HOT WATER TREATMENT ENHANCES BUDBREAK AND ROOT FORMATION IN BLACK CURRANT 'ÖJEBYN'

We studied the effects of hot water treatment on budbreak and root formation in black currant ‘Öjebyn’ shoot cuttings. Dormant cuttings (18 cm) taken from the tip, mid and base part of the one-year-old shoots were treated in 45°C water for 15 min or left untreated (control). After the treatments half of the samples were cut into single-bud pieces. All the cuttings were forced under mist in a greenhouse for six weeks. Budbreak after hot water treatment in single-bud shoot-base, shoot-mid-part and shoot-tip cuttings reached 43, 61, and 55%, respectively. Budbreak in untreated single-bud cuttings remained low at 10 to 20% in all the shoot parts. In 18-cm cuttings budbreak was highest in hot water treated shoot-mid-parts (85%) followed by shoot tips (73%), and shoot bases (54%). In the untreated 18-cm cuttings budbreak was 30 to 50%. Hot water treatment also enhanced root formation. Rooting percentage of single-bud cuttings was highest in hot water treated mid-part cuttings, 83%. However, in the untreated control samples most roots were formed in the shoot-base cuttings (42%). In 18-cm cuttings 100% rooting was observed after hot water treatment in mid- and base-part cuttings. In conclusion, hot water treatment at 45°C for 15 min enhanced both budbreak and rooting in dormant black currant cuttings. Both rooting and budbreak were enhanced in longer cuttings compared to single-bud cuttings. Hot water treatment might be used as a growth stimulating treatment in propagation of black currant by cuttings.