Ground Color as a Peach Maturity Index

Abstract

Changes in peach ground color were analysed over the periods of growth, maturation, and ripening for an early, mid-season, and late maturing cultivar. Color was measured with a tristimulus colorimeter in Hunter “L”, “a”, “b” coordinates. Ground color progressions over time were similar for the 3 cultivars. All color coordinates increased during the 3 weeks prior to harvest, with the “a” coordinate showing the largest rate of change with time. Ground color also was compared with a trial series of 6 uniformly spaced color references. High correlations between color reference selection and measured “a” value demonstrated the feasibility of a ground color reference maturity index even when color matches were not exact. Effects of packing house operations on ground color were investigated. Removal of fuzz by brushing had little effect on measured color, whereas wetting of the brushed surface caused a distinct decrease in lightness (“L” value) but little change in chromaticity (“a” and “b” value).

Characteristics of Fruit from High- and Low-quality Peach Cultivars

“…Because of the differences in genotype color, size, and firmness of the high-and low-quality cultivars, freshly harvested fruit were sorted into three stages of maturity using a combination of visual appearance, feel, color chips, and Minolta a values. Color chips, developed for yellow-fleshed cultivars (8), were used only to sort 'Jefferson' peaches. The three maturity stages were designated as immature, threshold mature, and mature, as described by Delwiche and Baumgardner (7).…”

“…By adopting the two-phase sterilization procedure with sodium hypochlorite and be nomyl/acetone, axenic culture of large num bers of asparagus seedlings is possible. Treatment 11 is routinely used in our labo ratory (8) for producing aseptic seeds, with contamination incidence rarely reaching 2%.…”