The purpose of this experiment was to study the effects of different shading conditions on the growth,physiological characteristics and biomass allocation of Polygonatum cyrtonema,which offered a theoretical basis for its cultivation.Different light environments(100%,80%,60% and 35% light transmittance) were simulated with shading treatments.Growth and photosynthetic indexes of P.cyrtonema were measured and the variances were analyzed.The results show that shading decreased superoxide anion radical(O-·2)production rate and hydrogen peroxide(H_2O_2) accumulation,kept the activity of SOD,POD and CAT enzyme at a high level.Furthermore,The content of chlorophyll a and chlorophyll b,net photosynthetic rate(Pn),stomatal conductance(Gs),transpiration rate(Tr),maximal photochemical efficiency of photosystem Ⅱ(Fv/Fm),photochemical quenching index(q P) and effective quantum yield of photosystem II(ΦPSⅡ) of P.cyrtonema were increased while the intercellular CO2 concentration(Ci),Foand NPQ were decreased by shading.Shading is beneficial to P.cyrtonema growth,can increase the total biomass P.cyrtonema.The allocation proportion of biomass on the aerial portion of P.cyrtonema increased but underground parts decreased with increasing shading conditions.In this study,P.cyrtonema can grow well in shading conditions,shading is beneficial to the formation of the yield and quality of the rhizomes of P.cyrtonema,especially in 65% light transmittance.
Keywords: Polygonatum cyrtonema; growth; photosynthetic characteristics; shading.