| Diosgenin is an ideal raw material for the synthesis of steroids.In this paper,seedling of Dioscorea nipponica was selected as experimental materials in the nursery of Forestry College of Shanxi Agricultural University.Five plots with different light intensity(5%,25%,50%,65% and 100% natural light)were selected to analyze the survival and proliferation of Dioscorea nipponica to disclose the effects of light intensity on leaf morphological,structure,physiological and diosgenin content in rhizome.The study would provide basic data for artificial cultivation of Dioscorea nipponica.The main results are as follows(1)The survival rate of Dioscorea nipponica seedlings under different light intensity was significantly different(P < 0.05).The seedlings were prone to be more survived under 50% and 65% light intensity,the survival rate was 89.17~93.28%.The seedlings were difficult to survive under 5% light intensity,which was of the lowest survival rate 28.40%.(2)It was significantly different on leaf morphological and structural indexes of Dioscorea nipponica among different treatment(P < 0.05).The length,width,area and fresh weight of leaves for seedlings treated by 65% natural light were all higher than other treatments.With the increase of light intensity,the indexes of leaf stomatal number,leaf thickness,epidermis thickness,palisade tissue thickness,spongy tissue thickness and leaf structural compactness were all significantly increased.The stomatal density was the highest under 65% light intensity(32.75~56.00 n.mm2).Thickness and vascular bundle area of vein for seedlings treated by 50% and 65% natural light were both larger than other treatments.The plasticity index of palisade tissue thickness was of 0.48,in other words,palisade tissue is more flexible to adjust by the environment.(3)The contents of chlorophyll and soluble protein in leaves of Dioscorea nipponica were both significantly changed by light intensity(P < 0.05).Under 65% natural light,the contents of chlorophyll a,chlorophyll b,total chlorophyll and carotenoid of leaves were all higher than under other light conditions.Under 100% light and severely weak light,the chlorophyll content was too low to maintain the normal growth of Dioscorea nipponica.Under medium light intensity,the soluble protein content of leaves was significantly higher,resulted in better growth of seedlings than seedlings treated by other light intensity.(4)The biomass and diosgenin content of rhizome for Dioscorea nipponica were both significantly affected by light intensity(P < 0.05).With the increasing of light intensity,the biomass and diosgenin content of rhizome increased firstly,then followed a decreasing trendy.The biomass of the plant was higher at 50% and 65% light intensity,which was 0.43-0.44 g.Under 65% natural light,diosgenin content of rhizome was 0.68 mg·g-1,which was higher than other treatments.The study showed that under 50% and 65% natural light,seedlings were prone to be survived and performed better aboveground growth,larger biomass and diosgenin content of rhizome.In conclusions,50%and 65% natural light could be the suitable light conditions for Dioscorea nipponica. |
