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Douglas A. Hopper and P. Allen Hammer

88 ORAL SESSION (Abstr. 528-533) FLORICULTURE: GROWTH AND DEVELOPMENT

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Jasim Uddain, Sanzida Islam Tripti, Mohammad Shah Jahan, Nasrin Sultana, Md Jahedur Rahman, and Sreeramanan Subramaniam

al., 2015 ). Vermicompost also significantly stimulates the growth and productivity of plants ( Edwards, 1998 ). Vermicompost is used as organic fertilizer to improve soil aeration and enhance soil microorganisms, plant growth, and eventually crop

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Muntubani D.S. Nzima, George C. Martin, and Chic Nishijima

We investigated the development of leaf area (LA) and the distribution of dry matter within branches of 25-year-old, alternate-bearing `Kerman' pistachio (Pistacia vera L.) trees that were in their natural “on” (heavy) or “off” (light) bearing cycles to determine the immediate and delayed effects of fruiting on shoot growth. Compared to “off” trees, individual leaves of “on” trees were greater in number and expanded twice as fast during the first 30 days after full bloom (FB) (FB + 30). Mature, fully expanded leaves of “on” trees were smaller (124.1±3.26 cm2) than those from “off” tree (163.3±3.40 cm2), indicating delayed demands of fruiting on initial leaf growth. Total LA per current shoot was greater in “on” than “off” trees because shoots of “on” trees averaged eight leaves, compared with six for “off” trees. More inflorescence buds per shoot (seven vs. three buds) abscised from “on” than from “off” trees. About 60% of the young developing nuts had abscised by FB + 30 when they weighed <250 mg each and another 25% abscised between FB + 30 and FB + 60 when individual nuts weighed ≈400 mg. The average total dry mass (DM) of individual branches of “on” trees increased 1322% (5·9 to 83·9 g) compared to 598% (4·2 to 29·3 g) in “off” trees. Besides nuts, leaves accumulated the greatest amount of dry matter within individual branches followed in decreasing order by current wood, 1-year-old wood, and inflorescence buds. DMs of individual leaves of “on” trees averaged between 15% and 48% greater than leaves of “off” trees. “Off” trees invested 4.6 g of dry matter into individual 1-year-old wood and 2.1 g into current wood. “On” trees, however, invested 1.3 g of dry matter into 1-year-old wood and 4.3 g of dry matter into current wood. One-year-old wood was an important major source of carbohydrates for developing leaves, current wood, rachises, and nuts. The immediate demands of fruiting on individual components of a branch were measured as losses in DMs. Individual leaves, current wood, 1-year wood, and rachises lost 1.1%, 0.3%, 1.1%, and 1.0%, respectively, of the average total DMs of individual branches of “on” trees. This loss was equivalent to 5.7%, 5.9%, 26.7%, and 16.4%, respectively, of the seasonal average peak DMs of the respective individual components of the branch.

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Bandara Gajanayake, K. Raja Reddy, Mark W. Shankle, and Ramon A. Arancibia

grown under furrow or drip-irrigated conditions in California ( Stoddard et al., 2013 ). Soil moisture stress is one of the crucial abiotic stress factors that limits growth and development of sweetpotato, affecting storage root production and yield

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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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Wlodzimierz Bres and Leslie A. Weston

`Buttercrunch', `Grand Rapids', and `Summer Bibb' lettuce (Lactuca sativa L.) seedlings were grown with the nutrient film technique (NIT). The influence of two K concentrations (150 and 225 mg·liter-1) and four solution pH levels (5.0, 5.5, 6.0, and 6.5) on lettuce tipburn was investigated in four experiments. Additionally, the influence of pH on foliar nutrient concentration was examined. Even though tipburn was observed in `Buttercrunch' and `Summer Bibb' lettuce, neither K nor pH level consistently affected tipburn incidence. No tipburn was observed in `Grand Rapids'. Solution pH generally did not affect concentration of total N and NO3-N in lettuce tissue. Increasing the pH increased K concentration and resulted in increased proportions of K compared to Mg or Ca. Although the influence of solution pH on P, Ca, and Mg concentration was significant, nutrient accumulation differences were not reflected in lettuce fresh-weight differences. The influence of K solution concentration and pH on lettuce yield was not significant. Tipburn incidence in NIT-produced lettuce appears to be primarily affected by environmental conditions maintained during greenhouse growth.

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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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Entin Daningsih, D. L. Coffey, J. Logan, and C. A. Mullins

97 ORAL SESSION (Abstr. 542-548) VEGETABLE CROPS: GROWTH AND DEVELOPMENT

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Patricia I. Garriz, Hugo L. Alvarez, and Angel J. Alvarez

145 POSTER SESSION (Abstr. 694–707) Growth and Development–Tree Fruits