Eco-physiological Mechanism Of High Yield Cultivation And Quality Control Of Scutellaria Baicalensis

Scutellaria baicalensis Georgi is a kind of perennial herbaceous plant in the labiatae family, and itsroot was used as Chinese Traditional Medicine (CTM) traditionally. Now, the wildlife resource of S.baicalensis can not meet the actual market demand with the developing modernization of CTM, thedemand was unceasingly increased while the wild resource was sharply reduced. Meanwhile the wild S.baicalensis was set to the protective endangered plant of third class by the authority. Today, the cultivatedS. baicalensis become the main source of medicine material. On the other hand, there was no systemicscientific research, on the cultivated of S. baicalensis. So, it is of key value to carry out the study ofstandardized cultivation techniques and eco-physiological mechanism on S. baicalensis to realize thesafety supply of raw medicinal materials and the stability quality controlling.Three different ecotopes were selected as the representative test plots including Linjiang, Changchunand Taonan in Jilin province. The factors affecting the quality of S. baicalensis were syntheticallyconsidered such as growing factors of seeding time, frequency, fertilization and best harvesting season andthe ecological factors of the moisture, illumination and soil. The yield, quality and eco-physiologicalcharacteristics were the key part of the study of growth and development law. The main effect factors thateffected the yield and quality were discussed among the different ecotopes, and the best feasible ecotopewas selected out. These results can provide scientific basis for construction of GAP cultivation bases andstandardized production of good quality for Chinese medicinal materials of S. baicalensis.The samples were periodical taken during the experiment for the morphological indices of root, stem,leaf, biomass, the content of baicalin and total anthoxanthin. The baicalin content was determined by 1100Agilent high performance liquid chromatography (HPLC) made in USA and total anthoxanthin contentwas determined by UV1700 ultraviolet spectrophotometer made in Japan. The photosynthetic ecophysiological indexes of S. baicalensis were determined by TPS-1 portable photosynthesis systemproduced by PP systems in England. The protective enzyme activity, contents of soluble protein and sugarwere determined by conventional methods.The main results were as follows:1 Effect of cultivated measures on yield and appearance quality of S. baicalensis1.1 Effect of environmental conditions on germination rate of seed and protective enzyme activity of S.baicalensis 1.1.1 Effect of environmental conditions on 1000-grain weight and germination rate of seedThe 1000-grain weight was changed in the different habitats, but the germination rate was not affected.Among the three plots, the different of germination rate was tiny and the change tendency of germinationrate was same. The germination rate decreased with the store years prolonged, and that stored over 2 yearswere not suitable to production. The feasible temperature of seed soaking was 40～50℃, and the last timewas 6h～12h, the feasible temperature of germination was 20～25℃, and the germination rate wassignificant improved with the dark..1.1.2 The relationship between germination and protective enzyme activityThe positive correlation between superoxide dismutase (SOD), peroxidase isozymes (POD), Catalase(CAT) activity and the germination rate of S. baicalensis seeds was significant or very significant. Theactivities of protective enzymes was in order of the new seeds > annual seeds > biennial seeds, theresistance decreased with the seed storing years prolonged.1.2 Effect of seeding time on rootThe yield of annual S. baicalensis that was planted in autumn or spring was higher than in summer,and the effect of seeding time on biennial was not remarkable.1.3 Effect of seeding pattern on rootThe accumulation and distribution law of dry matter was basically same between flat cultivation andridge cultivation of annual and biennial S. baicalensis. The flat cultivation had more branch roots thanthe ridge cultivation. And the condensed planting and hardened soil has more branch roots than the sparseplanting and soft soil.1.4 Effect of seeding density on rootThe branch roots were fewer in dense-planting and more in rare-planting. The suitably dense sowingwas good for the appearance quality and the higher yield per unit area, but the individual plant yield waslow. The sparse planting was good for the growth of the overground and underground and theaccumulation of dry matter, but the yield per unit area was low.2 Effect of ecological factors on yield and appearance quality of S. baicalensis2.1 Effect of water supply on yield of S. baicalensisThe biomass with 150mm water supply was decreased, the rhizome was thinner and the rhizomelength was shorten in the growing period, the distribution percentage between overground and undergroundwas changed, and the appearance quality was affected by this treatment. The flower and fruit biomass with450mm treatment was increased, but the yield of root and total biomass was smaller. The good influence of 250mm and 350mm treatments on root and stem were evident, the appearance quality was better, therhizome, overground biomass were highest. Otherwise S. baicalensis has better drought tolerance.2.2 Effect of fertilization on S. baicalensis yieldThe effect was evident that the application of nitrogenous fertilizer while the nitrogen, phosphorus andpotassium fertilizer was separately used on annual S. baicalensis, with which the main stem was longer andthicker But the yield would be affected by excessive application of it. Comparing with nitrogen, thephosphorus and potassium fertilizer had little affection on yield, but the dry matter was increased with theapplication of potassium.2.3 Effect of illumination on S. baicalensis yieldIt had good growth in the strong illumination under the same environmental condition, the root andtotal biomasses were increased.2.4 Effect of soil on S. baicalensis yieldThe root, stem, leaf and total biomasses of plant growed in the black soil of Changchun were more thanthose in the brown forest soil of Linjiang and sandy dark chestnut soil of Taonan.3 Growth rule and yield of S. baicalensis in different ecotopes3.1 Growth rule of annual and biennial S. baicalensisThe tendency of root and main stem length and biomass of annual S. baicalensis was increased, theoverground growth was dominant before August and then changed into the root after that. The biennial S.baicalensis had bigger growth rate of main stem before the middle of July, then decreased, and it hadslower growth rate of root length and biomass. The overground and total biomass fluctuated as single-peakcurves, and the peaks appeared at the end of August and after that it became slow.3.2 The qualitative difference in different ecotopes and explanationThe root biomass of annual S. baicalensis had significant difference in different ecotopes. The rootfrom Taonan was the rightest, and the root from Changchun was lighter than those from Linjiang in theprevious period, and then became the same in the later period. The annual S. baicalensis was easy infectedleaf blight because of much precipitation, heavy soil and air humidity in Linjiang. The seedling emergencewas hard because of Iittle precipitation in Taonan, so the biomass was small, and the yield per unit areawas also affected. The biomasS and the content of effective components were both higher in Changchunbecause of right precipitation and rich soil, which suitable for construction of standardized cultivationbases of S. baicalensis.4 Research on photosynthetic physiological ecology characteristic of S. baicalensis 4.1 Research on photosynthetic physiological ecology characteristic of annual and biennial S. baicalensisThe diurnal changes of net photosynthetic rate at top and middle leaves position of annual andbiennial S. baicalensis was basically same, and the photosynthetic rate in the morning and noon was high;the net photosynthetic rate at bottom leaves of biennial S. baicalensis was high in the morning, anddecreased a little, and than increased, The maximum appeared in the noon, the midday depression ofphotosynthesis was light.4.2 Photosynthetic characteristic in different periodThe diurnal changes of net photosynthetic rate of biennial S. baicalensis in different period were alldouble peak or many peaks curves, the time of valley-peak was different. The May was the vigorousgrowing period of S. baicalensis, the changes in the June was stationary, and the change of netphotosynthetic rate was very small in the August and September. The diurnal net photosynthetic rate inMay, June, August and September were 20.69μmolCO₂·m^-2·s^-1, 9.81μmol CO₂·m^-2·s^-1, 5.39μmolCO₂·m^-2·s^-1,4.37μmolCO₂·m^-2·s^-1, respectively.4.3 Relationships between photosynthetic physiological ecology and environmental factorsThe photosynthetic rate of annual S. baicalensis had very significant positive correlation with thephotosynthetic active radiation. The photosynthetic rate at bottom leaves position of biennial hadsignificant negative correlation with water vapor pressure, air relative humidity, but a positive correlationwith air temperature; The photosynthetic rate of S. baicalensis had significant positive correlation with thephotosynthetic active radiation and water vapor pressure in early growing stage and positive correlationwith photosynthetic active radiation in later growing stage, the relationship between photosynthetic rateand other environmental factors was marked different in different season.The reduction of the photosynthetic rate in different ecotopes was all because of the stomatallimitation, the important ecological factor influencing the reduction of the photosynthetic rate was the lowair humidity. The high temperature and humidity in Linjiang ecotope, the high leaf temperature and low airCO₂ concentration in Changchun ecotope, and the high temperature and low humidity in Taonan ecotopewere the main environmental factors influencing the net photosynthetic rate.5 Relationship between quality of S. baicalensis herb and physiological ecology factors5.1 Effect of water on quality of S. baicalensis herbThe content of protein and soluble sugar was increased with right water supply, with which theresistance increased. The net photosynthetic rate of S. baicalensis was high with 250mm～350mm watersupply in the growth period, the distribution of dry material in every organ was reasonable. The yield, thecontent of baicalin and total anthoxanthin were increased as the result. The baicalin and total anthoxanthin contents had positive correlation with the biomass yield of annual S. baicalensis by all the water supplytreatment.5.2 Effect of age and ecotopes on quality of S. baicalensis herb5.2.1 The difference of herb in different ecotopesThe baicalin content of annual S. baicalensis in Taonan was little higher than that in Changchun, andthe content in Linjiang was evident lower than others. The difference of anthoxanthin content in the annualroot among these plots was small. The mean baicalin content per unit area in Changchun was highest andthe Taonan was the last one. The baicalin content of biennial was in the order ofChangchun>Linjiang>Taonan.5.2.2 Quality difference of S. baicalensis herb in different ageThe change tendency of dynamic accumulation of anthoxanthin and baicalin in different seasons wasalmost the same, and its content in biennial was higher than that in annual. The baicalin content per unitarea of biennial was higher in middle ten days of September of Changchun.5.3 Relationships between quality and biomass of S. baicalensis herbThe relationships between quality and yield of S. baicalensis in different ecotopes werecomprehensive analyzed, the results showed: the content of baicalin and total anthoxanthin in annual andbiennial had very significant negative correlation with biomass accumulation of the root (p<0.01), thebaicalin and total anthoxanthin yield per unit area had positive correlation with the biomass yield of plantespecially the yield of root.5.4 Relationship between quality of S. baicalensis herb and soluble protein and sugarThe baicalin and total anthoxanthin contents of annual S. baicalensis had positive correlation with thesoluble protein and sugar in the leaf, and these contents of biennial had very little correlation with thesoluble protein and negative correlation with the soluble sugar.6 The optimal harvest time of S. baicalensisThe content of baicalin and total anthoxanthin in triennial was the highest, the biennial was the secondone, and the annual was the last. The mid-September or in the third spring is the optimal harvest time forthe biennial because of the highest yield of baicalin in unit area. And there would have enough time for theopen-air drying. So the best harvest time of S. baicalensis was the mid-September of the second year or thethird spring.