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  • Author or Editor: David Sugar x
  • Journal of the American Society for Horticultural Science x
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The anthocyanin in `Sensation Red Bartlett' pear skin was characterized and quantified, and the effect of light quality on fruit color development was evaluated. Anthocyanin concentration was related to fruit chromaticity values. Pigments were analyzed using high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC). One of two spots detected in the TLC chromatogram did not change color with molybdate sprays, indicating the possible presence of peonidin. HPLC analysis confirmed the presence of a major and a minor pigment, which co-eluted with cyanidin 3-galactoside and peonidin 3-galactoside. Monomeric anthocyanins in the pear skin extract were 6.83 mg/100 g of fruit peel. To study light quality, gelatin filters allowing passage of different wavelengths of-light were attached over the exposed side of `Sensation Red Bartlett' pears 1 month before harvest. Chromaticity was recorded before the filters were attached and after their removal at harvest using the Commission Internationale del'Eclairage (L*, a*, and b*) color space coordinates. Following color measurements, anthocyanin was extracted from individual skin disks. Skin beneath all filters yielded less hue than the control. Wavelengths that transmit above 600 nm had the largest effect on chroma, a*, and b* values. Fruit wrapped in aluminum foil to obscure all light had the highest luminosity. Wavelengths from 400 to 500 nm gave darker, less chromatic, and redder pear fruit. All treatments yielded higher anthocyanin content than the control. There was a tendency toward increased anthocyanin content with longer wavelengths. The simple linear regression of the log anthocyanin content on L* value and (a*/b*) provided an R 2 = 0.41.

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Putrescine at 10−5, 10−4, 10−3, and 10−2 m applied at anthesis increased fruit set of ‘Cornice’ pear (Pyrus communis L.) in 1985 and 1986. Ovule longevity and the effective pollination period were extended 2 days in 1985 and 5 days in 1986 by putrescine at 10−3 m. Pollen tubes reached the micropyle 2 days earlier in treated than in untreated flowers. High levels of evolved ethylene in flowers were related to pollination and fertilization and were unaffected by putrescine application. Increased ovule longevity and fruit set in treated flowers were associated with increased foliar and flower N and B levels after fertilization. Chemical name used: 1,4-diaminobutane dihydrochloride (putrescine).

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