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Chiwon W. Lee

Velvet flower (Salpiglossis sinuata, Solanaceae) can be used as an excellent demonstration plant for horticultural crop breeding classes. Salpiglossis produces large trumpetlike flowers exhibiting an assortment of corolla colors and pigmentation patterns. The pistil is large (3 to 4 cm or 1.2 to 1.6 inches long) with a sticky stigmatal tip and flowers can be easily emasculated prior to anthesis. The large pollen grains are shed in tetrads which can be separated and placed on the stigmatal surface. It takes eight to nine weeks from seeding to blooming, with a prolific flowering cycle that comes in flushes. Numerous seeds (about 750 per capsule) are obtained in three weeks after self- or cross-pollination. The influences of three genes that control flower color and pigmentation pattern can be conveniently demonstrated with their dominant and recessive alleles. The R gene controls flower color with red (RR or Rr) being dominant over yellow (rr). The D gene controls the density of pigmentation with solid (DD or Dd) color being dominant over dilute (dd) color. Corolla color striping is controlled by the St gene with striped (stst) being recessive to nonstriped (StSt or Stst) pattern. By using diploid lines of genotypes RRDD (red, solid), RRdd (red, dilute), or rrdd (yellow, dilute) and their crosses, students can easily observe a dominant phenotypic expression in the F1 hybrid and the digenic 9:3:3:1 segregation ratio in the F2 progeny. Another gene (C) that controls flower opening can also be used to show its influence on cleistogamous (closed, selfpollinated, CC or Cc) versus normal chasmogamous (open-pollinated, cc) corolla development. In addition, the induction and use of polyploid (4x) plants in plant breeding can also be demonstrated using this species.

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Shanqiang Ke and Chiwon W. Lee

Coleoptile tissues from dark-germinated seedlings of Kentucky bluegrass (Poa pratensis L.) cv. Touchdown were excised and cultured on MS medium supplemented with 1.5-2.5 mg/liter picloram plus 0.2 mg/liter benzyladenine (BA) or with 4 mg/liter 2,4-D. Embryogenic calli were formed on media containing 1.5 mg/liter picloram plus 2.5 mg/liter 2,4-D in the dark. When these embryogenic calli were subcultured on MS medium containing either 0.15-0.3 mg/liter picloram or 0.2-0.5 mg/liter 2,4-D in a 16-h day/8-h night photoperiod, 10.5% of the cultures regenerated shoots. Pretreatment of cultures in the dark for 2 weeks prior to light exposure slightly increased the plant regeneration efficiency to 15.5%. Pigmentation of the regenerants varied with a ratio of 8.5 completely green: 2.5 green plus albino: 1 completely albino plants. The shoots were multiplied in the medium containing 0.5 mg/liter BA plus either 0.2 mg/liter picloram or 0.1 mg/liter indoleacetic acid (IAA). Over 90% cultures in the shoot proliferation medium produced roots after 4 weeks.

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Hoon Kang and Chiwon W. Lee

The influence of increasing levels (0.0%, 0.05%, 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1.2%, 1.6%, and 2.0%) of NaCl on the germination of Kentucky bluegrass (Poa pratensis), annual ryegrass (Lolium multiflorum), perennial ryegrass (Lolium perenne), creeping bentgrass (Agrostis palustris), tall fescue (Festuca arundinacea), and crested wheatgrass (Agropyron cristatum) was investigated. Kentucky bluegrass, creeping bentgrass, and crested wheatgrass had a 50% reduction in germination at 0.2%, 0.6%, and 0.6% NaCl, respectively, compared to the control and completely lost germination at 0.6%, 1.2%, and 1.6% NaCl, respectively. Seed germination in both annual ryegrass and perennial ryegrass was only 50% of the control at 1.2% NaCl and completely inhibited at 2.0% NaCl. Tall fescue, red fescue, and creeping red fescue showed a 50% reduction in germination at NaCl concentrations of 1.2%, 1.2%, and 0.8%, respectively, while showing a complete inhibition of germination at 2.0%, 2.0%, and 1.6% NaCl, respectively.

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Sang Gyu Lee* and Chiwon W. Lee

The pattern of C14 carbohydrate translocation and distribution from source leaf to various plant parts in watermelon grown in the greenhouse and field was investigated. Seedling-grown plants were pruned to have two branches with only one of them carrying a fruit. When leaves at four different positions (on fruit-bearing node, on fifth node above and below it, and on fifth node from the base of the non-fruit-bearing stem) were exposed to 14CO, the distribution of C14 2 compounds to different parts (fruit, stem, leaf, root) of the plant varied. In all treatments, the fruit was the strongest sink, followed by stem, leaf and root tissues. The highest percentage of C14 photo-assimilates was transferred out of the source when the leaf borne on the fruit-bearing node was exposed to 14CO2 in both greenhouse and field grown plants. Translocation of C14 compounds from the leaves on the fifth node above and below the first fruit-carrying node was similar. Only 29% of C14 was transferred from the source leaf borne on the fifth node of the non-fruit bearing branch in the greenhouse, as compared to more than 46% of C14 from other source leaves. Accumulation of C14 in the root tissues was highest when source leaves were borne on the non-fruit bearing branch. In general, field-grown plants had higher percentages of C14 translocated as compared to greenhouse-grown plants.

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Sang Gyu Lee* and Chiwon W. Lee

The relationship between source leaf position and the photo-assimilate translocation and distribution was characterized for tomato (Lycopersicon esculentum Mill.) grown in the greenhouse. Three different positions of source leaf on the stem (first node above or below the first fruit cluster and fifth node above the first fruit cluster) were tested for their influence on 14CO2 assimilation and transfer to different parts of the plant. The leaves at the fifth node above the first fruit cluster transferred the highest (57%) proportion of C14 to other plant parts, followed by leaves borne on the first node below the first fruit cluster (50%), and the first node above the first fruit cluster (39%). In all treatments, fruits served as the strongest sink for C14, followed by stem, leaf, and root tissues. The leaf borne on the fifth node above the first fruit cluster transferred the largest amount of C14 to the second fruit cluster.

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Sang Gyu Lee* and Chiwon W. Lee

The pattern of translocation and distribution of C14 labeled photo-assimilates in watermelon and tomato grown in the greenhouse and field was characterized. Each of the mature leaves of the plant at active fruit development stage was exposed to 14CO2 (20 μCi radio activity) for 40 min and the leaves, stems, fruit, and roots were harvested 3, 6, 9, or 12 hours after treatment. One half of the plants were grown under natural light and the other half in the dark during the experimental period. The activity of C14 in the dry tissues of the leaves, stems, fruits, and roots was determined, using a liquid scintillation analyzer. Both watermelon and tomato plants grown in the greenhouse and field contained C14 in all tissue types 3 hr after treatment, regardless of exposure to light or dark during the experimental period. Watermelon and tomato, respectively, transferred 22% to 61% and 9% to 26% C14 from the source leaf in 3 hours. Fruit tissues served as the strongest sink, with the highest percentages of C14 transfer in watermelon (99%) and tomato (90%) in plants grown in the field. The rate of C14 translocation was highest when plants were kept in the dark after 14CO2 feeding. In general, total translocation of C14 compounds from the source leaf was higher in watermelon than in tomato plants. For both watermelon and tomato, most field-grown plants showed a higher rate of C14 translocation as compared to greenhouse grown plants for a given period of time.

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Sung Eun Lee*, Sang Gyu Lee and Chiwon W. Lee

The influence of plant density on yield of three confectionery seed pumpkin accessions was investigated under non-irrigated field conditions. Seeds of Golden Delicious (GD), open-pollinated Chinese snow-white seed (CS), and a selection from Austrian hull-less (HL) pumpkin were planted 30, 60, and 90 cm apart in rows that were 127 cm apart with seedlings thinned to one plant per hill. Plants were grown from 23 May to 18 Sept. One fruit per plant was harvested from five plants for each of the three replications. The number of seeds (and dry weight of seed) per fruit were 242 (59 g), 304 (87 g), and 334 (106 g), respectively, at 30, 60, and 90 cm spacing for GD. The number of seeds (and dry weight of seed) per fruit were 219 (108 g), 266 (108 g), and 258 (106 g), respectively, at 30, 60, and 90 cm spacing for CS. The number of seeds (and dry weight of seed) per fruit were 376 (76 g), 404 (94 g), and 304 (82 g), respectively, at 30, 60, and 90 cm spacing for HL. Highest seed yield was at 60 cm plant spacing for CS and HL, whereas GD produced highest seed yield at 90 cm plant spacing. The differences in total seed yield, seed size, and confectionery seed quality, as influenced by plant density and seed source, were also characterized.

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Chun-Ho Pak and Chiwon W. Lee

Foliar micronutrient toxicity symptoms of Petunia hybrida `Ultra Crimson Star' were induced by elevated levels (from 0.25 to 6 mM) of boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn) in the nutrient solution. Foliar toxicity symptoms of most micronutrients (except Fe) were characterized by leaf yellowing, interveinal chlorosis, and marginal necrosis. Mo toxicity was most severe. Leaf abnormality was not induced by Fe in the concentration range tested. Visible foliar toxicity symptoms developed when nutrient solution contained 5.4, 32, 28, 24, and 16 mg· liter-1, respectively, of B, Cu, Mn, Mo and Zn. Biomass yield was reduced when the fertilizer solution contained (in mg· liter-1): 22 B, 64 Cu, 335 Fe, 28 Mn, 24 Mo, and 33 Zn.

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Edward S. Dehmer and Chiwon W. Lee

The influence of NaCl concentration on seed germination in blue grama grass (Bouteloua gracilis), salty alkaligrass (Puccinellia distans) and Kentucky bluegrass (Poa pratensis) were investigated. When seeds were germinated in petri dishes containing 0, 2.5, 5.0, 7.5, 10, 12.5, 15, 17.5, 20, 22.5, 25, 27.5, and 30 g·liter–1 NaCl at 22 C for 4 weeks, blue grama grass was most salt-tolerant with 50% germination at 17.5 g·liter–1. The salt concentrations that provided 50% germination for salty alkaligrass and Kentucky bluegrass were 5 and 1.5 g·liter–1, respectively. The upper limits of salinity that allowed any germination were 30 g·liter–1 (1%) for blue grama grass, 27.5 g·liter–1 (1%) for salty alkaligrass, and 5 g·liter–1 (2%) for Kentucky bluegrass. Germination was quickest in blue grama grass (90% germination in 1 week) followed by salty alkaligrass (50% in 3 weeks) and Kentucky bluegrass (50% in 4 weeks). The tissue contents of Na+ and Cl as influenced by increasing levels of NaCl were also determined.

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Byoung Ryong Jeong and Chiwon W. Lee

Ageratum houstanianum Mill. (tolerant), Tagetes patula L. (French marigold, very sensitive), Petunia hybrida Vilm. (sensitive), and Salvia splendens F. Sellow et. Roem & Schult. (very sensitive) were grown with NO3 -, NH4 +NO3 -, or NH4 + as the N source to examine whether NH4 +-related growth suppression (NH4 +-RGS) in the NH, -sensitive species was associated with excessive Cl- absorption from the nutrient solution. Amounts of Cl- applied were 4 or 11 meq·liter-1 (Expt. 1) and 0 or 4 meq·liter-1 (Expt. 2). When fertilized with NH4 + as a sole N source, marigold, petunia, and salvia showed NH4 +-RGS symptoms with yield reduction regardless of altered Cl- levels in the nutrient solution, while ageratum showed no such symptoms. When grown with NH4 + solution, these sensitive plants had shoot fresh and dry weight reductions of ≈ 50% compared to those grown with the NH4 + + NO3 - solution. Plants fertilized with NH4 + showed more severe NH4 +-RGS symptoms when grown in rockwool (RW) than in peat-lite mix (PL). The NH4 +-grown plants contained more NH4 + and much more Cl- in the tissue than plants fertilized with NO3 - or NH4 + + NO3 -, irrespective of the Cl- level in the nutrient solution. However; NH4 +-RGS symptoms in marigold, petunia, and salvia appear to be caused by the uptake of NH4 +, but not in association with Cl- from the nutrient solution.