Effects Of Light, Temperature And PH On Spore Germination And Early Gametophytic Development Of Four Species In Cyatheaceae

There are 12,000 species of ferns all over the world,and more than 2,600 species in China, covering one fifth of the whole species of the world.And there are 500-600 specific species in our country.Recently,due to the destroyed natural environment and unreasonable exploitation, some rare ferns are endangered.It is urgent to strengthen its correlative fundamental research, such as propagation and the effects of environment on ferns,which is very important to conservation and utilization of ferns.During in my three years of the research on ferns,we have made research on spore morphology by the means of scanning electron microscope(SEM) and gametophyte development.Based on these result,the effects of light,temperature and pH on spore germination and early gametophytic development of Cyatheaceae was implemented. The main results are showed as follows:(1) Spore morphology of 4 species of Cyatheaceae from China was examined by the means of scanning electron microscope.The spores are radially symmetrical and trilete.The spores are often triangular in polar view,and hemispheric or flabellate in equatorial view.The surface of Alsophila spinulosa spores is striate.In typeⅡ,the surface of spores is echinatestriate. Alsophila podophylla,Alsophila metteniana and Alsophila gigantea have this type of surface ornamentation of spores.(2)The spores were cultured in the inorganic medium,and the gametophyte development were observed and recorded under microscope.The spore germination and the formation of gametophyte in each development stage were recorded.The germination of the Cyatheaceae are the Cyathea-type and the gametophyte development are of the Ceratopteris-type. Morphological characteristics of filament stage of Alsophila podophylla,Alsophila metteniana and Alsophila gigantea is biserial protonema,Alsophila spinulosa is uniserial protonema.In addition,The spores of Alsophila podophylla,Alsophila metteniana and Alsophila gigantean germination times were 18 d,14 d and 11 d,respectively.Alsophila spinulosa spores germinated in one week.These results would be useful for the further studies of ferns propagation technology and the evolutionary process and taxonomy of ferns.(3) We determined the effects of light intensity and quality,temperature,and pH on spore germination rates and early gametophytic development of Alsophila spinulosa,Alsophila podophylla,Alsophila metteniana and Alsophila gigantean.The optimal light intensity for spore germination and early gametophytic development was 40-80μmol·m^-2·s^-1,while spore germination was completely prohibited in darkness.Light intensity was not a major but necessary factor for germination and development of Cyatheaceae spores.Light quality had no obvious influence on spore germination of Alsophila spinulosa and Alsophila podophylla,but it had obvious influence on Alsophila metteniana and Alsophila gigantean.The influence degree of light quality on spore germination of Cyatheaceae is red light>yellow light>blue light. When growing under white and blue light,gametophytes developed into normal cordateshaped prothallus.When growing under red and yellow light,however,gametophytes developed into uniseriate filaments consisting of mostly elongated cells.For spore germination and gametophytic development,the optimal temperature is from 20℃to 30℃,the suitable pH is from 3.7 to 6.7.