Regulating the rooting process of rose softwood cuttings by foliar citric and malic acid spray on stock plants

We evaluated the effects of spraying different concentrations of citric and malic acids on stock plants in the greenhouse prior to the propagation and rooting of rose (Rosa × hybrida ‘Love Letter’) cuttings. Malic and citric acids (3, 6 and 9 mM) were sprayed several times at 14-day intervals on rose plants in a commercial cut flower producing greenhouse. Single-node cuttings taken from flowering stems were rooted under misty conditions, and the rooting parameters including root count and dry root weight were measured. A distinct change was observed in rooting features in response to the applied organic acids. Malic acid significantly enhanced rooting at the intermediate concentration while retarding it at both the higher and lower concentrations. On the other hand, the effect of citric acid was best at the highest concentration applied. We conclude that in softwood cuttings taken from rose plants these organic acids can act as a potential alternative to the currently applied methods of promoting rooting.