A Study On Resource Allocation Of Adenophora Jasionifolia And Reproductive Ecology Of Three Adenophora Species

Resource allocation often varies among flowers. Is the variation relative to flowering order or floral position? In most plants the flowering order within inflorescences proceeds acropetally with the resource allocation declining. We cannot distinguish between the temporal and spatial factors in that the basal flowers are both temporally and spatially superior. There are two proximate hypotheses for the variation in allocation among flowers, namely resource competition and architectural effect. The former and latter attribute the variation to competing for resource among flowers and architecture respectively. Manipulation in the previous studies was usually conducted at only one stage of floral ontogeny. Moreover, the traditional definitions of resource competition and architectural effect highlight the difference of them so that the link between them has been overlooked. Mating environment hypothesis has been proposed for the inter-flower variation in floral sex allocation. The hypothesis attributes the variation to factors changing mating environment experienced by flowers, including dichogamy, directional movement of pollinators and temporally varying floral display size.In Shangri-la, Yunnan Province, we studied the problems raised above with a herb of Campanulaceae. Our results demonstrated that resource allocation among flowers varies with flowering order rather than floral positions in Adenophora jasionifolia and protandry results in it. Floral sex allocation (flower size, pollen and ovule production) cannot be changed by either of temporally different thinning manipulations but seed set can indeed be changed by early-thinning manipulation, in contrast to the result of late-thinning manipulation. When inflorescences suffer resource scarcity, architectural effect is replaced by resource competition with respective to seed production.Floral longevity is a key trait determining the reproductive success of plants. It is postulated that floral longevity was determined by the trad-off of pollination success and cost of keeping flowers. Theoretically, the longevity of flowers with more pollen and ovules should extend longer than the flowers with less to output and input pollen completely. Floral longevity is significantly correlated with floral sex allocation and floral longevity of female stage is not affected by pollination.The concept of pollination syndromes is being reevaluated and suspected with different arguments. Studies on sympatric related species will enhance understanding the role played by pollinators in flower evolution and reveal whether the floral traits reflect the selection of pollinators. We conducted quantitative study on the reproductive ecology of three sympatric Adenophora species, confirming that species with divergent floral syndromes show different attraction to visitors and they depend on different visitors in pollination. The three Adenophora species differ significantly in coloration, odour, morphology, anthesis, tempo of nectar secretion and concentration. Bumblebees favoured A. jasionifolia, honeybees favoured A. khasiana, and moths favoured A. capillaris subsp. leptosepala. Pollination of A. jasionifolia depends exclusively on bumblebees. Honeybees contribute most to pollination of A. khasiana while moths play a minor role. Moths contribute more to pollination of A. capillaris subsp. leptosepala than bees.