The Breeding System And Pollination Characteristics Of Gymnocarpos Przewalskii Maxim

In order to understand the sexual reproduction characteristics and explore the life history strategy of the species. Through field observation and control experiment on desert relict plant Gymnocarpos przewalskii flowering phenology, floral traits, breeding system and pollination characteristics were studied. The main results are as follows:The two populations of G. Przewalskii were flowering once in a year; At individual level, the flowering phenology of two populations were similar, the plant has the characteristics of high flowering synchrony and exhibiting a typical “mass flowering” pattern; The flowering duration of a single flower of two populations were not significant in different years, but the single flower of Wuqia population slightly longer than the Hami population; the number of seeds all increase along with the increasing number of flower of the two G. przewalskii populations, pearson correlation analysis showed that there is significant positive correlation between flower number and seed number, and while the synchrony indices had negative correlations with relative flowering intensity. The results showed that these differences of the two populations may be caused by its own genetic characteristics and environmental changes.The flowers of G. przewalskii are small, bisexual, this species has two floral morphs, red flowered and yellow-green flowered. It has 10 stamens and is divided into two rounds, the inner round of five stamens with anthers, the outer five stamens are aborted; anther cracking in batches, with successive shedding characteristics; there is a small amount of nectar and unpleasant smell during the flowering period, the stamens position higher than stamens or the stamens and pistil are of the same high in the flowering stage. The flower of G. przewalskii having floral characteristics to adapt insect and wind pollination and its breeding system is mainly outcrossing, partially self-compatible. Have temporary and permanent closure of its flowers, meteorological factors such as humidity, temperature, wind speed and precipitation have no effect on flower closure. Partial female first ripe, there is an overlap of 46 h between male and female functions; the pollen-ovule ratio(P/O) is 1371.67 ± 236.21, the outcrossing index(OCI) is 3; differences in pollen tube growth rates of different sources of pollination, geitonogamy and xenogamy pollen tube growth faster, self-pollinated pollen tube grew most slowly and part pollen tube stop growing when it reaches the ovary and it can not enters the ovule; there is no apomixis, the natural seed setting rate is low, the seed setting rate of hand cross pollination increased.G. przewalskii by wind and insects for pollination, wind-pollinated in line with the local main wind direction; Formicidae sp. 1, Syrphidae sp. 1, Calliphora vicina and Coccinella undecimpunctata Linnaeus were major pollinators; Syrphidae sp. 1with higher frequency and pollen carrying capacity, but its residence time is shorter; The visiting frequency of Calliphora vicina was slightly lower Syrphidae sp. 1; Formicidae sp. 1 was dominant in number and visitation frequency, but because of its small size, its pollen carrying amount less than Syrphidae sp. 1 and Calliphora vicina; Coccinella undecimpunctata Linnaeus stay for a long time, but because of its small number and less flower visiting activities, the carrying amount of pollen is lower than other three insects.