Rhizogenesis and concentration of carbohydrates in cuttings harvested at different phenological stages of once-blooming rose shrubs and treated with rooting stimulants

ABSTRACT The aim of this study was to evaluate the effect of rooting stimulators on the rooting of rose cuttings harvested at different phenological stages of the stock plants and on concentrations of carbohydrates in the shoots and leaves of the rooted cuttings. Shoots from once-blooming, difficult-to-root cultivars Duchesse d’Angoulême, Hurdals, Maiden’s Blush, Mousseuse Rouge were cut at the phenological stages: flower buds closed; all flowers open; immediately after petal shedding; and 7–14 days after petal fall. Single node stem cuttings were treated with rooting preparations containing either 0.4% IBA (Ukorzeniacz Aaqua) or 0.2% NAA (Ukorzeniacz Baqua) or with biostimulants Bio Rhizotonic, Root JuiceTM or Bio Roots. The phenological stage of the stock plant shoots had an important role in the propagation of the cultivars. Effects of IBA, NAA and the biostimulants depended on the phenological stage and the cultivar. Cuttings of all cultivars from shoots with closed flower buds had good rooting ability despite low concentrations of total soluble and reducing sugars in the plant tissue. In Hurdals and Maiden’s Blush, none of rooting stimulators improved the rooting percentage in cuttings from shoots collected at 7–14 days after petal fall, which had a low rooting ability. Concentrations of reducing and total carbohydrates in leaves and shoots of cuttings harvested at 7–14 days after petal fall were not correlated with the rooting parameters. The use of biostimulants can be recommended to stimulate rooting of these once-blooming roses instead of preparations containing IBA or NAA.