Pollen cryopreservation of Japanese tree peony cultivars.

In order to prolong pollen viability,pollen of 23 Japanese tree peony ( Paeonia suffruticosa Andr.) cultivars were cryopreserved in liquid nitrogen.In vitro germination of both fresh and cryopreserved pollen was examined by the hanging-drop method.The results showed that the germination rate of fresh pollen varied with cultivars,with the highest value (60.89% ) in P.‘Shimane Chojuraku’and the smallest (3.49% ) in P.‘Shimadaijin’.At room temperature,pollen viability of most cultivars was lost within 15 days,but cryopreservation prolonged pollen viability for at least two years.After two years,cryopreserved pollen still retained a high germination rate,which was even higher than that of fresh pollen in some cultivars.We conclude that cryopreservation is applicable for long-term preservation of pollen of Japanese tree peony.