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Bjorn H. Karlsson and Jiwan P. Palta*

Supplemental calcium application has been shown in our previous work to improve tuber quality and reduce internal defects. We evaluated the response under field conditions of five commerically significant cultivars to a combination of calcium nitrate, calcium chloride and urea (168 kg·ha-1 per season) over three seasons. We were able to determine that the cultivar with the greatest response to supplemental calcium for reduced bruising, `Atlantic' had the lowest levels of tuber tissue calcium. Conversely, cultivars with least response to supplemental calcium, `Dark Red Norland' and `Superior', had the highest levels of tuber tissue calcium. `Snowden' was both intermediate in response to calcium and tuber tissue concentration. Based on data for 3 years, we determined that across cultivars the calcium concentration at which tubers no longer respond is ≈250 ppm and ranges for individual years from 195 to 242 ppm. These results suggest that seasonal variation for individual cultivars may affect the tuber need for calcium for reduced bruising. Although the exact mechanism is not known, we believe that calcium supplemented to bulking tubers may lead to improved cell membrane stability, increased wall structure or enhanced ability of tubers to repair following injury. The results of our study show that supplemental calcium fertilization has the ability to significantly reduce the incidence of tuber bruising for several cultivars.

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Jayson K. Harper and George M. Greene II

This study quantifies the discounts and premiums associated with various quality factors for processing apples (Malus domestica Borkh.). Discounts and premiums were estimated using a hedonic price model and quality data from a total of 137 samples representing three processing apple cultivars (45 `York Imperial', 43 `Rome Beauty', and 49 `Golden Delicious'). Price discounts in the sample were statistically significant for fruit size, bruising, bitter pit, decay, misshapen apples, and internal breakdown. Commonly cited defects, such as insect damage and apple scab, did not cause significant price discounts.

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Kathleen B. Evensen, Joseph M. Russo, and Harriet Braun

Grading criteria are proposed for judging potatoes (Solanum tuberosum) for chip quality and yield. The criteria were derived from a decision-making scheme developed from expert opinions, U.S. Dept. of Agriculture grades, and a statistical evaluation of stored potatoes. The criteria are presented as ranges of acceptable values for a limited set of variables found to be important for chip quality and yield. These variables include bruising, cracks, cuts, fusarium dry rot, lesions, and scab. The proposed criteria, besides being a practical decision-making tool for processors, could serve as a knowledge base for potato expert systems and the development of mechanized sorting equipment.

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S.R. Drake and E.M. Kupferman

Modified Atmosphere Packaging (MAP) in combination with temperature control were investigated for qualify enhancement of sweet cherries (Prunus avium L.). `Bing', `Lambert' and `Rainier' cherries (1 kg/pkg/rep) were wrapped in 1 of 3 different MAP films (5,303; 8,900 and 11,286 cc/sq M/24 hrs of O2 and stored at 0 or 4 C for 3 weeks. Post-storage evaluations included both fruit and stem color, fruit firmness, weight loss, soluble solids, titratable acidity, bruising and pitting valuations, respiration rates and visual assessment. MAP films helped maintain fruit and stem color, and fruit firmness, Whereas weight loss and bruising were reduced. Visual assessment was best with fruit in MAP film packages, There was little change in soluble solids and titratable acidity among fruit in the different MAP films. Control (unwrapped) fruit had considerably higher soluble solids and titratable acidity than wrapped fruit. This difference in soluble solids and titratable acidity between control and MAP fruit was associated with a considerable weight loss in the control fruit. Respiration rates of the fruit varied among the different MAP films and was cuitivar dependent. Fruit stored at 0 C had better quality after 3 weeks of storage than fruit stored at 4 C.

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S.R. Drake and D.C. Elfving

Three commercial `Lapins' sweet cherry (Prunus avium) orchards were used for this study during three crop seasons. Orchards were selected based on the historical average date of commercial harvest. The difference in commercial harvest date among the three orchards was 5 to 7 days. Three harvests were carried out in each orchard each year: 1) beginning 4 to 5 days before commercial harvest, 2) at commercial harvest, and 3) 4 to 5 days after commercial harvest. Fruit quality was determined after 0, 7, 14, and 21 days of storage. Harvesting fruit up to 5 days later than normal commercial harvest resulted in increases in fruit weight and soluble solids content along with no loss of firmness or change in acidity. Pedicel color did not change as harvest was delayed. Changes in visual ratings of both fruit and pedicel appearance with delayed harvest were detectable in only 1 of 3 years. Neither pitting nor bruising was influenced by harvest date. The amount of pitting or bruising present was related more to the year of harvest than to harvest date. Delaying harvest a short time beyond the normal commercial harvest date could enhance consumer appeal and increase fruit value. Storage time after harvest resulted in reduced fruit and pedicel appearance, but only beyond 14 days of storage.

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Shahrokh Khanizadeh, Michel J. Lareau, and Deborah Buszard

An experiment was conducted to evaluate the mechanical harvesting and processing suitability of four standard strawberry [Fragaria ×ananassa (Duch.)] cultivars (`Kent', `Glooscap', `Bounty', and `Midway') and the recent introductions `Chambly' and `Oka'. `Kent', `Glooscap', `Oka', and `Chambly' had the highest yields and heaviest fruit. Similar percentages of berries of all cultivars were destroyed by the harvester. `Oka' and `Midway' were not suitable for this type of mechanical harvesting due to their susceptibility to bruising during harvest. Based on total marketable fruit harvested mechanically, `Chambly' was the most and `Oka' was the least adapted cultivars for this particular harvester. `Chambly' and `Glooscap' were easiest to decap, followed by `Bounty', `Oka', and `Midway'. None of the cultivars tested were suited ideally for machine harvesting, and further breeding is required to produce well-adapted cultivars.

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Mario Mandujano, F.G. Dennis Jr., D.E. Guyer, E. Timm, and G.K. Brown

Michigan growers often have severe problems with soft `Montmorency' sour cherries. Causal factors may include weather conditions, orchard practices, harvesting methods, and conditions during hold of fruits prior to processing. In this study, efforts were concentrated on orchard practices, including shading to reduce solar radiation, irrigation, nutrient level, and application of growth regulators, especially ethephon and gibberellin. Fruit firmness decreased as maturity approached, then stabilized. Significant fruit softening occurred only during mechanical harvesting. No treatments, including sprays of calcium and potassium, consistently increased firmness, but firmness was reduced in 1993 by spraying with ethephon. Firmness varied among orchards, but no “soft” fruit, as defined by industry standards, were observed in harvested fruit. Softening appeared to be caused by excessive bruising, and was always associated with mechanical damage. Advanced maturity and heavy cropping appear to predispose the cherries to greater bruise damage.

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M. Meheriuk, D.-L. McKenzie, B. Girard, A.L. Moyls, S. Weintraub, R. Hocking, and T. Kopp

Kilogram quantities of `Sweetheart' cherries were stored in HDPE perforated bags (1993, 50.8 μ thickness, OTR = 750 ml·m–2·day–1) or in nonperforated bags (1994, 11 μ thickness, OTR = 5196 ml·m–2·day–1) at 0C. Samples were removed at 1, 2, 4, and 6 weeks of storage and evaluated for fruit and sensory quality. Bag atmospheres after 6 weeks of storage were 10% CO2 and 4.6% O2 for the perforated bags and 3.5% CO2 and 6.6% O2 for the nonperforated bags. Fruit brightness, firmness, and titratable acidity declined during storage. Skin color tended to be redder with the longer storage periods. Sensory evaluation in 1993 showed a decline in overall appearance and flavor with time, but texture and juiciness did not change. Acceptability remained high for the first 4 weeks of storage but dropped at week 6. Surface pitting was noticeable at weeks 4 and 6, particularly from stem bruising.

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R.N. Carrow and B.J. Johnson

A turfgrass wear injury study was conducted at Griffin, Ga., on `Tifway' bermudagrass (Cynodon dactylon × C. transvaalensis) using two golf car tires and three golf car types driven in a semicircular pattern to deliver 85 passes over the tread path plot area. Wear injury for the 14 days after wear was applied was assessed by visual quality, percent green coverage, leaf bruising, and verdure. Golf tire × car interactions occurred, but more wear occurred with the low pressure (48 × 103 Pa), dimpled tread tire with flexible sidewalls than the commonly used bias ply (4-ply), V-shaped tread tire with more rigid sidewalls. Significant differences in wear damage occurred for golf car type but were influenced by tire design. Thus, selection of golf car tire and golf car type can influence the degree of wear injury on turfgrass sites.

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J.R. Schupp

`Macoun' is a high-value apple cultivar in the northeastern United States that is very difficult to produce. It is difficult to thin and prone to alternate bearing. `Macoun' is also prone to preharvest drop. Small fruit size, bruising, and lack of red color are additional obstacles to profitable production. The objective of this study was to compare the efficacy of two chemical thinning treatments—accel plus carbaryl, or NAA plus carbaryl—with an untreated control. A second objective was to evaluate the efficacy of ReTain for delaying `Macoun' fruit maturity and to determine if there was an interaction between ReTain and thinning treatment on fruit characteristics at harvest. Both thinning treatments were effective in reducing fruit set in 1997. Accel plus carbaryl was effective again in 1998, while NAA plus carbaryl over-thinned. Accel increased fruit size in 1997 compared to unthinned controls, and both thinning treatments increased fruit size in 1998. Accel increased fruit firmness in both years. ReTain reduced preharvest drop and delayed fruit maturity both years. In 1997, firmness was greatest for fruit treated with accel and ReTain, while ReTain had no effect on firmness of fruit from NAA thinned trees. ReTain had no effect on fruit firmness in 1998.