Influence of proprietary rooting compounds and basal internode length on the rooting of potato stem cuttings

Potato stem cuttings, cv. Désitrée, were treated with a powder formulation of 4-indol-3-ylbutyric acid (IBA), a gel formulation of 1-naphthylacetic acid (NAA), or a powder formulation of NAA. Both the IBA powder and the NAA gel stimulated significantly more roots per rooted cutting than were produced by the untreated controls but the NAA gel also significantly reduced the number of root branches per rooted cutting (Table 1). Untreated cuttings of cvs. Désirée and Recond were more likely to form only roots when the basal internode was long and more likely to form only tubers when the basal internode was short (Table 2). We suggest that the number of stem cuttings forming roots would be increased if, where necessary, the cuttings were trimmed to leave a long basal internode.