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Some species of the genus Tillandsia (Bromeliaceae) are highly endangered in their natural habitats. This report introduces a method for induced lateral shoot development in atmospheric Tillandsias using the cytokinin BAP. Spraying or dipping the plants with BAP-solutions induced many lateral shoots. Even difficult-to-propagate species like T. cacticola L.B.SM developed up to 30 times more usable shoots than the control. Applying low concentrations (1 and 5 mg·L-1) over a longer period of time (10 weeks, 3 times a week) produced results similar to those using higher concentrations (50 mg·L-1) for shorter periods (2 weeks, 3 times a week). Chemical name used: 6-benzylaminopurine (BAP).

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Abstract

Leaf explants from ‘Sugar Daddy’ and ‘Sugar Plum’ petunia (Petunia hybrida L.) were pretreated in solutions of 0, 200, 400, and 800 mg/liter 6-benzylamino purine (BA) and were placed in a cytokinin-free modified Murashige and Skoog (MS) medium, to which 0.05, 0.1, or 0.2 mg/liter naphthaleneacetic acid (NAA) were incorporated to test interaction. NAA at 0.05 or 0.1 mg/liter increased shoot number, fresh weight, and shoot quality rating for ‘Sugar Daddy’, while in ‘Sugar Plum’ addition of NAA increased shoot fresh weight and improved shoot quality rating without any effect on shoot number.

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Abstract

A procedure to regenerate shoots in vitro from leaf sections of two blueberry genotypes, ‘Berkeley’ and ‘Bluehaven’, in Woody Plant Medium was established. The effect of 20 combinations of growth regulators: NAA at 0, 1, 2, and 4 µM and 2iP at 0, 5, 10, 15, and 20 µM were compared. Combinations containing NAA generally promoted callus formation and suppressed shoot regeneration. Conversely, media containing cytokinin promoted shoot regeneration and suppressed callus formations. The optimal medium for shoot regeneration contained 15 µM 2iP but no NAA. This procedure was highly efficient (70%–100%) in producing large numbers of shoots in a relatively short period (4 weeks). Chemical names used: N-(3-methyl-2-butenyl)-1-H-purine-6-amine (2iP); 2-(l-naphthyl)acetic acid (NAA).

Open Access

Explants of mature pot-grown Vaccinium corybosum L. cultivars were tested for initiation of new shoots using two growing conditions and four cytokinin treatments. Initiation tests with 12 genotypes showed significantly higher rates of new shoot growth on modified woody plant (MWPM) medium with 4 mg zeatin/liter at 25C under low light intensity than on any other treatment. Explants at 25C in light with 10 or 15 mg 2iP/liter initiated at a moderate rate, but significantly lower rates were found for all controls and at 4C in darkness. To determine the utility of zeatin for initiation of diverse genotypes, 96 Vaccinium accessions from the National Clonal Germplasm Repository, representing 22 species and 44 cultivars, were screened using 25C and low light intensity. Initiation rates higher than 60% were achieved for 89 of 96 accessions tested. Chemical name used: N6-[2-isopentenyl] adenine (2iP), 6-[4-hydroxy-3-methylbut-2-enylamino]purine (zeatin).

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In reciprocal grafts of tall (`Elberta' and `Loring') and dwarf (`Empress' and `Juseito') peach (Prunus persica Batsch.) phenotypes, we measured dry-matter partitioning, resistance to root system water flow, and phytohormone content of xylem exudate. Scion characteristics determined the phenotype and growth characteristics of the tree irrespective of the rootstock. Tall phenotypes had higher dry weight and lower root resistance to water flow than dwarf phenotypes. Cytokinin-like activity and auxin levels in xylem sap were higher in dwarf than in tall phenotypes; whereas gibberellin-like activity was unaffected by either rootstock or scion. The scion of peach influenced phytohormone levels and resistance to water flow in the root system in addition to root and shoot growth.

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. To become a viable commercial crop, an efficient system to supply rhizomes would be needed from specialty growers. Therefore, the objective of this research was to investigate shoot formation efficiency related to rhizome size and cytokinin treatment

Open Access

studied using explants of different origin (seedlings grown in vitro, mature, native, and greenhouse plants) for culture establishment, testing various cytokinins for shoot growth and proliferation, as well as examining various IBA concentrations and

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Changes in hormone concentrations in leaf, node, shoot tip, and fruit samples of three Turkish olive (Olea europaea L.) cultivars (`Gemlik', `Memecik', and `Tavsan Yuregi') were monitored at monthly intervals over two successive years of the alternate-bearing cycle. Concentrations of abscisic acid (ABA), indole acetic acid (IAA), gibberellic acid-like substances (GA), and kinetin-like cytokinin were determined and their relationship to flower bud formation were examined during “on” and “off” years. Results showed significant differences in IAA, ABA, GA3-like, and kinetin-like cytokinins between “on” and “off” cropping years in various tissues of olive trees. Relative balances between GA3-like and ABA concentrations of tissues appears to exhibit evidence of being a key regulator of floral development and alternate bearing.

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Lilium longiflorum Thunb. `Nellie White' plants were selected when their first flower buds reached 2 or 5 cm in length, sprayed with 2 mL of PBA at 0 or 500 mg·L–1, and then placed under 1440 or 60 μmol·m–2·s–1 photosynthetic photon flux (PPF) during flowering. PBA resulted in delayed anthesis and increased dry matter accumulation in flowers under the high PPF but had no effect under the low PPF. PBA did not decrease the severity of flower bud abortion under the low PPF. Application of PBA induced the formation of numerous bulbils in the leaf axils. Regardless of PPF, PBA-treated plants had less dry weight in the main bulbs than the control plants. Chemical name used: N-(phenylmethyl)-9-(tetra-hydro-2H-pyran-2-yl)-9H-purin-6-amine (PBA).

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Abstract

Gibberellins (GA) will stimulate parthenocarpic fruit development in apples (1, 4, 5, 9). Davison (4) found GA3 to increase fruit set in the Red Jersey variety to a greater extent than in Sturmer. Bukovac (1) observed that GA4 was more effective than GA3 in promoting fruit set in the Sops-of-Wine variety. Varga (9) reported that GA1, GA2, GA4, and GA7 promoted parthenocarpic fruit set in the Lombartscal-ville variety but not in the Winston or Golden Delicious varieties.

Open Access