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- Author or Editor: Mikal E. Saltveit Jr. x
Abstract
Basipetal auxin transport occurred in intact and excised Dracaena marginata stem sections at an apparent velocity of about 5 mm/hr. Application of 20 µl of 0.1 mm 2,3,5-triiodobenzoic acid (TIBA) to the basal cut end of a 3-cm stem segment excised 20 cm from the apex of 1-m-tall plants reduced basipetal auxin transport by 60%. Similar application to the apical end had no effect on acropetal auxin movement. Lateral auxin movement was observed 24 hours after application of radioactive auxin to decapitated stems which had grown horizontally for at least 30 days.
Abstract
A micropropagation procedure was developed to regenerate plants via tissue culture from excised axillary buds of harvested and stored heads of field-grown crisphead (iceberg) lettuce (Lactuca sativa L.). The procedure permits rescue of lettuce germplasm that shows resistance to postharvest physiological disorders and diseases. This procedure was used successfully to regenerate plants of ‘Winterhaven’ lettuce, which showed resistance to russet spot. More than 50% of the excised buds gave rise to viable plants.
Abstract
The degree to which white light stimulated ethylene production in germinating seeds of cucumber (Cucumis sativus L.) was influenced by the length of time the seed had been germinated in the dark before being exposed to light. Maximum stimulation occurred when 24 hour old dark-grown seedlings were exposed to 40 μE m−2 sec−1 light for 24 hours. Ethylene production increased with the duration and intensity of light exposure at all seedling ages. Neither the light or dark rates of ethylene, or carbon dioxide production, nor their ratios, were highly correlated with the sexual phenotype of the 9 cultivars examined.
Abstract
Growth patterns of cucumbers (Cucumis sativus L.) were studied by photographing developing fruit at 2- or 3-day intervals over a 30-day period beginning with pollination (day 0). Nine cultivars were studied: ‘Chinese Long Green’, ‘Sprint 440’, ‘Marketmore 76’, and ‘Minisol’ (all fresh-market types); ‘Riesenschal’ (a schälgurken type); and ‘Marbel’, ‘Kobus’, ‘Calypso’, and ‘Wisconsin SMR-18’ (all pickling types). Analysis of the photographs showed that all sections of the fruit grew in length at a constant rate during the 30-day period. The pattern of growth was fairly uniform, except that there was slightly more growth in the center section than at the ends, and slightly more growth at the blossom end than at the peduncle end of the fruit. Fresh-market and schälgurken types had the longest fruit over the 30-day period of growth, but pickling types had the highest percent change in length. Pickling types produced shorter fruit because they stopped growing earlier than the two other types (12 vs. 14 days, respectively).
Abstract
Compressed air was injected into fruit of pickling cucumber (Cucumis sativus L.) to simulate the build-up of gas during brining. Four size grades were tested from 4 cultivars over 2 harvests and 2 seasons. Carpel adhesion, as measured by the air pressure required to separate the carpels, was negatively correlated with fruit size. Higher air pressure was required to separate the carpels of cultivars resistant to balloon bloating. The formation of balloon bloaters in cucumbers brined in commercial tanks was correlated with results from the compressed air test of carpel adhesion, especially with fruit 45 to 51 mm in diameter.
Abstract
Foliar sprays of either 10 mM aminoethoxyvinylglycine or 3 mM silver ions applied 24 hours before potted poinsettia plants (Euphorbia pulcherrima Klotzsch ex. Willd., cv. Annette Hegg Diva) were sleeved for 24 hours, significantly reduced the development of leaf epinasty after removal of the sleeves.
Abstract
Mechanically bent petioles of potted poinsettia plants (Euphorbia pulcherrima Klotzsch ex. Willd., cvs. V-14, Eckespoint C-1 Red, Annette Hegg Diva, Annette Hegg White, and Annette Hegg Hot Pink) produced 3 to 70 times as much ethylene as petioles from unstressed plants. The Annette Hegg cultivars which were most susceptible to leaf epinasty after being sleeved for 24 hours showed the greatest enhancement of ethylene evolution after being mechanically stressed for 24 hours. Exposure to 10 ppm ethylene in air produced the same cultivar dependent pattern of epinasty in 4 hours as was produced by 24 hours of mechanical stress. Spraying with 250 ppm AgNO3, an antagonist of ethylene synthesis and action, reduced the severity of epinasty in ‘Annette Hegg Diva’ plants sleeved for 24 hours. The less susceptible ‘Eckespoint C-1 Red’ and ‘V-14’, produced less stress ethylene and were less susceptible to ethylene-induced epinasty.
Exogenous application of ethanol (EtOH) vapor to whole tomato fruit or excised pericarp discs inhibits ripening without affecting subsequent quality. Inhibitory EtOH levels are induced in whole tomatoes by a 72 h exposure to anaerobic atmospheres at 20C. In contrast to tomatoes, exposure to EtOH vapor (0 to 6 ml EtOH/kg FW, for 3 to 6 h at 20C) did not retard ripening (e.g., changes in external color, flesh firmness, and soluble solids) of avocado, banana, cucumber, melon, peach, or plum fruit. When the blocked replicates for nectarines were sorted by the firmness of the control fruit, higher levels of EtOH vapor appeared to delay softening of the firmer fruit. From 0 to 4 ml EtOH/kg FW was injected as 95% EtOH into the seed cavity of melon fruit through a surface sterilized area near the equator of the fruit with a plastic syringe fitted with a 7.5 cm long hypodermic needle. Injection of 1 to 4 ml EtOH/kg FW inhibited the softening of `Honey Dew' and muskmelons. Slight tissue necrosis near the site of injection was noted in a few fruit. Unlike the ripening inhibition of tomatoes which is relatively insensitive to the stage of maturity, the inhibition of melon ripening by EtOH appeared to be significantly affected by the maturity of the fruit.
Abstract
Inhibitors of ethylene biosynthesis—aminoethoxyvinylglycine, aminooxyacetic acid, and α-aminoisobutyric acid—inhibited ethylene and lycopene biosynthesis in 1.5-cm disks of excised pericarp tissue of tomato (Lycopersicon esculentum Mill. cv. Michigan-Ohio Hybrid). Application of 10 μl/liter ethylene promoted normal lycopene synthesis, but did not stimulate ethylene synthesis.
Abstract
Parthenocarpic cucumber fruit (Cucumis sativus L. cv. Deliva) of marketable maturity (10 to 14 days after anthesis) were held at 12.5° or 20°C in reduced O2 levels for 5 or 18 days before transfer to air. Carbon dioxide production at reduced O2 levels was generally less than in air; however, at O2 levels < 0.5%, anaerobic respiration resulted in increased rates of CO2 production. Upon transfer to air after 18 days, all samples from reduced O2 showed increased CO2 production rates that equalled or exceeded that of the air controls. Except at 0.0% and 0.25% O2 levels, ethylene production was increased in reduced O2. After transfer to air, ethylene production increased and the increase was inversely related to the previous O2 level. Ethanol and acetaldehyde production were measureable for fruit held in 1% O2 after 18 days at 12.5° and showed dramatic increases at lower O2 levels. Low-O2 injury (pitting) developed on most fruit held at 0.0% O2 and on many fruit held at 0.25% O2. Only minima! commercial benefits are likely to be realized from storage of 1 to 3 weeks in 0.5% to 2.0% O2 at 12.5°.