Growing Mechanisms Of Stem Apex And Cumulation Trend Of Polysaccharide Of Dendrobium Candidum And D. Loddigesii

Caulis Dendrobii, traditional Chinese medicinal material, which origin is plants of Dendrobium, has been in a condition of much demand but poor supply for long-term. Lack of Caulis Dendrobii is principally attributed to retarded growth of the plants, especially of the tiny stem species, such as Dendrobium candidum Wall Ex Lindl and Dendrobium loddigesii Rolfe. To study on the growing mechanism and growth-promoting technique applying is considered optimum key to the problem.History used as medicine of Caulis Dendrobii was expatiated and the consistency of medicine name "Shihu" all through the ages was shown by herbal textual. Varieties applied both ancient and modern were collated, evolution of efficacy was also explained, and the diversity of trueborn producing areas was confirmed by both herbal textual and modern literature research. Resource and habitat of the plants in Guangxi province were studied on the spot.Cell divisional rhythm of stem apex of D. candidum and D. loddigesii was discovered. Fastigiumof divisional index was found to be at 9:00AM, which reached 1.5×1O^-5 in D. candidum and in 3.3×1O^-4 in D. loddigesii; Cell division generated around the clock. May was found the most active month while monthly rhythm was reviewed. The low divisional index of stem apex cells was considered the reason for retarded growth of D. candidum and D. loddigesii.Structure differentiation of stem growing tips of D. candidum and D. loddigesii was found and effects of intervention by 6-BA spraying and specific lighting were found.Kind of cell death occurred in D. candidum stem apex and D. loddigesii stem apex was ascertained to be necrosis,which opposite kind is programmed cell death, by applying microscope, transmission electron microscope, terminal deoxynucleotibyl transferase mediated dUTP-biotin nick-end labeling and acridine orange staining.Location of adenosine triphosphatase in cell was shown by cytochemical reaction and observed by using transmission electron microscope. Difference of ATPase activity among experimental groups were revealed. Resistance to environmental stress in May, October and January of the year ensuing, shown by activity of peroxidase, catalase, and the content of malomdiadehyde in D. candidum leaves and D. loddigesii leaves,was studied. Difference of the three indexs among experimental groups were revealed. In comparison among groups, activity of POD and CAT in control group was found to be the lowest both in candidum and D. loddigesii, while content of MDA to be the highest.In monthly comparison, activity of POD and CAT, in hormone group and lighting group of D. candidum, was found to be the highest in May, while to be the lowest in October. No significant difference was found in the activity of POD in hormone group and lighting group of D. loddigesii, while step-up trend shown in controlgroup. Same monthly change of CAT activity and MDA content was revealed in D. loddigesii as in D. candidum. So was of MDA content. Sucrose synthase activity in leaves of was also assayed. Activity of sucrose synthase was found to be the highest in May in control group of both plants, while found to be the lowest in Oct. and Jan.the the year ensuing, on the contrary.Polysaccharide content of D. candidum stems and D. loddigesii stems of all groups, grown for different time, was determined and compared. Quanlity of the Caulis Dendrobii was valued by the polysaccharide content and the effects of intervention,6-BA spraying and specific lighting, were discovered. Step-up trend of polysaccharide content, assayed in seriate growth periods before 18th month, was discovered both in D. candidum stems and D. loddigesii. In particular, polysaccharide content in hormone group of D. loddigesii was detected to be the lowest before 12th month's growth, but to be the highest in 18^th month.