Pollination Biology Of Dendrobium Fimbriatum And Coelogyne Viscose (Orchidaceae)

Plant pollination is affected by population habitats, which is possibly a key factor leading some species to being endangered. Studies on the pollination biology of orchids could provide insights into their conservation due to their unique pollination mechanisms. Focusing on the pollination biology of two orchid species, Dendrobium fimbriatum and Coelogyne viscose, the article is aimed to probe into scientific conservation and management strategies for the two orchid.1. Pollination biology of Dendrobium fimbriatumThe field observation and experiments were investigated in Lvshilin Forest Park, Menglun, Xishuangbanna and artificial pollination, seed viability and germination tests were carried out to D. fimbriatum introduced from Yinchang (a natural forest near Menglun Town) at Xishuangbanna Tropical Botanical Garden (XTBG). The results indicated that D. fimbriatum had no spontaneous autogamy and its'pollination success was dependent on pollinators. Pollinators were scarce in Lvshilin Forest Park and there was no fruit observed under natural conditions or even by hand pollination. The experiments done at XTBG showed that the fruit set, percentage of viable seeds and seed germination following cross-pollination between populations were significantly higher than following self-pollination, and furtherly, the percent viable seeds of crossing between populations was higher than within population. Partially self-incompatible and inbreeding depression were thus observed.2. Pollination biology of Coelogyne viscoseField experiments were conducted in Lvshilin Forest Park during two consecutive years. The results showed that C. viscose was partially self-incompatible and need pollen vector for its reproduction. The rewardless flowers may attract visitors by the color of labellum and olfactory stimulus. Apis cerana cerana was the only pollinator. Morphological analysis both on the C. viscose and honeybees showed that the morphological features of C. viscose matched well with the behaviors of honeybees on the flower, which resulted in high effectiveness of pollination. The honeybees visited mainly during the early and peak flowering periods. Pollinators may bring self-pollination to the orchid because of visiting flowers continuously. Partially self-incompatibility, pollinators'visiting behavior and pollination frequency are the main factors influence the fruit set of C. viscose.3. Reproduction success of C. viscose in different habitatsWe studied pollinia removal, pollinia receipt and fruit set of C. viscose in three populations, a habitat well-preserved at Lvshilin and other two isolated, fragmented at Yinchang and Gongbinxincun. The results showed that Gongbinxincun, the most seriously fragmented population, occured the highest pollinia removal and receipt rate because a Apis cerana cerana population nested in the site. It seems that pollination frequency is not directly correlated with landscape fragmentation, but mainly correlated with the distribution and characteristics of pollintors. However, the fruit set production of C. viscose in fragmented habitats was significantly lower by comparison. Lower fruit/pollen receipt ratio of isolated populations indicated pollen source was more important for fruit set pollen quantity.4. Suggestion on conservationD. fimbriatum:based on the above results, we suggest:(1) activating a wide range of in-situ conservation area which may cover diversity distributed populations, (2) recruiting more individuals to natural populations are necessary to improve the population survival ability, (3) seting up an introduction base if necessary and building up breeding and propagation projects to prepare seedlings and adult plants for reintroduction.At presnt, C. viscose does not need much intervention. However, concerns should be given to the dynamics of populations in fragmented habitats and the living status of its pollinator (Apis cerana cerana).