Reproductive Allocation Of Dimorphic Cleistogamous Plant Viola Tuberifera And Its Response To Environments

Mixed-mating systems of alpine plants have interested by amounts of scholars. Researches on reproductive allocation is significant to expression of alpine plants' mixed-mating system, reflecting plants choosing and trading-off mixed reproductive strategies. The study chose dimorphic cleistogamous plant Viola tuberifera endemic to Qinghai-Tibetan plateau as material, probing into trade-offs exist in resource allocations among different reproductive strategies in life history under inner and outside elements(individual sizes?seasons?altitudes?habitats), in order to providing experimental evidence for reproductive adaptation and selective evolution of mixed mating system in alpine environment. The results showed that:(1)Viola tuberifera generally passes bloom of chasmogamous flowers ?tranversion from chasmogamous flowers to cleistogamous flowers?formation of aerial cleistogamous flowers?bloom of cleistogamous flowers?bloom of bulbs five periods.are changing with life history. During bloom of chasmogamous flowers, plants via chasmogamous flowers reproducing offsprings,cleistogamous flowers not formed or begin to develop. During tranversion from chasmogamous flowers to cleistogamous flowers and formation of aerial cleistogamous flowers,chasmogamous flowers set fruits,cleistogamous flowers increasing gradualy. During blossom of cleistogamous flowers,cleistogamous flowers achieve to the maximum and parts fructification, new bulbs begin to develop. During bloom of bulbs, several chasmogamous flowers formed,cleistogamous flowers come to fructification,large amount of new bulbs produced,securing through winter. In bloom of chasmogamous flowers, invest on chasmogamous flowers is far higher than subterranean cleistogamous flowers. Trade-off exists between chasmogamous and subterranean cleistogamous flowers,via chasmogamous flowers as major strategy,assisted with subterranean cleistogamous flowers to securing reproduction together. During bloom of cleistogamous flowers,investments of total sexual reproduction are higher than the asexual. In sexual reproduction,invest on aerial cleistogamous flowers is slightly higher than the subterranean. Plants trade-off sexual and asexual reproduction?aerial and subterranean cleistogamous flowers,via cleistogamous flowers as major strategy,assisted with bulbs,securing continuation of plants together.(2)With increase of altitudes: total biomass?reproductive investments show falling trend. In bloom of chasmogamous flowers,total biomass changes violently among altitudes. In which investments of sexual chasmogamous flowers is higher than subterranean cleistogamous flowers,chasmogamous flowers account for total reproduction is increasing with altitudes. In low altitude region,plants choose chasmogamous and subterranean cleistogamous flowers sexual reproduction,whereas in high eleviation district,choosing chasmogamous flowers reproducing offsprings. That is to say, trade-off exists between chasmogamous and subterranean cleistogamous flowers. In bloom of cleistogamous flowers, total biomass changes slightly among altitudes. In which investments of asexual reproduction is lower than the sexual,asexual reproduction account for total reproduction is rising with altitudes. In sexual reproduction,invest on subterranean cleistogamous flowers is slightly higher than the aerial,and subterranean cleistogamous flowers account for sexual reproduction is increasing with eleviations. In low altitude region,plants choose aerial and subterranean cleistogamous flowers as major strategies,while in high eleviation district,via subterranean cleistogamous flowers sexual reproduction and bulbs asexual reproduction producing offsprings. That is to say,trade-offs exist in sexual and asexual reproduction?aerial and subterranean cleistogamous flowers.(3)Under different habitats,total biomass?reproductive allocations basically achieve to maximum in the degraded mound habitat, minimum in Kobresia meadow. While in full-blossom of cleistogamous flowers, reproductive allocation of aerial subterranean flowers is highest in Potentilla fruticosa shrub habitat. In bloom of chasmogamous flowers,total biomass changes acutely among habitats. In which invest on sexual chasmogamous flowers is higher than subterranean cleistogamous flowers. Under different habitats,plants trade-off resources on sexual reproduction,via chasmogamous flowers as major sexual reproductive strategy,assisted with subterranean cleistogamous flowers securing reproduction. In blossom of cleistogamous flowers,total biomass changes slightly among habitats. In which invest on sexual reproduction is higher than the asexual. In sexual reproduction, aerial cleistogamous flowers is slightly lower than the subterranean. Under different habitats,plants via trade-off sexual and asexual reproduction?aerial and subterranean cleistogamous flowers, choosing cleistogamous flowers cleistogamy as major reproductive strategy,assisted with bulbs producing offsprings.(4)In bloom of chasmogamous flowers, reproductive allocations of chasmogamous and subterranean cleistogamous flowers are controlled by individual size,and trade-off exists in chasmogamous and subterranean cleistogamous flowers,plants choose chasmogamous flowers as major reproductive strategy; in cleistogamous flowers bloom period, reproductive allocations of sexual subterranean cleistogamous flowers and asexual bulbs are also size-dependent,and trade-off exists between subterranean cleistogamous flowers and bulbs,plants choose subterranean cleistogamous flowers as major sexual reproductive strategy.To sum up, dimorphic clesitogamy plant---Viola tuberifera endemic to Qinghai-Tibetan plateau, by trading-off different reproductive strategies(vegetation and reproduction?sexual and asexual reproduction?chasmogamous and cleistogamous flowers reproduction?aerial and subterranean cleistogamous flowers reproduction) and changing proportions of reproductive allocations(growth period, altitudes, habitats and individual size), selecting the most appropriate reproductive strategy in response to the changes of time, space and resources condition, ensuring existence and continuation in the harsh and changeful high altitude environment, providing siginificant reproductive assurance.