Study On The Reproductive Biology Of Camellia Chekiangoleosa

Camellia chekiangoleosa Hu. is an endemic species in China. It has high values in ornamental and economic, but resource damage is very serious. It was listed as a rare and endangered plants. The paper studied the Biological Features of Flowering, Flower bud differentiation, Male gametophyte development and Seed biological characteristics of Camellia chekiangoleosa Hu. It has the practical significance to reveal the reproductive biology and develop the breeding work in future. The main results are follows:(1) Biological Features of Flowering: Camellia chekiangoleosa Hu. has the long flowering period,group plant flowering about in the last third of February to the last third of March, early flowering stage to flowers terminal can last about 26 days, single plant flowering can last about 24 days, blossom period can last about 7days. The trees growing need more sunshine, in the top of the canopy where has enough sunshine and in sunny areas, the buds were more plump, with a large number of flower, flowering long time and have a high frute-setting rate. But where the light is not sufficient, the buds were little and less, flowering time is short and low seed. The present phenomenon showed that it was the intolerant tree species, suitable for sunny environment..The stigma had the receptivity in the day before blooming. The receptivity of stigma was last about 7 days.(2) Floral morphology: The flower color of Camellia chekiangoleosa Hu. is dark red, flower diameter is 8-12 cm, no handle, small horn shape, bracts persistent, bracts 5-9 pieces and with silver-gray hair, arrangement for imbricate, petals 5-7 pieces, base together, the top of the petal have tow light columns; The number of stamens is 200-340, more of them arranged in two round, and the outer filaments basally connate, accreted with the petals, inner filaments free; yellow anthers, anther and filament was “T” shaped, two-compartment longitudinal; Three ovary chambers without hair, style single, linear, the top of the stigma have 3-5 crack. In the investigation of flower organs found that the development of some stamens were not synchronized,but without stamens rudimentary phenomenon.(3) Pollen viability: Methods of culture in vitro is the most effective to the determination of pollen viability. The best combination for pollen germination is 150g/L sucrose with 0.1g/L H3Bo3 in which the rate of germination was 88.36%. Ultra-low temperature is not suitable for the pollens of Camellia chekiangoleosa Hu..The pollens of Camellia chekiangoleosa Hu. sealed under the 4℃ low temperature was benefical to maintain the pollen vitality.(4) Flower bud differentiation: The flower bud differentiation of Camellia chekiangoleosa Hu. starts from early late July to the late February in the second year. Included pro-differentiation stage, speals formation stage, petals formation stage, stamens and stamens formation stage, ovary and anther formation stage, pistil and stamen mature stage. But every differentiation stage overlapped each other to a certain degree. Flower bud development were not concentrated in a short period, but in batches and with a large time span.(5) Male gametophyte development: Anthers are 4-sporangiate, the wall of anther consists of tapetum, middle layers, endothecium and epidermins from inside to out. The development of anthers are classified as basic and the tapetum cell is glandular type. The wall of anther develop into a thickening. Cytokinesis is simultaneous. Microspore tetrads arrange for tetrahedral. Mature pollen grain was 2-cell type with three germ pores. Throughout the process of gametophyte development, there are no significant anomalies developmental.(6) Seed biological characteristics: The seed have dark brown skin and cutin hard, smooth, have hilum, the seed length-18.57, width-15.83, thickness-11.71 mm, 1000-weight-1177 g. The seed water absorption ability tested by 3different treatments showd that the seed without exopleura had the best water absorption ability. The viability of seed testd by the TTC staining metnod showed that the viability of seeds was 85%. The germination characteristic test with different seed soaking temperature in 24 hours showed that the seeds soaked in the 25℃ water is beneficial to germination, germination rate is 73%.