Study On Anaatomy And Technique Of Bark Regeneration After Skining Of P. Chinense Schneid. Var. Glabriusculum Schneid

P. chinense Schneid. Var. glabriusculum Schneid. in Yingjing county Sichuan province was used in this experiment. Through observing the healing rate and changing of trunk appearance after large-area skinning in succession in the fields, some technical measures to help to develop new bark were sought. Meanwhile, paraffin-cut section method was used for studying on callus formation, cork cambium and vascular cambium initiation. UV spectrophotometric method was used for analysing the berberine content in regenerated bark and original bark. On this basis, some physiological reactions were observed. The results were as follows:1. Technical factors that influenced bark regeneration of P. chinense Schneid. Var. glabriusculum Schneid. : Packing with plastic film or not after skinning and packing time influenced the healing of barked surface directly. Effect of skinning period and skinning intensity on the healing of barked surface was very small, but it influenced succedent growth of regenerated bark. In favor of initiation and growth of regenerated bark, the best technical measures of regenerated bark was: skinning period was from the last ten-day of May to the last ten-day of June; plastic film should be packed on the barked surface immediately after stem was to be girdled 1 meter long, and unpacking time had better be between 10 days and 15days after girdling.2. The trait of organize differentiation: During girdling most of vascular cambium cells were stripped from the stem. Then immature xylem cells and ray cells were composed of the barked surface, and vascular cambium cells in part portion were remained. Several days after girdling, the ray cells near the surface dilated and proliferated outward to form callus. Then other immature xylem cells rehabilitated the ability of cell division and took part in the formation of callus. About 15 days after girdling, a cork cambium developed near the surface of callus, then developed normal periderm rapidly. Approximately 20 days later, the immature xylem cells differentiated vascular cambium cells at the place where callus bound xylem. Two months later, the new cambium activity proceeded periclinally so as to establish a complete ring of cambium zone gradually. Subsequent differentiation of newly formed cambium followed the normal pattern ofvascular tissue development in the plant.3. The comparison of microstructure between regenerated bark and original bark: the original bark of 8-year-old P. chinense Schneid. Var. glabriusculum Schneid. consisted of peri derm, shrinked cortex, unfunctional phloem and functional phloem. There were many lumpy stone cells in cortex and unfunctional phloem. Many fasciculuses distributed in phloem. The microstructure of 2-year-old regenerated bark was basically similar to original bark: phellem was deeper, a lot of lumpy stone cells distributed in cortex and phloem, but phloem fasciculuses distributed incontinuously.4. The comparison of the berberine content in original bark and regenerated bark: The maximum of the berberine content in original bark was 7. 2052%. The berberine content of 1-year-old and 2-year-old regenerated bark was 7.4952% and 7. 7640%respectively, higher than that of original bark. As the material to produce the berberine, regenerated bark was better than original bark. As a kind of Chinese traditional medicine, regenerated bark was preliminarily feasible.5. Some reactions after girdling: The leaf grew yellow earlier, and the leaf-shed was earlier than those in the normal trees in the current year. The bud-burst was delayed in the next spring. But the change of leaf was not evident after the next autumn . Timber growth of girdled portion was greater than that of upper and lower non-girdled portion in the girdled trees. Also regenerated bark was apt to infect bacterium in the current year.General speaking, new bark could not only be produced after large-area girdling, but also its microstructure and berberine content was basically similar to original bark. According to this, girdling techniques were preliminarily feasible. This technique could utilize bark without cutting trees. With this technique,it was able to improve using rate of bark and reduce water loss and soil erosion as well. If this technique could be extended in the production fields, both of economic and ecological benefit would be obtained. The results could be used for reference of bark regeneration after skinning in other areas, where environment conditions were similar to Yingjing.