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Hyperhydricity of shoots initiated in vitro, poor shoot extension, inability of shoot cultures to maintain good growth over an extended time, and unsuccessful ex vitro rooting have limited the development of a commercial scale micropropagation system for hemp (Cannabis sativa). We present a culture initiation method that prevents shoot hyperhydricity using vented-lid vessels with 0.2-mm pores and medium containing agar at 1% (w/v). To optimize shoot multiplication in vitro, a controlmedium(mediumA) and four treatmentmedia (medium B,C,D, and E), with varying inorganic nutrients and vitamins were tested. Control medium A consisted of 1×Murashige and Skoog (MS) with vitamins plus 3% (w/v) sucrose, 0.5 mg·AL-1 metatopolin, 0.1 mg·AL-1 gibberellic acid, and 0.8% agar (w/v) at pH 5.7. The four treatment media differed from the control medium as follows: medium B, 2.5·MS with vitamins; medium C, 1·MS with vitamins plus added mesos [calcium chloride (anhydrous), magnesium sulfate (anhydrous), and potassium phosphate (monobasic) nutrients]; medium D, 1· MS with vitamins plus added vitamins; and medium E, 1· MS with vitamins plus added mesos and vitamins. Medium C and medium E produced more microcuttings than the control at 6 weeks after the initial subculture with shoot multiplication media and all other treatments at 9 and 12 weeks. Shoots grown on these twomedia displayed optimal extension and leaf lamina development; however, they exhibited slight chlorosis by 12 weeks after subculture with shoot multiplication media. In a separate experiment, medium E was supplemented with ammonium nitrate at 0, 500, 1000, or 1500 mg·AL-1, and cultures grown with 500 mg·AL-1 produced the most microcuttings and exhibited the best combination of shoot extension and leaf lamina development. We provide a method of prerooting microshoots in vitro that has resulted in 75% to 100% rooting ex vitro in rockwool. Using 10 recently micropropagated plants, 300 retip cuttings (cuttings taken fromnew shoots fromrecentlymicropropagated plants) were harvested over 10 weeks. The average weekly rooting was more than 90%. Retipping can produce ninetimes as many plants in a similar amount of floor space as stem cuttings derived from traditional stock mother plants. The micropropagation/retipping method proposed can be a more efficient way to generate clonal liner plants for commercial-scale production. [ABSTRACT FROM AUTHOR]

ABSTRACT:New Jersey tea (Ceanothus americanus L. [Rhamnaceae]), sand cherry (Prunus pumila L. [Rosaceae]), and sweetbells (Eubotrys racemosa L. [Ericaceae]) are eastern US native shrubs with high potential for expanded landscape use because of their numerous ornamental attributes and adaptability. Micropropagation protocols were developed for these species that produce acceptable shoot multiplication rates, 100% microcutting rooting, and high-quality liner plants. New Jersey tea is not easily produced from seed or stem cuttings for commercial purposes, but we have demonstrated that micropropagation is a viable method for commercial propagation. In addition, micropropagation can be effectively used to rapidly propagate new superior genotypes of sand cherry and sweetbells.

Red-flowered elepidote rhododendrons (Rhododendron sp.) are favored by consumers, but cold-hardy red-flowered rhododendrons frequently have blue-red flower hue rather than the preferred red flower hue. Flower longevity, color, and color stability over 14 days were studied for the following eight elepidote rhododendron cultivars possessing red flowers: Besse Howells, Burma, Cary's Red, Firestorm, Francesca, Henry's Red, Low Red Frilled, and Nova Zembla. The eight cultivars were separated by flower hue into two distinct groups of four cultivars each. Rhododendron cultivars Burma, Firestorm, Francesca, and Henry's Red produced flowers with red hue and Besse Howells, Cary's Red, Low Red Frilled, and Nova Zembla produced flowers with blue-red hue. Flower longevity among rhododendron cultivars varied with Francesca blooms lasting the longest at over 14 days, and Besse Howells and Firestorm blooms lasting the shortest at ≈10 days. As flowers aged, hue angle decreased (became bluer), lightness increased, and chroma decreased or remained unchanged. The degree of change in flower color over time differed among cultivars, with 'Francesca' demonstrating the least change (ΔE00 ≈ 3) and 'Besse Howells' the most change (ΔE00 ≈ 11). [ABSTRACT FROM AUTHOR]

A conference paper about the better breeding of Aronia Plants that was presented at the 63rd annual meeting of North America held from October 9-13, 2013 in Illinois. Topics discussed include studying Aronia as an ornamental crop and fruit crop, information on the Aronia's germplasm, ploidy and apoximes, and intergeneric hybridization in the pyrinae.

Survey data from 114 members (42% response rate) of the Connecticut Nursery and Landscape Association were analyzed to evaluate preferences for different potential solutions to reduce the annual sale of billions of dollars of invasive ornamental plants. The majority of respondents accurately identified key invasive plant characteristics, considered themselves to be knowledgeable about invasive plants, and cited trade journals and professional organizations as their sources of invasive plant information. Although industry members generally considered norway maple (Acer platanoides), japanese barberry (Berberis thunbergii), and winged euonymus (Euonymus alatus) to be invasive, only 14.5% and 8.1%, respectively, considered the emerging invasive species japanese silver grass (Miscanthus sinensis) and butterfly bush (Buddleja davidii) to be invasive. In comparing different approaches to reducing the sale of invasive ornamental plants, strong support was expressed for marketing noninvasive alternative plants (mean rank of 2.5) and for development of genetically altered sterile forms of invasive ornamentals (mean rank of 2.9; on a scale from 1 = most favorable to 6 = least favorable). Respondents strongly disfavored taxation as a method of reducing invasive plants sales (mean rank of 5.0) even if proceeds were directed toward invasive plant control and research. Plant bans (mean rank of 4.1) were also an unpopular choice for economically important crops, and respondents desired provisions for cultivars with reduced invasive risk to be included in plant bans. To foster maximum green industry participation in invasive plant control efforts, future directions should focus on creation of sterile forms of popular landscape plants, identification of consumer preference for noninvasive alternatives, and development of strong consumer education programs. [ABSTRACT FROM AUTHOR]

Discusses the reproduction and seedling traits of berberis thunbergii cultivars. Nature of berberis thunbergil; Varieties of berberis thunbergii; Relevance of the seed production levels and seedling traits of berberis thunbergii in the plant's invasive potential.

Container production of nursery crops is intensive and a potential source of nitrogen release to the environment. This study was conducted to determine if trickle irrigation could be used by container nursery producers as an alternative to standard overhead irrigation to reduce nitrogen release into the environment. The effect of overhead irrigation and trickle irrigation on leachate nitrate N concentration, flow‐weighted nitrate N concentration, leachate volume, and plant growth was investigated using containerized rhododendron (Rhododendron catawbienseMichx. ‘Album’) supplied with a controlled‐release fertilizer and grown outdoors on top of soil‐monolith lysimeters. Leachate was collected over two growing seasons and overwinter periods, and natural precipitation was allowed as a component of the system. Precipitation accounted for 69% of the water entering the overhead‐irrigated system and 80% of the water entering the trickle‐irrigated system. Leachate from fertilized plants exceeded the USEPA limit of 10 mg L−1at several times and reached a maximum of 26 mg L−1with trickle irrigation. Average annual loss of nitrate N in leachate for fertilized treatments was 51.8 and 60.5 kg ha−1for the overhead and trickle treatments, respectively. Average annual flow‐weighted concentration of nitrate N in leachate of fertilized plants was 7.2 mg L−1for overhead irrigation and 12.7 mg L−1for trickle irrigation. Trickle irrigation did not reduce the amount of nitrate N leached from nursery containers when compared with overhead irrigation because precipitation nullified the potential benefits of reduced leaching fractions and irrigation inputs provided under trickle irrigation.

Leaf explants harvested from shoot proliferating cultures and intact plants of Liquidambar styraciflua ‘Variegata’ were placed on solidified Woody Plant medium supplemented with 0.1 mgl-1 (0.5 µM) naphthaleneacetic acid and 2.5 mgl-1 (11.1 µM) benzyladenine to initiate shoot meristems directly. Leaves from intact plants produced over 4 times more adventitious shoots than leaves from in vitro shoots and had a greater tendency to form shoots on the lamina. The relative developmental age of leaf tissue used dramatically influenced the shoot organogenic response observed for leaf explants from intact plants of L. styraciflua ‘Variegata’ and ‘Moraine’.-Leaves that were either 20% or 50% of full size and still actively expanding were superior to other developmental stages for shoot organogenesis. As developmental leaf age increased throughout the period of leaf expansion, the number of shoots forming on the petiole stub remained constant, whereas shoot formation on the lamina increased 8 fold. Shoots derived from ‘Variegata’ leaves rooted well and grew normally as plants. Differences in rooting ability and plant size could be detected between groups that had been separated according to explant source (in vitro vs. intact plant) and the location of shoot formation (petiole vs. lamina).

Shoot tip cultures of Amelanchier arborea Michx.f. were grown on Murashige & Skoog or Woody Plant (WP) medium containing 4.4 µM benzyladenine and various concentrations of agar. Increases in agar concentration affected various culture growth variables, decreased culture hyperhydricity and increased tissue nitrate concentration. Additions of ammonium nitrate to cultures grown on WP medium containing 0.4% agar increased all growth variables measured except percent dry weight. Hyperhydricity and tissue nitrate concentration also increase in response to increasing ammonium nitrate in the medium. Since hyperhydricity was shown to be both positively and negatively correlated with increases in tissue nitrate content, it is unlikely that tissue nitrate level alone directly affects hyperhydricity.

Shoot tips ofHalesia carolina L. andMalus domestica Borkh. ‘Golden Delicious’ collected at various times during the spring growth flush varied considerably in their ability to initiate shoot proliferating cultures. Shoot tips collected during, or at the end of, the period of most rapid shoot elongation exhibited weak shoot proliferation potential, while shoot tips collected before or after this period were capable of strong shoot proliferationin vitro. Benzyladenine concentrations in the culture media above 22.5 µM (Halesia) or 44.5 µM (Malus) were inhibitory during the period between bud break and rapid shoot elongation. Benzyladenine concentrations of 22.5 or 44.5 µM were useful in enhancing shoot proliferation potential in shoot tips collected after the period of rapid shoot elongation, but before the onset of summer dormancy. Benzyladenine concentration did not affect the shoot proliferation potential of shoot tips collected during the rapid shoot elongation phase of the spring growth flush.Halesia andMalus shoot tips behaved similarly in this study. For deciduous woody perennials, the time of explant collection for culture initiation could be refined on the basis of these results.

Halesia carolina L., a small, ornamentally valuable tree, is difficult to propagate due to the complexity of seed propagation and the unavailability of propagules for conventional vegetative propagation. A micropropagation system was developed to facilitate easy propagation of this species. Actively growing shoot tips achieved optimum shoot proliferation from axillary buds when placed on Woody Plant Medium supplemented with 1.0 to 2.5 mg/l benzyladenine. The addition of 0.1 mg/l naphthaleneacetic acid had little effect on culture performance. Murashige and Skoog medium was incapable of supporting vigorous shoot proliferation. Non-sterile rooting conditions provided better rooting and subsequent plantlet growth, when compared to an in vitro rooting method. The seasonal fluctuations in the stock plant dramatically affected the shoot proliferating potential of the explants in vitro. Rapidly elongating shoots formed shoot proliferating cultures more slowly than explants taken either before or after the rapid elongation phase.

The pattern of protein production during rejuvenation of in vitro cultured Betulawas determined. Comparisons were made between half‐sib seedlings and micropropagated, grafted, and cutting‐propagated mature‐phase birch grown under similar conditions. Three clones were examined at 1, 4, and 8 mo postpropagation, for differences in total denatured protein and peroxidase and esterase isozymes. Polyacrylamide gel electrophoresis was employed to produce protein banding patterns representative of each type of plant at each time postpropagation. Evaluation of total denatured protein banding patterns indicated that micropropagated plants are initially more like seedlings than mature plants. Peroxidase and esterase isozyme analyses detected differences in isozyme activity and composition between the variously propagated plants and supported evidence provided from the denatured protein patterns. The type of plant part that is evaluated is critical in determining if isozyme banding patterns can be seen. Specific proteins or enzymes that mediate phase change in birch could not be detected consistently between clones or tissue types.

The extent of rejuvenation that occurs during in vitro culture and propagation of Betulawas determined. Comparisons were made between half‐sib seedlings and micropropagated, grafted, and cutting‐propagated mature‐phase birch plants grown under similar conditions. To measure relative levels of juvenility, three clones were examined at 1, 4, and 8 mo postpropagation, for differences in stem and leaf morphology and the presence or absence of reproductive structures. Numerous morphological indicators of phase change in Betulawere identified. Micropropagated plants are not initially morphologically identical to conventionally propagated mature plants and display many features characteristic of seedlings. Micropropagated plants that exhibited juvenile morphology developed mature morphology more rapidly than did plants grown from seed. However, some mature‐phase morphological characteristics did not return to micropropagated plants during the time frame of the study. Rejuvenation of Betulaappears to occur during in vitro micropropagation, but the level of juvenility that is regained may not be equivalent to that of a seedling. Not all morphological indicators of phase change are affected equally by in vitro rejuvenation.

The article discusses the influence of propagation medium in sweet fern rhizome cutting success. It examines the effect of media on the success of rhizome cutting, and the determines the plant size that could be obtained in one growing season from rhizome cuttings. It reveals that cuttings propagated in vermiculite had 100 percent survival rate.