Propagation of Corylus avellana L. by Means of Semi-hardwood Cutting: Rooting and Bud Retention in Four Italian Cultivars

The effects of the application of indole-3-butyric acid (IBA) and 1,4-diaminobutane (putrescine) on the rooting and bud retention of cuttings from ‘Tonda di Giffoni’, ‘Tonda Gentile delle Langhe’, ‘Daria’ and ‘Tonda Romana’ Italian hazelnut cultivars has been investigated. Semi-hardwood stems were collected in July from the canopy and cut at every third node; the cuttings from the apical and basal portions of the stem were treated separately with IBA 1000 mg L–1, IBA 1000 mg L–1 combined with putrescine 1600 mg L–1, IBA 1500 mg L–1, IBA 2000 mg L–1. The cuttings were then placed on a planting bench for 60 d under mist. The presence of callus and the rooting, bud retention, number of roots per rooted cutting and mean root length were recorded. The dead cuttings and live cuttings without roots were also counted. The rooting ability resulted to be influenced by genotype, hormonal dosage and cutting diameter. The application of IBA 1000 mg L–1, IBA 1000 mg L–1 with putrescine and IBA 1500 mg L–1 increased the rooting percentage in ‘Tonda di Giffoni’, ‘Tonda Gentile delle Langhe’ and ‘Daria’, but different responses and percentages of bud retention were observed. ‘Tonda di Giffoni’ showed the highest percentages of rooting and bud retention, while ‘Tonda Gentile Romana’ showed poor rooting, even under the hormone treatments. The results have shown that IBA promotes rooting in hazelnut cuttings, but there is also a significant effect on bud retention in relation to the hormone concentration. In general, the use of basal cuttings from vigorous stems, together with treatments with the lowest dose of IBA able to induce rooting, is recommended to reduce bud abscission.