Effect Of Shading On Growth And The Content Of Secondary Metabolites In Saliva Miltiorrhiza Bunge

Salvia miltiorrhiza has been a staple Chinese traditional medicinal material,its demand has soared in recent years because of its remarkable curative effect on cardiovascular and cerebrovascular diseases,standardized production of Chinese herbal medicine has become the trend of Chinese herbal medicine production,breakthroughs in traditional cultivation techniques are urgently needed.Planting herbs under forest or fruit trees can make reasonable use of the upper space of the field,which has become a unique production mode of some herbs in China.S.miltiorrhiza is a kind of heliophiles,weather it adapt to shading environment,realize the interplanting under forest or fruit trees,open a new chapter of the cultivation technology of S.miltiorrhiza.In this experiment,we put up different shading sheds which shading rate were 40%(S1,mild shading),60%(S2,moderate shading)and 80%(S3,severe shading)using different specifications of the shading net and planted S.miltiorrhiza in the sheds as the research object which flower is purple,with no shading as the control,surveyed and recorded the morphological characteristics,material accumulation,leaf structure,photosynthetic characteristics,antioxidant system and the key enzymes activity of secondary metabolism of S.miltiorrhiza under different treatments in different period and research the effect on growth and secondary metabolite content of S.miltiorrhiza under different shading environment in Tongchuan area,in order to provide technical and theoretical support for the standardized production of S.miltiorrhiza.The main conclusions are as follows:1.The light shading is benefit to the spatial expansion on the part above ground of S.miltiorrhiza,promotes dry matter accumulation and increase the root length and yield per unit area of S.miltiorrhiza,but it has no significant effect on the maximum root diameter and the root number and it is not conducive to the increase of root shoot ratio and dry matter ratio,the parameters above will reduce with increasing of shading degree.The test clearly shows that lightly shading environment is suitable for the growth and dry matter accumulation of S.miltiorrhiza.2.In the noon of summer,shading could alleviate the “midday depression” phenomenon,and the light shading could improve the photosynthetic performance of S.miltiorrhiza and enhance the net photosynthetic rate from 10:00 to 14:00;However,the net photosynthetic rate,transpiration rate and stomatal conductance decrease and the inter cellular CO2 concentrationincrease with the increase of shading degree.Generally,light shading can improve the photosynthetic efficiency of S.miltiorrhiza in summer,but it is not conducive to improve the photosynthetic efficiency in the period of the quality formation(late October).3.Shading will reduce the thickness of every structure and the density of stomatal on the lower epidermis of leaves;Light shading caused no significant effect on the thickness of palisade tissue and the stomatal density of S.miltiorrhiza;larger and thinner leaves are the adaptation performance of weak-light environment,larger leaf area helps to absorb light,and thinning the leaves is in favor of photons getting into chloroplasts for photosynthesis and the gas exchange.4.The content of MDA and soluble sugar in the leaves of S.miltiorrhiza decreased under shading net,and the antioxidant enzymes are improved in different degrees,especially the each index in the moderate shading changes most obviously,it shows the S.miltiorrhiza with shading alleviate the stress of high temperature and drought in summer or the frost damage in late October by improving the activity of antioxidant system,and alleviate the membrane lipid peroxidation,the conclusion shows a protective effect of shading on the field planting and delaying or prolonging growth period of S.miltiorrhiza.5.In late October,planting with moderate shading or severe shading decreased the activity of PAL and TAT significantly,and may cause the content of salvianolic acid B in roots was significantly lower than the control or the roots treated in light shading when harvesting S.miltiorrhiza;Light shading increased the yield and the content for salvianolic acid B lightly,but the shade environment is not conducive to the accumulation of tanshinone IIA,and the inhibition increased with the increase of shading degree;Delaying harvest period reasonably is conducive to increase the yield and the content of secondary metabolites of S.miltiorrhiza,the content of salvianolic acid B harvested in early December with light shading is 8.02% and accord with the national pharmacopoeia standard(more than 3%).