Immature zygotic embryos of Quercus variabilis were as explants to induce somatic embryogenesis. Several factors influencing somatic embryogenesis have been assayed. Somatic embryos can be induced in MS and WPM basal ...Immature zygotic embryos of Quercus variabilis were as explants to induce somatic embryogenesis. Several factors influencing somatic embryogenesis have been assayed. Somatic embryos can be induced in MS and WPM basal medium, but there was more quantity, big size and high induction rate in MS medium. Induction rate was not significant cultured in light and dark condition. Zygotic embryos, collected in middle of July, gave higher rate of somatic embryogenesis than those collected on the earlier or later date. By adding 6-BA in medium individually, somatic embryogenesis appeared directly on the zygotic embryos without detectable callus. Secondary embryogenesis appeared in medium with 2,4-D individual or combined with 6-BA or TDZ. High induction frequency of 90% was achieved in MS medium supplemented with 0.5 mg·L -1 6-BA and 2,4-D, whereas the rate in hormone-free medium was only 16.7%. The genotypes of mother trees had an great impact on the inducing rate. Zygotic embryo surgery treatments were not favorable to embryogenesis. It was best to inoculate with entire zygotic embryos. The hypocotyl was a crucial part on somatic embryogenesis for Q. variabilis.展开更多
This paper discusses the mechanism of structure characteristics and dynamics for spruce forest in Qinling Mountains through the investigation and comparison of Chinese spruce( Picea asperata ) forests at different sta...This paper discusses the mechanism of structure characteristics and dynamics for spruce forest in Qinling Mountains through the investigation and comparison of Chinese spruce( Picea asperata ) forests at different stages.The result shows that there is a large amount of seed sources and a little number of saplings at age below 20 years,but only this species is the dominant regeneration tree species in mature forest of Picea asperata. In the regeneration forest under selection cutting system,the height growth of poplar and birch is very fast during first 30 years,and dominates rapidly over the canopy. Picea asperata shows a lower growth rate and most tolerant tree species in first growth stage so that it will replace gradually all the other trees.After clear cutting,poplar and birch often occur dominant,only a small number of saplings are Picea asperata in the regeneration forest.In nature conditions,it will take a long time to recover the Chinese spruce forests.The amount of saplings and seedlings in the spruce forest is a key factor in the maintain of the steady state of the spruce forest.This dynamics process can be controlled and improved by human activity.展开更多
文摘Immature zygotic embryos of Quercus variabilis were as explants to induce somatic embryogenesis. Several factors influencing somatic embryogenesis have been assayed. Somatic embryos can be induced in MS and WPM basal medium, but there was more quantity, big size and high induction rate in MS medium. Induction rate was not significant cultured in light and dark condition. Zygotic embryos, collected in middle of July, gave higher rate of somatic embryogenesis than those collected on the earlier or later date. By adding 6-BA in medium individually, somatic embryogenesis appeared directly on the zygotic embryos without detectable callus. Secondary embryogenesis appeared in medium with 2,4-D individual or combined with 6-BA or TDZ. High induction frequency of 90% was achieved in MS medium supplemented with 0.5 mg·L -1 6-BA and 2,4-D, whereas the rate in hormone-free medium was only 16.7%. The genotypes of mother trees had an great impact on the inducing rate. Zygotic embryo surgery treatments were not favorable to embryogenesis. It was best to inoculate with entire zygotic embryos. The hypocotyl was a crucial part on somatic embryogenesis for Q. variabilis.
文摘This paper discusses the mechanism of structure characteristics and dynamics for spruce forest in Qinling Mountains through the investigation and comparison of Chinese spruce( Picea asperata ) forests at different stages.The result shows that there is a large amount of seed sources and a little number of saplings at age below 20 years,but only this species is the dominant regeneration tree species in mature forest of Picea asperata. In the regeneration forest under selection cutting system,the height growth of poplar and birch is very fast during first 30 years,and dominates rapidly over the canopy. Picea asperata shows a lower growth rate and most tolerant tree species in first growth stage so that it will replace gradually all the other trees.After clear cutting,poplar and birch often occur dominant,only a small number of saplings are Picea asperata in the regeneration forest.In nature conditions,it will take a long time to recover the Chinese spruce forests.The amount of saplings and seedlings in the spruce forest is a key factor in the maintain of the steady state of the spruce forest.This dynamics process can be controlled and improved by human activity.
