Pollination Biology Sichuan Peony

Paeonia decomposita is one of the China’s second level endangered species, and medicinal plants and potential ornamental plants. In order to reveal the pollination biology characteristic, mating system and pollinators of Paeonia decomposita,and to verify the feasibility of OCI index and P/O index, the author selected three populations of Paeonia decomposita and studied the pollination biology systematically in Jiaomuzu village, Barkam County, Aba Tibetan and Qiang Autonomous Prefecture,Sichuan province. The main results and conclusions are as follows.1. Biological characteristics of Paeonia decomposita(1) Floral characteristics:Torus is bowl shaped and there’s a projection in the middle; There are3-5Bracts which are green, lanceolate, foliate or dendritic of each flower. Sepals are green, aposepalous. Of each flower there are3-5sepals whose shape may be Oval or spatulate, and apex is sharp; Corolla is radial; aestivation is imbricate; Diameter of flower range from67-188mm; Longth of petal range from41-87mm and its width range from34-57mm; The number of petals of each flower range from8-12, and the color is white, pale purple or dark red; Normally from opening to die, the flower grows bigger and the color of petals becomes lighter; Stamens are polyadelphous stamens, ranging from128-203a flower. Filaments are all white; anthers are yellow. From the flower’s opening to withering, filament grows, anther twists and becomes shorter. Longth of filaments range from6.9-9.8mm and longth of anthers range from4.4-7.7mm; Anther is longitudinal dehiscence; Apocarpous pistil, carpels range from2-6, glabrous; In early days after opening of flower, the color of carpels are yellow, kelly or green which will change over time. The stigma is beige with a bent head which is like a flat hook; Marginal placentation, superior ovary; The flowers have no nectaries but a strong smell which will change over time. A single flower’s florescence is between6-13d. Florescence of populations is from April9th-June4th.(2) Pollen viability test of a single flower:pollen viability of a flower on the tree increases to the peak firstly, then decreases from opening to withering. Pollen viability of flower picked and inserted in the water is irregular. The regulation of pollen viability of a single stamen is similar to those flowers on the tree. A flower begins to spread pollen1-2d after opening and the viability of pollen reaches the peak in the3th day or4th day after opening.(3) Stigma receptivity:stigma receptivity begins2-3d after the flower opening, and exist till11d after flower opening. Receptivity will reach the peak in6-8d. Mucus from stigma exist from3or4d to9d.2. Mating system of Paeonia decomposita. According to the results of controlled pollination experiment, Paeonia decomposita has very strong outcrossing ability (21.49%seed-setting rate), relatively weaker selfing ability (7.13%seed-setting rate) and extremely weak ability of apomixis (0.06%seed-setting rate). The mating system of Paeonia decomposita is mixed mating system. Because ISI(Index of Self-Incompativity)=0.9, Paeonia decomposita’s mating system is partially self-compatible. In summary, Paeonia decomposita is mixed mating system, outcrossing more than selfing and partially self-compatible. This result is supported by OCI(Out-Crossing Index) index. The OCI index of Paeonia decomposita is4. According to the OCI index criteria, the mating system should be outcrossing, partially self-compatible. While the P/O(Pollen/Ovule) index test results cannot be used to determine mating system, because the values are much more greater than the greatest value which Cruden summaried.3. Pollinators of Paeonia decomposita. Controlled pollination test proved that the results of artificial pollination is most elose-to the results of the natural ones.They show that Paeonia decomposita needs pollinator. While it is not wind. Birds, bats and other creatures were not found in observation except insects and spiders. So the pollinators can only be insects or spiders. Through observation,the author found that spiders treat flowers as their hunting places, and their behaviors can hardly result in pollination. But insects have many chances to touch the pollen and stigma which makes it possible for pollination.The observation results show that there were16species visiting the flowers of Paeonia decomposita, belonging to6orders.Apis cerana abanisis is the most effective species. Oxycetonia jucunda Faldermann and flea beetle are two species mostly observated.