Iona roots out growth issues

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A Stranraer Academy student has been getting to the roots of challenges created by horticultural legislation, thanks to a Nuffield Foundation Undergraduate Research Bursary and its associated project at Logan Botanic Garden.

Now, 17-year-old Iona Brisbane will have the findings in her paper – Investigating Rooting Hormones – put to practical use when some of the UK’s leading horitculturists take them into account for everyday practice.

Iona, of Little Tongue Farm, based her summer research on the use of auxin-based rooting powders and liquids, which have been commonly used in horticulture for many years to stimulate, speed up and increase the rooting of cuttings.

Recent changes in legislation, however, have meant that the UK products of Seradix and Synergol – both containing a mix of two artificial auxins, known as IBA and NAA – are no longer available on the market. Her aim was to establish the efficiency of the next commercially available product.

Richard Baines, curator at Logan, who supervised Iona, explained: “When Seradix and Synergol were taken off the market the option for Logan and its parent organisation, the Royal Botanic Garden Edinburgh, was to use a Dutch product Rhizopon, which is available in many strengths and also as either NAA or IBA, but not combined.

“Iona’s research work involved trialling various auxins on several plant species to investigate how well they work and which concentration best promotes root growth.”

The experiment involved taking plant cuttings from various species, measuring the length of these cuttings and treating them with increasing concentrations of auxin before planting them in a range of rooting media. After four weeks, they were lifted, measured and results taken. Before the experiment it was predicted that a medium concentration of auxin around 0.4 per cent to 0.6 per cent would show best results. However, the final results indicated the best root growth came from much stronger auxin concentrations: as much as 0.8 per cent to one per cent.

Iona’s longer-term aim is to study agriculture. She described the project as challenging and fulfilling. “When I started, it appeared as though medium concentrates would provide us with the optimum results because they would allow root growth without any inhibiting effects on the plants. But, this was not the case at all, as it was found that cuttings rooted better when treated with a high-strength auxin and planted in a 50 per cent peat 50 per cent perlite rooting medium, as it allowed good water transport throughout the cuttings.”

Paying tribute to Iona’s research, Mr Baines concluded: “Iona is to be congratulated on the quality of her work. Her thorough research has demonstrated what the ideal strength of hormone rooting powder is to maximise root stimulation. It has been a fantastic opportunity to work with Iona and Stranraer Academy on a real-life, hands-on, project.”