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Charles S. Vavrina

The research reviewed here represents the majority of the information available on transplant age to date. When the results of these studies are distilled down to the “ideal” transplant age for setting of a specific crop, we generally arrive at the recommendations found in the 1962 edition of Knott's Handbook for Vegetable Growers. The conflicting results in the literature on transplant age may be due to the different environmental and cultural conditions that the plants were exposed to, both in the greenhouse and in the field. The studies did reveal that the transplant age window for certain crops might be wider than previously thought. Older transplants generally result in earlier yields while younger transplants will produce comparable yields, but take longer to do so. Our modern cultivars, improved production systems, and technical expertise enable us to produce high yields regardless of transplant age. The data, in general, support the view that if a vegetable grower requires resets after an catastrophic establishment failure (freeze, flood, etc.), they need not fear the older plants usually on hand at the transplant production facility.

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Donald T. Krizek, Steven J. Britz, and Roman M. Mirecki

The influence of ambient UV radiation on growth and flavonoid concentration of Lactuca sativa L. (`New Red Fire' lettuce) was examined. Plants were grown outdoors for 31 days from seed in window boxes covered with one of three different UV filters—UV transparent tefzel (10%T, 245 nm), UV-B-absorbing polyester (10%T, 319 nm), or UV-Aand UV-B-absorbing Llumar (10%T, 399 nm). Plants were grown in plastic pots filled with vermiculite and subirrigated with nutrient solution. Lettuce plants grown in the absence of solar UV-A and UV-B radiation showed a significant increase in leaf number and biomass of tops and roots as compared to those grown under ambient UV-A and UV-B. They also had a lower concentration of flavonoids and other UV-absorbing substances at 270, 300, and 330 nm (on both an area and on a dry-weight basis). These findings should be of interest to researchers involved in protected cultivation because the transmission of UV-B radiation is greatly attenuated by standard greenhouse glass. Our results also have implications for human nutrition, since bioflavonoids are important as antioxidants.

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Thomas E. Marler and Cecil Stushnoff

The influence of plant size on recovery following defoliation of `Tainung 1' papaya was used to study the role of respiratory sink size relative to photosynthetic surface area and the carbohydrate pool size available for remobilization. Defoliated (D) plants at three different ages: oldest, 24 weeks posttransplant (PT), supporting ≈8 weeks of fruit set; intermediate, 10 weeks PT, ≈2 weeks from initial flowering; and youngest, 4 weeks PT, were compared to an equal number of control plants. The oldest plants abscised all fruit <5.5 cm in diameter as a result of defoliation. Increase in stem height and basal circumference ceased on all plants and increase in fruit circumference ceased on the oldest plants following defoliation. Increase in stem height of D plants began again 3 weeks postdefoliation (PD) and returned to that of control plants by 6 weeks PD. Increase in basal circumference of D plants began again 6 weeks PD. Root density was observed on observation windows, and fine roots completely disappeared within 1 week PD. Root density returned to that of control plants by 6 weeks for the youngest and intermediate plants and by 8 weeks for the oldest plants. Increase in fruit circumference of pre-existing fruit for the oldest D plants never returned to that for control plants. These plants began setting fruit again ≈8 weeks PD. Defoliation delayed initial flowering of the intermediate plants 6.5 weeks and of the youngest plants ≈2 weeks. Thus, the greatest impact of defoliation on reproductive growth occurred with the two oldest age groups.

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James M. Wargo and Chris B. Watkins

`Honeycrisp' apples (Malus × domestica) were harvested over 3-week periods in 2001 and 2002. Maturity and quality indices were determined at harvest. Fruit quality was evaluated after air storage [0.0 to 2.2 °C (32 to 36 °F), 95% relative humidity] for 10-13 weeks and 15-18 weeks for the 2001 and 2002 harvests, respectively. Internal ethylene concentrations (IEC), starch indices (1-8 scale), firmness and soluble solids content (SSC) did not show consistent patterns of change over time. Starch hydrolysis was advanced on all harvest dates, but it is suggested that a starch index of 7 is a useful guide for timing harvest of fruit in western New York. After storage, firmness closely followed that observed immediately after harvest, and softening during storage was slow. No change in SSC was observed during storage in either year. Incidence of bitter pit and soft scald was generally low and was not affected consistently by harvest date. The incidence of stem punctures averaged 18.5% over both years, but was not affected by harvest date. Development of stem end cracking in both years, and rot development in one year, increased with later harvest dates. A panel of storage operators, packers, growers, and fruit extension specialists evaluated the samples for appearance and eating quality after storage, and results suggested that a 2-week harvest window is optimal for `Honeycrisp' apples that are spot picked to select the most mature fruit at each harvest.

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Timothy K. Broschat

Royal palms [Roystonea regia (HBK.) O.F. Cook], coconut palms (Cocos nucifera L. `Malayan Dwarf'), queen palms [Syagrus romanzoffiana (Chamisso) Glassman], and pygmy date palms (Phoenix roebelenii O'Brien) were grown in a rhizotron to determine the patterns of root and shoot growth over a 2-year period. Roots and shoots of all four species of palms grew throughout the year, but both root and shoot growth rates were positively correlated with air and soil temperature for all but the pygmy date palms. Growth of primary roots in all four species was finite for these juvenile palms and lasted for only 5 weeks in royal palms, but ≈7 weeks in the other three species. Elongation of secondary roots lasted for only 9 weeks for coconut palms and less than half of that time for the other three species. Primary root growth rate varied from 16 mm·week-1 for coconut and pygmy date palms to 31 mm·week-1 for royal palms, while secondary root growth rates were close to 10 mm·week-1 for all species. About 25% of the total number of primary roots in these palms grew in contact with the rhizotron window, allowing the prediction of the total root number and length from the sample of roots visible in the rhizotron. Results indicated that there is no obvious season when palms should not be transplanted in southern Florida because of root inactivity.

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David R. Hershey

John H. Patterson, founder and president of the National Cash Register Co. (now NCR Corp.), is best known for his innovative business practices which made the cash register a standard product, Less well-known was his program of industrial welfare for NCR employees which included many uses of horticulture. Illustrations of the landscaping contests Patterson sponsored in his factory neighborhoods are shown in a collection of early 1900's glass lantern slides recently discovered in the University of Maryland Horticulture Building attic. The noted Olmsted landscaping firm was hired to design the NCR factory grounds. Neighborhood children were given company land, tools, instructions, and awards, enabling them to grow vegetables to sell and to give to their families. Patterson created these `Boys Gardens' to occupy youngsters who might otherwise break windows in the NCR factory and give the factory neighborhood a bad reputation. Although his program of industrial welfare was unique in an era of worker exploitation, Patterson justified the program because “It pays”.

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N.G. Beck, M.L. Arpaia, J.S. Reints Jr., and E.M. Lord

Deformations consisting of longitudinal ridges in the rind of Citrus fruits have recently been found in Southern California Citrus groves. Here, we report the correlation between ridge formation and applications of chlorpyrifos (Lorsban, Dow Chemical Company, Midland, MI) during the feather-growth stage of bud break. All chlorpyrifos formulations resulted in significant ridging. Addition of agricultural oil and 2,4-D (2,4-dichlorophenoxyacetic acid (2,4-D) to chlorpyrifos resulted in the greatest ridging damage and widened the window of susceptibility by 2 weeks in 1988. In 1989, no significant difference was seen between treatments of chlorpyrifos, although all were significantly greater than the control. The susceptible stages of bud growth are described, as are the non-susceptible stages which precede and follow it. Floral buds in which carpels are initiating are susceptible to fruit ridging upon application with chlorpyrifos. These ridges are the result of an increase in cell size of the flavedo tissue which may be the result of a polyploid chimera.

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James E. Motes, Brian A. Kahn, and Niels O. Maness

Our objective was to increase the percentage of marketable red fruit at harvest time on paprika pepper (Capsicum annuum L.) plants intended for mechanical harvest by using ethephon [(2-chloroethyl)phosphonic acid] to remove late-developing blooms and green fruit. We conducted three experiments on field-grown plants in southwestern Oklahoma. We tested ethephon solutions of 0, 1000, 2000, 3000, and 4000 μl·liter–1 as a one-time foliar application on various dates. Total dry weight of harvested fruit decreased linearly with ethephon rate in all three studies. Marketable fruit as a percentage of total harvested fruit weight increased linearly with ethephon rate in two studies. There was no consistent effect of ethephon on the intensity of red pigment extracted from dehydrated marketable fruit. With proper timing, as little as 1000 μl ethephon/liter was enough to alter the distribution of total harvested fruit weight toward marketable fruit and away from green fruit. A target spray “window” of the last 10 days in September seemed appropriate for southwestern Oklahoma, and the recommended rate of ethephon was between 2000 and 3000 μl·liter–1.

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Bruce W. Wood

Inadequate cross-pollination of pecan [Carya illinoinensis (Wangenh.) K. Koch] occurred in block-type orchards generally thought exempt from pollination-related crop losses because of an abundance of nearby potential pollinizers. “Off-genotypes” appeared to be potentially major assets in such orchards due to their role as backup pollinizers; hence, their presence insures against crop losses due to poor pollination. Fruit-set in `Desirable' main crop rows declined sigmoidally as distance from 'Stuart' pollinizer rows increased. For 15.4-m row spacings, rate of decrease was maximum between 49 and 78 m, depending on crop year. Maximum fruit-set was in rows immediately adjacent to the pollinizer. Tree age/size and spring temperature influences on the characteristics of flower maturity windows are probably primary factors contributing to pollination-related fruit-set losses in block-type orchards relying upon pollen from a single complementary pollinizer or from neighborhood trees. For example, flower maturity was earlier in older/larger trees, and higher spring temperatures accelerated catkin development relative to that of pistillate flowers. Maximum fruit-set occurred when pistillate flowers received pollen around 1 day or less after becoming receptive, whereas no fruit-set occurred when they were pollinated around four or more days after initial receptivity. These findings indicate that many block-type orchards in the southeastern United States are exhibiting pollination-related crop reductions and that future establishment of such orchards merits caution regarding the spatial and temporal distribution of pollinizers.

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Christopher Lindsey, Gary Kling, and Mark Zampardo

UIPLANTS is a program developed under Microsoft Windows to help students in woody plant materials courses. Its many options include an encyclopedic format that displays 256-color high-resolution images of plant identification characteristics and ornamental features coupled with text, side by side image comparisons, “book markers” to return to selected screens, and a slide show that runs a display of images in a user-defined format. The system is being used to study how students learn information presented to them through computers and which program features are most effective in improving plant knowledge. Through computer logging of all student activity within the program and surveys given to the test groups, some basic usage patterns were derived. Students using the program with no incentive tended to use the program in a more comprehensive manner, switching back and forth between the slide show and encyclopedic entries with equal time spent in each. The comparison and “bookmark” features were used but less frequently. Half of the students, given an extra credit incentive based on time, followed this same usage pattern, but the other half simply used the slide show with minimal student–computer interaction.