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- Author or Editor: Mikal E. Saltveit Jr. x
- HortScience x
Abstract
A simple, inexpensive method is presented to prepare an effective chemical scrubber which oxidizes volatile organic contaminants in gases. The scrubber is made by mixing 100 ml of 1 M KMnC4 per liter of dust-free Perlite in a large clear plastic bag.
Abstract
Gas samples are often extracted from horticultural produce for analysis of ethylene, carbon dioxide, oxygen, and other gases by gas chromatography. This paper outlines procedures for extracting gas samples either by using a syringe needle to puncture a cavity within the fruit or vegetable or by subjecting the fruit or vegetable to a partial vacuum.
Abstract
A device is described which maintains a set temperature ± 0.8°C from 5 to 30° above ambient in an inexpensive controlled-temperature chamber. Present construction cost is about $65. Ten chambers have performed satisfactorily during the past 3 years in research projects on chilling injury, seed germination, seeding growth, tissue culture growth, fruit storage, tree storage, and winter dormancy.
Abstract
A 39-week production schedule is described in which container-grown apple trees (Malus domestica Borkh. cvs. Red Chief Delicious, Sundale Spur Golden Delicious, and Paulared) are cycled through 4 weeks of cold acclimation, 7 weeks of chilling, 5 weeks of growth before flowering, 21 weeks of fruit growth and maturation, and 2 weeks growth after fruit harvest.
Abstract
A survey was conducted to measure the variability among gas chromatographic analyses of ethylene and the variability among the ethylene gas standards used in 22 laboratories in the United States and Canada. The linearity of gas chromatographic responses to injections of 10.0, 1.0, and 0.1 μl/l ethylene in air mixtures had an average coefficient of linear determination (R 2) of 0.9984, with a SD among the R 2 values of only 0.33%. The ethylene concentrations calculated for the laboratory standards varied from 11.3% higher to 21.7% lower than the value assumed by the participant; with an average variance of about 6% lower.
Abstract
Prolonged physiological studies using gas mixtures containing μl/liter levels of a specific gas component (e.g. ethylene or propylene) require a flowthrough system to ensure that the plant or plant part under study is exposed to a relatively constant gas concn. This prevents tissue incorporations and/or emanations (e.g. biosynthesis of ethylene or CO2) from altering the physiological effective gas concn (1).
Abstract
Firmness of ‘Starkrimson Delicious’ and ‘Golden Delicious’ apples was not significantly different when tested at 0° and 20°C after 26 weeks of storage at 0°. The volume of bruises produced in these cultivars by mechanical impact injury increased with increasing temperature (0°, 10°, 20°, and 30°) when injured, and with increasing holding temperature (0°, 10°, 20°, and 30°) during bruise development.
Ethylene induces arenchyma formation in corn roots and other plant tissues, and abscisic acid (ABA) induces arenchyma in celery petioles. Pithiness (i.e., arenchyma) in celery can be measured as a decrease in density. Density was calculated for two cm long petiole segments by dividing their weight by their volume as calculated from the weight of water displaced upon immersion. The relationship between density (g/ml) and subjective pithiness rating (1 = none, 9 = severe) was linear (r2 = 0.87). Petiole segments exposed to 0 to 200 ppm ethylene in air at 5C for two weeks did not exhibit any significant differences (p = 0.05) in density among the treatments. Entire petioles were treated with 0, 1, 10, and 100 μM ABA in water for 96 h at 25C. The petioles were cut into thirds and the center 2 cm from each portion was excised and the density measured. Although density decreased in the top to the bottom portions over all ABA conc, the differences were not significant. Density was significantly reduced in segments excised from the bottom and middle of petioles treated with 10 and 100 μM ABA, compared to 0 and 1 μM ABA. There also was a decrease in density with ABA conc in the top portion, but the decrease was only significant for the 100 μM ABA conc.
A method is described for the rapid determination of the anaerobic compensation point (ACP) of plant tissue, i.e., the O2 concentration at which CO2 production is minimum. The rate of CO2 production is measured from tissue exposed to an exponentially declining O2 concentration produced by a flow of N2 into a dilution bottle initially containing air. Too rapid a rate of O2 decline produces abnormal data because of the time required for the tissue to respond to changes in O2 concentration. The ACP is easily determined from a plot of CO2 production vs. O2 concentration. Rates of CO2 production and ACPS calculated using the exponentially declining system are similar to those calculated from traditional methods of continuously holding tissue under various O2 concentrations.
The content of acetaldehyde (AA) and ethanol (EtOH) increases in ripening climacteric fruit. Application of EtOH inhibits tomato (Lycopersicon esculentum) fruit ripening without affecting subsequent quality, and AA enhances organoleptic quality. AA inhibited ripening of mature-green tomato discs (MGTD) at about 30% conc of EtOH. The relationship between EtOH and AA inhibition of tomato fruit ripening is unclear. The inter-conversion of AA and EtOH is catalyzed by alcohol dehydrogenase (ADH) which is inhibited by 4-methylpyrazole (4-MP). No adverse physiological effects upon ripening were observed in MGTD receiving 20 μL of 4.0 mM 4-MP. Treating MGTD with 0.5 to 4.0 mM 4-MP in concert with AA (≤2.0 μL/g FW) or EtOH (≤8 μL/g FW) was not deleterious to ripening. A rapid, efficient method for the analysis of tissue AA and EtOH was linear (r2 = 0.97) for discs spiked with 0 to 45 μL EtOH. No temporal (0 to 42 h) changes in tissue AA and EtOH were detected in MGTD receiving 2.0 mM 4-MP. MGTD treated with 2.0 mM 4-MP and 8 μL/g FW EtOH had a 360-fold increase in AA after 6 days of ripening, but had no differences on EtOH conc. These conditions maximally inhibited ripening as determined by lycopene content.