ISHS Acta Horticulturae 227: International Symposium on Vegetative Propagation of Woody Species
HORMONE APPLICATIONS AND ADVENTITIOUS ROOT FORMATION IN CUTTINGS - A CRITICAL REVIEW |
| Author: | K. Loach |
| Abstract:
The proved effectiveness of auxinic hormone applications in promoting adventitious root formation in cuttings has attracted more interest than any other topic in propagation research. However, in trials using these compounds, reproducible results are not easily achieved. Examples are presented from the literature; these relate to the effects of hormone concentration, application methods, comparative effectiveness of different synthetic auxins and of applications at different times of year. It is easy to see how inconsistent results can arise. First, applications as powder or solution dips are imprecise and the amount of hormone taken up by the cutting depends on its condition and on the environment. Secondly, the applied auxin works alongside a (usually) undetermined background of endogenous indolyl acetic acid (IAA), whose level will vary with the type of cutting and stock plant condition as affected by weather. Auxins interact with other endogenous hormones which also vary in concentration. Finally, the plant material studied is often from mixed clonal origins and it is well-established that clones can respond differently to applied hormone. Because of the highly interactive nature of the factors affecting adventitious root formation, many detailed studies have used cuttings raised and propagated in standard conditions. Typical results are reviewed, but these again illustrate the complexity of the processes involved. The practical implications are discussed and the necessity of repeating experiments over several seasons is emphasised. | |
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