Cellular Kinetics of Compression Wood Formation in Slash Pine


  • L. E. Nix
  • C. L. Brown


Southern pine, compression wood, cellular kinetics, tracheid differentiation


The kinetics of auxin-induced compression wood formation in slash pine (Pinus elliottii Engelm.) seedlings were investigated with regard to rate and duration of cambial cell division, radial enlargement, and secondary wall formation. Exogenous lateral application of auxin (indole acetic acid) in lanolin paste to the basal portion of the seedling stems markedly increased the rate of cambial cell division and radial enlargement with a nearly proportionate decrease in the duration of both stages. The auxin application had little effect on the rate of secondary wall formation of differentiating tracheids but significantly increased the duration of this stage, resulting in a large increase in tracheid wall thickness. Untreated control seedlings exhibited no evidence of changes in cellular kinetics during the treatment period. Results indicate that the increased wall thickness of compression wood tracheids in slash pine results from an extended duration of secondary wall deposition rather than an increased rate of deposition as previously thought.


Brown, C. L. 1970. Physiology of wood formation in conifers. Wood Sci. 3:8-22.nDenne, M. P. 1972. A comparison of root- and shoot-wood development in conifer seedlings. Ann. Bot. 36:579-587.nKennedy, R. W., and J. L. Farrar. 1965. Tracheid development in tilted seedlings. Pages 419-455 in W. A. Côté, ed. Cellular ultrastructure of woody plants. Syracuse University Press, Syracuse, NY.nMorey, P. R., and J. Cronshaw. 1968. Induction of tension wood by 2,4-dinitrophenol and auxins. Protoplasma 65:393-405.nNix, L. E. 1974. The role of growth regulators in tracheid differentiation of southern pines. Ph.D. dissertation, University of Georgia, Athens, GA. 69 pp.nSass, J. E. 1958. Botanical microtechnique. Iowa State University Press, Ames, IA. 228 pp.nScurfield, G. 1973. Reaction wood: Its structure and function. Science 79:647-655.nSkene, D. S. 1969. The period of time taken by cambial derivatives to grow and differentiate into tracheids in Pinus radiata D. Don. Ann. Bot. 33:253-262.nWesting, A. H. 1968. Formation and function of compression wood in Gymnosperms. II. Bot. Rev. 34:51-78.nWodzicki, T. J. 1971. Mechanism of xylem differentiation in Pinus silvestrisL. J. Exp. Bot. 22:670-687.nWolter, K. E. 1968. A new method for marking xylem growth. Forest Sci. 14:102-104.n






Research Contributions