Red color of 2 strains (`Bisbee' and `Red Chief) of `Delicious' apples was increased (25%) by a 10 day delay beyond recommended harvest date. Color of `Oregon Spur' did not change during this 10 day period. Soluble solids content and size were also increased, but firmness decreased by 12%. In 2 of 3 years, firmness at harvest was 73 N or greater in all strains and these fruit lost little firmness during 9 months of CA. Poor firmness (<63 N) at harvest resulted in fruit with unacceptable firmness (53 N) after storage regardless of harvest time or strain. Loss in fruit quality was evident after a 5 day delay in atmosphere establishment with no further loss after a 10 day delay. `Oregon Spur' had the best color regardless of harvest, followed by `Bisbee' and `Red Chief. All strains (`Oregon Spur', `Bisbee' and `Red Chief) had good quality after long term CA. Sensory panelists could not distinguish flavor differences between strains, harvest dates or delay in storage establishment.
S.R. Drake and Tom Eisele
Mark A. Bennett, David M. Francis, and Elaine M. Grassbaugh
Ethephon (2-chloroethyl phosphonic acid) has been widely used under field conditions as a growth regulator to trigger the ripening of processing tomatoes prior to mechanical harvesting. Recent interest in whole-peeled and diced tomato products has raised questions about ethephon rates, and possible split applications for top quality. This 3-year field study tested two commercial cultivars of processing tomatoes (`OH8245' and `P696') and the effect of various ethephon applications on fruit firmness, color uniformity, and peeling variables. Transplants were established in mid to late May of 1996–1998 on raised beds in single rows at the OSU/OARDC Veg. Crops Branch in Fremont, Ohio. Ethrel applications for each cultivar were: 0, 0.58, 0.58 × 2 applications, 1.17, 1.17 × 2 applications, 1.75, 2.34, 4.68, and 7.02 L·ha–1. Fruit were tested for firmness, color uniformity, pH, titratable acids, and soluble solids. Samples from ethephon treatments of 0, 1.17 × 2 applications, 2.34, 4.68, and 7.02 L·ha–1 were peeled and canned for color inspection and firmness after 18 months storage. Three-year data for red fruit yield showed a typical response to increasing amounts (0 to 7.0 L·ha–1) of applied ethephon. While high rates (4.7 or 7.0 L·ha–1) gave some of the highest red fruit yields, and the greatest percent red fruit values, high rates were also linked with among the lowest fruit solids values. Split application comparisons showed little influence on quality variables examined in this study. However, chroma values were improved (more vivid color) when 2.3 L·ha–1 was applied vs. 1.17 L·ha–1 applied twice. Split applications also tended to produce softer fruit. Our results suggest that single ethephon applications of 1.17 to 2.34 L·ha–1 provide optimal fruit ripening and quality under midwestern U.S. conditions.
James R. Cooksey, Brian A. Kahn, and James E. Motes
While ethephon [(2-chloroethyl) phosphonic acid] has increased yields of red fruits, its use as a pepper (Capsicum annuum L.) fruit ripening agent has been limited by premature fruit abscission and defoliation. We tested ethephon solutions of 0, 1500, 3000, 4500, and 6000 μl·liter-1 with or without 0.1M Ca(OH)2 as a one-time foliar application to field-grown paprika pepper in southwestern Oklahoma. There was a linear increase in fruit abscission with increasing ethephon rates in two out of three years, with or without added calcium. Ethephon at 6000 μl·liter-1 improved the percent of total fruit weight due lo marketable fruits in two out of three years, primarily by decreasing the weight of harvested green fruits. However, ethephon never significantly increased the dry weight of harvested marketable fruits over that obtained from the control. There also was no effect of ethephon on the intensity of red pigment extracted from dehydrated marketable fruits. The only significant effect of Ca(OH)2 was an undesirable increase in the retention of green fruits on the plants. Ethephon had little value as a fruit ripening agent for paprika under the conditions of our studies, and Ca(OH)2 was not useful as an additive to ethephon sprays.
Peter D. Petracek, D. Frank Kelsey, and Craig Davis
The effect of high-pressure washing (HPW) on the surface morphology and physiology of citrus fruit was examined. Mature white (Citrus paradisi Macf. `Marsh') and red (Citrus paradisi Macf. `Ruby Red') grapefruit, oranges (Citrus sinensis L. `Hamlin'), and tangelos (Citrus reticulata Blanco × Citrus paradisi Macf. `Orlando') were washed on a roller brush bed and under a water spraying system for which water pressure was varied. Washing white grapefruit and oranges for 10 seconds under conventional low water pressure (345 kPa at cone nozzle) had little effect on peel wax fine structure. Washing fruit for 10 seconds under high water pressure (1380 or 2760 kPa at veejet nozzle) removed most epicuticular wax platelets from the surface as well as other surface debris such as sand grains. Despite the removal of epicuticular wax, HPW did not affect whole fruit mass loss or exchange of water, O2, or CO2 at the midsection of the fruit. Analysis of the effect of nozzle pressure (345, 1380, or 2760 kPa), period of exposure (10 or 60 seconds), and wax application on internal gas concentrations 18 hours after washing showed that increasing nozzle pressure increased internal CO2 concentrations while waxing increased internal ethylene and CO2 concentrations and decreased O2 concentrations. An apparent wound ethylene response was often elicited from fruit washed under high pressures (≥2070 kPa) or for long exposure times (≥30 seconds).
Richard Bestwick, X. Good, J. Kelloogg, D. Langhoff, W. Matsumura, W. Wagoner, and G. Cloud
The gene encoding S-adenosylmethionine hydrolase (SAMase) was transferred to tomato (Lycopersicon esculentum, cv. large red cherry) as a means of reducing ethylene biosynthesis in the ripening fruit. S-adenosylmethionine (SAM), the penultimate precursor to ethylene in plants. is converted to methylthioadenosine and homoserine by SAMase thereby reducing the capacity of the transgenic plant to synthesize ethylene. We have used both constitutive and fruit-specific tomato promoters to regulate SAMase gene expression. Whereas the constitutive CaMV 35S:SAMase chimeric gene expressed active SAMase and conferred a 50-60% reduction in ethylene biosynthesis in a leaf disc assay, there was little effect on fruit ethylene synthesis or postharvest ripening physiology. The use of either the tomato E4 or E8 promoters restricted SAMase expression to ripening fruit which caused a substantial (80-90%) reduction in fruit ethylene synthesis and a profound effect on fruit ripening. SAMase expression levels reached 0.1% of total cellular protein as measured on western blots using anti-SAMase monoclonal antibodies. Field trial fruit picked al the mature green stage accumulated less lycopene and were twice as firm as controls over a six week period. Vine-ripened fruit had near-normal levels of lycopene, were firmer at harvest than controls, and did not lose firmness over a two week period. Taste, vitamin content and tomatine content were superior or equivalent to control tomatoes.
D. Handley, M. Schupp, T. Work, R. Work, and A. Bushway
Twelve early to midseason ripening tomato cultivars were evaluated for early and total marketable yield, fruit size, and external characteristics under the cool, short growing season of northern New England. The acceptability of external and internal color, texture, and flavor of four cultivars was evaluated by a sensory panel of 50 members. There was little difference between cultivars in total yield. This was probably due to an early frost that destroyed much of the later ripening fruit. `Summerset' had the highest early and overall yields but the smallest fruit size. `Johnny's 361` had high overall yield and large fruit with good early yields. `Pilgrim' had high early yield, good overall yield, and fair fruit size. `Jetstar' and `Daybreak' fell into the middle of the range for total yield and fruit size, but `Jetstar' had very low early yield. `Pik Red' and `Pik Rite' had low early and total yields but good fruit size. `Moreton Hybrid' had fair early and total yields and small fruit size. In the sensory analysis, `Sunrise' had the highest rated external color, while `Moreton Hybrid' had the lowest rating. Internal color ratings did not vary greatly, although `Sunrise' was least acceptable in this characteristic. `Jetstar' was rated highest for flavor and texture, followed by `Moreton Hybrid', `Sunrise', and `Valley Girl'.
Jalapeños are versatile peppers with both green and mature-red peppers used fresh and in processed products. Peppers can be dried, pickled whole in brine or as salted mash for sauces. Mature fruit can also be smoked and dried to produce chipotle which can be used in several ways including preparation of sauces. Although there are many individual cultivars of jalapeño peppers available, little is known of their processing characteristics. Most food processors still rely on fresh-market supplies rather than contracting specific cultivars which might provide better processing characteristics. A study was begun in Summer 2005 at LSU to provide information concerning the processing characteristics of commonly available jalapeño cultivars. Over a 3-year period, each cultivar will be evaluated in fresh form, as pickled whole fruit, as salted mash and as smoked chipotle. Besides good cultural production qualities, pepper cultivars that will be manufactured into processed products should have 1) acceptable and consistent heat content, 2) good stable color and, 3) consistent/suitable size (for whole pack). Seventeen jalapeño cultivars were evaluated in fresh green, brine-cured green and mature-red state for fruit surface color, average fruit weight, dry weight, and percent seed.
R.J. Hilton, H. Riedl, and P.H. Westigard
Handgun treatments of abamectin and oil applied between mid-June and late August caused distinct epidermal rings where drops of spray liquid dried on the surface of pear fruit (Pyrus communis L.). The severity of epidermal injury was related to the concentration of oil in the abamectin spray mixture (abamectin applied without oil caused no fruit damage). Of six pear cultivars tested, `Anjou' was most susceptible to injury, followed by `Cornice' and `Bartlett'. `Sensation Red Bartlett', `Bosc', and `Seckel' showed little or no phytotoxicity symptoms from abamectin and oil treatments with oil concentrations from 0.125% to 2.0% (v/v). On sensitive cultivars, the concentration of oil should not exceed 0.25% (v/v) when combined with abamectin to reduce the risk of epidermal injury. Oil at 0.25% provides for adequate leaf penetration of abamectin and results in commercially acceptable spider mite (Tetranychus urticae Koch) control. Chemical names used: avermectin B1 (abamectin).
S.R. Drake and T.A. Eisele
appreciation to the Washington State Tree Fruit Research Commission for funds partially supporting this study. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use