Studies On Blossom Biology Of Chimonobambusa Sichuanensis

Chimonobambusa sichuanensis offen blooms sporadically in bamboo garden of Nanjing Forestry University in recent years, which provided a good opportunity for study. There are important theoretical and practical significances on carrying out of the research on blossom biology of Ch. sichuanensis and further discussing the bamboo flowering mechanism.Blossom biological properties, spikelet and flower structure, pollen morphology and pollen viability, macrosporogenisis, microsporogenisis, development of female and male gametophyte, and physiological changes in blooming period were studied systematically by using morphological anatomy, scanning electron microscopic, paraffin section and physiological methods in this paper. The results were as followed:Ch. sichuanensis has terminal inflorescence which basal unit is spikelet. Each floret included a lemma, a pelea, three lodicules, three stamens and a pistil, and the pistil had ovary, stigma and short style. Seed setting ratio was only 1.39%. Ch. sichuanensis was a monochogamy species, but adopted cross pollination mostly.Pollen grains were spheroidal or subspheroidal. Pollen abortion rate was over 50%. And pollen was not tolerant to storage.Anther walls were consisted of four layers of epidermis, endothecium, one middle layer and tapetum. The tapetum was of typical glandular type. The anther walls development followed the Monocotyledonous type. The cytokinesis in the microsporocyte meiosis was of the successive type, and microspore tetrads were arranged bilaterally. Mature pollen grains were mostly two-celled, rarely three-celled.The ovary was bicarpellary syncarpous and unilocular. Single ovule was anatropous, tenuinucellatae and biteginous. The megasporocyte underwent meiotic division to form four megaspores arranged in a line, and the micropylar megaspore was the functional one. The formation of the embryo was of Polygonum type. The embryo had many antipodal cells.During blooming period, contents of Chlorophyll and soluble sugar decreased; activities of SOD, contents of soluble protein and free proline increased initially and then decreased; activities of POD and MDA content increased. Ch. sichuanensis senescence was accelerated by flowering, and flowering bamboos senesced more than no flowering bamboos.