Vegetative propagation of Khaya ivorensis (African mahogany): effects of stockplant flushing cycle, auxin and leaf area on carbohydrate and nutrient dynamics of cuttings

Vegetative propagation of Khaya ivorensis (African mahogany): effects of stockplant flushing cycle, auxin and leaf area on carbohydrate and nutrient dynamics of cuttings. Four clones of Khaya ivorensis were grown in tropical glasshouses in Edinburgh. Single-node cuttings were treated with IBA and set under mist. Duplicate batches of cuttings were dried and analysed for their soluble carbohydrate and starch contents after 0,10, 20 and 30 days in the propagator. The first experiment tested the factorial combination of two levels of IBA (0 and 200 Hg) and two leaf areas (50 and 100 cm2). The primary effect was the enhanced rooting of auxin-treated cuttings. In the reducing sugar and starch contents (mg/cutting) of both leaf and stem, there was a decline up to day 10, with subsequent increase to day 20, especially in the larger-leaved, auxin-treated cuttings. In the second experiment, cuttings from dormant and flushing shoots were trimmed to 50 cm2 leaf area and treated with 200 fig IBA. Cuttings from dormant shoots tended to root better than those from flushing shoots, this effect being significant in clone 8002. Flushing shoots had a greater concentration (% of dry mass) of soluble carbohydrates than dormant shoots throughout the 30-day propagation period. N, P, K concentrations were not significantly different in dormant or flushing shoots. Cuttings from basal nodes had greater NPK, soluble carbohydrate and starch contents, especially in dormant shoots. Rooting in dormant shoots peaked at node 7, but fluctuated between node positions in flushing shoots. It is concluded that there is no evidence of carbohydrates being a major factor affecting the rooting ability of K. ivorensis cuttings.

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