| Panax ginseng (Pg) and Panax quinquefolium (Pq) are famous herb medicine which are planted at large area in Jilin province. As poly-year shade medicine crops, both Pg and Pq are growing very slowly. It will take at least four years in Pq and at least six years in Pg, the yield is very low and it is a limitation factor for the production of Pg and Pq. In order to investigate the characteristics of photosynthesis and matter production, and provide physiological basis of high yield culture in Pg and Pq follow photosynthetic, physiological and structural characteristic were studied;(1) Microstructure and ultra structure of Pg leaves grown under different light conditions were observed under light microscope and electronic microscope.(2) Response characteristic of photosynthesis and photosynthetic efficiency (Apparent Quantum Yield, AQY) to light intensity, light quality and temperature during the growth were measured by model Beckman 865 and QGD-07 infrared gas analyzer.(3) Changes of different growth stage and diurnal of photosynthesis, stomatal conductance, transpiration, water usage efficiency (WUE) and intercellular CO2 concentration (Ci) under different growth region were measured infrared gas analyzer and model Li-1600 stable porometer.(4) Chlorophyll content, starch content, soluble sugar content were analyzed by normal chemical method.The main results are as follows:1. The light intensity during the growth for Pg was arranged with 5%, 10%, 20%, 30%, 40% and 50%, six light transmission rate (LTR) shades; and Pq was arranged with 10%, 20%, 30%, 40% and 50%, five LTR shades. Leaf growth, microstructure, ultrastructure chlorophyll content and photosynthetic characteristic were studied with leaves grown under different light conditions. Specific leaf weight (SLW), leaf thickness, number of mesophyll cell and surface area of mesophyll cell per unit leaf area were increased as the increase oflight intensity grown under 5%, 10% and 20% LTR shades in Pg leaves. Changes of leaf structure were not obvious in leaves grown under 20%, 30% and 40% LTR shades, and SLW, leaf thickness, number of mesophyll cell per unit leaf area and surface area of mesophyll cell per unit leaf area were showed decreased changes in leaves grown under 50% LTR shade. The system of granum lamella in chloroplast was well developed in leaves grown under 5% LTR shade, as the increase of light intensity the system of granum lamella was decreased in leaves grown under 20% to 50% LTR shades. Highest chlorophyll content were measured in leaves grown under 10% LTR shade, as the increase of light intensity, chlorophyll content was decreased and chlorophyll a/b ratio was increased.Starch grain in chloroplast as a product of photosynthesis, were changed dramatically under different light conditions. There was almost no starch grain in chloroplast in the leaves grown under 5% LTR shade, as the increase of light intensity, the size and number of starch grain were increased in chloroplast. Under 50% LTR shade, most of space of chloroplast was occupied by starch grain, the maximum diameter of starch grain was in 3 to 4um in chloroplast.Net photosynthetic rate (Pn), light compensation point and light saturation point were increased as the increase of light intensity in leaves of Pg grown under 5%, 10%, 20% and 30% LTR shades and Pq grown under 10%, 20% , 30% LTR shades. Photosynthetic characteristic was nearly same in leaves of Pg and Pq grown under 30% and 40% LTR shades. Pn in leaves of Pg and Pq grown under 50% LTR shade was showed slightly decreased.2. Growth of stem length and leaf area in Pg were inhibited grown under blue and violet light, and were promoted under red and green light. The stem and leaf grown under yellow light were same as those grown under white light. There were higher total chlorophyll content, chlorophyll b content, leaf thickness and number of mesophyll cell per unit leaf area grown under blue and violet light than those grown under other light quality. Under low light intensity (70uE m-...
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