Study On The Reproductive Characteristics Of Cave Plant Primulina Hunanensis

Primulina hunanensis is a high-value ornamental plant,which living in caves.In order to develop and utilize the wild germplasm resources of P.hunanensis,the role of the floral syndrome,breeding system,and associated plants on its growth and reproduction process was evaluated.The flowering phenology,floral features,flower-visiting insects,and main associated plant species of P.hunanensis were recorded by field observation.We combined with artificial pollination experiment to test its breeding system.Besides,a leaf-cutting experiment was conducted to provide the data of the asexual propagation techniques of P.hunanensis.The main results are as follows:1.Studies on the floral syndrome and breeding system of P.hunanensisThe length of the flowering span of P.hunanensis was about 40 days(from May to July,a single flowering cycle was about 3 to 8 days).When the flowers of P.hunanensis are just open,its pollen vigor is the most energetic(> 90%)in the flowering span and the stigma is inactive at this time,but the growth of its stamens are almost stopped and its pistil continues to elongate after flowering,indicates that both dichogamy and herkogamy have occurred in this species.The ratio of pollen and ovule(518.36)and the hybridization index(5)indicated the breeding system of P.hunanensis was outcrossing,partial self-compatibility,and demanded pollinators.The seed setting rate of P.hunanensis is 0 in the bagged and emasculation experiment,and there was no apomixis.Many kinds of flower-visiting insects were surveyed in the P.hunanensis population.During the flowering span of P.hunanensis,Bombus sp.was the most effective pollinator,which is adapted to its floral syndrome.2.Study on the leaf-cutting propagation technology of P.hunanensisIn the leaf-cutting tests,the rate of survival,the time of occurrence of adventitious roots and adventitious shoots,and the number of seedlings of P.hunanensis were affected by either cutting methods,IBA concentrations,or substrate types.In the leaf-cutting methods test,whole leaf-cutting of P.hunanensis had the highest survival rate,the shortest time required to produce adventitious buds,and the first half leaf-cutting of P.hunanensis had the largest number of seedlings.In the IBA-treated tests,leaves of P.hunanensis at a concentration of 200 mg/L IBA had the shortest time to produce the adventitious roots and adventitious buds,and the highest rate of survival and number of seedlings.In the substate tests,leaf-cutting of P.hunanensis growing in the substrate is peat mixed perlite(Volume: Volume = 1:1)had the shortest time to produce adventitious buds,the highest survival rate,and the largest number of seedlings.3.Investigation of the main associated vascular plants of P.hunanensisP.hunanensis prefers a warm,moist,well-ventilated,and scattered light environment with no stagnant water and high canopy density.It grows mostly on limestone rocks,avoiding competing directly with other species for living space.There are 74 species of associated vascular plants of P.hunanensis in 71 genera and 47 families,including 11 species in 10 genera and 8 families of Ferns,and 63 species in 61 genera and 39 families of Seed Plants.Most of the associated plants of P.hunnanensis are herbaceous plants,and most of them are tolerant to damp and shade environments.Woody plants form dense forests,which avoid direct sunlight to P.hunanensis and provides suitable habitats for them.Karst caves or other associated plants can provide a relatively shaded environment for P.hunanensis.It is very important to protect the karst habitats and its surrounding associated plants for the survival and reproduction of P.hunanensis.