Studies On Photosynthetic Characteristic Of Gensengs Under Forest Under Different Light Intensity And Altitude Conditions

Panax ginseng is the perennial,inveterate root medicinal herb,which belongs to the Araliaceae.It is the most precious living fossil plant that fortunately survived from the Tertiary Period.It distributes in North America,Central Asia and East Asia.Along with the forest resources' massive reductions and wild ginseng's over excavation,the wild ginseng is listed as our country's first-level protection plant and rare,precious and faces threatened plant.In "Pharmacopoeia of People's Republic of China"(2005 version),wild ginseng's definition had already been obliterated and "Ginsengs under Forest" was inserted in.Therefore,recent years, cultivation of Ginsengs under Forest has gotten the world particularly domestic's attention.But by now,the existing cultivation methods of the "Ginsengs under Forest" are still build upon experience primarily and the related scientific research reports are few.Cultivating the ginseng under forest is a highly effective compound ecology economic system pattern. Planting ginseng under the forest plants need not to loose soil or remove weeds,needn't apply fertilizer and the agricultural chemicals.What we need is to creat the ecological environment condition which suits its growth and lets things growth natually.Therefore,how to choose or create this kind of ideal ecological environment condition,specially the light environment,plays a key role in ginseng's success growing.Solar radiation,which is the main energy of the forest worker system,has the extremely important meaning to ginseng's growth.This article determines the ginseng shape and the photosynthesis characteristics and the physiology ecological factor that associate with the ginseng's grows.1.Suppose the under-forest region into three luminous intensity regions:the high light area,PAR≥25 (μmol.m^-2.s^-1),occupies the total experiments unit 11.7%;the middle light area,PAR value in 10-25 (μmol.m^-2.s^-1),occupies the total experiments unit 58.3%;the weak light area,PAR≤10(μmol.m^-2.s^-1), accounts for 30%.The PAR value of effective photosynthesizes radiation's strong or weak immediatly influences the leaf blade's P_n(photosynthesize rate) size.No matter the effective photosynthesizes radiation or the pure photosynthesize speed different lightly to the different light intension.The total performance tendency is that:the glare area daily changes obviously then the effective photosynthesizes radiation or the pure photosynthesize rate different scope to be big;the light area,the change scope is weaken obviously; weak light area change flatten out;pure photosynthesize rate of Ginsengs under Forest displays a negative value in early morning and the evening.2.Applying the test statistical method to analyze the P_n and PAR's daily movements,we can get that: In the glare area,both's dependent equation is y=29.536x+9.9488,R²=0.9423;In the middle light area, both's dependent equation is y=18.171x+9.2519:R²=0.9034;In the weak light area,both's dependent equation is y=5.5332x+5.0406,R²=0.4802.With the influence of the forest's up crown level light,in the strong or middle light area under the forest,they once linear correlation,and the degree of correlation is very high;But in the weak light place,their degree of correlation is very low or even non-correlated.3.Analyzing the Gs and Tr with the similar method we could get the dependent equation is y=118.6x+5.0735,R²=0.9705(value time limit in morning 7:00 to afternoon between 17:00,R² is decision coefficient).That is to say that their degree of correlation is about 97%.This dependent equation and the decision coefficient indicates that:leaf blade blowhole leading and the transpiration rate of Ginsengs under Forest is remarkable related.Blowhole leading Gs is the easiest influenced by the luminous intensity,the suitable luminous intensity is good to the blowhole opening,and affects the transpiration rate.4.With manually controlling Ye Shi condition,meatures leaf blade's light saturation point and the light compensation point of Ginsengs under Forest as well as the photosynthesis temperature response,leaf blade's light saturation point of Ginsengs under Forest is between 80μmol.m^-2.s^-1～150μmol.m^-2.s^-1,light compensation point is between 3μmol.m^-2.s^-1～6μmol.m^-2.s^-1;Ginsengs under Forest optimum growing temperature is between 16℃～25℃.5.Comparing the leaf blade photosynthesis factors of Ginsengs under Forest through the different elevation area,we can get that:with different elevation area,leaf blade photosynthesis effective radiation PAR and the light saturation point of Ginsengs under Forest do not display differently;But the photosynthesize rate and the light saturation point display remarkable different.