The Pollination Biology Of Epimedium Wushanense (berberdiaceae)

To study the pollination biology of Epimedium wushanense, a species endemic to China, different methods such as field and microscopic observations and laboratory measurement were adopted, the results were as follow:1. The flowering span of the population, individual, inflorescence and single flowering was approximately 22～27,12～17 and 3～4d, respectively. Flowering amplitudes curves were a single peak and marked synchrony, and the E. wushanense exhibited a "mass-flowering" pattern with similar at the three populations. Correlation analysis between phenology index and number of the fuirt set indicated that number of the fuirt set had a positive correlation to the peak flowering date, last flowering date, number of buds, duration per plant respectively, and had not a correlation to first flowering date. Comparisons of means and CV of flowering phenology suggested that means of flowering phenology indexes were very significant difference among duration per plant, duration per flower, end date, peak flowering date and fruit numbers, and significant among total flowers, flowering amplitude, fruit setting, but on significant between synchrony and onset. The CV of flowering phenology was remarkably different in phenology indexes, except Synchrony. The fuirt set was also affected by the spur of E. wushanense. The conclusion was that the flowering phenology and reproductive features are affected by micro-environment, and the fuirt set was also affected by the spur of E. wushanense.2. Three distinct kinds of flowers were observed in this species:(1) about 54% of the flowers had pistils that were of equal length or shorter than the stamens (PESS); (2) in 23.5% of the flowers, the pistils were longer than the stamens (PLS), and (3) in 22.5% of the flowers, the styles were positioned axially away from the anthers (SAA). No significant difference in fruit setting rate was observed between PLS and SAA flowers, but PESS flowers set less fruits than the other two. During flowering, the pollen vigor of E. wushanense was 40%～90% and could be maintained for 4～5days. Spatial ectopia, protogyny and indefinite inflorescence were observed to be the characteristics of most reproductive organs of E. wushanense, and the bottom-up pathway of flower visiting by visitors could therefore reduce the possibility of self-cross abortion which caused by cross pollination in one plant. The out-crossing index and pollen-ovule ratio (P/O) was 4 and 3959.51±386.83, respectively. A breeding experiment also indicated that the species was self-incompatible, and revealed that the presence of PLS and SAA could increase outcrossing and fruit set. A field experiment showed that open-pollinated flowers of E. wushanense produced significantly less fruits than an artificial xenogamy experiment. The results therefore showed that floral morphology could significantly affect fruit set in E. wushanense.3. Nine species of hymenoptera and diptera were recorded as visitors, three of them were effective visitors. The principal visitors and effective pollinators were. Bombus spl and Bombus sp2., and the rewards were pollen and nectar. The highest visiting frequency in a day was observed at 13:00～14:00. There was a positive correlation between the nectar volume and the flowering day of E. wushanense, and the nectar volume significant increased at second flowering day in bag flowers. Daily variation of nectar volume of E. wushanense gradually increased, and the nectar volume of the time of after 13:30 was significant higher than the time before 13:30. Because of pollinators, the nectar volume gradually reduced during a day, and the pollinators had more behavior between 13:00 and 15:30. Daily variation of sugar content of nectar of E. wushanense was a single peak, and the reach to top value at 13:30. which reveal that variation of sugar and pollinator, and the nectar secretion andvariation of sugar could affect the reproductive success by pollinators. The attractant experiments indicated that the fruit set of flowers whose spurs were removed was significantly lower than that of flowers whose stamens were removed, suggesting that the spurs of the flowers could strongly increase the pollinator visitation and fruit set.4. The survey of the fruit-setting characteristics of E. wushanense revealed in the three habitats indicated:(1) the resource and reproduction of floral characteristics had no difference among the three habitats, eg. No significant differences of branches per plant, inflorescences number per plant and flowers per plant were observed among the three habitats. (2) Fruit-setting rate per plant Fruit-setting rate per plant Fruit setting per inflorescence fruit setting rate per inflorescence of PLS and SAA were remarkably higher than the PESS. (3) The branches per plant and inflorescences number per plant of three floral characteristics had no difference in three habitats. The flowers per plant and fruit set of population 1 was less than the other populations. (4) The full seed per fruit, percentage of seeds abortion per fruit and number of seeds abortion per fruit were significant different in three floral characteristics, but among the population, which revealed the seeds per fruit had been affected more by floral characteristics. (5) The three floral characteristics had no difference in seeds per fruit, but the PLS and SAA were remarkably longer than the PESS in the length and wide of seed. This indicated the quality of seed have been strongly affected by floral characteristics. The result suggest that the seed setting characteristics of E. wushanense were affected by its flower types and habitats and more bv the latter.5. The significant effects of space on reproductive success of E. wushanense. The fruit morphological parameters of base and middle were higher than the top, the percentage of seeds abortion at base and middle were higher than top. The parameters of fruit and seed of fruit in the early and middle stage of flowering were bigger and much more than the last stage of flowering. In three flowering stages, no significantly was measured in width of seed, but the length of seed. The percentage of seeds abortion at the last stage of flowering were higher than the early and middle stage of flowering, which suggested the weight of fruit in the early and middle stage of flowering were remarkably weightier than the last stage of flowering. So, the of space and flowering time significant effected on reproductive success of E. wushanense. And in order to make work more effective,we should pick the fruits of E. wushanense at the early or middle stage of flowering, and the base position of the inflorescences to do experiment or for medicine.6. Based on the results of regression, the intensity of density dependence effect was enhanced, and more resources were allocated to sexual rep roduction with the density of clone fragments increased. The results of nonparametric test revealed that the leaf number and leaf breadth of clone were gradually increased to gain more resource to enhance the rep roduction capacity. 7.The pollen germination and pollen tube growth of E. wushanense would be enhanced when the concentration of borate, calcium nitrate and sucrose of the culture medium were within a certain range. If the concentrations were too high or low, the pollen germination and pollen tube growth would be inhibited. The effect of magnesium and kalium on pollen germination and pollen tube growth were insignificant. Sucrose, Ca(NO3)2·4H2O and H3BO3 had significant effect on pollen germination, but the interactions among medium components were insignificant. The optimum culture medium and environment conditions which support the germination and growth were 20% sucrose+10 mg/L H3BO3+20 mg/L Ca(NO3)2·4H2O, pH 5.0,20℃and 600 LX light intensity respectively.8. All parts of the icariin contents in wild and cultivated E. wushanense cannot meet the standard, which might be related to harvest seasons. Both of the flavonoids contents in wild and cultivated leaves of E. wushanense can meet the standard, while other parts can not. Because of the relative light intensity increased in cultivated, the effective composition content of two kinds of Epimedium increased. The dwarf phenomenon was occurred in cultivated E. wushanense, but the number of branches per plant in Cultivated were more than wild, the output of E. wushanense increased. Because of environment changed, the flowering span of the population, individual, inflorescence and single flowering in cultivated were longer than the wild population, and the flowering amplitudes of wild were higher than the cultivated. Flowering amplitudes curve of was a single peak and marked synchrony, and the E. wushanense exhibits a "mass-flowering" pattern with similar at wild population. And no pollinators would lead to the less reproductive success in cultivated E. wushanense.