Pollination Biology And Seed Germination Of Dendrobium Wangliangii

Dendrobium is the second largest genera of Orchidaceae,which has important ornamental value and medicinal value.In recent years,with the deterioration of the natural environment and the destruction of man-made excavations,it's survival has been greatly threatened.The research on breding system and pollination biology of Dendrobium is very important for the protection and development and application of germplasm resources of orchids.In this study,studies on the breeding system of Dendrobium and the seed symbiotic germination of Dendrobium wangliangii were carried out in order to explore the characteristics of the floral characteristics and pollination mechanisms of Dendrobium wangliangii.The germination characteristics of Dendrobium wangliangii were expected from the reproduction.And pollination perspective to discuss the protection and management strategies of Orchidaceae plants.1.Breeding systems of DendrobiumThis research preliminarily studied the breeding system of Dendrobium,which laid the foundation for research on pollination biology of Dendrobium wangliangii.Through artificial pollination experiments,it was found that 14 species of Dendrobium were self-compatible and 9 species of Dendrobium were self-incompatible.The breeding system of Dendrobium is dominated by outcrossing.The highest rate of outcrossing in Dendrobium plants was up to 78.57±6.57%,which was significantly higher than that of self-crossing(P=0.032).2.Pollination biology and seed symbiosis germination of Dendrobium wangliangiiThis research is based on the breeding system of Dendrobium.Field observations and experiments were conducted on the natural populations of Dendrobium wangliangii,and the morphology and flowering phenology of Dendrobium wangliangii were described.The breeding system of Dendrobium wangliangii was studied and the pollination mechanism of automatic self-pollination was clarified.The main results are as follows:(1)Field observations of flower morphology and flowering phenology of Dendrobium wangliangii were conducted.We found that the Dendrobium flowers were small and pink,and the two yellow patches are on the lips.The average number of flowers per single stem was 1.04±0.05,and the average number of single plants was 2.038±0.116.In early June of flowering period,about 15 days,the flowers in the population were completely open 42.26± 13.34%,and the average single flower life of the blooming flowers was 2.33± 0.15 d.The self-crossed and self-crossed pollination rate of the self-crossing pollination system of Dendrobium wangliangii was significantly higher than that of outcrossing pollination(10.98±1.75%).Self-pollination dominated the breeding system(P<0.05)..Bagging treatment can be robust(33.33±4.71%),and self-pollination phenomenon occurs in Dendrobium wangliangii.After detasseling treatment,there was no parthenogenesis phenomenon in Dendrobium wangliangii.The natural seed setting rate(53.37±9.54%)of the blooming flowers and the natural seed setting rate of the unopened flowers(53.37±9.54%)were not significantly different(P>0.05).(2)By anatoming the flowers of Dendrobium wangliangii,the self pollination mechanism of Dendrobium wangliangii was elucidated.During the propagation process of Dendrobium wangliangii,the pollen grains slide out of the cap and reach the stigma cavity under the action of gravity.The pollination process can be completed in the closed and full bloom state.This pollination mechanism is the result of the flower morphology and habitat adaptation of Dendrobium wangliangii,which can reduce the energy consumption in the reproductive process,ensure the success of pollination and ensure its own reproduction.(3)Through the observation of the interviewers,there is no effective pollinator pollinating the Dendrobium wangliangii during its inflorescence.The visiting insects only crawled on the outside of the flower.They did not enter the interior of the flower and touched the stigma or pollen.No pollinating animal visited the flower,and no pollen was entered or moved out.3.Symbiotic germination of Dendrobium wangliangiiIn this study,the seeds of Dendrobium wangliangii were collected and germinated,and the symbiotic fungi were isolated from the obtained protocorm,and the strains were sequenced and identified.The effective symbiotic fungi that could promote the germination of Dendrobium wangliangii were screened by the symbiotic germination of the seeds and fungi on the medium.The main results are as follows:(1)The protocorms of Dendrobium wangliangii were produced by symbiotic germination technology.11 pure colonies were successfully isolated from the protocorms cultured on PDA medium.Using molecular sequencing,9 isolates were identified as Fusarium,1 were Chaetomium and 1 were Alternaria.(2)Through the symbiotic germination of Dendrobium wangliangii seed and culture medium,4 strains of 11 strains which can effectively promote seed germination are Fusarium,indicating that the seed germination of Dendrobium wangliangii is specific to the symbiotic fungi.The germination rate of the four bacteria-infected treatments was up to 47.04±4.74%,which was significantly higher than that of the control group(P<0.05),indicating that Fusarium was an effective symbiotic fungus that promoted the germination of Dendrobium wangliangii.This paper studied the breeding system of 23 species of Dendrobium and the pollination biology and seed symbiosis germination of Dendrobium wangliangii,it provided theoretical and practical basis for the protection of Dendrobium wangliangii,and laid the necessary scientific basis for the future introduction,domestication and breeding of Dendrobium wangliangii.