Cuttings of Ficus benjamina L. and Chrysanthemum × morifolium(Dendranthema grandiflora tzvelev.) were rooted in aero-hydroponics to study the effect of dissolved oxygen concentrations in the range of 8 mg·liter. (ambient saturation) to 0 mg·liter−1. The results of this study indicate that dissolved oxygen is essential to root formation and root growth. Woody (Ficus) and herbaceous (Chrysanthemum) cuttings responded similarly. Lowering the dissolved oxygen concentration increased the time required to form adventitious roots, reduced rooting percentages, reduced numbers of roots formed per cutting, and reduced average root lengths. Comparisons between stirred and unstirred water suggested the development of an area of depleted oxygen concentration (boundary layer) at the stem-water interface on cuttings immersed in unstirred water. Cuttings in water stirred constantly rooted sooner and formed more roots than did those in unstirred water. Maximum rooting occurred in misted (high dissolved oxygen concentrations) sections of cuttings suspended in the aero-hydroponics chambers. Chemical name used: potassium salt of lH-indole-3-butyric acid (K-IBA).
Visiting Horticulturist. Permanent address: Institute of Field and Garden Crops, Agriculture Research Organization, The Volcani Center, Bet Dagan 50250, Israel.
Received for publication 3 Apr. 1987. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.