Tuber Yield Components And Tuber Dormancy Physiology Of Chinese Yam (Dioscorea Opposite Thunb)

10 Chinese Yams(Dioscorea opposite Thunb)varieties were planted in Hohhot for there years successively which were collected from different regions of China. The botany characters and biological characteristics were observed and investigated focus on leaf size, leaf shape, leaf index, leaf base and flowering and tuber shape, tuber size, tuber weight and fresh weight of ground and other major biological characteristics for description the relationship between tuber yield components.Furthermore,tuber dormancy physiology of Chinese Yam(Dioscorea opposite Thunb)was studied by detecting the activity of related enzymes and the levels of endogenous hormone of tubers of Chinese Yam. The results would play important roles for Chinese Yam cultivation with good quality and high tuber yield and for Chinese Yam physiological and biochemical mechanism research work. The results were as follow:1.The seeds of Chinese Yam(Dioscorea opposite Thunb)began to sprout after the 40-45d in Hohhot. The period of rapid growth of the shoot was appeared 55-90d after sowing. The period of flowering and fruiting was appeared 85-110d after sowing. Plants on the ground began to wilt during late October to early Novembe. The tubers began to dormancy in this period. The whole growth period is about 150-180d. The generation of bulbil was shoter 10d than tubers in same condition. But the tuber yield of the tubers as seeds was significantly higher than the tuber yield of the bulbils as seeds 173.7%.2.It was showed from the correlation analysis between yield components of Chinese Yam(Dioscorea opposite Thunb)and its biomass of overground. Plant height and the number of leaves plays more important roles on tubers yields respectively than leaf characteristics and flowing. The correlation beween tubers yield components and tubers yield was biomass of overground > plant height > the number of leaves > tuber diameter> seedling > leaf index> flowering> tuber length. YF2, HX20, JP1 could be planted in Hohhot with their better commercial characters than others. Particularly, JP1 was the prior cultivar could be planted in Hohhot with its high quality and short and thick yam shape.3.The activity of amylase and starch phosphorylase and peroxidase and polyphenol oxidase were investigated of different Chinese Yam(Dioscorea opposite Thunb) materials at their different stages respectively during the storage period. The results showed: there was a big different of the amylase activity during the storage period of different materials. The trend variety of the activity of starch phosphorylase and peroxidase and polyphenol oxidase was the same situation. The activity of amylase and polyphenol oxidase was high in the beginning of the storage period in case of the higher tuber respiratory intensity. The activity of polyphenol oxidase and peroxidase was declined sharply after 60d storaged. It was showed amylase and peroxidase and polyphenol oxidase played more important roles in tuber dormancy period of Chinese Yam(Dioscorea opposite Thunb)respectively.4.The results showed both the absolute content of GA3 and the ratio GA3/ABA were gradually increasing during the tubers storage while the ABA content was decreased in the process. The changes of ZR (zeatin riboside) content were gentlely. The length of tuber dormancy of Chinese Yam was adjusted by the content of ABA and GA. The level of ABA content of the tuber played a key role in dormancy release.5.It was showed that the key period of dormancy release was 60d after harvest by the changes of the activity of related enzymes and the levels of endogenous hormone of tubers of Chinese Yam. The transition period was 60d-150d during storaged from the dormant state to sprouting state. Therefore, it could be reduce or break dormancy after 60d storage (dormancy start) by force.