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  • Author or Editor: D. R. Dilley x
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Abstract

Immersion of cut carnation, Dianthus caryophyllus L. ‘Red Sim’ at the open, partially open or tight bud stage for 6-24 hours in 5-methyl-7-chloro-4-ethoxycarbonylmethoxy-2, 1, 3-benzothiadiazole (MCED) at 5 ppm in combination with 8-hydroxyquinoline sulfate (8HQS) at 200 ppm and 1.5% sucrose increased flower life. The greatest increase occurred when flowers were immersed in the solution at the partially open and tight bud stages for 12 to 24 hours.

Open Access
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Abstract

The longevity of cut carnations (Dianthus caryophyllus L.) was enhanced by solutions containing kinetin and sucrose compared to kinetin alone. Flowers developing during periods of low light intensity senesced rapidly and responded to kinetin only when supplemented with sucrose. Flowers supplemented with sucrose senesced less rapidly when treated with ethylene or abscisic acid than those not treated with sucrose.

Open Access

Abstract

A method is described for the measurement of internal ethylene concentration in fruits on the tree. Ethylene levels in ‘Red Delicious’ fruits immediately after harvest were similar to those in fruits on the tree during development and ripening. The levels varied mostly between 0.02 to 0.15 ppm during the period from 83 to 140 days from bloom and sharply increased from 10 to 1000-fold within 5 days as autocatalytic ethylene production began. Ripening followed the upsurge in ethylene production. Isolating fruit from leaves by girdling plus defoliation of spur leaves hastened the increase in internal ethylene by approximately 1 month. Girdling or defoliating the spur did not markedly alter the onset of autocatalytic ethylene production compared to that observed by fruits on normal spurs. The data support the concept that fruits receive a ripening inhibitor from the leaves.

Open Access

Abstract

Ethylene and other olefinic compounds cause apples and other climacteric fruits to ripen. Propylene, which fruits do not produce, was employed to determine, 1) the stage of maturity apples must attain to autocatalytically produce ethylene, and 2) the effect of O2 tension on autocatalysis. ‘Red Delicious’ apples harvested at developmental stages representing 52, 58, 65, and 75% of maturity were gassed with propylene at concentrations of 0, 10, 50, 100, 500, and 1000 ppm for 1 week at 20°C. Propylene induced ethylene synthesis at all stages of maturity. Its ability to stimulate ethylene production, however, increased progressively with fruit maturation, although rate of production following treatment with 500 ppm propylene was constant. A shorter lag time to the onset of autocatalytic production was observed in more mature fruits which reflects a natural increase in sensitivity. Propylene administered at 6.5% O2 or less did not induce ethylene production, but an anaerobic atmosphere was necessary to completely inhibit ethylene synthesis in fruits once autocatalysis began.

Open Access

Abstract

Preclimacteric ‘Bosc’ pears held continuously at 20°C produced ethylene at a very low rate and resisted ripening for 12 days. However, if held at 5 or 10° for the first 7 days, ethylene production at 20° began to increase almost immediately. Rapid and uniform ripening resulted. Storage at 0° was considerably less effective in this regard. Further, the longer pears were held at 5, up to 6 days, the greater was their ethylene production capacity at 23°. Softening lagged behind the onset of autocatalytic ethylene production. Thus, cold stress induces a metabolic change leading to accelerated ethylene production which in turn initiates other ripening reactions in ‘Bosc’ pears.

Open Access

Abstract

A continuous gas flow system is described which utilizes a paramagnetic O2 analyzer and an infra-red CO2 analyzer to automatically sample, analyze, and record respiratory gas exchange of plant material. The system monitors gas exchange of up to 96 plant samples sequentially, repeatedly, and over extended time periods.

Open Access

Abstract

Germination of freshly dehisced or partially dried 1-day-old pollen of lily (Lilium longifolium Thumb cv. Ace) was greatly enhanced by exposure to high humidity prior to inoculation in germination medium. Half the maximum response was obtained with 40% humidity or with 5 min humidifying time at saturation.

Open Access

Abstract

Dipping ‘Jonathan’ apples in CaCl 2 solution prior to storage greatly reduced the development of internal breakdown (IB) and retarded flesh softening during 19 weeks at 2.2°C plus 1 week at 23°C. Infiltration of fruit with sorbitol produced IB symptoms, whereas glucose caused a dissimilar browning coloration and sucrose yielded no visible damage. Infused Ca inhibited IB symptoms and browning, retarded respiration, reduced the metabolism of endogenous substrates, and increased the oxidation of exogenous substrates. The results suggest Ca inhibits IB by enhancing the uptake and compartmentation of substrates, particularly sorbitol.

Open Access

Abstract

The production of CO2 by apple and pear fruit was measured during and after alternating 12-hr exposures to air and N2 atmospheres. Typical stimulation of CO2 evolution in the absence of O2 was observed. Five or more anaerobic cycles imparted a permanent reduction on the subsequent aerobic respiration rate. The differences between control respiration and aerobic CO2 evolution by fruit exposed to cyclic anaerobiosis indicated that the capacity for aerobic respiration was reduced by the early anaerobic cycles. Suppression of the anaerobic stimulation of CO2 production was observed after several cycles suggesting that the capacity for fermentation was accumulatively impaired. Subsequent measurements of physical characteristics showed that flesh softening and chlorophyll degradation, processes which generally coincide during ripening, were differentially affected by cyclic anaerobiosis. Apple scald was induced by anaerobiosis. Pear fruits subjected to anaerobic cycles or continuous anaerobiosis did not ripen during the 14-day poststorage period at 21°C.

Open Access