The Studies On Reproductive Biology Of Ceratoides Arborescens

Ceratoides arborescehs is a good kind of herbage and ecological conservation resource, and has an important role in improving grassland and treatmenting desertification in arid and semi-arid region. In this research, flower organization development, flowering phenology, pollen and stigma characteristics, pollination biology and seed development were studied. The main results as fellows:(1)The development of anther wall was elementary type. The tapetum belonged to glandular type. The cytokinesis of microspore mother cell was simuteneous, and most of the tetrad was tetrahedral, decussation also observed. Mature pollen grain was 2-cells. The embryo sac was Polygonum type. There was no abnormal phenomenon except empty pollen grains were observed at the stage of haploid nuclear microspore. The ratio of empty pollen was small, and was not main reason for embryo abortion and lower seed set rate.(2)The flowering phenology was stable in the middle of Inner Mongolian. The male flower onset was at the beginning of August, and flowering duration was 18～22d, and female was in the middle of August, duration was 15～18d. Flowering duration of single male and female flower was 4～5d. Both female and male inflorescence were single peak of curve. There is a significant negative correlation between the date of first flowering and duration of female and male inflorescence, and a significant active correlation between flowering numbers and duration. During long term evolution of Ceratoides arborescens had an adaptive stratege of female and male flowering time was not encounter, which reduce proportion of geitonogamy and improve seed set rate.(3)The highest pollen viability was 82.54%～94% in Hohhot, average pollen life was 6～7d, receptivity of stigma was 6～9d after stigma sprouted, the best pollination time was 6～7d after flowering, which had the biggest seed set rate. Reproductive ability of pollen and stigma was stronger, and had no reproductive barrier. Ceratoides arborescehs had no apomixe, the breeding system is mixed with self-compatible and outcrossing. In order to avoid geitonogamy, it took dichogamous and sexual dimorphism. In the advantage of having xenogamous, it took geitonogam simultaneous, which is significant for wild population restoration.(4)Pollination began at the beginning of August in the middle of Inner Mongolia. Pollination duration was 18～21d. Average pollen density was 8542 grain/m3·d, had obvious characteristics of anemophilous. It has a sharp single apex in pollination period. Pollen density had a significant active correlation with wind speed and temperature, a significant negative correlation with relative humidity. Pollination was explosive, which can avoid bad environment.The pollination efficiency was high. The experiment of pollen germination and pollen tube growth showed: the pollen tube of xenogamous grew faster than geitonogamy. Both pollen germination rate was higher, and most pollen tube can grow to upper of ovary.(5)The embryo development was Chenopodiad type. The style of endosperm development was nuclear type. We observed abnormal development phenomenon in later globular embryo, they did not undergo normal divisions, which was one of the reason of embryo abortion. The nutrient transportation was associated with the persistent synergid. The nutrient that needed for embryo development had been supplied mainly by endosberm since the embryo differentiation period. The nutrient of endosperm mainly came from amylase of funicle, and partly come from synergids. Moisture of seed was 39.89% after 40d since flowering, and was stability. Nutritent accumulation tended to stabilize after 36d since flowering, It was suitable for harvest after 36d since flowering, because it can decrease loss. It had 30d dormancy after seed maturation. Germination after 35d since harvest showed: There were a few of seeds germinate in 2h of 3 years old plant, The whole seeds germination completed in 14h.(6)The seed set rate and 1000 seeds weight of 4 years old plant were higher than 8 years old plant. Seed set rate was related to the time of flower differentiation and the floret sites. Flowering earlier produced larger seeds than those flowering later, and basal flower produced larger seeds than the middle and distal. Flower of early flowering and lower layer produced lower seed set rate by the reason of pollen restriction. The flower-fruit transformation was lower, and existed selective abortion. Seed set existed resource and pollen restriction in cultivated population. The seed set rate and 1000 seed weight obviously increased through advisable trimming branches, decreasing the density and supplied fertilizer, which can control plant theirself resource and suppling resource. It was unsuitable to spray micro-fertilizer for seed storage, supply Nitrogen and Potassium feitilizer was suitable for seed storage.