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Albert Z. Tenga, Beverley A. Marie, and Douglas P. Ormrod

Field experiments in open-top chambers were conducted to study the recovery of tomato (Lycopersicon esculentum Mill. cv. New Yorker) plants from ozone (O3) injury. Plants were pot-cultured and exposed for 7 hours per day for 4 days at a vegetative or flowering stage to charcoal-filtered air, 0.06, 0.09, 0.12, 0.18, or 0.24 μl O3/liter. Half of the plants were harvested 2 or 3 days after the O3 exposure; the remaining plants were held in open-top field chambers in filtered air and harvested after the appearance `of the first red fruit. Ozone exposure at either growth stage resulted in visible foliar injury and decreased leaf area of plants harvested 2 or 3 days after exposure. In spite of extensive foliar injury after O3 exposure at the vegetative stage, there was no significant decrease in fruit yield or change in fruit quality at the final harvest. In contrast, exposure of plants to O3 at flowering progressively reduced fresh weight of fruit and, to a lesser degree, its concentration of titratable acidity.

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R.J. Bula, R.C. Morrow, T.W. Tibbitts, D.J. Barta, R.W. Ignatius, and T.S. Martin

Development of a more effective radiation source for use in plant-growing facilities would be of significant benefit for both research and commercial crop production applications. An array of light-emitting diodes (LEDs) that produce red radiation, supplemented with a photosynthetic photon flux (PPF) of 30 μmol·s-1·m-2 in the 400- to 500-nm spectral range from blue fluorescent lamps, was used effectively as a radiation source for growing plants. Growth of lettuce (Lactuca sativa L. `Grand Rapids') plants maintained under the LED irradiation system at a total PPF of 325 μmol·s-1·m-2 for 21 days was equivalent to that reported in the literature for plants grown for the same time under cool-white fluorescent and incandescent radiation sources. Characteristics of the plants, such as leaf shape, color, and texture, were not different from those found with plants grown under cool-white fluorescent lamps. Estimations of the electrical energy conversion efficiency of a LED system for plant irradiation suggest that it may be as much as twice that published for fluorescent systems.

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Peter M Hirst and David C Ferree

Floral development was studied in buds of `Starkspur Supreme Delicious' apple trees growing on B.9, M.26 EMLA, M.7 EMLA, P.18, and seedling rootstocks. In each of 3 years, buds were sampled from the previous years growth at intervals throughout the growing season and dissected to determine whether the apex was domed, indicating the start of floral development. Number of bud scales and true leaves increased during the early part of the growing season, but remained fairly constant beyond 70 days after full bloom. The type of rootstock did not affect the number of bud scales or transition leaves, and effects on true leaf numbers were small and inconsistent. Final bract number per floral bud was similarly unaffected by rootstock. The proportion of buds in which flowers were formed was influenced by rootstock in only one year of the study, which was characterized by high temperatures and low rainfall over the period of flower formation. Bracts were observed only in floral buds, and became visible after doming of bud apices had occurred. Flowers were formed during the first 20 days in August, regardless of rootstock or year. The appendage number of vegetative buds was constant from 70 days after full bloom until the end of the growing season, but the number of appendages in floral buds increased due to the continued production of bracts. The critical bud appendage number for `Starkspur Supreme Delicious' before flower formation was 20, and was stable among rootstocks and years. Buds with diameters above 3.1 mm were generally floral, but on this basis only 65% of buds could be correctly classified. Spur leaf number, spur leaf area, and spur leaf dry weight were not good predictors of floral formation within the spur bud.

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L. Manivel, R. Raj Kumar, S. Marimuthu, and V. Venkatesalu

146 ORAL SESSION 45 (Abstr. 338–343) Growth Regulators/Cross-commodity

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Chun Ho Pak, Seung Won Kang, and Chiwon W. Lee

Poster Session 30—Floriculture: Mineral Nutrition/Pest Management/Growth Regulators 20 July 2005, 12:00–12:45 p.m. Poster Hall–Ballroom E/F

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Amir Rezazadeh, Richard L. Harkess, and Guihong Bi

Red firespike is a vigorous ornamental shrub growing to ≈6 ft in height. It has an upright growth habit and is commonly cultivated as an ornamental plant in the garden due to its attractive tubular red flowers ( Daniel, 1995 ). The plant has

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Marianne Andresen and Nina Cedergreen

selection, breeding, and genetic engineering and by improvement of the crop growth environment through irrigation, fertilization, and the use of plant protection products. Chemical growth regulators are also one of the tools used to improve both crop growth

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Lisa E. Richardson-Calfee, J. Roger Harris, and Jody K. Fanelli

Growth periodicity is generally conceived as a set pattern of growth incited by internal factors and influenced by environmental conditions ( Morrow, 1950 ). The inherent alternation between periods of abundant root and shoot growth and little or

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Thomas E. Marler and L.E. Willis

101 POSTER SESSION 17 (Abstr. 733-762) Growth and Development

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Matt E. Berman and Theodore M. DeJong

101 POSTER SESSION 17 (Abstr. 733-762) Growth and Development