Study On Light Adaptation And Anti-Resistance Of Several Species In Ilex L.

1 There are many species in Ilex L. .Several ornamental species among them have been applied in gardens more widely and frequently .But some species of Ilex L. grow rather slow and need many years to become tree seedlings that can be used in the garden. Light density is one of the direct factors that affect growth and development of plants, so the researches of photosynthetic characteristics of Ilex species are of importance both in the theory and application. But so far, few researches has been done on this field . In this paper ,we studied photosynthetic characteristic, diurnal photosynthetic changes, diurnal variation of chlorophyll fluorescence parameters, leave pigments changes and antioxidative enzyme activities of three species of Ilex, Ilex chinensis, I.viridis and I.cornuta var. fortunei, under different light environment (100%, 45%, 20% natural light intensity ). The main results are as follows :(1) Changes of light response characteristics and physiological characteristics of Ilex chinensis, I.viridis and I.cornuta var. fortunei under different light environmentThe maximal net photosynthetic rate of the three species increased with the increasing of light intensities; The maximal net photosynthetic rate of I.cornuta var. fortunei was higher than that of I.viridis and the maximal net photosynthetic rate of I. chinensis was the lowest. Chlorophyll content of the three species increased with the increasing of shading. Chlorophyll content of I.cornuta var. fortunei was more than those of the other species under 20% natural light intensity. Chlorophyll a content / Chlorophyll b content and specific leaf weight decreased with the the increasing of shading. Antioxidative enzyme activities of I .chinensis. and I.cornuta var. fortunei, such as SOD, POD, CAT and APX did not significantly increase with the increasing of light intensity. CAT and APX enzyme activities of I.viridis were significantly higher under 100% natural light intensity than those under 45% and 20% natural light intensity.(2) Diurnal photosynthetic changes of three species of Ilex under different light environmentWe studied how light intensity affected the diurnal photosynthetic changes in autumn. The results showed that the net photosynthetic rates of the three species of Ilex under full light were higher than those under 45% of full light, which were higher than those under 20% of light, and the diurnal net photosynthetic rates varied in a double—peak curve, which showed that the three Ilex species were...