Studies On The Desiccation Sensitivity And Dormancy Mechanism Of Osmanthus Fragrans Seeds

The seed desiccation sensitivity and dormancy characteristics of Osmanthus fragrans seeds were studied by measuration of the physiological characteristics during natural dehydration and during the stratification, so that the mechanisms of desiccation sensitivity and dormancy of O. fragrans seeds were revealed. The results were as follows:1. The moisture content of mature O. fragrans seeds was 36% and the seed viability declined to 6% when the seed moisture content was naturally dehydrated to 11.6%, indicating that O. fragrans seeds were recalcitrant.2. The seed electrical conductivity increased during desiccation but the superoxide dismutase (SOD) activity decreased rapidly at the same time. The peroxidase (POD) activity fluctuately increased at first then declined rapidly during dehydration. Superoxide anion radical content decreased at the beginning of dehydration, but it would increase rapidly at last. Malondialdehyde(MDA) content increased with decreasing seed water content.3. The O. fragrans seed embryos developed normally during seed maturation. And the dormancy of O. fragrans seeds should belong to physiological dormancy as the seed embryo could not germinate in embryo culture. Moreover, the dormancy of O. fragrans seeds could be broken after stratification for about 80 days and exdogenous GA was also proven to be effective for breaking dormancy.4 The content of ABA in O. fragrans seed embryos would ascend at first then descend during stratification, but the contents of GA3, IAA and ZR would ascend at the same time. The hormone contents in the seed endosperms did not change orderly. The ratios of GA/ABA,IAA/ABA,ZR/ABA and(GA+IAA)/ABA would ascend during stratification, but the changes of those in seed endosperms were relatively less, indicating little relation with seed dormancy.5 The content of soluble sugar would descend at first then be stable during stratification, but the content of starch would descend as a whole. The content of soluble protein would descend at first then ascend but be stable at last. The activity of amylase would ascend then be stable during stratification, but the activity of acid phosphatase would ascend at first then descend but be stable at last.