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One strategy to reduce postharvest losses of fruits to pathogens is to introduce organisms with biological control capabilities. Our objective was to determine the effectiveness of two yeast isolates in inhibiting lesion development caused by Botrytis cinerea (Bc) on freshly harvested apples differing in maturity. `Golden Delicious' apples were harvested on 29 Aug., 23 Sept., and 10 Oct. 1995. Apples receiving the seven treatments [control, wound, Cryptococcus humicola (Ch), Sporobolomyces roseus (Sr), Bc, Ch + Bc, Sr + Bc] were placed in plastic boxes with damp paper towels. Each day for 7 days, ethylene production and lesion diameter at the wound were recorded. Ethylene production was not affected by treatment, and increased with later harvest date. Lesion diameter on apples treated with Bc was smaller on the first harvest than on the second and third harvests. Sr provided partial control on the second and third harvests, and Ch completely inhibited lesion development except for day 7 of the third harvest.
Strategies to reduce postharvest losses of fruit to pathogens include low-temperature storage, fungicides, and use of organisms with biological control capabilities. Our objective was to determine the effectiveness of two yeast isolates in inhibiting lesion development caused by Botrytis cinerea (Bc) on freshly harvested apples of different maturity. `Golden Delicious' apples were harvested on 29 Aug., 23 Sept., and 10 Oct. 1995. Apples comprising the seven treatments [control, wound, Cryptococcus humicola (Ch), Sporobolomyces roseus (Sr), Bc, Bc + Ch, Bc + Sr] were placed in plastic boxes with damp paper towels. Each day for 7 days, ethylene and CO2 production and lesion diameter at the wound were recorded. Ethylene and CO2 production were not affected by treatment. Lesion diameter on apples treated with Bc was smaller on the first harvest, compared with the second and third harvests. Sr provided partial control on the second and third harvests, and Ch completely inhibited lesion development on all harvests.
A series of experiments were conducted to determine the sensitivity of radish to four light alcohols (ethanol, methanol, 2-propanol, and t-butanol) identified as atmospheric contaminants on manned spacecraft. Radish (Raphanus sativus L. `Cherry Bomb' Hybrid II) seedlings were exposed for 5 days to concentrations of 0, 50, 100, 175, 250, and 500 ppm of each alcohol and the effect on seedling growth was used to establish preliminary threshold response values. Results show a general response-pattern for the four alcohol exposures at threshold responses of 10% (T10), 50% (T50) and 90% (T90) reduction in seedling length. There were differences in the response of seedlings to the four alcohols, with the T10 for t-butanol and ethanol (25 to 40 ppm) being 3 to 5× lower than for methanol or 2-propanol (110 to 120 ppm). Ethanol and t-butanol exhibited similar T50 values (150 to 160 ppm). In contrast, T50 for methanol (285 ppm) and 2-propanol (260 ppm) were about 100 ppm higher than for ethanol or t-butanol. Chronic exposures to 400 ppm t-butanol, ethanol or 2-propanol were highly toxic to the plants. Radish was more tolerant of methanol, with T90 of 465 ppm. Seeds did not germinate at the 500 ppm treatment of t-butanol, 2-propanol, or ethanol. There were significant differences in projected performance of plants in different environments, dependent upon the regulatory guidelines used. The use of exposure guidelines for humans is not applicable to plant systems.
Research to determine protocols for greenhouse forcing of woody shrubs was initiated as part of the New Crop Research program at the University of Georgia. About 15 woody taxa were initially selected for the program based on habit, foliar qualities and flowering (if present). All plants were subjected to 1.7–4.4 °C for 0, 6, or 10 weeks in a controlled temperature cooler. Based on growth and visual characteristics, Leptodermis oblonga, Indigofera pseudotinctoria `Rose Carpet', Forsythia ×intermedia `Golden Peep' and Philadelphus coronaria `Manteau d'Hermaine' was discarded. Caryopteris x clandonensis `Sunshine Blue', Leycesteria formosa `Golden Lanterns', Sambucus nigra`Black Lace', Philadelphus coronaria`Variegata' and Physocarpus oblongifolius `Summer Wine' were investigated further. Data presented for Physocarpus suggested that cooling was not necessary for growth; however, 10 weeks of cooling resulted in the least time to finish in the greenhouse. Ten, six, and zero weeks cold resulted in 17, 10, and 7 weeks finish time respectively. Additional work conducted in 2005 and future research will be discussed.
As part of the New Floriculture Crop Program at the University of Georgia, a research project was initiated in Fall 2004 to determine production protocols for forcing woody shrubs in the greenhouse. The influence of cooling on greenhouse forcing of three woody taxa (Caryopteris ×clandonensis `Sunshine Blue', Leycesteria formosa `Golden Lanterns' and Sambucus nigra `Black Lace') was evaluated. Dormant rooted liners (7 cm) were received in November 2004 and were cooled for 0, 6, or 10 weeks at 1.7–4.4 °C. With 0 weeks cooling, Caryopteris ×clandonensis `Sunshine Blue' never reached an acceptable finish stage. With 6 weeks cooling, plants were not of sufficient quality to be saleable; however with 10 weeks cooling, plants finished in 7 weeks in the greenhouse. With 0 weeks cooling, Leycesteria formosa`Golden Lanterns' was saleable in 13 weeks. With 6 weeks cooling, plants finished in 7 weeks. With 10 weeks cooling, plants finished in 8 weeks. With 0 weeks cooling, Sambucus nigra `Black Lace' never reached a saleable stage. With 6 weeks cooling plants were saleable in 11 weeks; with 10 weeks cooling plants finished in 6 weeks. The data suggest that cold is necessary for greenhouse forcing of Caryopteris and Sambucus, and that 10 weeks of cold resulted in the shortest production time. Data suggest that 6 weeks cooling of Leycesteria resulted in the shortest production time; however cooling is not necessary to produce a finished plant of good quality.
Knowledge engineering offers substantial opportunities for integrating and managing conflicting demands in greenhouse crop production. A fuzzy inference system was developed to balance conflicting requirements of producing a high-quality, single-stem rose crop while simultaneously controlling production costs of heating and ventilation. An adaptive neuro-fuzzy inference system was built to predict the rose status of `Lady Diana' single-stem roses from nondestructive measurements. The fuzzy inference system was capable of making a critical decision based on the principle of economic optimization. Temperature set points for two greenhouses with similar rose status were treated significantly different by the fuzzy inference system due to differences in greenhouse energy consumption. Moderate reduction in heating energy costs could be realized with the fuzzy inference system.
Abstract
Tomato fruits, initially mature-green and held at 55° F for 6 weeks, kept significantly better in 3% O2 and zero CO2 than in air. Three or 5% CO2 combined with the low-O2 atmosphere did not materially affect the amount of decay, and sometimes resulted in CO2 injury. Mature-green tomatoes ripened to a full red when held in air for 6 weeks at 55°. When stored in an atmosphere containing 3% O2, tomatoes ripened to pink. Red color development was further retarded in a low-O2 atmosphere supplemented with 3 or 5% CO2.
Exposing mature-green tomatoes to air for 16 hours midway in a 6-week holding period in low-O2 did not affect the decay or color of the fruits while in storage as compared to a continuous holding in low-O2. After ripening, however, the tomatoes from the interrupted treatment did not keep as well as those from the continuous treatment.
Mature-green tomatoes stored at CO2 levels of 3 or 5% tended to be more acid after ripening than tomatoes held in CO2-free atmospheres.
Abstract
‘Orlando’ tangelo (Citrus reticulata Blanco × Citrus paradisi Macf.) trees not irrigated in the fall, but protected by under-tree sprinkling during a frost, sustained the lowest percentage of leaf and fruit damage as determined 6 weeks after the frost. Trees irrigated both in the fall and during a frost, or those receiving no fall irrigation or under-tree sprinkling, were intermediate in fruit damage. Fall irrigation without sprinkling the night of a frost contributed to the most severe damage to leaves and fruit. Soil moisture content of irrigated blocks was significantly greater than for non-irrigated blocks during the fall, yet afternoon leaf xylem water potential and stem water content were comparable. Leaf freezing point of detached leaves of ‘Orlando’ and navel orange (Citrus sinensis (L.) Osbeck) was poorly correlated with leaf xylem water potential, abaxial diffusion resistance, and relative water content. Leaf freezing and killing temperature was unaffected by fall irrigation and ranged from -5.8 to -6.8°C from October until December in 1978 and 1979.
Our objective was to determine whether repeated applications of 2-chloroethylphosphonic acid (ethephon) + gibberellic acid (GA3) to stock chrysanthemum plants that are day-neutral for flower bud initiation would increase the number of quality cuttings. Across five cultivars, there were no significant differences between controls and plants receiving 250 ppm ethephon in the total number of cuttings per plant. The percentage of cuttings with crown buds was greater for cuttings from controls than for ethephon-treated plants. Applying 500 ppm ethephon significantly reduced the number of cuttings. We conclude that chrysanthemum clones day-neutral for flower bud initiation and development with low long-day leaf number could be selected to form a 4 to 5 week production group.