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  • Author or Editor: Yin-Tung Wang x
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Uniconazole and paclobutrazol were tested for their effects on greenhouse production of four foliage species. Soil drenches of uniconazole retarded shoot and petiole elongation of Brassaia actinophylla Endl. Paclobutrazol reduced shoot elongation, but required higher doses than uniconazole and did not reduce petiole growth. Foliar sprays with either retardant at 12.5 mg·liter-1 resulted in short stems on lateral shoots of Codiaeum variegatum (L.) Blume `Karen' after pinching, but soil drenches at low rates were less effective. Soil drenches of uniconazole or paclobutrazol were equally effective in reducing stem growth of Syngonium podophyllum Schott `White Butterfly' and increasing leaf width, but had no effect on the rate of leaf production or blade length. Both retardants induced short petioles in this species. Severe growth reduction occured on Plectranthus australis R. Br. even at the lowest rates of uniconazole and paclobutrazol (0.025 and 0.20 mg/pot, respectively) as soil drenches. Production of lateral shoots was inhibited for P. australis by both retardants. Chemical names used: (E)-1-(p-chlorophenyl)-4,4-dimethy1-2-(1,2,4-triazol-1-yl)-1-penten-3-ol (uniconazole); (2RS,3RS)-1-(4-chlorophenyl)-2-(1,1-dimethylethyl)-(H-1,2,4-triazol-l-Yl-)Dentan-3-ol (paclobutrazol).

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Rooted cuttings of Euphorbia pulcherrima Willd. ex Klotzsch cv. Gutbier V-14 Glory were planted in 2-liter containers with growth media having 0% to 75% composted cotton burrs (CCB) in combination with sphagnum peat and/or composted pine bark. Leachates from media with 50% or more CCB had higher initial electrical conductance (EC) (3.7 to 4.0 dS·m-l) than that from media with 25% or no CCB (2.8 to 3.0 dS·m-l) 2 weeks after planting. The differences in leachate EC declined after an additional 9 weeks. Media containing CCB produced slightly shorter and narrower plants with 10% smaller inflorescences and less dry weight than plants grown in a medium consisting of equal volumes of peatmoss and bark. Number of branches and bracts, days to bloom, and plant grade after 30 days under 15 μmol·s-l· m-2 photosynthetic photon flux were unaffected by media.

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Presently, there are no standards for producing Phalaenopsis Blume (the moth orchids) as a flowering, potted crop. Determining optimal irradiance for in vitro and greenhouse production will help optimize growth and flowering. Four-month-old, aseptically propagated Phalaenopsis Atien Kaala seedlings with 1.0 cm leaf spread were transferred to a sterile agar medium in November 1995. They were placed under 10, 20, 40, or 80 μmol·m-2·s-1 photosynthetic photon flux (PPF) from cool-white fluorescent lamps. In June 1996, plants grown under 40 or 80 μmol·m-2·s-1 in vitro PPF had 38% greater fresh weight (FW), wider leaves, and more roots than those under the two lower PPF levels. Plants from each in vitro PPF were then transplanted and grown ex vitro in a greenhouse (GH) under high, medium, or low PPF, representing 12.0%, 5.4%, or 2.6% of full sunlight, respectively. Full sunlight at this location was 2300 and 1700 μmol·m-2·s-1 in August 1996 and January 1997, respectively. In November 1996 and June 1997, plants that had received 40 μmol·m-2·s-1 in vitro PPF and then grown under the high or medium GH PPF had the greatest FWs. Overall, plants under the high, medium, or low GH PPF had average FWs of 61, 36, or 17 g, respectively, in June 1997. By mid-September 1997, plants had increasingly larger leaves and higher concentrations of malic acid, sucrose, and starch as GH PPF increased. Leaf glucose and fructose concentrations remained constant as GH PPF increased; however, sucrose level doubled and malic acid concentration increased by nearly 50% from the low to high GH PPF. Each doubling in GH PPF more than doubled plant FW. Plants grown under the high, medium, or low GH PPF had 98%, 77%, or 2% flowering, respectively, in Spring 1998. Anthesis occurred 2 weeks earlier under the high GH PPF. Plants grown under the high GH PPF had twice as many flowers and larger flowers than those grown under the medium PPF.

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Research was conducted to investigate the interaction of water-soluble fertilizer and medium composition on vegetative growth and the concentration of mineral nutrients in media and in leaves of a hybrid moth orchid (Phalaenopsis Blume.). The vegetatively propagated `TSC 22' clone of the hybrid Phalaenopsis Atien Kaala plants 15 cm in leaf spread were potted in a medium consisting of either 100% fine grade douglas fir [Pseudotsuga menziesii (Mirb.) Franco] bark or a mixture of 7 fir bark: 3 sphagnum peat (by volume). Plants were fertigated at each irrigation with a soluble 10N-13.1P-16.6K, 20N-2.2P-15.8K, or 20N-8.6P-16.6K fertilizer, or a 2N-0.4P-1.7K 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, greater fresh weights (FW), and larger total leaf areas than those in 100% bark. In the bark medium, the 20N-2.2P-15.8K fertilizer resulted in plants of the highest quality, 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 FW and 40% larger leaf area than the other fertilizers without urea. With any given fertilizer, plants had similar root FW in both media. Media and fertilizers had limited or no effect on the concentrations of mineral nutrients in the second mature acropetal leaves, except P, which nearly doubled in leaves of plants grown in 100% bark. High leaf Mg concentration was associated with low Ca. Water extracts from the bark-peat medium had lower pH, higher electrical conductivity, and much higher levels of NH4-N, Ca, Fe, Na, Cl, B, and Al than those from 100% bark. Extracts from the bark medium did not have detectable levels of NO3-N, whereas extracts from the bark-peat medium all had similar levels of NH4-N, regardless of which fertilizer was applied. Levels of P and K were not different between the two media.

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The levels of hydration of several hydrophilic polymers (hydrogels) varied greatly. Starch-based polymers had the fastest rate of hydration (<2 hours), followed by a propenoate-propenamide copolymer. Polyacrylamide materials required 4 to 8 hours to become fully hydrated. Maximum water retention in distilled water varied from 400 to 57 g of water per gram of dry material. All hydrogels retained less water in the presence of metal ions or fertilizers in the soaking solution, with substances releasing Fe+2 being the most detrimental. After exposure to fertilizers and ions, the water-holding capacity of a polyacrylamide with a high degree of cross linkage, but not that of hydrogels of the other structures, was fully recovered by subsequently soaking in distilled water. Pots amended with a polyacrylamide polymer but without Micromax (a micronutrient source) reached maximum water retention after six irrigations, while those with Micromax required 10 irrigations to reach peak water retention. The amounts of water being held in pots decreased after repeated fertilization. Medium volume increased with increasing levels of the polyacrylamide Supersorb C (0, 2, 4, or 6 g/pot). Micromax incorporated in medium amended with Supersorb C caused a depression in volume. Medium bulk density, total water retention, and water retention per unit volume of medium were increased by the incorporation of the hydrogel, regardless of the presence of Micromax. Noncapillary porosity measured at container capacity in medium amended with Micromax progressively decreased as the amount of hydrogel increased, but remained unchanged in medium without Micromax. Repeated drying and dehydration of the medium resulted in reduced water retention and increased noncapillary pore space.

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Abstract

To simulate the developmental sequence of the Easter lily flower (Lilium longiflorum Thunb. ‘Nellie White’), flower buds from 4.5 cm to 16 cm (anthesis) were cut from field-grown plants on a single date. Fresh weight increased with bud length and was highest at anthesis, whereas dry matter reached a maximum of 1.6 g when buds were 14 cm long. The percentage of dry matter declined from 16% in the smallest bud to only 9% at anthesis. Respiration rates, both per bud and per unit dry weight, increased with bud size, reaching peak values of 3.0 mg CO2 · bud-1 · hr-1 and 1.8 mg CO2 · g-1 dry wt · hr -1 at anthesis before declining to a markedly lower rate. From these data, the total dry matter needs of flowers on field-grown plants were estimated.

Open Access

Abstract

Ponytail palms (Beaucarnea recurvata L.) were grown in three media having similar water holding capacities but different porosities, under 70%, 50%, or 27% full sunlight and fertilized with each irrigation or once every three irrigations. Plants grown in media with lower porosities grew more than plants in a peat-lite medium but required more frequent irrigation. Plants grew less under 27% full sun than at the two higher light levels. Frequent fertilization did not increase plant size but decreased pH and increased electrical conductivity of the growth medium leachate substantially. Plant acclimatization increased with decreasing production light intensity and noncapillary porosity of the medium.

Open Access

Abstract

Growth was reduced from leaf-bud golden pothos [Epipremnum aureum (Linden & Audre) Bunt.] cuttings taken from an apical node with the most recent, fully expanded leaf. Days to first leaf unfolding increased as cuttings were taken more basipetally from the second apical node to node 14. Accelerated growth of the axillary shoot and increases in leaf number, stems length, leaf area, and shoot fresh weight were associated with cuttings from the apical nodes. Shoot growth was accelerated when cuttings had a 3-cm or longer internode below the nodes. Retaining a 6 to 8-mm section of the old aerial root on cuttings promoted axillary shoot growth.

Open Access

Vegetatively propagated plants (15-cm in leaf spread) of a white-flowered Phalaenopsis Taisuco Kaaladian clone were imported bare-root in late May and planted in a mix consisting of three parts of medium-grade fir bark and one part each of perlite and coarse Canadian peat (by volume) or in Chilean sphagnum moss. All plants were given 200 mg·L-1 each of N and P, 100 mg·L-1 Ca, and 50 mg·L-1 Mg. K concentrations were 0, 50, 100, 200, 300, 400, and 500 mg·L-1. After 7 months, plants grown in moss produced an average of two more leaves than those in the bark mix (4 to 5 vs. 2 to 3 leaves), regardless of K rates. In any given medium, K rate did not alter the rate of leaf production. The K rate did not affect the size of the top leaves when grown in the bark mix. However, plants grown in moss had increasingly longer and wider top leaves as K rate increased. The lower leaves on plants in the bark mix receiving no K showed deficiency symptoms of purple tinting, yellowing, necrosis, and even death. Yellowing and necrosis started from the leaf tip and progressed basipetally. The K at 50 mg·L-1 reduced and 100 mg·L-1 completely alleviated the symptoms of K deficiency. Plants grown in moss and receiving no K showed limited signs of K deficiency. Flowering stems started to emerge (spiking) from plants in the bark mix up to 4 weeks earlier than those planted in sphagnum moss. For plants receiving no K, all plants in the bark mix bloomed, whereas none planted in sphagnum moss produced flowering stems. Overall, at least 200 mg·L-1 K (∼250 mg·L-1 K2O) is recommended to produce quality plants with maximum leaf growth and early spiking.

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