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  • Author or Editor: Yin-Tung Wang x
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The woody stem core of kenaf (Hibiscus cannabinus L.) was ground and used without composting as a container medium amendment for the production of several tropical foliage and nursery species. Media made of various proportions of kenaf and peat moss were amended with micronutrients, gypsum, dolomitic lime stone powder, superphosphate, Osmocote, a wetting agent and a fungicide. Plant growth in these media was compared to that in two widely used commercial media. Brassaia actinophylla in kenaf amended media grew taller and had more leaves, heavier weight, and better root grade than those produced in the two commercial media. Pittosporum tobira plants in kenaf media were taller, wider, and heavier than those grown in the commercial media. Other species tested also responded favorably to media amended with kenaf. Media containing the ground kenaf core tended to maintain the optimum pH better and their leachate samples had lower electrical conductivities than the commercial media. Shrinkage was a problem when 100% fine ground kenaf was used, but this was greatly reduced by adding peat moss or using a coarser grind. Media containing kenaf required more frequent watering than did the commercial media.

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Abstract

Live oak (Quercus virginiana Mill.) traditionally has been propagated by seed because vegetative propagation has not been successful on a commercial scale (Flemer, 1962; Maynard and Bassuk, 1987; Morgan and McWilliams, 1976). However, as a result of seedling variability, live oaks offered for sale exhibited varied growth forms with variable quality.

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A study was initiated to determine the effect of GA3 as a counter measure to restore the growth of over-retarded poinsettia. Euphorbia pulcherrima `Sonora Red' plants were treated once foliarly with paclobutrazol at 40 or 80 mg·L-1 one week following pinching. Four weeks later, plants receiving the 80 mg·L-1 rate were treated once foliarly with GA3 at 0, 10, 20, 30 or 40 mg·L-1. The effect of GA3 was visible within 3 days of application. GA3 between 10 and 40 mg·L-1 caused long internodes, excessive stem elongation, as well as small leaves and bracts, resulting in unmarketable plants. Plants receiving 10 mg·L-1 GA3 were nearly twice the height of the over-retarded plants (31 vs. 17 cm), with increasingly taller plants at higher concentrations, up to 30 mg·L-1. In a second experiment, single-stemed plants were treated with one foliar spray of 50 or 150 mg·L-1 paclobutrazol two weeks following the beginning of short days. After another 3 weeks, the overdosed plants were then foliarly treated once with 0, 3, 5, 10, or 15 mg·L-1 GA3. GA3 at all rates promoted stem elongation and resulted in large bracts and much increased inflorescence diameter. The 15 mg·L-1 GA3 rate resulted in undesirable long internodes on the upper stem. Plants that received 3, 5, or 10 mg·L-1 GA3 were of excellent quality, with their heights and inflorescence sizes similar to those of plants receiving 50 mg·L-1 paclobutrazol (26 cm). Parallel experiments using `Burgundy Cortez' had similar results.

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Vegetatively propagated Phalaenopsis Atien Kaala `TSC 22' plants 10 cm in leaf spread were potted in a medium that consisted of either 100% fine grade Douglas fir bark or a mixture of 70% fir bark and 30% sphagnum peat. Plants were fertigated at each irrigation with 10N-13.1P-16.6K (10-30-20), 20N-2.2P-15.8K (20-5-19), 20N-8.6P-16.6K (20-20-20), or a 2N-0.4P-1.7K (2-1-2) liquid fertilizer at a common N rate of 200 mg•L-1. After 1 year in a greenhouse, plants grown in the bark/peat medium produced more leaves and had heavier fresh weights and larger total leaf areas than those in 100% bark. In the bark medium, the 20N-2.2P-15.8K fertilizer resulted in best plants, despite its low P concentration (22 mg•L-1). When grown in bark/peat, the two fertilizers (20N-2.2P-15.8K and 20N-8.6P-16.6K) containing urea as part of their N source (10% and 52%, respectively) resulted in plants with 40% to 50% heavier shoot fresh weight and 40% larger leaf area than the other fertilizers. With any given fertilizer, plants had similar root weights in both media. Media and fertilizers had limited or no effect on the concentrations of minerals in the second mature acropital leaves except P, the concentration of which nearly doubled in leaves of plants grown in 100% bark. Water extracts from the bark/peat medium had lower pH, higher EC, and elevated levels of NH4-N, Ca, Fe, Na, Cl, B, and Al than those from 100% bark. Exacts from the bark medium did not have detectable levels of NO3-N, whereas extracts from the bark/peat medium all had similar levels of NO3-N, regardless of which fertilizer was applied.

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Live oak trees raised from acorns are highly non-uniform and many produce numerous undesirable rhizomic shoots. The objectives of this study were to 1) compare the growth rates between (Quercus virginiana Mill.) trees from seed and cutting in four production systems and 2) determine if trees from cuttings produce rhizomic shoots. Rhizomic shoot cuttings 25–30 cm long were taken from a single tree about 50 years old in late Aug. 1990, rooted, and planted in 2.6-L pots after 2 months. During the same week, acorns were collected from the same tree and germinated. All trees were planted into 13-L pots in July 1991 and then to a field in July 1992. Trees from both sources were planted either directly in the ground, in 36.6- or 45.7-cm-diameter polypropylene fabric bags buried in the ground, or in 13-L pots on the ground. Trunk circumference 10 cm above the soil line was roughly measured yearly between 1992 and 1999. Initially, trees from cuttings grew slightly slower than seedlings, having a smaller trunk circumference, diameter, and cross-sectional area. These differences diminished and all trees had similar circumferences after 1996. In 1992, trees in 36.6-cm bags and pots had more growth than trees in the ground. In 1993, trees in pots had better growth than those in the ground. After 1993, all trees had similar circumferences until the end of this study, probably due to roots extending beyond the bags and pots into the surrounding soil. About one-third of the seedling trees produced rhizomic shoots, whereas none of the trees from cuttings did. The rhizomic shoots of trees in pots were contained within the pot and none from the ground. Another significance of this research is that the cloned trees from cuttings were extremely uniform in growth habit and form.

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Abstract

In the article “Respiration and Weight Changes of Easter Lily Flowers during Development” by Yin-Tung Wang and Patrick J. Breen [HortScience 19(5):702-703] the captions for the 2 graphs were reversed

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Lilium longiflorum Thunb. `Nellie White' plants grown under 1300 μmol·m-2·s-1 maximum photosynthetic photon flux (PPF) in a greenhouse deliberately were completely defoliated when the oldest flower bud was 2, 4, or 7 cm long. Plants were then placed in growth chambers in darkness or in the light (250 μmol·m -2·s-1 PPF, 10 hours) with 25C air, along with intact plants as controls; all were harvested at the completion of flowering. Defoliation at the 2- and 4-cm bud stages resulted in complete flower abortion, with or without light. Plants defoliated at the 7-cm stage and kept in light had 60% of the flower buds develop to anthesis but depleted more scale reserves. Those defoliated at the 7-cm stage and kept in darkness had complete flower abortion; however, bulb weights remained similar to those of the intact plants kept in the light.

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Drench paclobutrazol or uniconazole applications (0.1-1.0 mg/0.5-liter pot or 0.05-0.2 mg/pot, respectively) were effective in suppressing stem elongation of golden pothos [Epipremnum aureum (Linden & Andrè) Bunt.]. Although the leaf production rate was reduced by both retardants, treated plants produced larger leaves than the controls, resulting in greater total leaf areas. Response to foliar paclobutrazol or uniconazole applications (0-200 and 0-100 mg·liter-1, respectively) was similar to the soil drench patterns, except that the leaf production rate was unaffected. Following 10 weeks in an interior environment, plants previously treated with either retardant produced shorter stems, fewer but larger leaves, and lower fresh weights than the nontreated plants. Cuttings collected from stock plants previously treated with a paclobutrazol or uniconazole soil drench (0.1 or 0.05 mg/0.5-liter pot, respectively) produced longer stemmed shoots, more and larger leaves, and heavier shoot fresh weights than cuttings from the nontreated plants. Foliar paclobutrazol application (0-200 mg·liter-1) to stock plants resulted in cuttings producing larger leaves and heavier shoot fresh weights than controls. Chemical names used: (2RS,3RS)-1-(4-chlorophenyl)-4,-4-dlmethyl-2-(l,2,4-trizol-l-yl)pentin-3-ol (paclobutrazol);(E)-1-(4-chlorophenyl)-4,-4-timethyl-2-(1,2,4-trizol-l-yl)l-penten-3-ol (uniconazole).

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Bare-root seedling plants of a white-flowered Phalaenopsis hybrid [P. arnabilis (L.) Blume × P. Mount Kaala `Elegance'] were grown in five potting media under three fertility levels (0.25, 0.5, and 1.0 g·liter-1) from a 20N-8.6P-16.6K soluble fertilizer applied at every irrigation. The five media included 1) 1 perlite:1 Metro Mix 250:1 charcoal (by volume); 2)2 perlite:2 composted pine bark:1 vermiculite; 3) composted pine bark; 4) 3 perlite:3 Metro Mix 250:1 charcoal; and 5) 1 perlite:1 rockwool. During the first flowering season, plants in the 1 perlite: 1 Metro Mix 250:1 charcoal medium had slightly fewer but larger flowers and thicker stalks (section of the inflorescence between the base and oldest flower) than those in the 1 perlite:1 rockwool medium. Medium had no effect on stalk length. Two media (3 perlite: 3 Metro Mix 250: 1 charcoal and 1 perlite: 1 rockwool) resulted in root systems that were inferior to those in the others. Fertilizer level had no effect on bloom date or flower size. Regardless of medium, increasing the fertility from 0.25 to 1.0 g·liter-1 increased flower count, stalk diameter and length, and leaf production following flowering. During the second flowering season, media had limited effect on plant performance. Increased fertility promoted earlier inflorescence emergence and blooming. Higher fertilizer rates also caused a linear increase in the number of flowers and inflorescences per plant, and in stalk diameter, total leaf count, and leaf size.

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Bare-root, mature, hybrid Phalaenopsis seedlings were dipped in one of three growth retardant solutions for 5 seconds or sprayed with a growth retardant 4 weeks following planting during inflorescence elongation. Dipping the entire plant in daminozide (2500, 5000, or 7500 mg·liter-1) before planting delayed flowering by 5-13 days, whereas foliar applications had no effect. Paclobutrazol (50, 100, 200, or 400 mg·liter-1) or uniconazole (25, 50, 100, or 200 mg·liter-1) dips did not affect the bloom date but effectively restricted inflorescence growth below the first flower (stalk). Increasing concentrations produced progressively less growth. Foliarly applied retardant treatments were less effective than dipping. Flower size, flower count, and stalk thickness were unaffected by treatments. Dipping in high concentrations of paclobutrazol (200 or 400 mg·liter-1) or uniconazole (100 or 200 mg·liter-1) caused plants to produce small, thick leaves. During the second bloom season, inflorescence emergence and bloom date were progressively delayed by increasing concentrations of paclobutrazol and uniconazole. Neither retardant affected flower count or size. Foliarly applied daminozide increased stalk length. In another experiment, foliar paclobutrazol treatment restricted stalk growth more effectively when sprayed before inflorescence emergence. Its effect progressively decreased when treatment was delayed. Paclobutrazol concentrations from 125 to 500 mg·liter-1 were equally effective in limiting stalk elongation when applied to the foliage. Chemical names used: butanedioic acid mono (2,2-dimethylhydrazide) (daminozide); (E)-1- (p -chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol(uniconazole); (2 RS, 3 RS) -1-(4-chlorophenyl)-4,4-dimethyl-2-(1 H- 1,2,4-triazol-1-yl) pentan-3-ol (paclobutrazol).

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