Stem Scar Research Articles

EFFECT OF FILM PERFORATION ON THE QUALITY OF INDIVIDUALLY SEAL PACKAGED TOMATOES

ABSTRACTFreshly harvested, ethylene treated, mature green tomatoes (Lycopersicon esculentum Mill. cv. ‘Flora‐Dade’) were individually packaged in heat‐shrinkable perforated films and stored at 21°C and 55% RH. The degree of film perforation (exposed surface area, A) was varied as 0, 1.4, 4.5, 11 and 100%, with the hole diameter, D, being constant at 8 mm or D was varied as 0.7, 4, 8 and 16 mm, while A was kept constant at 11%. Films with A = 0 or 1.4% drastically reduced weight loss and tissue softening resulting in tomatoes of good eating quality and bright red color. Off‐flavor was detected when films with D = 0.7 mm were used. Large size holes (D = 16 mm) allowed free gas exchange between the fruit and the environment. Results indicated that fruits transpire throughout the entire skin surface area, but respire primarily through the stem scar.

Diffusion of carbon dioxide in tomato fruits during cold storage in modified atmosphere

SummaryTreatments with 20% CO2 of tomato fruit produced a beneficial extension of storage life. The diffusion of CO2 in tomato (Lycopersicon esculentum Mill) cv. Platense was measured chromatographically and the concentration profiles in the internal gaseous atmosphere of the fruit were determined for non‐steady state conditions to establish minimum treatment times that can ensure adequate penetration of the gas.The effective diffusivity of CO2 in the tissue was determined by fitting concentration data, obtained from experiments with whole fruit without skin, to the non‐steady state solution of the diffusion equation, assuming negligible external mass transfer resistance. The diffusivity was modelled using Maxwell‐Eucken expressions, taking account of the heterogeneous structure of the tissue.The resistance of the fruit skin was evaluated using whole fruits with the stem scar covered with paraffin and fitting experimental data to the solution in terms of mass Biot number; the specific resistance of the peel was some 200 times greater than that of the stem scar.

Waxing and Plastic Wraps Influence Water Loss from Papaya Fruit during Storage and Ripening

Abstract The effect of waxes and plastic shrink wraps on weight loss from papaya (Carica papaya L.) fruit during ripening was determined. Loss of ≈8% of initial weight from mature-green papaya produced “rubbery”, low-gloss, unsalable fruit. The rate of weight loss from ripening papaya was ≈0.1% initial weight/day per mbar. The highest rate of weight loss occurred via the stem scar (nearly 3500 mg·cm−2·day−1) while 4.4 mg·cm−2·day−1 was lost through the skin. The major mode of weight loss was the skin because of its larger surface area. The stomata did not appear to function in ripening fruit. The skin's resistance to water movement increased at the start of ripening, then declined with no apparent change in the rate of total water loss. Part of the decline in resistance was associated with the disruption of the cuticle with latex, especially after the 50% ripe stage. These results suggest that the major site of resistance to weight loss changed late in ripening. Fruit waxing reduced weight loss by 14% to 40%, while plastic shrink wraps reduced loss by ≈90%. The loss of water was the major component of weight loss. Some waxes and one wrap delayed ripening by 1 to 2 days at ambient temperatures, after storage for up to 2 weeks at 10C. Occasionally, off-flavors occurred in waxed and wrapped fruit when the fruit cavity CO2 level exceeded ≈7% at the full-ripe stage.

‘Georgiagem’ Blueberry

Abstract ‘Georgiagem’, a new low-chilling cultivar. is the first highbush blueberry (Vacciniwn corymbosum L.) cultivar developed from the cooperative blueberry breeding program of the Georgia Agricultural Experiment Station and the USDA. Although ‘Georgiagem’ originated mostly from tetraploid highbush blueberry parentage, it obtained adaptation to the southern U.S. environment from the diploid species, V. darrowi, selected from the wild in Florida (2). ‘Georgiagem’ is early ripening, moderately productive, and has fruit of medium size with good color, small stem scar, firmness, and pleasant flavor.

Fruit Quality Characterization of 11 Vaccinium Species

Abstract Eleven species in sections Cyanococcus and Polycodium of the genus Vaccinium were compared among themselves and with standard cultivars for soluble solids, titratable acidity, soluble solids/acid ratio, weight/berry (g), stem scar diameter (pedicel diameter at the berry), scar depth, fruit removal force (picking ease), and firmness. Vaccinium ashei Reade populations collected in either Florida or Georgia showed consistent differences in acidity, fruit size, and firmness. No such pattern in geographical differences occurred with V. corymbosum L. Vaccinium stamineum L. (section Polycodium) was outstanding for high soluble solids, large fruit size, small scar diameter, and firmness. Vaccinium elliottii Chapm. seemed promising for mechanical harvesting and processing with high-acid fruit, a favorable soluble solids/acid balance, small scar diameter, and easily harvested fruit. Vaccinium angustifolium Ait. was noted for high soluble solids, small shallow scar, and picking ease; V. pallidum Ait. for high soluble solids and small shallow scar; V. amoenum Ait. for small shallow scar and picking ease; and tetraploid V. corymbosum for high acidity and favorable soluble solids/acid balance. Sufficient variability occurred among and within species for selection for improvement of most traits; however, several generations of backcrossing or recurrent selection would be required for producing genotypes with commercial fruit size.

‘Brightwell’ Rabbiteye Blueberry

Abstract ‘Brightwell’ rabbiteye blueberry (Vaccinium ashei Reade) is a new cultivar originating from the cooperative blueberry breeding program of the Georgia Agricultural Experiment Stations and the U.S. Department of Agriculture. It is productive, early ripening, and has medium-size fruit with excellent color, stem scar, firmness, and pleasant flavor. ‘Brightwell’ is intended for those areas of the southern United States where rabbiteye blueberries are successfully grown. This cultivar is named in honor of W.T. Brightwell who bred rabbiteye blueberries for over 30 years at the Coastal Plain Experiment Station, Tifton, Ga. He is known for the many excellent cultivars that he and his cooperators originated.

EFFECT OF CULTIVAR, MODIFIED ATMOSPHERE AND RAPESEED OIL ON RIPENING AND DECAY OF MATURE-GREEN TOMATOES

Mature-green fruit of tomato (Lycopersicon esculentum ’Cabot’ and ’Cal J’) were stored at 13 °C in air, or in a modified atmosphere (MA) formed by sealing five fruit in a 1-mil low-density polyethylene bag. MA fruit ripened more slowly and decayed less than those in air. Cal J fruit had a higher dry matter content, ripened more slowly, decayed less, and produced MA atmospheres with 2% lower carbon dioxide and 17 μL/L less ethylene than Cabot. Weight losses in storage were measured. The main rot organisms were Alternaria alternata and Fusarium spp. Coating the stem scars with rapeseed oil had little effect on ripening and resulted in more Penicillium expansum rot. MA storage could extend the field crop marketing period.Key words: Tomato, modified atmosphere, storage, diseases, ripening

Growth and reproduction of American ginseng (Panax quinquefolius) in Wisconsin, U.S.A.

The phenology and development of southern Wisconsin populations of wild ginseng (Panax quinquefolius L.) are described. In natural forests, ginseng plants grow slowly, and most plants do not reach reproductive maturity until they are at least 8 years old. Ginseng flowers are perfect, but maturity of male and female reproductive parts is separated temporally in each flower. Ginseng individuals are not obligate outcrossers, and the flowers are visited by generalist pollinators. Exclusion of pollinators did not reduce fruit or seed set. Aging techniques usually underestimate age. Number of leaves (plant stage) is a more appropriate indicator of development than is the number of "annual" stem scars on the rhizome. The number of seeds produced by a plant may be predicted from the number of leaves and the leaf area of the largest leaflet. Accurate estimates of the number of ginseng plants in an area can be made by sampling early in the summer. However, projections of survival and reproductive success in a ginseng population must account for mortality and for plants that senesce early in the summer months before producing seeds. We recommend that ginseng harvesting in Wisconsin be allowed only after September 1 to insure that fruits on mature plants are ripe.

A Simple Method for the Determination of Resistance to Gas Diffusion in Plant Organs

A simple method was developed for the determination of resistance coefficients for ethylene diffusion in plant tissues based on the kinetic analysis of the efflux of preloaded ethane gas. Efflux curves were analyzed to obtain first-order rate constants and resistance coefficients. Resistance coefficients determined by the ethane efflux and steady-state methods were found to agree well. Employing the ethane efflux method, it was shown that over 97% of gas exchange of tomato (Lycopersicum esculentum Mill., cv. ;Ace') fruits occurs through the stem scar. The resistances to diffusion of tomato skin and stem scar were found to be 280,000 and 300 seconds per centimeter, respectively; the combined resistance of intact tomato fruits was approximately 7,800 seconds per centimeter. The ethane efflux method was employed to show that plastic shrink-wrapping of English cucumbers (Cucumis sativus L. var anglicus Bailey) increased the resistance to ethane diffusion from 1.1 x 10(3) to 23 x 10(3) seconds per centimeter.

‘Bluechip’ Blueberry1

Abstract ‘Bluechip’ is a cane canker-resistant midseason cultivar of highbush blueberry (Vaccinium corymbosum L.). It has very large fruit, excellent color, stem scar, firmness, and a pleasant acid flavor. The name is intended to suggest that this cultivar possesses exceptionally desirable fruit flavor and texture. Released cooperatively by the North Carolina Agricultural Research Service and the U.S. Department of Agriculture, ‘Blue-chip’ is intended principally for fresh fruit production in areas subject to cane canker caused by Botryosphaeria corticis (Demaree & Wilcox) Arx & Muller.

‘Doreen’ Muscadine Grape1

Abstract ‘Doreen’ is a bronze muscadine grape (Vitis rotundifolia Michx.) that can be made into wine equal in quality to ‘Carlos’ and ‘Scup-pernong’. It is self-fruitful, high-yielding, vigorous, resistant to berry shatter, adapted to mechanical harvesting with 50–60% dry fruit stem scars, winter-hardy in the southeast, and is generally disease resistant, including Pierce's disease. It requires 125 days from full bloom to harvest, compared to 100 days for ‘Carlos.’ It ripens in September in south Mississippi and Florida, and in October in North Carolina and north Mississippi.

‘Sterling’ Muscadine Grape1

Abstract ‘Sterling’ is a bronze-fruited Vitis rotundifolia Michx. cultivar released by the North Carolina Agricultural Research Service. It is perfect-flowered, self-fruitful, productive, winter-hardy in muscadine growing areas, vigorous and resistant to berry shatter. When ripe, it picks with a reasonably good stem scar and has 6.5-g fruit. ‘Sterling’ is suited for pick-your-own and fresh fruit sales and can be made into a white wine comparable to that of ‘Scuppemong’ and ‘Carlos’.

Postharvest Decay of Muscadine Grapes (Carlos) in Relation to Storage Temperature, Time, and Stem Condition

Muscadine grapes (Carlos) (<i>Vitis rotundifolia Michx.</i>) decayed twice as fast at 20°C as at 10°C and three times as fast at 10°C as at 0°C. Decay potential and percent of grapes with dry (untorn) stem scars varied according to source (grower). Grapes stored for short periods (one week) at 0°C had little decay, regardless of stem condition. Grapes with torn stem scars, stored for one week at 10°C or three weeks at 0°C, had six to ten times more decay than grapes with dry stem scars. Storage for two weeks at 10°C or for one week at 20°C is not recommended since most of these Carlos grapes decayed regardless of stem scar condition. The stem scars of muscadine (Carlos) grapes appear to be a prime site for entrance of pathogens.

Reevaluation of Heated Water Dip as a Postharvest Treatment for Controlling Surface and Decay Fungi of Muskmelon Fruits1

Abstract Fruits of muskmelon (Cucumis melo L.) dipped in water at 24° and at 57°C did not differ significantly in incidence of Fusarium roseum (LK) emend. Syn. &amp; Hans. ‘Semitectum’ and Diaporthe melonis Beraha &amp; O’Brien and stem scar and rind decay fungi. Immersion time of fruits, regardless of water or chemical treatment, had no significant effect on stem-scar decay, rind fungal growth, fusarium lesions, or general appearance. The value of hot water as a postharvest treatment of muskmelon fruits was to increase efficacy of fungicides.

WMR 29 Muskmelon Breeding Line1

Abstract WMR 29 is a productive, watermelon mosaic virus (WMV) 1 resistant muskmelon adapted for desert culture with excellent shipping characters: nearly spherical shape; heavily netted; dry stem scar; firm blossom end; very firm flesh at full slip; bright salmon-orange flesh; high soluble solids; small, dry seed cavity; and pleasant taste and aroma. Watermelon mosaic virus causes severe stunting and malformation of stems and leaves, and yield reduction of muskmelons in the American desert Southwest. WMV 1 and WMV 2 are contributing factors in declining muskmelon acreage in Imperial Valley during the last 40 years. It is common for Imperial Valley fields to be 100% infected by end of harvest. Dominant, single gene resistance to WMV 1 was found in PI 180280 (1). Resistance to WMV 2 has not yet been reported although cultivars appear to vary in field tolerance to WMV 2.

Effect of Ethephon on Ripening of ‘Cowar’ Muscadine Grapes1

Abstract Concentrations of 0, 50, 100 and 200 ppm (2-chloroethyl)phosphonic acid (ethephon) were applied to replicated 3-vine plots of nearly ripe ‘Cowar’ muscadine grapes (V. rotundifolia Michx.) and fruits harvested 24, 48, and 72 hours after treatment evaluated for ripeness and quality. Force required to release berries from stems decreased as ethephon concentration and time after treatment increased. Soluble solids were significantly lower in the 100 and 200 ppm treated fruit while percent dry stem scar increased. Acidity and soluble solids/acid ratio showed no changed from the control. Penetration force (berry firmness) did not differ from the control for ethephon concentration but had decreased 48 hours after treatment.

Seed-sprouting in tomato fruits

Although tomato juice possesses properties which are inhibitory to seed germination, sprouting of seeds has been observed frequently in ripe tomatoes of mechanical harvest cultivars ‘VF 145’ and ‘VF 13L’. Juice from these cultivars was less inhibitory to tomato seed germination, as determined by bioassays, than that of other cultivars. There was no difference in the inhibition between juice from the pulp and that from the locular gel. Soluble solids accounted for 44% of the inhibition, osmotic concentration 2%, and pH only 0.2%; and the remainder came from other constituents in the juice. Abscisic acid and 2 unidentified substances in the juice isolated by extraction and chromatography were shown to inhibit seed germination; the degree varied with maturity and cultivar. Injection of abscisic acid into the vascular tissue of the stem scar inhibited sprouting within the fruit. Gibberellic acid and kinetin gave variable results, depending upon harvest dates. Fruits from plants grown in low potassium nutrient culture solutions had increased sprouting of seeds. Presented at the XXth International Horticultural Congress, Sydney, Australia, August 1978, Abstract 1189

‘Summit’ Muscadine Grape1

Abstract ‘Summit’ muscadine grape (Vitis rotundifolia, Michx.) is a new cultivar released by the University of Georgia Agricultural Experiment Stations (Fig. 1). It is large-fruited with high soluble solids, and a relatively dry stem scar.

Vulnerability of Stem-End Scars of Blueberry Fruits to Postharvest Decays

CAPPELLINI, R. A. and M. J. CEPONIS. 1977. Vulnerability of stem-end scars of blueberry fruits to postharvest decays. Phytopathology 67:118-119. The principal locus of infection in harvested blueberry occurred at stem scars. The incidence of stem-end decay in fruits was the stem scar. Ninety percent of all decays that stemless berries was 10-fold greater than in berries with their developed in blueberries held for 2, 4, and 6 days at 21 C stems attached.

Ethephon Improves Marketability of ‘Schmidt’ Sweet Cherries Picked without Stems1

Abstract Orchard application of 300 ppm (2-chloroethyl)phosphonic acid (ethephon) to sweet cherries (Prunus avium L. cv. Schmidt) enhanced fruit abscission and decreased fruit injury from stem scar tearing when harvested without stems. Postharvest pitting of the fruit at the stem scar and the development of brown rot were reduced by ethephon. Even so, treated fruit picked without stems was unmarketable after 5 days at room temperature because of excessive amounts of decay, regardless of fungicidal treatment or storage for 0 to 6 weeks at 0 and 5°C.