, Volume 7, Issue 4, pp 208–213 | Cite as

Effect of shade stress on growth, morphology, and carbon dynamics of loblolly pine branches

  • Bert M. Cregg
  • Robert O. Teskey
  • Phillip M. Dougherty


Shade treatments were applied to the terminal portions of branches in loblolly pine trees to test whether portions of branches were autonomous with respect to carbohydrates. The shade treatments reduced light by 50% and 72% compared with full sun conditions resulting in significant reductions in net photosynthesis. Branch growth (branch diameter and length, branch and needle biomass) decreased significantly within the shaded portion of the branch. Branch and needle morphology were also affected by shading. Lateral branches subtending terminal shoots were labelled with 14C 2 times during the growing season. No movement of 14C into the terminal portions of the branch was evident during the first growth flush. However, during the second flush of growth small but statistically significant amounts of 14C were imported into the terminal portion of the shaded branches from subtending laterals. It was concluded that loblolly pine shoots were usually autonomous with respect to carbohydrate supply, but that carbohydrate movement into the terminal shoot from subtending foliage could occur under conditions of very high stress.

Key words

Net photosynthesis Carbon allocation Pinus taeda 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Bailey RL, Grider GE, Rheney JW, Pienaar LV (1985) Stand structure and yields for site-prepared loblolly plantations in the piedmont and upper coastal plain of Alabama, Georgia, and South Carolina. Univ Ga Agric Exp Stn Bull 328Google Scholar
  2. Blechschmidt-Schneider S, Eschrich W (1985) Microautoradiographic localization of imported 14C-photosynthate in induced sink leaves of two dicotyledonous C4 plants in relation to phloem unloading. Planta 163: 439–447Google Scholar
  3. Dickson RE, Nelson EA (1982) Fixation and distribution of 14C in Populus deltoides during dormancy induction. Physiol Plant 54: 393–401Google Scholar
  4. Fites JA, Teskey RO (1988) CO2 and water vapor exchange of Pinus taeda in relation to stomatal behavior: test of an optimization hypothesis. Can J For Res 18: 150–157Google Scholar
  5. Gordon JC, Larson PR (1968) Seasonal course of photosynthesis, respiration and distribution of 14C in young Pinus resinosa trees as related to wood formation. Plant Physiol 43: 1617–1624Google Scholar
  6. Gordon JC, Larson PR (1970) Redistribution of 14C-labeled reserve food in young red pines during shoot elongation. For Sci 16: 14–20Google Scholar
  7. Kramer PJ, Kozlowski TT (1979) Physiology of woody plants. Academic Press, New YorkGoogle Scholar
  8. Kuhns MR, Gjerstad DH (1988) Photosynthetic allocation in loblolly pine (Pinus taeda L.) seedlings as affected by moisture stress. Can J For Res 18: 285–291Google Scholar
  9. Long SP, Hallgren JE (1985) Measurements of CO2 assimilation by plants in the field and the laboratory. In: Coombs J, Hall DO, Long SP, Scurlock JMO (eds) Techniques in bioproductivity and photosynthesis. Pergamon Press, Oxford, pp 62–94Google Scholar
  10. Quinlan JD, Weaver RJ (1969) Influence of benzyladenine, leaf darkening, and ringing on movement of 14C-labeled assimilates into expanded leaves of Vitis vinifera L. Plant Physiol 44: 1247–1252Google Scholar
  11. Quinlan JD, Weaver RJ (1970) Modification of pattern of the photosynthate movement within and between shoots of Vitis vinifera L. Plant Physiol 46: 526–530Google Scholar
  12. SAS Institute Inc. (1985) SAS procedures guide for personal computers. Version 6 Edition. SAS Institute, Cary, N. C.Google Scholar
  13. Sprugel DG, Hinckley TM, Schaap W (1991) The theory and practice of branch autonomy. Annu Rev Ecol Syst 22: 309–334CrossRefGoogle Scholar
  14. Thrower SL, Thrower LB (1980) Translocation into mature leaves — the pathway of assimilate movement. New Phytol 86: 145–154Google Scholar
  15. Turgeon R (1989) The sink-source transition in leaves. Annu Rev Plant Physiol 40: 119–138Google Scholar

Copyright information

© Springer-Verlag 1993

Authors and Affiliations

  • Bert M. Cregg
    • 1
  • Robert O. Teskey
    • 1
  • Phillip M. Dougherty
    • 1
  1. 1.School of Forest ResourcesUniversity of GeorgiaAthensUSA

Personalised recommendations