The response of Acacia karroo plants to defoliation of the upper or lower canopy Academic Article uri icon

abstract

  • The response of Acacia karroo trees to defoliation of either the upper or lower canopy only, was compared experimentally with that of plants whose whole canopies had been defoliated at a range of defoliation levels. These plants were very sensitive to defoliation of the upper canopy. A 100% defoliation of the upper canopy only, resulted in the same amount of growth as 100% defoliation of the whole canopy. This was considerably less than the growth of plants defoliated overall, at 25% and 50% leaf removal. In contrast, defoliating the bottom half of the canopy only, stimulated growth in the whole canopy to the same degree as defoliation of the whole canopy at 25-50%. The increases of growth were due largely to increased growth in the top half of the canopy. Plants were very sensitive to defoliation in the early-flush phenophase. This probably masked the positive effects of the partial defoliations applied at this phenophase. Die reaksic van Acacia karroo borne op ontblaring van slegs die hoer of laer blaardak, is eksperimenteel vergelyk met die van plante waarvan die hele blaardak ontblaar is. Hierdie plante was baie gevoelig vir ontblaring van die hocr blaardak. Totale ontblaring van slegs die boonste blaardak het dieselfde hoeveelheid groei tot gevolg gehad asn totale ontblaring van die hele blaardak, wat weer hcclwat laer was as die groei van plante wat teen 25% of 50% ontblaar is. In tecnstelling hiermee het die totale ontblaring van slegs die onderstc helfte van die blaardak die groei van die hele blaardak tot dieselfde mate gestimuleer as ontblaring van die hele blaardak teenn intensiteit van 25-50%. Die toename in groei is grootliks toe te skryf aan verhoogde groei in die boonste helfte van die blaardak. Plante was baie gevoelig vir ontblaring gedurende die vroe ontwikkeling-stadium. Hierdie feit het moontlik die positiewe invlocd van gedceltelike ontblaring, gedurende hierdie stadium, verberg. 1989 Taylor & Francis Group, LLC.

published proceedings

  • Journal of the Grassland Society of Southern Africa

author list (cited authors)

  • Teague, W. R.

citation count

  • 3

complete list of authors

  • Teague, WR

publication date

  • December 1989