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  • Author or Editor: Robert L. Geneve x
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The influence of flowers on root formation in mum cuttings was evaluated for stock plants grown under long (LD) or short (SD) days. SD plants showed visible flower buds after 20 days and color after 30 days. Cuttings were taken from LD or SD plants at 10-day intervals until flowers were fully open. Cuttings from LD plants rooted at 100% throughout the study, with 24 or more roots per cutting. Cuttings from SD plants showed a gradual reduction in rooting percentage and number as flower development increased. After 30 days, roots per cutting for SD plants was reduced by 85% compared to LD cuttings and only 30% of SD cuttings rooted. In a separate experiment, cuttings were taken from stock plants after 40 long or short days. Partial or all flower buds were removed from SD plants prior to sticking. SD cuttings (regardless of flower bud removal) rooted at <47%. LD cuttings rooted between 23.6 to 43.8, while SD cuttings rooted between 3.1 and 8.5 roots per rooted cutting. The data indicates that cuttings taken from flowering plants show reduced potential for rooting and that this effect was not influenced by removal of flowers prior to sticking cuttings.

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Marigold seedlings were grown in four containers that differed in both volume and shape. Seedlings grown in 1.5-gal containers showed the greatest potential for shoot and root development 20 days after sowing. These seedlings had greater leaf area, shoot and root dry weight, and total root number and length compared to seedlings grown in 406 plug trays, 72-cell packs, or 6-inch containers. There was a positive correlation (r 2 = 0.81) between cell volume and seedling growth as well as a positive correlation (r 2 = 0.89) between container height with seedling growth. An attempt was made to separate the impact of container volume vs. container height on seedling growth. Containers were designed using acrylics to vary the container height while keeping the volume constant at 1500 cm3. There was a positive correlation (r 2 = 0.87) between shoot and root dry weight with container height. The data suggest that both container volume and height contribute to overall seedling growth in marigold, but when container volume is not limiting, container height has a large impact on seedling development.

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Seed coat anatomy in the hilar region was examined in dry, imbibed and germinating seeds of Eastern redbud. A discontinuous area was observed between macrosclereid cells in the palisade layer of the seed coat which formed a hilar slit. A symmetrical cap was formed during germination as the seed coat separated along the hilar slit and was hinged by the macrosclereids in the area of the seed coat opposite to the hilar slit. The discontinuity observed in the palisade layer was the remnant of the area traversed by the vascular trace between the funiculus and the seed coat of the developing ovule. There were no apparent anatomical differences in the hilar region of the seed coat between dormant and non-dormant imbibed seeds. However, the thickened layer of mesophyll cells of the seed coat in this region and the capacity of the endospetm to stretch along with the elongating radicle may contribute to maintaining dormancy in redbud seeds.

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Abstract

Adventitious root initiation decreased in ‘Berken’ mung bean cuttings treated with ≥ 10−4 m (2-chloroethyl) phosphonic acid (ethephon). Ethephon at 10−3 but not 10−5 m reduced root length and caused a redistribution of roots along the hypocotyl. The application of ethephon in combination with indoleacetic acid (IAA), indolebutyric acid (IBA), naphthaleneacetic acid (NAA), and 2,4-dichlorophenoxyacetic acid (2,4-D) reduced root initiation. An initial treatment of ethephon followed by NAA, or NAA followed by ethephon, inhibited root initiation to the same degree. Ethephon—whether applied at the time of cutting preparation or up to 12 hours later—inhibited root initiation to the same extent.

Open Access

Abstract

Ethylene liberated from control and auxin-treated cuttings of Vigna radiata (L.) R. Wilcz cv. Berken was monitored for 14 hours. For root initiation, naphthaleneacetic acid (NAA) and indolebutyric acid (IBA) were the most effective with indoleacetic acid (IAA) intermediate and 2,4-dichlorophenoxyacetic (2,4-D) the least effective. No correlation was observed between the quantity of auxin-induced ethylene evolved and the number of roots formed. Decreasing the NAA solution pH from 7.0 to 3.0 reduced the evolution of ethylene but did not alter the rooting response of the cuttings. It was concluded that stimulation of adventitious root initiation by auxin is not mediated by ethylene.

Open Access

An interactive computer version of a traditional Extension educational publication was developed for delivery over the Internet. Large Trees for Kentucky Landscapes is a 40-page publication describing suggested species adapted to Kentucky conditions. It is illustrated with numerous color photographs. This type of Extension publication has a limited distribution because it is relatively expensive to publish. The digital version of this publication allows for inclusion of additional information and illustrations. It was designed to be interactive with the user selecting the species and the information about that species from a screen menu. The user also has the option to print a one page informational sheet on that species. The initial audience for this digital version of the publication is the county Extension agent and Division of Forestry personnel, but it may also be useful at retail horticultural outlets.

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Satin flower (Clarkia amoena ssp. whineyi: syn. Godetia whitneyi) is a cool temperature, high light plant grown as a cutflower in Japan, Europe and California. In preliminary greenhouse cutflower and pot plant trials, satin flower plants flowered in 10-11 weeks when grown under 24hr supplemental HID lighting compared to 20-22 weeks under ambient winter conditions. In Sept. and Nov. 1989, satin flower plants were treated with the following supplemental and photoperiodic lighting treatments ambient light; SD (ambient day, black cloth 1600 to 800 HR); LD (ambient day, incandescent light 1600 to 400 HR, 5 μmol s-1 m-2); SD-SPL (ambient day supplemented with 100 μmol s-1m-2 HPS, black cloth 1600 to 800 HR); LD-SPL (ambient day supplemented with 100 μmol s-1m-2 800 to 400 HR), Node number and days to flowering were significantly different between the treatments. Plants grown under LD-SPL flowered in 10 weeks and had 32 nodes, LD -13 weeks and 37 nodes (weak, spindly, few flowers), SD-SPL - 17 weeks and 70 nodes, SD - 21 weeks and 75 nodes. Strategies for supplemental lighting for greenhouse cutflower production will be discussed.

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Warm season annual flowers were trialed as field grown cutflowers in the summer of 1989. Plants were transplanted to the field in early or late May and grown at densities of 40 plants m-2 in beds with black plastic mulch, trickle irrigation and support wires. Tall ageratum, `Horizon Blue'., plants were harvested throughout the summer with total yields of 290 stems m-2with stem lengths over 36 cm long. Stem lengths increased significantly over the summer; 40% of the stems harvested in September were over 56 cm long. Spray asters, `Matsumoto Blue', Matsumoto Red' and `Serene Red', were harvested eight weeks after transplanting with yields of 20 to 30 stems m-2; 60% of the stems were 36-45 cm long and 40% were 46-55 cm long. Tall, crested celosia, `Red Chief', `Gold Chief' and `Fire Chief', plants were harvested 8 weeks after transplanting with yields of 45 stems m-2 over 60% of the stems were 45 cm long or longer. Godetia, `Grace Red' and `Grace Salmon', plants sown March 3 and planted in the field April 10, performed well; later plantings were much less successful. Plants were planted at a density of 5 m-2 and produced 25 to 50 flower stems per plant; stem lengths were 30 to 38 cm long.

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A laboratory exercise is presented that demonstrates the impact of seed coverings and hormones on seed dormancy and release in seeds with endogenous, physiological dormancy. The materials and methods are simple and inexpensive and can be accomplished as an on-campus laboratory or as a distance education exercise. The execution of the laboratory is rapid (≈1 hour), and the results are obtained in 2 weeks. The exercise generates an opportunity for the discussion of a complex subject that involves the interaction of two tissue types within the seed (the embryo vs. the seed coverings) and nicely illustrates their role in seed dormancy maintenance.

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Exogenous ethylene could not substitute for NAA to induce adventitious root initiation in juvenile petiole explants of English ivy (Hedera helix L.), indicating that the action of auxin-stimulated root initiation was not directly mediated through ethylene production. Mature petioles did not initiate roots under any auxin or ethylene treatment combination. Ethephon or ACC supplied at 50 or 100 μm was inhibitory to NAA-induced root initiation in juvenile petioles. The pattern of ethylene production stimulated by NAA application was significantly different in juvenile and mature petioles. Ethylene evolution by juvenile petioles declined to near control levels during from 6 to 12 days after NAA application. Reduction in ethylene production was due to reduced availability of ACC in juvenile petioles. Mature petioles continued to produce ethylene at elevated levels throughout the course of the experiment. Ethylene does not appear to play a significant role in the differential root initiation response of juvenile and mature petioles treated with NAA. However, ethylene appeared to have an inhibitory effect during root elongation stages of adventitious root development in juvenile petioles. Chemical names used: 1-aminocyclopropane-1-carboxylic acid (ACC); 1-napthaleneacetic acid (NAA); 2-chloroethylphosphonic acid (ethephon).

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