Both kinetin and BA promoted in vitro shoot formation from hypocotyl explants of Lupinus texensis Hook. placed on Murashige and Skoog (MS) medium. With either cytokinin, shoot formation was best at ≈4.5 μm. Adventitious root formation was observed only on tissue culture-derived shoots placed in MS media containing 5.4 to 54 μM NAA. IAA and IBA, at concentrations ranging from 5 to 55 μm, failed to stimulate rooting. Even at the optimal concentration of NAA, only 14% of the shoots produced roots. Thus, although hypocotyl explants readily produced shoots, adventitious root formation on these shoots occurred with relatively low frequency. Chemical names used: 6-benzylaminopnrine (BA); indole-3-acetic acid (IAA); indole-3-butyric acid (IBA); 6-furfurylaminopurine (kinetin); 1-naphthaleneacetic acid (NAA).
Several studies were conducted to evaluate the effects of cultivar, cutting length, and leaf number on rooting of poinsettia. Cuttings were rooted under mist in a soilless medium with 50 cuttings per treatment. Visual rootball ratings were performed after 3 wk. In the first experiment, rooting of ten poinsettia cultivars was compared. The rooting hormone was 0.1% indole-3-butyric acid (IBA). Rooting of `V-14 Red' and `V-14 Marble' was the highest. `V-17 Pink' and `V-17 Marble' had the highest number of callused cuttings. `V-17 White' produced the highest number of extensively rooted cuttings. `V-14 Pink' (3-lf) cuttings 12 cm long rooted better than 5 cm cuttings. Rooting of (7 cm) 3- and 4-leaf cuttings was higher than rooting of 2-leaf cuttings. `V-14 Pink' cuttings treated with 0.8% IBA or 1% IBA + 0.5% 1-napthaleneacetic acid (NAA) rooted better than with 0.1% or 0.3% IBA.
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).
The responses of several Moroccan and French olive (Olea europaea L.) cultivars to various strategies for in vitro establishment and culture were compared. A cultivar effect was clearly observed with `Haouzia' cultivar being more readily multiplied. ZR produced the best response in all the cultivars studied, in particular when considering the time elapsed between explant inoculation and budbreak for 50% of the explants (lag phase), growth of the primary shoot and the multiplication rate. Treatments with BA alone or combined with NAA increased the number of axillary buds and internodes without improving their growth. Root induction with IBA in the dark using a two-phase scheme resulted in the best rooting rate in shoots obtained in vitro, and this for all cultivars. Chemical names used: 6-benzyladenine (BA), indole-3-butyric acid (IBA), alpha-naphthalene acetic acid (NAA), zeatin riboside (ZR).
A protocol was developed to make in vitro graft unions among Lycopercicon spp., and regenerates from cultured graft unions were evaluated for chimera formation. Young seedlings were preconditioned for 4 to 6 days in liquid 1/2-strength Murashige & Skoog (MS) basal medium supplemented with 8.9 μM benzyladenine and 1.0 μM indole-3-butyric acid. Preconditioned seedlings exhibited increased biomass and enhanced graft union survival. In particular, survival of cleft grafts increased from 37% to 95% with the seedling preconditioning. When graft unions among different genotypes were excised from apex-to-apex in vitro cleft grafts and plated on MS basal medium supplemented with 9.1 μM zeatin and 3.9 μM ancymidol, as many as 100 plantlets were regenerated from a single graft union. However, no chimeric regenerates were recovered, indicating that asymmetric responses to grafting may be a limiting factor to in vitro chimera formation.
Hardwood stem cuttings of eastern redcedar (Juniperus virginiana L.), taken from containerized stock plants fertilized weekly with 0, 5, 10, 20, 40, 80, 160, 320, or 640 ppm N, were treated with 7500 ppm IBA and placed under intermittent mist for 12 weeks. Foliar starch and sucrose concentrations within cuttings at time of excision were significantly correlated with percent rooting and root length, respectively. Of the mineral nutrients analyzed (N, P, K, Ca, Mg, Mn, and B), only B and K were significantly correlated with rooting response. A threshold N level (20 ppm), applied weekly, maximized rooting; higher concentrations decreased response. Although N fertilization of stock plants affected adventitious rooting, there were no significant correlations between foliar N levels and measures of rooting response. Chemical name used: 1 H- indole-3-butyric acid (IBA).
Seeds of Chinese elm cultivar King's Choice were collected from field-grown plants and germinated aseptically. Hypocotyl segments were excised from 2-week-old seedlings and cultured on Murashige and Skoog (MS) medium supplemented with TDZ alone or in combination with 0.05 mg/L NAA. At least 50% of explants produced shoots 4 weeks after culture initiation. At thidiazuron (TDZ) from 0.05 to 5.0 mg/L, the number of shoots/explant increased as concentration increased. Addition of 0.05 mg/L NAA stimulated shoot regeneration when TDZ concentration was 0.5 mg/L or less, but suppressed it if TDZ concentration was higher than 0.5 mg/L. Regenerated shoots elongated quickly on MS medium supplemented with 1 mg/L gibberellic acid and initiated rooting on MS medium containing 0.1 mg/L indole-3-butyric acid.
During Fall and Winter 1999-2000 and 2000-2001, a study was conducted to evaluate the effects of exogenous IBA application (0, 2000, or 4000 ppm) and inoculation with Agrobacterium rubi (strains A1, A16, or A18) alone or in combination with each bacterial strain on rooting of hardwood stem cuttings of two rose selections (ERS 14, Rosa canina, and ERS 15, Rosa dumalis). Treatments of hardwood stem cuttings with IBA, bacteria alone and in combination with IBA were found to promote rooting. The highest rooting percentage was obtained among ERS 14 cuttings when treated with 4000 ppm IBA plus A. rubi A16. However, optimal rooting of ERS 15 was obtained when treated with 2000 ppm IBA plus A. rubi A18. Better rooting was observed in thornless ERS 15 genotype than in thorny ERS 14 genotype in both years. Chemical name used: 1H, indole-3-butyric acid (IBA).
Stem cuttings of golden euonymus (Euonymus japonicus `Aureo-marginatus'), shore juniper (Juniperus conferta `Blue Pacific'), white indian hawthorn (Rhaphiolepis indica `Alba'), and `Red Cascade' miniature rose (Rosa `Red Cascade') were successfully rooted in plugs of a stabilized organic substrate that had been soaked in aqueous solutions of the potassium salt of indole-3-butyric acid (K-IBA) at 0 to 75 mg·L–1 before inserting the cuttings. Cuttings were rooted under intermittent mist in polyethylene-covered greenhouses with rooting periods appropriate for each species. Rooting percentages showed some increase with increasing auxin concentration with juniper cuttings, but were similar among treatments for the other three species. Number of roots per rooted cutting increased with increasing auxin concentration with cuttings of juniper, Indian hawthorn, and rose, and was greatest using around 60 mg·L-1 K-IBA for cuttings of juniper and Indian hawthorn and 30 to 45 mg·L-1 K-IBA for cuttings of rose.
A micropropagation system was developed for hazelnut cultivars. Grafted greenhouse-grown plants produced many more viable explants than upper branches of mature field-grown trees. Shoots from grafted greenhouse-grown plants collected March through July and suckers of mature field-grown trees collected in July produced the most growing explants (46% to 80%). Three- to five-fold multiplication was obtained after 4 weeks of culture on NCGR-COR medium supplemented with 6.7 μm BA and 0.04 μm IBA. Roots were produced on 64% to 100% of shoots grown on half-strength NCGR-COR mineral salts and 4.9 μm IBA for 4 weeks. Ex vitro rooting by a brief dip in 1 or 5 mm IBA was equally successful. Transplant survival was 78% to 100%. Chemical names used: N 6-benzyladenine (BA); indole-3-butyric acid (IBA).