Studies On The Reproduction Of Dendroncalamus Sinicus

With the development of reproductive biology, the research in process of germanous plants, such as: corn, rice and wheat is increasing rapidly. But the study on sexual reproduction of bamboo is very slowly, because that the flowering of bamboo is very rare and experimental material is scarce .Dendrocalamus sinicus Chia et JL Sun is Large-scale tropical caespitose bamboo. Dendrocalamus sinicus is belong to Gramineae, Bambusoideae, Dendrocalamus. Due to largest-size culm and growing quickly, it is precious and economical bamboo. There are very important economic value and broad using in it. However, it is very difficulty in promotion of this excellent bamboo species, because this type only grow in the local region of Yunnan, cold intolerance, and fewer flowers, flowering cycle is continued very long period, usually to death after flowering, sexual reproduction is limited, natural setting rate is low, their natural regeneration is rare. Recently, in Yunnan Ximeng and Cangyuan, there are scattered flowering, seed setting Dendrocalamus sinicus, providing opportunities to research work in it sexual reproduction .This study focuses on the flowering behaviors, generative organs structures, and pollen vitality of fruit characteristic and anatomical structure of Dendrocalamus sinicus .At the same time, it is trying to establish the ovary culture method in vitro. The research accumulates primitive information to comprehensive understanding of sexual reproduction and ontogeny of bamboo, meanwhile, it establishes foundation for cell culture, cell protoplasts isolated and hybrid, genetic transformation and so on. The Dendrocalamus sinicus could be fully protected and utilized.The mostly results are as follows:(1) The inflorescence of the Dendrocalamus sinicus is continued occurrence false inflorescence, numerous flowers on the main stem, called leafless flowering bamboo, There are no leaves or less leaves on base of the spikes. The spikes are primary flower, gradually shaping and flowering. The floret is achyrophytum. The stamen out of spikelet is the signs of flowering a flower opening up features. Development of florets in one spike is not in same speed, the florets in the base shape and open after that in the peak. (2)There were 2～4 sterile glumes at the base of the Dendrocalamus sinicus spikelet, differented from 2 sterile glumes reported before. Lemma which is unclosed ellipse, has 13～17 vascular bundles in the transverse section. Palea which is composed of quadrate cell is on the inside of Lemma.(3)The mature pollen of Dendrocalamus sinicus is nearly spherical with a single germinal aperture ,which is globose under microscope. Pollination is in 3 - cell period including a vegetative nucleus and the two sperm cells. Germination rate of fresh pollen is as high as 75%. But it is to decline rapidly with in vitro time extension. After 30 minutes in vitro, the pollen germination rate down to 3%. After 60 minutes of in vitro capacity of the pollen germination completely lost. Experimental results showed that life of Dendrocalamus sinicus pollen is very short. The pollen life would be even shorter, under natural conditions, because sunlight, moisture and temperature factors are uncertain.(4)Integrate embryo sac which surround with some antipodal cells is separated by using enzyme disassemble method. A large number of relatively large antipodal cells could be observed surround with the embryo sac. Antipodal cells are pellet under the microscope, their cytoplasm are denseness. They exist in the embryo sac relatively long period, until the formation of embryonic, a small number of antipodal cells could be observed.(5)Dendrocalamus sinicus'fruit is grain ,stigma preserving. Endosperm surrounded with aleurone layer, contained a great deal of starch granules, occupies vast majority of the fruit. Embryo is at beside of the endosperm, and joining endosperm. Embryonic-type formula is F + PP type, which is the vascular bundle detached at the same branch point, then enter into scutum and embryonic bud; there is epiblast in embryo; scutum is separate from coleorhiza; there are some vascular bundles in wraped euphylis. Embryo of Dendrocalamus sinicus is great horn embryonic bud, great horn radical and adorsal.(6)The reason for the Dendrocalamus sinicus low seeding rate is mainly in the following three aspects. Dendrocalamus sinicus is cross-pollination and flowering cycle length, scattered flowering in the wild , different cluster are rarely flowering at same time, so normal fertilization is very limited, resulting in low seeding rate②Dendrocalamus sinicus'pollen life is very short, test results showed that pollen germination rate in 30 minutes from 75 % reduced to 3 per cent, after 60 minutes the germination ability complete loosed.③Pest is serious in flowering period. 45% of the spikelets are damaged by pest, anther and ovary lost their vitality.