Abstract: Celastrus orbiculatus Thunb is widely grown in China. It is a member of traditional medicinal and ornamental plants. Bionomics of pollen and stigma of this cultivar under specified condition have never been reported up to now. The pollen and stigma morphology of C.orbiculatus was studied with the aid of scanning electron microscopy. Pollen viability of male flowers was determined by 2,3,5-triphenyl tetrazolium chloride (TTC) after 36 h duration at -20℃, 4℃, 15℃, 25℃, 35℃ and 50℃, respectively. A medium for pollen germination, composed of 50 g·L^-1 sucrose, and 0.3 g·L^-1 boric acid solidified with 6 g·L^-1 agar, has been optimized in this work. Subsequently, the temperature effect on the germination of pollens of male flowers served as an indicator. The basic shape of the pollen grains in both male and hermaphrodite was exceedingly similar, which was described as prolate, elongated-elliptical in equatorial view, sub-3-lobed-circular in polar view, and had 3 colporates. The morphological changes in the female and hermaphrodite stigma organs were similar in different development periods, but different from that of male. The result of different storage temperatures demonstrated that low temperature greatly contributed to pollen storage. In this study, we found 25℃ was optimum for pollen germination, while germination decreased at 20℃ and 30℃. This study observed morphology of pollen and stigma, and investigated the effect of storage temperature on pollen viability as well as the influence of varying temperatures on pollen germination and pollen tube growth. Such information would allow a deeper understanding of how specific factors impact on the effective pollination period in C.orbiculatus, and moreover provide more valuable information for other species’ theoretical study.

Key words: Celastrus orbiculatus Thunb, pollen morphology, stigma morphology, pollen viability, pollen germination, pollen tube