Studies On Activity Rhythm Of Vascular Cambium And Development Process Of Secondary Xylem In Cinnamomum Camphora (L.) Presl

The yield of forest product depended on the activity pattern of vascular cambium, especially for the use of wood. There is a significant to study the relationship between activity rhythm of cambium and development of cells in xylem. the wood of camphora is one of rare material, this study aiming at providing anatomy information for further studies about mechanism of wood generation, and produced theory reference of plantation directive breeding. We investigated the progress of vascular cambium and pattern of differentiation, analysis made in content of polysaccharose during active phases, development of oil cell was observed, too. Quantification anatomy and histochemistry was applied to reveal the relationship between morphological character of cells in secondary xylem and cambium in activity cycle. main results as follows:(1) Tunica-corpus structure was found in the shoot apex of camphora trees, procambium came into being along with leaf primordium swelling. Two phases were investigated in the development:firstly, apical meristem translated into residual meristem, then residual meristem translated into procambial strand, which is continuous processing. the translation rate of the former is more faster than the latter, which is about 4 days. Approximately, the transform is complete at the time of first leaf maturate in twigs. The borderline between procambium and vascular cambium is not distinct. Procambiumcells comes from the similar cells differentiating into the short and long cells. Primary vascular bundle has some connection with leaf trace.(2) Periodicity was found in cambium in camphor trees grown trees in Wuhan: cambium of twigs entered reactivate phase before bud swelling during end of February to Mid-March, luxuriance growth began with one week before bud sprouting; In cambium active phase, phloem differentiation got rapid before mid April and then continued up to early October at a slow speed. Whereas the differentiation of xylem was two weeks later than phloem, and ceased in the end of October, which is 1 week later than phloem. In generally, the active time was seven months, entered dormancy period in November and remained till the next spring. And the cambium is non-storied, the rays were biserial or uniserial.(3) Polysaccharide grains content in vascular tissue shows a periodicity by means of histochemical method. It began to decrease when cambium entered reactivate phase, nearly no one existed in the samples through May to August, when the cambium was in luxuriance active period; polysaccharide grains accumulated in the end of October, up to maximum in the end of December, then showed a downtrend to the next January. Analytically, eat and flow of polysaccharide grains content had positive correlations with cambium activity cycle.(4) The development and distribution of oil cells and mucilage cells in the shoot and lignified stem of camphora were studied with the method of parafin section. The results are as follows:Oil cell and mucilage cell showed an early development than other cells around them, the earliest oil cells can be seen initiate from the ground meristem in the second leaf primordium, with the development of cells differentiation, cortex and pith of shoot became the main place of oil cells, with a large volume, big nuclei. And the cell number increased with tissue differentiation. Develop process of oil cell could main be segmented into three phase:develop of initial cell, cell vacuolation phases, cell maturation and disintegration of protoplasm. The development style of mucilage cells in the earlier vacuolation stage is similar to that of oil cells, different after late vacuolation phases.’Cup’structure could be seen in the two types of cells.(5) The changes were determined in the anatomical properties of cambial cells and xylem cells during cambial active phase. No significant differences in tangential and radial width of cambial fusiform cell, length and width, lumen of fiber were significantly different, there was a significant differences in length of vessel during different stages.Correlation analysis indicated that cambial cell number had strong positive correlations with fiber width, a strong negative correlation with fiber length ratio of length to width and double wall to lumen; Moreover, the tangential width of cambial fusiform cells had strong positive correlations with ratio of fiber length to width and ratio of double wall to lumen, and a strong negative correlation existed between tangential width of cambial fusiform cell and fiber lumen. The radial width of cambial fusiform cells had positive correlations with fiber width, and strong negative correlation with fiber ratio of length to width. Meanwhile cambial cell number had strong positive correlations with vessel width, and strong positive correlations with vessel lumen. In generally, the correlation between cambium and fiber were bigger than that of vessel in cambial active phases.(6) Secondary thickening of cell wall in TEs and the lignification progress were observed by fluorescence microscope. Results suggested that wood fiber thicken rapid after differentiation, lignin deposition reached its peak after about half a mouth. autofluorescence of fiber cell wall got stronger and stronger in the developmet, and finally became stable. Meanwhile the differential vessel is earlier deposit lignin, fluorescence is stronger than that of fiber. Similarly, intensity of fluorescence assimilated the same finally. Phloroglucinol- hydrochloric acid reaction, namely Wiesner reaction in high power microscope which proclaimed that lignin began to deposit after secondary thickening, first deposition in the middle lamella and then in cell corner and secondary wall.