Leaf Morphological Diversity Of Discorea Nipponica And Its Correlationship With Photosynthate And Active-ingredient

Dioscorea nipponica is a traditional medicinal source plant.In this paper,two-year-old plants from the provenances of Manghe and Guandishan in Shanxi Province were took as experimental materials.Leaf morphology diversity of the species was analyzed,the contents of chlorophyll and photosynthetic products of different leaf morphology in different phenophase were measured,and the content of active-ingredient diosgenin in rhizome was determined.On these basis,correlationships between leaf morphology,photosynthate and diosgenin content were analyzed.The aim of this study is to select high quality germplasm of Discorea nipponica.The main results were as follows:(1)Phenophase of Discorea nipponicaThe seedling date and fruit date of Manghe provenance were both 5 days earlier than that of the Guandishan,and leaf-expansion date was 2 days earlier than the Guandishan.The two sources of the flowering date and withering date were almost of the same time;The total growth period of both sources of Discorea nipponica is about 204-221 days,Manghe provenance is 7 days longer than the Guandishan.(2)Morphological leaf diversity of Discorea nipponicaThere were two leaf colors in the Discorea nipponica:the dark green leaves were mostly of thick paper quality,and the light green leaves were mostly of thin paper quality;Two leaf types were found of long and broad leaf types,and long leaf type was dominant in two provenances.Leaves have 3 to 7 cracks,leaf angle was between 40°?70°.There were significant correlations between above morphological indicators.(3)Chlorophyll content of Discorea nipponicaChlorophyll content was significantly different among different leaf color and leaf crack.Chlorophyll content of dark green leaves was significantly higher than that of light green leaves.Chlorophyll content of leaves with three and six cracks was significantly higher than that of other crack leaves.Chlorophyll content was lasting increased from leaf-expansion stage to fruit stage,rose to the maximum at fruit stage,and dropped rapidly at withering stage.(4)Photosynthate content in Discorea nipponica leavesThere are significant differences among varied leaves in photosynthetic products such as soluble protein,soluble sugar,starch and reducing sugar.Photosynthate content of dark green leaves was significantly higher than the light green leaves.Photosynthate content of three-cracks leaves was significantly higher than other leaves.The leaf angle was positively correlated with photosynthate content.Content of soluble protein,soluble sugar and starch was all significantly increased from leaf-expansion stage to flowering stage,but declined in fruit stage.The content of reducing sugar has been increasing steadily from leaf-expansion stage to the fruit stage,and then decreased.(5)Photosynthates and diosgenin content in rhizome of Dioscorea nipponicaContent of Photosynthates and diosgenin content in rhizome of Manghe provenance were higher than Guandishan provenance.The photosynthates and diosgenin contents in dark-green-leaf plants were significantly higher than light-green-leaf plants.The content of four photosynthates of rhizome was significantly related to the content of active-ingredient diosgenin.(6)Screening quality germplasm of Discorea nipponicaCombining the Discorea nipponica leaf morphology,photosynthates,and rhizome diosgenin content,the dark-green-leaf plants in Manghe provenance were selected as high quality germplasm.Leaf morphology of high quality germplasm was of following characteristics:? Leaf color is dark green;?Leaves are mainly of 3 cracks,5 cracks and 6 cracks.The greater ratio of 3 cracks leaves,the better quality;? Leaf angle is greater than 50°.The larger the angle,the better quality.