Primary Assessment On Germplasm Resource Of Dioscorea Plant

Dioscorea opposita Thunb. and Dioscorea alata L. which both belong to Dioscorea L.genus and Dioscoreaceae. are rich in nutrition serving as food or medicine, being more and more popular among people.But there is a little study about Dioscorea opposita Thunb. and Dioscorea alata L.The morphological and genetic characteristics are extensive and complicated.They are natural polyploidy. We collected 115 germplasm accessions of Dioscorea alata L. and 136 germplasm accessions of Dioscorea opposita Thunb. originating from 5 provinces,such as Guangxi,Fujian,Hainan,Yunnan,Guangdong and put primary germplasm assessment on them. The main results are as follows:(1) 136 germplasm accessions of Dioscorea opposita Thunb. and 115 germplasm accessions of Dioscorea alata L. were evaluated by 13 morphoagronomic descriptors and identified by 8 morphoagronomic descriptors(young leaves colouration,petiole colouration,pigmentation of stem at emergence,pigmentation of veins,stem wing colouration,leaves length,leaves width and Lamina shape,skin colour and flesh colour of bulbuls).Five major groups and five single branches of morphotypes were identified refer to Dioscorea opposita Thunb; seven major groups and one single branch of morphotypes were identified refer to Dioscorea alata L.(2) 124 germplasm accessions of Dioscorea opposita Thunb. and 103 germplasm accessions of Dioscorea alata L. were evaluated for the nutritional characteristics of the tubers (percent cellulose,percent dry matter,proteins content,pH,acidity,percent amylose,percent starch,percent insoluble ash,percent total ash,percent water-soluble sugar,percent K,Ca content,Mg content,Fe content,Mn content,Cu content,Zn content) and identified by 10 nutritional descriptors and skin colour and flesh colour on central transverse section.We chose the highest percent starch of 10 germplasm accessions of Dioscorea opposita Thunb. and 103 germplasm accessions of Dioscorea alata L and found there may be some relationships between the high percent starch and the morphotype.Six major groups and four single branches were identified refer to Dioscorea opposita Thunb;seven major groups and three single branches were identified refer to Dioscorea alata L(3) Chromosome numbers and morphotypes of 20 germplasm accessions of Dioscorea opposita Thunb. and 19 germplasm accessions of Dioscorea alata L. were studied The chromosome numbers were 40 or 60, we may conclude that the germplasm accession which have 40 chromosomes was tetraploid and the germplasm accession which have 60 chromosomes was hexaploid.There were some relationships between chromosome numbers and leaves length and leaves width. The karyological study on 3 germplasm accessions were carried out. The number and karyotypes of metaphase chromosomes were formulated to be K=2n=4x=40=20m+20sm,K=2n=6x=54m+6sm and K=2n=6x=6st+30m+24sm.