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Bernard B. Bible and Suman Singha

Differences in color development between exposed and shaded fruit during the growing season were determined for `Loring' and `Raritan Rose' peach (Prunus persica L. Batsch). The surface color of fruit exposed to sunlight in the upper canopy, and in the shade in the lower canopy, was measured with a tristimulus calorimeter, and L* a* b* values were recorded for each fruit from 17 July through harvest. Color changes (ΔE* ab) during maturation for both cultivars at either canopy position were characterized by large changes in hue (Δ H*ab) and lesser changes in lightness (Δ L*ab) and chroma (Δ C*ab). Upper canopy fruit of both cultivars were redder and darker than the lower canopy fruit initially and at harvest. Flesh firmness for `Loring' and `Raritan Rose' tended to correlate with color change from initial sampling to harvest.

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George D. Nanos and F. Gordon Mitchell

Storage at 0C of `O'Henry' and `Fairtime' peaches and `Red Jim' and `September Grand' nectarines (Prunus persica L. Batsch) resulted in significantly longer postharvest life than did storage at 5C, due to differences in the development of internal breakdown (IB) symptoms. Conditioning at 20C for 2 days before storage at 0 or 5C generally prolonged the storage life of fruit of these cultivars. The use of elevated CO2 during conditioning helped maintain fruit firmness. Addition of 5% CO2 to air gave the best results in maintaining fruit firmness and freedom from IB symptoms for up to 6 weeks. Reducing the O2 content kept flesh firmness high after storage but did not delay the appearance of IB. Conditioning at 30C using various atmospheres was less effective than conditioning at 20C.

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Jon M. Clements and Joseph F. Costante

A randomized complete block study was initiated in 1991 in a fifteen year old `Rogers Red McIntosh'/9-106 interstem orchard to investigate the effect of three dormant pruning regimes- an unpruned control, selectively thinned, and heavily structured or “tiered”, on tree canopy light distribution and fruit and spur quality. Fruit quality parameters being measured for the 1991 and 1992 harvests include skin color (% red blush), weight (g.), flesh firmness (kg.), soluble solids concentration (% Brix), and packout (% fancy grade). Pruning treatment effect on fruit spur quality, in terms of spur bud diameter (mm.) and spur efficiency (leaf dry weight/spur), is also being evaluated at time of harvest. Light distribution is being measured (% PAR, umol/s/m2.) within the tree canopy from petal fall through harvest. Preliminary findings indicate there is a difference in tree canopy light distribution and some fruit quality measurements, including red skin color, between pruning regimes. Complete analysis of results from 1991 will be presented.

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Carl E. Mitchell and John A. Barden

In 1992, branches on `Triple Red Delicious'/M.7 were girdled. A factorial of treatments (control, 9mm girdle-uncovered, 9mm girdle-covered) and timings: 0, 15, 30, 60, & 90 days after full bloom(DAFB) was used. With `Golden Delicious'1M.7, branch treatments were: control, score, and 6mm, 9mm, & 12 mm covered girdles, each applied at 0, 15, 30, & 60 DAFB. In 1993, treatments were: control, 9mm uncovered girdle, & pruning saw cut; each was applied 0, 7, 14, and 21 DAFB. Each girdle was a complete ring of bark; scoring was a knife cut through the bark.

The 2 cultivars responded similarly to girdling. Effects were greatest to treatments at 0-30 DAFB, and included increased fruit set or retention, temporary suppression of vegetative growth, and increased levels of soluble solids in the fruit. Treatments affected starch levels in the fruit and flesh firmness, but these effects were inconsistent.

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Mosbah M. Kushad

Seasonal variation in polyamines were evaluate during growth of fruit and seed of peach (Prunus persica L. cvs. Loring and Biscoe) starting at fruit set. In both cultivars, putrescine and spermidine increase significantly while spermine increase only slightly during the early stages of development then declined at the later stages. During pit hardening, polyamines in the flesh remained unchanged but their level in the seed continued to decrease. In both cultivars, polyamine levels corresponded to changes in fruit and seed sizes. when polyamines were vacuum infiltrated into commercially mature Biscoe fruits, flesh firmness, ethylene biosynthesis, and flesh color were significantly different from untreated tissue. The relationship between polyamines, seed development, and fruit development and ripening will be examined.

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C.B. Watkins and J.F. Nock

The inhibitor of ethylene binding, 1-methylcyclopropene (1-MCP) has been applied to `Gala', `Cortland', `McIntosh', `Empire', `Delicious', `Jonagold', and `Law Rome' apples under air and/or controlled atmosphere (CA) storage conditions. 1-MCP gas concentrations ranged from 0 to 2 mL·L–1. Effects of 1-MCP were greater in CA than air storage. A dose response of internal ethylene concentrations and flesh firmness to 1-MCP was found in cultivars such as `McIntosh' and `Law Rome', whereas in others, such as `Delicious' and `Empire', ripening was generally prevented by all 1-MCP concentrations. We have further investigated the effects of 1-MCP on `McIntosh' by increasing rates of the chemical to 50 mL·L–1, and confirming that fruit of this cultivar respond poorly if fruit have entered the climacteric prior to 1-MCP application. Efficacy of 1-MCP is affected by cultivar and storage conditions, and that successful commercial utilization of the chemical will require understanding of these relationships.

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M.C. Dever, R.A. MacDonald, M.A. Cliff and W.D. Lane

Cherry cultivars (Prunus avium L.) from the breeding program located at Agriculture and Agri-Food Canada, Research Centre, Summerland, B.C., were profiled for their sensory characteristics. Judges scored six visual attributes, five flavor/texture attributes, and the degree of liking on 10-cm anchored line scales. There were significant differences (P ≤ 0.001) in external firmness, size, and color intensity as well as differences in flesh firmness, juiciness, sweetness, sourness, and intensity of cherry flavor among the cultivars. Principal component analysis (PCA) showed the relationships among the internal sensory attributes, including a calculated sum of perceived sweetness and sourness, and the analytical values (pH, soluble solids concentration, sugar: acid ratio). Factor scores located individual cultivars on the PCA plot and provided a graphic illustration of their sensory characteristics.

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Roisin McGarry, Jocelyn A. Ozga and Dennis M. Reinecke

Ethephon was applied in two consecutive years to saskatoon (Amelanchier alnifolia Nutt.) shrubs (`Northline' and `Smoky') to determine its effects on synchronizing fruit ripening. Ripeness can be visually assessed by color (green = immature; red = mature, not ripe; purple = mature, fully ripe). Ethephon (applied when fruit were ≈ 70% red) at 250, 500, and 1000 ppm increased the percentage of ripe fruit obtained from `Northline' by 2%, 4%, and 6%, respectively. Due to pronounced seasonal yield differences for `Smoky', ethephon had no effect on the percentage of ripe fruit obtained in 1994. However, in 1995, ethephon (applied at 70% red fruit stage) at 500 and 1000 ppm increased the percentage of ripe fruit obtained from `Smoky' by 4% and 2%, respectively. Fruit quality, evaluated with respect to surface color development, flesh firmness, fruit size, soluble solids concentration, titratable acidity, and the soluble solids: titratable acids ratio, was not significantly affected by ethephon treatments. This work was supported in part by AARI-FFF grant no. 940442.

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Duane W. Greene and Wesley R. Autio

BA, NAA, and carbaryl at 75, 6, and 600 mg·liter-1, respectively, were applied alone or in combination to `Starkrimson Delicious' in 1989 and `Redspur Delicious' apples (Malus domestica Borkh.) in 1990. BA was effective alone, but when combined with carbaryl it thinned excessively. Thinning failed when BA was combined with NAA because many seedless pygmy fruit were formed and they persisted until harvest. BA and carbaryl were more effective than NAA at increasing return bloom. Return bloom was more closely related to total seed count than to final set. BA improved flesh firmness at harvest and after cold storage. None of the treatments influenced the development of calcium-related storage disorders following air storage. Chemical names used: benzyladenine (BA); naphthaleneacetic acid (NAA).

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Duane W. Greene and James R. Schupp

AVG was evaluated for its effect on controlling preharvest drop and influencing ripening of `McIntosh' apples in Maine and Massachusetts. AVG consistently and effectively retarded preharvest drop. AVG was superior to NAA and comparable to daminozide in drop control. Dilute or 2× applications were more effective than applications made at lower water volumes. One application of AVG made 4 weeks before anticipated normal harvest was more effective in controlling preharvest drop than split applications of the same amount made earlier or later. In general, AVG delayed ripening as assessed by a retardation in the development of red color, maintenance of flesh firmness, delayed degradation of starch, and a delayed onset of the ethylene climacteric. We conclude that AVG is an effective drop control compound that is also useful as a management tool to extend the harvest window for blocks of `McIntosh' that would otherwise ripen simultaneously. Chemical names used: aminoethoxyvinylglycine (AVG), naphthaleneacetic acid (NAA), succinic acid-2,2-dimethylhydrazide (daminozide, Alar).