Effect of growth regulators on hop (Humulus lupulus L.) propagation

The expansion of hops (Humulus lupulus L.), an essential input for the brewing industry, into new growing areas has intensified the demand for quality seedlings. However, scientific studies and recommendations for effective hop propagation methods that are suitable for growers and nurseries in terms of production volume and low cost are still scarce. Therefore, the aim of this study was to evaluate the ability of auxin and cytokinin to accelerate the propagation of Cascade hop stem cuttings. Four doses of indole-butyric acid (IBA) and 6-benzylaminopurine (BAP) were tested at 0, 1000, 2000, 3000 and 4000 mg L-1. The variables evaluated were the percentage of rooted cuttings, the percentage of cuttings that produced shoots, the greatest root length, the length of the shoots, the dry mass of the root, the dry mass of the shoots and the number of leaves. The use of IBA had a significant effect on most of the variables, except for the percentage of shoots and the number of leaves. The use of BAP had a significant effect on all the variables evaluated. In both experiments, there was a quadratic fit for all the variables analyzed. These results confirm the efficiency of using IBA and BAP as rooting promoters for hop cuttings. The most efficient concentration of IBA for rooting cuttings was 2580 mg L-1 (97%), and for BAP it was 1490 mg L-1 (88%). An economic analysis suggested that the use of IBA provides better rooting results than BAP at lower costs.