Comparative Study On Photosynthetic Characteristics And Chemical Components Of Houttuynia Cordata Thunb. Under Different Light Intensities

In order to know more about Physiological characteristics of Houttuynia cordataThunb. and provide a theoretical basis for optimizing cultivation conditions, thisarticle take Houttuynia cordata Thunb. as material, did the research and analysis ofthe impact of photosynthesis and features, chemical composition, as well as volatileon effects of different light intensity(full-light treatmen,shading60%treatment, andshading80%treatment).Shading reduced net photosynthesis rate (Pn) and transpiration rate (Tr)significantly. In vigorous growing period (May), the diurnal variation of Pn showed asingle peak curve in full-light, for7.23μmol·m-2·s-1in average, it showed a doublepeak curve in shading60%and80%, for6.05μmol·m-2·s-1and3.28μmol·m-2·s-1inaverage. Tr diurnal average were4.75mmol·mol-1,4.08mmol·mol-1and3.23mmol·mol-1in full-light, shading60%and80%. WUE diurnal average is1.49mmol·mol-1,1.43mmol·mol-1and0.99mmol·mol-1in full-light, shading60%and80%.In growing stagnation of groud part(August), the diurnal variation of Pn showed adouble peak curve in full-light and shading60%, for10.22μmol·m-2·s-1and5.94μmol·m-2·s-1in average, it showed a single peak curve in shading80%, for3.22μmol·m-2·s-1in average. Tr diurnal average were7.58mmol·mol-1,5.95mmol·mol-1and5.93mmol·mol-1in full-light, shading60%and80%. WUE diurnal average were1.4mmol·mol-1,0.94mmol·mol-1and0.5mmol·mol-1in full-light, shading60%and80%. In second crop of seedling period (November), the diurnal variation of Pnshowed a double peak curve in full-light and shading60%, for4.23μmol·m-2·s-1and3.19μmol·m-2·s-1in average, it showed a single peak curve in shading80%, for1.8μmol·m-2·s-1.In average, Tr diurnal average were2.76mmol·mol-1,2.02mmol·mol-1and1.77mmol·mol-1in full-light, shading60%and80%. WUE diurnalaverage were1.47mmol·mol-1,1.53mmol·mol-1and2.05mmol·mol-1in full-light,shading60%and80%. Physiological factors related to photosynthesis such as Gs, Ciand Tl all showed some differences in shading treatments. Other environmentalfactors suah as PFD, Ci and RH also for shading showed differences. The totalchlorophyll contents of Houttuynia cordata Thunb. in growth stagnation was highestin shading80%, and lowest in full-light.The growth, morphology, nutritive components of Houttuynia cordata Thunb. were wide influence by light intesity. With the reduction of light intensity, the height,upground and underground stem diameter, leaf width and length, ground internode aswell as petiole length of Houttuynia cordata Thunb. were increased. In upground parts,the highest content of vitaminC was22.26±1.05mg/100g in shading60%, sugar andcrude fat were31.22±1.64mg/g and12.65±0.005%in full-light, protein and waterwere16.03±0.40%and86.87±0.002%in shading80%. In underground part, thehighest content of vitaminC, soluble sugar and crude fat were6.38±1.30mg/100g，146.57±3.76mg/g and8.71±0.001%in full-light, crude protein content and waterwere8.68±0.06%and83.69±0.015%in shading80%.In growing stagnation, the total and components cotent of flavonoid weredifferent in each treatment. In upgroud part, the total content were37.34±1.49mg/100g,31.81±0.48mg/100g and28.73±0.92mg/100g in full-light, shading60%and80%,while the undergroud part were11.99±0.31mg/100g,10.75±1.26mg/100g and8.27±0.31mg/100g. There was wide influence in GC-MS map of volatile oils byshading treatments.23components were identified and the contents of them decreasedor increased with shading. The content of the main active components was highest inshading60%.