Effect of Antitranspirants and Plant Growth Retardants on the Rooting of Rosa hybrida‘ M-Red’ Cuttings

Abstract

This experiment was conducted to increase the rooting efficiency of rose plants by using antitranspirants or plant growth retardants during the greenwood cutting propagation of roses without mist or closed facilities. After the insertion of the ‘M-Red’ cutting stem into the rooting media, antitranspirants (Wilt Pruf or Cloud Cover at 1%, 2%, 4%, 8%) and growth retardants (paclobutrazol 10, 20, 40, 80 mg･L-1 or diniconazole 100, 200, 400, 800 mg･L-1) were applied using the foliar spray method. The effect of the antitranspirants was dependent on the commercial products. Wilt Pruf improved the survival ratio, shooting ratio and rooting percentage of cuttings, but did not affect the number of shoots and roots, or the root length of rooted cuttings. Cloud Cover did not improve the survival and rooting ratio, but did increase the shooting ratio as the concentration increased, which was the highest at 4% and 8%. The effect of the growth retardants also varied dependent upon the commercial product used. Paclobutrazol did not affect the survival and rooting ratios, but increased the shooting ratio. The shooting ratio was highest in the 1% treatment, then decreased as the concentration increased. In contrast, diniconazole tended to improve the survival and rooting ratio when treated with 100 and 200 mg･L-1, but was lowest at the high concentration of 200 mg･L-1.