The Reproductive Biology Of Tulipa Sinkiangensis

Tulipa sinkiangensis is a perennial early spring ephemeral of Tulipa L. in Liliaceae and is an endemic species in the northern piedmont of the Tianshan Mountains, Xinjiang. In southern Junggar Basan, this species is one of the spring grass species that has a high feeding value. It is also an important spring field flower which possess a high breeding value, because it owns a particular phenomenon of multiple flowers which is an important genetic material for breeding new species of Tulipa with multiple flowers. In this paper, we studied the relationship between reproductive characteristics and resources allocation, and the charateristics of mating system. And we discussed the relationship between these characteristics and the desert environment. The main results of this study are as follows:(1)This species could produce 1-8 flowers per individual in natural population, and the plants proportion to the population was significantly decreased as the numbers of flowers on the individual increased, with the ratio of plants with 1-5 flowers was higher than 1% in the population.(2) Numbers and biomass of flowers, numbers and biomass of fruits were positively correlated to plant size. Allocation to reproductive organs was highly dependent of plant size. During the flowering period and the phase of fruit maturity, there was a trade-off of resource allocation between nutrient organs and reproductive organs. There was a negative position-dependent effect of resource allocation to flowers or fruits within inflorescence or infructescence. There was a significant competition for resources among flowers or fruits in different positions of the same inflorescence or infructescence. Besides, the number of flowers or fruits in the same inflorescence or infructescence was the main factor which affected on competition for resources. Resource allocation to flowers and fruits decreased as their positions in inflorescences or infructescences decreased, which was relative to the time of differentiation of reproductive organs within inflorescence..(3) Flowering period of the population was 15-17d, and its flowering pattern was massflowering pattern at the population level. What's more, flowers could open and close temporarily according to the variations of temperature and humidity. There were a significant differences in longevity of flowers during the different flowering periods of the population and in the flowering duration on different days of flowering period of simple flower. In addition, processes of anther dehiscence and pollen presentation were gradual presentation.(4) There were significant differences between lengths and between pollen numbers of the tow wheel stamens (P<0.05), so it was heterostemony. During the flowering period, the locations of pistils and stamens were stable, and stamens were longer than pistils, and this species was reverse herkogamy and incomplete protandry, so it could not avoid selfing completely.(5) Flowers had thick nectar and excreted little scent, and the amount of scent from flowers was significantly different during male phase and female phase(P<0.05); This species had a generalist pollination system; The effective pollinators of this were Apis mellifera and Pieris rapae, with their visiting frequences were 0.66±0.20 and 1.25±0.40·flower^-1·h^-1, respectively. There were significant differences between visiting numbers and visiting duration on simple flower the visitors (P<0.01).(6) Self-compatibility coefficients and self-fertilization rate of this species were 0.64⁰.82 and (5.16⁶6.62)% respectively, so the species owned high self-compatibility. Flowers could produce fruits after self-pollination and cross-pollination; thus, the mating system of this species was mixed mating system; This species exhibited pollen limitation(7.84¹8.55)% and pollinator limitation(9.90³9.91)%, which were occurred in the early spring ephemerals.