Studies On Breeding Ecology Characteristics Of Celastrus Orbiculatus Thunb

Celastrus orbiculatus Thunb, a member of the family Celastrus Celastraceae, is adeciduous shrub, which is widely distributed in China. A variety of organs from this species,including stems, roots, leaves, fruits and seeds, have been extensively used as traditionalChinese medicines. It is also used often as ornamental plants in gardens due to its gracefulappearance. The charming fruits covered in red fleshy aril. C. orbiculatus can survive in awide range of environments and its creeping growth characteristics play a unique role indesertification controlling engineering. The research on characteristics of breeding ecologywill be carried out to make its application and cultivation in high-efficiency.In order to understand the breeding biology of C. orbiculatus Thunb, we investigated theflowering process, floral syndrome, the species of floral visitors and visit frequency by thefield observation. Indices related to floral morphology and pollination system such as the sizeof flower structures, pollen viability, and stigma receptivity, and seed germinationcharacteristics of C. orbiculatus Thunb were also examined. The main results are as follows:C. orbiculatus Thunb plants bloom from May to June, lasting for approximately20days.The timing of C. orbiculatus early flowering period was influenced significantly by springtemperature, especially in April. Single flowers’ anthesis, however, was not affecteddramatically. The typical life spans of anthesis for female, male and hermaphrodite flowerswere about5-7,2-3and4-5days, respectively.The morphology of the pollen grains in both male and hermaphrodite was exceedinglysimilar, which was described as prolate, elongated-elliptical in equatorial view,sub-3-lobed-circular in polar view, and had3slender colporates and ornamentation of exineshowing typical reticulate sculpture. The pollen fertility of male and hermaphrodite was(92.0±1.3)%and (84.2±2.8)%, respectively.Pollen viability varies remarkably by gender and plant habitats. Under similar survivalconditions, the pollen vitality of andromonoecy was higher than that of male plants. Thepollens under sunny circumstance were more dynamic as comparison with those from thesame gender plants in shady environment. The high viability of pollens from male flowers ofandromonoecism plants could be maintained for6-8h after pollens released, and the life spanof these pollens was2days. The high viability of pollens from male plants, however, could be maintained only for0-2h following pollen release, and the life span was only1day.Analysis on the effect of storage temperature on pollen vitality demonstrated that lowtemperature greatly improve pollen storage. In this report, we discovered that the optimaltemperature for pollen germination was25°C, and pollen germination decreased at20°C and30°C. The times for pollen tubes to reach the ovary bases of female and hermaphroditeflowers were20h and24h after pollination, respectively.There were no differences of stigma morphologies, three-lobed stigma with a hole in central,among different gender flowers. For the size, however, female stigma was thicker than malestigma, with their diameters of1.3~1.7mm and0.22±0.05mm, respectively. Themorphological changes in the female and hermaphrodite stigma organs were found to besimilar in different development periods, but different from those in the male stigmas.The stigma receptivity of female was the strongest within24~72h (from the second day tofourth day) after blooming. However, the hermaphrodite stigma had the highest receptivity in48~96h (from the third day to fifth day) after blooming.The visiting insects recorded on different gender plants were similar, and most of thembelong to Hymenoptera and Diptera of Insecta. Among them, Apis melliferaligustica Spinola,Episyrphus balteata De Geer and Camponotus japionicus were the main visitors. Thebehavior and activity rules of visiting insects were influenced by plant sex and temperature.During one day, there were two visiting peaks on male and andromonoecy plants, but thepeaks arose at different points in time because of plant habitat, while the female only had onepeak in the afternoon. The bees activated in the highest frequency when the temperature wasduring25-30℃.Thousand Kernel Weight (TKW) of seed of female plant lived in sunny condition was6.53±0.061g (cv=0.9%), and in case of the female plant under shady circumstance,3.13±0.076g (cv=2.4%) was measured. There were great deals of differences in length, width,thickness, TKW of seed between female plants in different habitat. The seed germination wassignificantly affected by temperature, and20℃was most suitable for germination.The results presented in this study would allow a deeper understanding of how factorsinfluence breeding process in C. orbiculatus, and also provide valuable information for otherspecies.