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- Author or Editor: W. M. Proebsting x
Abstract
The effects of naphthaleneacetic acid (NAA) and indolebutyric acid (IBA) on rooting, root quality, and budbreak of Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] stem cuttings were studied. Between 1 and 100 him, NAA was more effective than IBA in stimulating rooting. Regression analysis indicated that the highest rooting response to NAA was centered on 7.4 mM, whereas 100 mM IBA, the highest concentration tested, was the most effective. NAA concentration significantly affected budbreak percentage. Root quality was weak, but not significantly affected by auxin concentration.
Abstract
The role of scion water relations was studied using Colorado blue spruce (Picea pungens Engelmann ‘Hoopsi’) scions on Norway spruce [Picea abies (L.) Karst.] rootstocks grown either in a greenhouse or in a covered, unheated lath house. In greenhouse-grown grafts, total water potential (ψT) and relative water content (RWC) of the scions declined rapidly the first 2 weeks. Thereafter, both ψT and RWC were maintained or gradually increased in successful grafts. With scion budbreak, ψT rapidly increased to −1.0 MPa. This increase occurred 1 to 2 weeks after tracheid connections matured, based on dye movement through the graft union. At the same time, the ψT and RWC of unsuccessful grafts declined rapidly. Osmotic potentials (ψw) increased 3 weeks prior to budbreak in successful grafts. However, ψπ declined in unsuccessful grafts more rapidly than ψT, resulting in increased calculated turgor pressures with graft failure. Lath house-grown grafts had higher scion ψT and higher graft success than those in the greenhouse, but required more time for union development. Based on this data and previous work, an hypothesis relating changes in ψT, maturation of connecting tracheids, and scion budbreak to graft success or failure is presented.
Abstract
Succulent branch terminal cuttings of Douglas-fir [Pseudotsuga menziesii (Mirb) Franco] placed horizontally (adaxial side up) curved slightly. Cuttings placed vertically, horizontally (adaxial side down), or on a horizontal clinostat exhibited significant adaxial-convex curvature. The response is regulated, in part, by substances exported from the needles and terminal bud. Gibberellic acid (GA3), (2-chloro-ethyl)phosphoric acid (ethephon), amino-ethoxyvinylglycine (AVG), indolebutyric acid (IBA), triiodobenzoic acid (TIBA), and 6-benzylamino purine (BA) failed to affect the curvature of vertically placed shoots.
Hazelnut (Corylus avellana L.) softwood cuttings of the cultivars Ennis and Casina were propagated under mist during June and July 1987 and 1988. Rooting of stem cuttings was stimulated by both Agrobacterium and IBA treatment; however, IBA caused nearly complete bud abscission. Better rooting and bud retention were observed in `Casina' than in `Ennis' in 1988. Bud retention on Agrobacterium -inoculated cuttings improved as the cuttings approached the semi-hardwood stage. Six months after transplanting, Agrobacterium -inoculated hazelnut cuttings had an extensive root system, characteristic of hairy root. Although the mechanism remains unclear, strains of Agrobacterium rhizogenes are effective rooting agents in hazelnut and may cause less bud abscission than IBA. Chemical name used: 1 H -indole-3-butyric acid (IBA).