Study On The Relationship Of Embryo Development, Dormancy And Seed Endogenous Hormones Of American Ginseng

According to the dynamics of seed endogenous hormones and the hormonal regulate to material metabolism and enzyme of American ginseng(Ponax quinquefolium L.) seed, the mechanism of embryo development and dormancy was studied in this article. It shows that the physiological and biochemical mechanism was different during the stages of embryo morphlogical afterripening and seed dormancy of American ginseng seed.It was suggests that during the stage of fruit formation, there was no endogenous ABA in ginseng seed; therefore, the development of endosperm and endocarpium regulated by IAA, Z+ZR, ETH, and GA₃. The seed ethylene releasing shows a type of "low-high-low" changing. Although seed IAA, Z, ZR and GA3 shows "S" variation, the peak of the formmer two present in the voilet fruit stage, and the latter two appear in the red fruit stage. During postharvest stage, seed stratification tests indicated that both IAA and ABA have two peaks after stratifying 60 days and 120 days, respectively, the difference was that no ABA was determined before 40 days after stratification, and IAA was determined from the begin of stratification. GA3 and Z also have two peaks , the first peak of the two hormones was presents in different stage: GA3 was determined just after the begining of stratification, and Z emerges after the first peak of IAA and ABA; the second peak of GA3 and Z appears during mid to late stage of embryo morphlogical afterripening. Based on the analysis to the relationship between embryo:endosperm length ratio(EELR) and endogenous hormones variation, we can summarized mat (1)the first peak of ABA maybe associated with the onset of embryo development, and the second peak, coordinated with IAA, inhibits precocious germination; and (2)the first peak of GA₃ and Z coincides with cell differenciation and elongation growth, and the second peak have the function of releasing seed dormancy.With embryo development, the activities of seed POD, G6PDH, α- and β-amylase became higher and higher, but CAT shows a higher activity during early stage after stratification, then keep a decreasing tendency. Use respiratory inhibitor NaN₃ to imbibe ginseng seeds that have had achieved morphlogical...