Study on cryopreservation and genetic stability of embryogenic calli induced from Dioscorea bulbifera microtuber Cryopreservation Technique of Jiangxi Yanshan Red Bud Taro(Colocasia esculenta L. Schott var. cormosus CV.Hongyayu) Embryogenic Callus by Droplet-vitrification The Study on Potato Shoot Tips Viabilities during Cryopreservation by TTC Staining MethodResources