The California table olive (Olea europaea L.) industry relies exclusively on hand harvesting of its primary Manzanillo cultivar. Increased harvesting costs have intensified industry interest in identifying an abscission agent that can be used with developing mechanical harvesting technologies to increase removal rates. Table olives are harvested immature green at horticultural maturity but before physiological maturity. The goal of this research was to reevaluate the potential of ethylene-releasing compounds (ERCs) as olive-loosening agents and to screen additional candidates previously shown to accelerate citrus fruit abscission. Eleven compounds were screened at two separate table olive-growing sites (Fresno and Tehama counties) in California in September until Nov. 2006. Compounds were applied at various concentrations alone or in combination. Fruit detachment force (FDF) and percent fruit drop were measured and leaf loss assessed. Of the compounds evaluated, the ERC ethephon (2-chloroethyl phosphonic acid) and 1-aminocyclopropane-1-carboxylic acid were the most efficacious. In whole tree applications, concentrations of ethephon or 1-aminocyclopropane-1-carboxylic acid above 1000 mg·L−1 reduced FDF to less than 50% of the untreated control within 17 days, but leaf drop increased with increasing concentrations. Addition of 1-methylcyclopropene reduced efficacy of ethephon and delayed leaf drop. Monopotassium phosphate + ethephon (4% and 1000 mg·L−1, respectively) reduced FDF and leaf loss was equivalent to the ethephon alone treatment. Compounds such as methyl jasmonate, coronatine, dikegulac, MAXCEL, traumatic acid, and 5-chloro-3-methyl-4-nitro-1H-pyrazole were not efficacious.
Jacqueline K. Burns, Louise Ferguson, Kitren Glozer, William H. Krueger and Richard C. Rosecrance
D.J. Makus and J.R. Morris
Supplemental Ca was supplied to `Cardinal' and `Fern' strawberry (Fragaria ×ananassa Duch.) plants grown in an Enders clayey silt loam soil as a foliar spray of Ca glutarate, as soil incorporated gypsum, as fertigated calcium nitrate (CaNO3), or as a combination of the above. Controls received no Ca. Individual fruits were partitioned into six parts: proximal, distal, inner and outer receptacle, and proximal and distal achenes. Mineral nutrient concentrations (dry mass basis) found in the inner and outer receptacle, and in achenes were, in descending order, K, P, Ca, Mg, Al, Na, Fe, Mn, Zn, B, and Cu; K, P, Ca, Mg, Na, Mn, Fe, Zn, Al, B, and Cu; and Ca, P, Mg, K, Na, Fe, Mn, Zn, Al, Cu, and B, respectively. Many nutrients, including Ca, tended to occur in greater concentrations in the proximal portion of the fruit than in the distal part. With the exception of Al, nutrient concentration gradients were lowest in the inner receptacle. Fruit Ca concentrations were highest in achenes and lowest in inner receptacle tissue. Differences among cultivars in Ca concentration were found in achenes but not in receptacle tissue. Calcium treatment had no effect on receptacle tissue Ca concentrations, regardless of cultivar, but CaNO3 and combination treatments increased Ca concentrations in the achenes in the proximal half of `Cardinal' fruit. Concentrations of all other nutrients except Mn were unaffected by supplemental Ca treatments.
Louise Ferguson, Hesham Gawad, G. Steven Sibbett, Mark Freeman and James J. Hatakeda
A stepwise multiple regression analysis, using payment by processors as the dependent variable (Y) and numerous physical and chemical characteristics as the independent variables (X), demonstrated that the primary factor determining `Manzanillo' olive (Olea europaea L.) value at harvest was size. Optimal crop value correlated strongly with the combined percentage of standard, medium, large, and extra-large olives; R' values were 0.93***, 0.93***, and 0.42 (ns) in 1984, 1985, and 1986, respectively. As the harvest season progressed, increased percentages of olives within these size classifications, not weight increases of individual olives within the size categories, produced the increase in value. Individual olives within size categories maintained the same weight through the harvest season, regardless of tree crop load. The best criterion for predicting optimal harvest time “is the total percentage of standard, medium, large, and extra-large olives.
R. López-Gómez and M.A. Gómez-Lim
A rapid and simple procedure is described for efficiently extracting intact RNA from mango (Mangifera indica L. cv. Manila) mesocarp, a tissue rich in polysaccharides. The RNA can be used for in vitro translation, northern blots, and cDNA synthesis. This method is applicable to other fleshy fruits rich in polysaccharides.
Muharrem Ergun, Steven A. Sargent and Donald J. Huber
Grape tomatoes (Lycopersicon esculentum Mill. `Santa') harvested at light-red (>90% color) and full-red stages were treated with 1 μL·L–1 1-methylcyclopropene (1-MCP) for 24 hours at 20 °C and stored at 20 °C. After 1 day of storage, fruit harvested at light-red stage treated with 1-MCP had a 56% lower respiration rate than untreated fruit. By day 7, respiration rates of the two treatments had converged at about 2 mL·kg–1·h–1. Ethylene production of light-red stage tomatoes treated with 1-MPC was 24% lower than untreated during storage, with rates converging by day 11. For fruit harvested full-red, 1-MCP had similar effects on respiration and ethylene production, although convergence occurred earlier, by day 5. Subsequent tests were conducted only with fruit harvested at full-red stage, since fruit harvested at the light-red stage had lower soluble solids content (4.3%) than fruit harvested at the full-red stage (5.5%). Several combinations of 1-MCP concentrations and exposure times were applied at 20 °C: 1 μL·L–1 for 24 h, 5 μL·L–1 for 6 or 12 h, 25 μL·L–1 for 6 or 12 h, and 50 μL·L–1 for 6 or 12 h; following the respective pretreatment fruits were stored at 20 °C. 1-MCP pretreatment extended marketable life by 1 d, irrespective of pretreatment regime, where untreated and pretreated fruit remained marketable (<15% of fruit soft, decayed and/or shriveled) for 6 and 7 d, respectively. However, 1-MCP did not affect whole fruit firmness, epidermal color, internal color, soluble solids content (6.5%), total titratable acidity (0.64%), or pH (4.3). In a third test simulating commercial handling procedures, full-red harvested tomatoes were treated with 1 μL·L–1 1-MCP for 24 h at either 13 or 20 °C, stored for 4 d at 13 °C, and then transferred to 20 °C. Under these conditions, marketable life for untreated and 1-MCP-treated tomatoes was 7 and 8 d, respectively.
Steven A. Sargent, Jeffrey K. Brecht and Judith J. Zoellner
Internal bruising (IB) caused by handling impacts results in disruption of normal ripening in tomato (Lycopersicon esculentum Mill.) locular gel. It was selected as an injury indicator to investigate the effect of drop height (O, 10, 20, 30 cm) onto an unpadded surface and number of impacts (one or two) for three tomato cultivars. For mature-green (MG) tomatoes, significant incidence of IB (5% to 45%) was found in all cultivars for single drops on opposite sides of fruits from 20 cm; two drops on the same location from 20 cm caused 20% to 30% IB. Breaker-stage (BR) tomatoes were more sensitive to impacts than MG. Single drops from 10 cm on opposite sides of BR fruits caused 15% to 73% IB, depending on cultivar. Two drops on a single location from 10 cm caused 50% to 68% IB. `Sunny' was less susceptible to IB than `Solar Set' or `Cobia' (formerly NVH-4459).
Muharrem Ergun, Jiwon Jeong, Donald J. Huber and Daniel J. Cantliffe
`Galia' (Cucumis melo var. reticulatus L. Naud. `Galia') melons exhibit relatively short postharvest longevity, limited in large part by the rapid softening of this high quality melon. The present study was performed to characterize the physiological responses of `Galia' fruit harvested at green (preripe) and yellow (advanced ripening) stages and treated with 1-methylcyclopropene (1-MCP) before storage at 20 °C. Treatment with 1.5 μL·L-1 1-MCP before storage delayed the climacteric peaks of respiration and ethylene production of green fruit by 11 and 6 d, respectively, and also significantly suppressed respiration and ethylene production maxima. Softening of both green and yellow fruit was significantly delayed by 1-MCP. During the first 5 d at 20 °C, the firmness of green control fruit declined 66% while 1-MCP-treated fruit declined 46%. By day 11, firmness of control and 1-MCP-treated green fruit had declined about 90% and 75%, respectively. The firmness of control yellow fruit stored at 20 °C declined 70% within 5 d while 1-MCP-treated fruit declined 30%. The 1-MCP-induced firmness retention was accompanied by significant suppression of electrolyte leakage of mesocarp tissue, providing evidence that membrane dysfunction might contribute to softening of `Galia' melons. The mesocarp of fruit harvested green and treated with 1-MCP eventually ripened to acceptable quality; however, under the treatment conditions (1.5 μL·L-1 1-MCP, 24 h) used in this study, irreversible suppression of surface color development was noted. The disparity in ripening recovery between mesocarp versus epidermal tissue was considerably less evident for fruit harvested and treated with 1-MCP at an advanced stage of development. The commercial use of 1-MCP with `Galia'-type melons should prove of immense benefit in long-term storage and/or export situations, and allow for retention of quality and handling tolerance for fruit harvested at more advanced stages of ripening.
Charles F. Forney
Volatile compounds are responsible for the aroma and contribute to the flavor of fresh strawberries (Fragari×anannassa), red raspberries (Rubus idaeus), and blueberries (Vaccinium sp.). Strawberry aroma is composed predominately of esters, although alcohols, ketones, and aldehydes are also present in smaller quantities. The aroma of raspberries is composed of a mixture of ketones and terpenes. In highbush blueberry (Vaccinium corymbosum), aroma is dominated by aromatic hydrocarbons, esters, terpenes and long chain alcohols, while in lowbush blueberries (Vaccinium angustifolium), aroma is predominated by esters and alcohols. The composition and concentration of these aroma compounds are affected by cultivar, fruit maturity, and storage conditions. Volatile composition varies significantly both quantitatively and qualitatively among different cultivars of small fruit. As fruit ripen, the concentration of aroma volatiles rapidly increases closely following pigment formation. In storage, volatile concentrations continue to increase but composition depends on temperature and atmosphere composition. Many opportunities exist to improve the aroma volatile composition and the resulting flavor of small fruit reaching the consumer.
Daniel Stanley* and Donald Huber
Banana production is geographically isolated from consumer markets in temperate regions. This disparity has prompted study of ethylene antagonists such as 1-methylcyclopropene (1-MCP) to extend marketable shelf life. Banana fruit (Musa acuminata v. Cavendish) were treated with ethylene (100 ppm) in sea containers (24 h,14.4 °C, 90% RH). After venting, one container was provided with 300 ppb 1-MCP (12 h, 15 °C). Controls were maintained in similar containers without 1-MCP. After treatments, ripening was monitored at 18 °C. Color was graded from values of 2 (green) to 7 (yellow, with sugar spots). During storage at 18 °C, control fruit remained within the color range of 4 to 6 (considered the most marketable) for 3 d compared with 6 d for 1-MCP-treated fruit. The time to reach stage 7 occurred at 8 and 13 d, respectively, in control and 1-MCP treated fruit. Sugar spots occurred after 6 to 7 d for both control and 1-MCP-treated fruit. Thereafter, incidence diverged significantly, with 1-MCP-treated fruit remaining below 10% for 11 d and control fruit exceeding 30% by 10 d. Through the first 5 d, firmness (initially 75 N) declined at comparable rates in both treatments, with control fruit declining to 20 N after 15 d. 1-MCP-treated fruit remained near 40 N throughout storage. Ripening variability did not differ within the treatments. Informal sensory analysis showed that some participants preferred the taste and firmness properties of 1-MCP-treated fruit while others preferred the lower firmness of traditionally ripened fruit. The sweetness of treated fruit was only slightly lower than that of control fruit, yet was still considered acceptable. Work in progress is addressing sugar transformations in 1-MCP-treated banana fruit.
Angela D. Myracle, Zakkary J. Castonguay, Amber Elwell and Renae E. Moran
this research were to determine if the partially ripe stage of maturity is as acceptable as the tree-ripe stage of maturity in several asian plum cultivars and to determine the consumer acceptability of three plum types that possess cold hardiness in U