Pollination Biology Characters Of Clematis Tangutica

In order to achieve effective pollination,the plants that survive in the alpine environment will adapt to the pollinator and non-pollinator factors in the extreme environment through the specialization of floral architecture and the life extension of each part of the floral organ.When the pollinator is limited,the plant will protect breeding via delayed selfing and autonomous selfing.Therefore,the study of plant pollination biology characteristics can be more in-depth understanding of plants reproduction in adverse environment.The breeding and pollination systems of Clematis tangutica(Maxim.)Korsh.in eastern Qinghai-Tibetan Plateau were discussed for exploring pollination mechanism in plateau ecological environment.Meanwhile,through the phenomena of downward corolla and gradually developmental stigma,the adaptive relationship between the floral architecture and pollination process of Clematis tangutica was further elucidated.The main conclusions are as follows:1.The breeding system of Clematis tangutica(Maxim.)Korsh.was out-crossing and part self-compatibility,non apomixis when comparing the results of bagging experiments with the results of out-crossing index and pollen-ovule ratio.The single flower seed rate of Naturnal pollinationor control was 77.04%,Isolation without emasculation(complete self pollination)was 39.39%,Natural pollination with emasculation(complete pollination)was 57.69%,Artificial geitonogamy and Artificial xenogamy were 80.44% and 80.83%,respectively.Artificial pollinations improved reproductive success,suggesting that sexual reproduction may be influenced by pollen limitation and pollinators limitation in nature.2.Population initial flowering time of Clematis tangutica began in the early July,full flowering stage presented from July 19 th to July 23 rd,the population flowering lasted until September,then entered the seed ripening stage;Anthesis lasted 8 days;Bud stigma receptivity consisted in the day before anthesis,and lasted 6 days;Stamens began to gradually spread pollen at the day after anthesis and lasted 4 days.There are partial dichogamy and herkogamy in the function of male and female.Pistil higher than stamen,to a certain extent,is restriction of self pollination,but when the pollination insects arelimited and unable to complete the hybridization,the pistil stigma will be bent to the back close to the stamen anther and complete autonomous selfing.3.The main pollinators of Clematis tangutica are Bombus spp.and Apis cerana cerana Fabricius.Bombus spp.drills into the bud with strong physique and takes the nectar.At the same time,pollen from other flowers spread on the stigma of bud flower which are already receptivity to achieve the precise outcrossing.Meanwhile,both of Apis cerana cerana Fabricius and Bombus spp.contribute to the spread of pollen with high quality and quantity in order to complete pollination,the visiting frequency are 0.1406time/h/flower and 0.2371 time/h/flower,respectively.4.The flower drooping phenomenon of Clematis tangutica reduced the impact from non pollinator factors,such as the negative effects of excessive rainwash and strong ultraviolet sunlight on pollen quality;However,there was no significant effect on pollinator visitation and flower visiting frequency;The single flower seed rate and seed germination rate were significantly higher than those in experimental group with upward corolla.The above conclusion indicated that the male fitness and female fitness in downward corolla flower were improved significantly,which ensured the reproductive success.5.The stigmas of Clematis tangutica were on the ventral sides of the styles,and developed into stigmatic papillae by cells along the ventral slits.During anthesis the receptive surfaces matured in a sequence from the apical towards the basal ends of the styles;Observation results of pollen deposited and pollen tube growth by fluorescent microscope also indicated that this stigma development pattern of Clematis such extended the function of pollination surface in time and space,increase the probability of successful pollen deposited and to maximize the function display in the female structure.According to the above conclusion,Clematis tangutica were fully adapt to the environment of the alpine pollination,because the life of floral organ and floral architecture were responsed to the pressure with pollinator factors and non pollinator factor.Flowering dynamics,floral structure and function are suitable with each other for achieving pollination in high quality and efficiency;When the pollination insects arelimited,the pistil stigma will be bent to the back close to the stamen anther and complete autonomous selfing by reducing difficulty of self pollination to ensure reproduction.It is obvious that the pollination biology of Clematis in the eastern margin of Qinghai Tibet Plateau has ensured its reproductive success in the alpine environment.