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  • Author or Editor: Harlan K. Pratt x
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Abstract

Gas samples from the central cavities of 3 cultivars of muskmelon fruits (Cucumis melo L.) were resolved by gas chromatography into at least 12 organic volatile fractions. Harvesting of ‘Top-Mark5 and ‘PMR-455 cantaloupe up to 12 days before normal abscission did not reduce the final concentration of volatiles attained. Production of volatiles by cantaloupe was inhibited while still attached to the parent plants, but no evidence for inhibition by the parent plant was obtained in ‘Honey Dew’, nor was the final concentration of volatiles reduced by early harvest. High concentrations of exogenous ethylene applied to harvested melons accelerated the onset of production of the organic volatiles but did not significantly affect their ultimate concentrations. Exogenous ethylene altered the relative amounts of at least 2 fractions. The production of volatiles is closely coordinated with the other aspects of ripening, but the control mechanisms appear to be different.

Open Access

Abstract

The watermelon [Citrullus lanatus (Thunb.) Mats, and Nak.] is a climacteric fruit when harvested at 30 to 50 days after anthesis. At 20 days the fruit is too immature and at 60 days too overmature to show this pattern. An increase in ethylene production is associated with the respiratory peak and final senescence. Initiation of increased respiration occurred about 53 days after anthesis and final senescence at 70 to 74 days, regardless of age at harvest. Optimum harvest maturity occurs at about 45 days, when the fruit is still preclimacteric.

Open Access

Abstract

The star apple is a nonclimacteric fruit and does not respond appreciably to treatment with ethylene, propylene, or ethephon. Its respiration rate at 20°C is 25 to 50 mg CO2 per kg-hr, and ethylene production ranges from 10 to 100 nl per kg-hr. Both respiration rate and ethylene production increased with the onset of fruit decay caused by species of Pestalotia and Diplodia.

Open Access

Abstract

A simplified colorimetric method for CO2 is presented based on use of the readily available Spectronic 20 spectrophotometer. An air stream is bubbled through a bicarbonate solution containing the pH-sensitive dye, bromthymol blue, and the percent CO2 is determined from the percent transmission of light at 615 nm.

Open Access

Abstract

The cashew-apple (Anacardium occidentale L.) grows very slowly until the nut (true fruit) matures. It then grows very rapidly and ripens. Removal of the nut from the receptacle initiates rapid growth of the “apple” and earlier ripening. The pattern of ethylene production confirms that the cashew-apple is nonclimacteric.

Open Access

Abstract

Fruits of muskmelon (Cucumis melo L., cv. Honey Dew and Powdery Mildew Resistant No. 45) were harvested at weekly intervals after anthesis, and weight, shape, flesh firmness, flesh color, and the content of total solids, alcohol insoluble solids, total sugars, reducing sugars, glucose, fructose, and sucrose were measured. Total sugars (mainly sucrose) increased rapidly between the 28th and 42nd days; hence early harvest must inevitably lead to loss in quality. Ethylene treatments of fruits harvested less than fully mature did not alter sugar content since melons have no starch reserve.

Open Access

Abstract

Chinese gooseberry fruits or “kiwifruit” (Actinidia chinensis Planchon, cv. Bruno) were harvested for analysis at intervals throughout the season. On a fresh weight basis, immature fruit contained high concentrations of starch which was hydrolyzed after the fruit reached full size. Concurrently, there was a rapid increase in the concentrations of sucrose, glucose, and fructose, which were the major sugars present. This increase was reflected in a linear rise in soluble solids content of the fruit. Malic and quinic acid concentrations decreased during the early part of fruit growth, rose to a maximum after the fruit reached full size, and then declined slightly. The concentration of citric acid rose linearly during fruit growth, then fell gradually after the fruit reached full size. Ascorbic acid and amino nitrogen concentrations fell during the early part of fruit development, then remained relatively constant. The relationships between patterns of chemical change and the triple sigmoid growth curve of this fruit are discussed.

Open Access

Abstract

The muskmelon cultivar Honey Dew (Cucumis melo L.) has unique horticultural and physiological characteristics, most notably an unusually long period between attainment of acceptable horticultural maturity and self-ripening in the field. Patterns of flowering, fruit set, fruit growth, solids accumulation, softening, ethylene production, respiration, and variation among individual fruits were studied during several seasons. Internal ethylene concentration may be estimated by the following formula: ppm internal = 3.7 ± 1.2 × rate of production in µl/kg-hr. The act of harvesting had no effect on ethylene production or internal concentration. Full ripening required an internal ethylene concentration of about 3 ppm. Horticultural maturity was attained at 35 to 37 days after anthesis, but self-ripening required about 47 days. Commercial harvests include fruits in this range of ages, so treatment with ethylene is required for uniform ripening and consumer satisfaction.

Open Access