthesis and fluorescence:In I. henryi,net photosynthesis and LSP increased at first and then decreased, however, the tendency of LCP is on the opposite direction; under different illumination controlling treatments, the variations of Fo and YNO were existed, meanwhile there is no variation of Fm; furthermore, there are significant variations of Fv/Fm and reached to the biggest value under the full illumination treatment; the variations of Ft, YII, YNPQ, NPQ, q1 are extremely significant. In A. crenata, the full illumination treatment LSP is the biggest, and the point of LCP decreased with the decline of sunlight; variations of Fo among different treatments were not existed, however, variations of Fv/Fm, YII were existed, there were significant variations of Fm, q1 among different treatments.6.Characteristics of super-micro structure:The two plants with the light intensity decreased, the overall number of chloroplasts decreased, whlie cells dissolved some organs and the plasmolysis phenomena exited.7.Plasticity index:the A.crenata's morphology and structure plasticity indices are greater than that of I. henryi, so is the physiology indices plasticity, from the perspective of Photosynthetic pigments and osmolyte plasticity indices of I. Henryi are greater than that of A. crenata.In a word, I. henryi mainly through the physiological regulatory mechanism to adapt to changing light environment, the ecological amplitude of light in I. henryi is greater than in.