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Sarada Krishnan, Bahman Pirastah and Harrison Hughes

The evergreen Ceanothus velutinus and semi-evergreen C. fendleri are native Colorado, drought-tolerant shrubs. They are of interest for landscaping and rock gardens, but have poor seed germination as well as vary considerably in growth form and habit. Asexual propagation methods would be important for commercial development of these species. Basal hardwood cuttings of C. velutinus were rooted using four different concentrations of IBA. The highest concentration of IBA (0.8%) showed the highest rooting (14.8%), while the average number of roots per cutting was highest for 0.1%. Ceanothus fendleri shoot tips were cultured on MS medium with four BA (0.89, 4.4, 8.9 and 17.8 μM) and three 2ip concentrations (24.6, 49.0 and 73.6 μM). After nine weeks an average of six shoots were produced in treatments having 4.9 μM of BA. Lower concentrations of BA up to 9.8 μM were better than higher concentrations of BA or 2ip. There was a tendency for production of callus at the higher levels of 8A and all levels of 2ip.

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Randall H. Hagen and David A. Palzkill

The `Desert Museum' hybrid between the Blue, Foothills, and Mexican palo verdes has been well received by the public. However, it has remained unavailable due to difficulties in asexual propagation. Studies were conducted on effects of IBA cone. (0 to 10,000 ppm), cutting position along the stem, size of cutting, season, and temperature of the medium.

For `Desert Museum', basal cuttings of slightly hardened new stem growth rooted much better than apical cuttings. Best rooting for apical cuttings was 79% using IBA from 2,500-5,000 ppm. Basal cuttings averaged 95% rooting and showed no response to IBA. Rooting of cuttings taken in September declined to 10% for apical and 2170 for basal cuttings averaged over all IBA levels. Six other species or hybrids of Cercidium and Parkinsonia and five of Prosopis were also rooted.

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Randall H. Hagen and David A. Palzkill

The `Desert Museum' hybrid between the Blue, Foothills, and Mexican palo verdes has been well received by the public. However, it has remained unavailable due to difficulties in asexual propagation. Studies were conducted on effects of IBA cone. (0 to 10,000 ppm), cutting position along the stem, size of cutting, season, and temperature of the medium.

For `Desert Museum', basal cuttings of slightly hardened new stem growth rooted much better than apical cuttings. Best rooting for apical cuttings was 79% using IBA from 2,500-5,000 ppm. Basal cuttings averaged 95% rooting and showed no response to IBA. Rooting of cuttings taken in September declined to 10% for apical and 2170 for basal cuttings averaged over all IBA levels. Six other species or hybrids of Cercidium and Parkinsonia and five of Prosopis were also rooted.

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Sarada Krishnan, Kurt Shultz and Harrison Hughes

In recent years there has become an increased demand for native, drought-tolerant species for private landscaping and revegetation of disturbed sites; especially in the Rocky Mountains and high plains states. Sheperdia canadensis and S. rotundifolia, native to much of this area, have already increased in popularity due to their drought tolerance and general hardiness. Micropropagation and rooting of cuttings have been investigated for these two species. S. canadensis hardwood stem cuttings were successfully rooted with 0.8% IBA at 46.5% as compared to less than 5% from previous research. S. rotundifolia produced a greater number of axillary shoots on WPM as compared to MS medium and at a moderate concentration of BA.

Open access

Benjamin E. Deloso, Anders J. Lindström, Frank A. Camacho and Thomas E. Marler

successful asexual propagation protocols. Additionally, some cycad species such as Cycas micronesica K.D. Hill that are adapted to frequent tropical cyclones may form natural vegetative propagules after falling, where they subsequently form adventitious

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Daniel Struve, Francesco Ferrini, Chandra Bellasio and Alessio Fini

from the main bole of swamp white oak and northern red oak Can. J. For. Res. 33 705 711 Griffin, J. Bassuk, N. 1996 Preliminary progress on the asexual propagation of oaks Proc. Int'l. Plant Prop. Soc. 46 487 493 Head, R.H. 1999 Cutting-grown Quercus

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W. Msikita, H.T. Wilkinson and R.M. Skirvin

A system to propagate tronchuda (Brassica oleracea var. tronchuda Bailey syn. costata L.) from main stem and side shoot cuttings was developed by removing the main stem (three to four leaves) and, later, side shoots from S-week-old plants, transplanting them into small pots, and growing them under a mist system for 4 weeks. New root growth appeared on cuttings within 3 weeks. Rooting frequency varied among cultivars and explant types. For all cultivars, side shoot cuttings rooted better than main stem cuttings (99.7% vs. 84.8%). For all cultivars, seed-propagated plants and side shoot cuttings produced leaves with significantly higher fresh weight than the main stem cuttings for three of the five cultivars. The average number of leaves per plant for four cultivars was, however, not significantly affected by propagation method. Average leaf count and fresh weight per plant were significantly higher for `Portuguesa' than for `Ana Maria'. `Couve Penca'. `Vilinda', and `Penca de Chaves' for all three propagation sources.

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Thomas E. Marler

conservation and restoration and 2) that large stem cuttings may be further considered for tree restoration projects only if more research identifies constraints to improved success rates. Asexual propagation of healthy Cycas plants is routinely accomplished

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Hongyi Zhang, William R. Graves and Alden M. Townsend

We determined transpiration rate, survival, and rooting of unmisted, softwood cuttings of `Autumn Flame' red maple (Acer rubrum L.) and `Indian Summer' Freeman maple (Acer ×freemanii E. Murray). Effects of perlite at 24, 30, and 33 °C were assessed to determine whether responses of cuttings would be consistent with cultivar differences in resistance to root-zone heat previously shown with whole plants. During 7 d, cutting fresh mass increased by ≈20% at all temperatures for `Autumn Flame' red maple, but fresh mass of `Indian Summer' Freeman maple decreased by 17% and 21% at 30 and 33 °C, respectively. The percentage of cuttings of `Indian Summer' that were alive decreased over time and with increasing temperature. Transpiration rate decreased during the first half of the treatment period and then increased to ≈1.1 and 0.3 mmol·m-2·s-1 for `Autumn Flame' and `Indian Summer', respectively. Mean rooting percentages over temperatures for `Autumn Flame' and `Indian Summer' were 69 % and 16%, respectively. Mean rooting percentages at 24, 30, and 33 °C over both cultivars were 74%, 29%, and 25%, respectively. Over temperatures, mean root count per cutting was 41 and seven, and mean root dry mass per cutting was 4.9 and 0.4 mg, for `Autumn Flame' and `Indian Summer', respectively. Use of subirrigation without mist to root stem cuttings was more successful for `Autumn Flame' than for `Indian Summer'. Temperature × cultivar interactions for cutting fresh mass and the percentage of cuttings remaining alive during treatment were consistent with previous evidence that whole plants of `Autumn Flame' are more heat resistant than plants of `Indian Summer'. Mass and survival of stem cuttings during propagation in heated rooting medium may serve as tools for screening for whole-plant heat resistance among maple genotypes.

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Wayne A. Mackay, Brent Pemberton, Joseph Maxim and Suresh D. Pillai

Pelargonium × hortorum ‘Tango Dark Red’, ‘Tango Pink’, ‘Americana Red’, and ‘Rocky Mountain Lavender’ unrooted cuttings were subjected to Electron beam (E-beam) irradiation at 0 (control, no treatment), 0.61 ± 0.04, 0.83 ± 0.07, or 1.02 ± 0.01 kGy (mean ± se, n = 4) in Expt. 1 and 0 (control, no treatment), 0.08 ± 0.00, 0.16 ± 0.00, 0.31 ± 0.00, or 0.57 ± 0.02 kGy (mean ± se, n = 4) in Expt. 2. Cuttings exposed to E-beam irradiation other than the control treatment did not root or form callus and exhibited a change in leaf color from green to red and eventually yellow. Our results suggest that the use of ionizing irradiation for preventing the accidental importation of biothreat agents through unrooted Pelargonium cuttings is not feasible.