ReTain™, a commercial plant growth regulator containing aminoethoxyvinylglycine, an inhibitor of ethylene production, was applied 4 weeks before normal harvest to `Jonagold' trees and the effects on fruit maturity and quality at harvest, and quality after air and controlled atmosphere storage was investigated. When fruit were harvested from 3 to 6 weeks after treatment, fruit ripening was inhibited as indicated by lower internal ethylene concentrations, delayed starch hydrolysis, and lower levels of skin greasiness. A number of factors indicated that other aspects of fruit metabolism were affected by the compound. Treated fruit were softer than nontreated fruit at the first harvest, and the benefits of ReTain on firmness appeared only at the later harvests. Also, at each harvest date, average fruit weight of ReTain-treated fruit was lower than nontreated fruit. We have investigated the possibility the ReTain and/or the accompanying surfactant, Silwet, inhibited leaf photosynthesis, thereby leading to altered carbon metabolism. Trees were unsprayed, or sprayed with surfactant, and ReTain plus surfactant. No treatment effects on photosynthesis were detected. However, leaf photosynthesis rates were generally low and quite variable. Measurements of fruit diameter confirmed that the increase in fruit volume following treatment was ≈2% less on the ReTain plus surfactant-treated fruit than nontreated fruit. The increase in fruit volume for the Silwet treatment was ≈1.5% less than in untreated fruit. The data indicates a rapid change in fruit volume as fruit changed in color. Inhibition of ethylene by ReTain may be an important factor influencing fruit size.
Chris B. Watkins, Randolph M. Beaudry, Terence L. Robinson, and Alan N. Lakso
Jianjun Chen, R.W. Henley, R.J. Henny, C.A. Robinson, and R.D. Caldwell
Aglaonema is among the most popular tropical ornamental foliage plants used indoors because of its bright foliar variegation, low light and humidity tolerance, and few pests. Aglaonema, however, has been labeled as one of the most chilling-sensitive foliage plants. The dark, greasy-appearing patches on leaves injured by chilling can result in completely unsalable plants. With recent breeding activity, more and more Aglaonema cultivars have been developed and released. How new cultivars respond to chilling temperatures is, however, mostly unclear. This study was undertaken to evaluate cultivar chilling responses to identify chilling-resistant cultivars. Twenty cultivars were chilled at 1.7, 4.4, 7.2, 10, and 12.7 °C for 24 h using a detached single-leaf method and also whole-plant assay. Results indicate that great genetic variation exists among the cultivars, ranging from no injury at 1.7 °C to severe injury at 12.7 °C. A popular cultivar, Silver Queen, is the most sensitive, while the cultivar Stars is the most resistant. There was also a chilling response difference based on leaf maturity. Young leaves showed less injury than did either mature or old leaves. In addition, there was a significant correlation between the single-leaf and whole-plant assay for chilling resistance in Aglaonema'; the single leaf assay could be particularly useful for a quick test.
Zhiguo Ju, Yousheng Duan, and Zhiqiang Ju
Effects of different plant oils (soybean oil, corn oil, olive oil, peanut oil, linseed oil, and cotton seed oil) and oil component emulsions on scald development in `Delicious' apples were studied. Prestorage treatment with commercial plant oils reduced scald development, but was not as effective as 2000 mg•L-1 diphenylamine (DPA) after 6 months of cold storage. Different oil components played different roles in affecting scald. At 6% or 9% concentrations, neutral lipids (mono-, di-, and tri-acylglycerols), and phospholipids inhibited scald to the same level of 2000 mg•L-1 DPA treatment. Free fatty acids partially reduced scald, while α-tocopherol at 3% or higher concentrations accelerated scald development. There were no differences in scald inhibition between unsaturated neutral lipids and saturated neutral lipids or among the different acylated neutral lipids. When α-tocopherol was stripped from plant oils, the stripped plant oils at 6% or 9% controlled scald to the same level of 2000 mg•L-1 DPA treatment. Emulsions of 6% or 9% neutral lipids, phospholipids, or stripped plant oils did not induce greasiness on fruit skin. Fruit treated with lipids, phospholipids, or stripped plant oils looked greener and fresher compared with the control by the end of storage.
Christopher B. Watkins, Mustafa Erkan, Jacqueline F. Nock, Kevin A. Iungerman, Randolph M. Beaudry, and Renae E. Moran
`Honeycrisp' is a new apple [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] cultivar that has been planted extensively in North America, but the storage disorders soggy breakdown and soft scald have resulted in major fruit losses. The effects of harvest date and storage temperature on fruit quality and susceptibility of fruit to these disorders have been investigated in Michigan, New York, and Maine. Internal ethylene concentrations were variable over a wide range of harvest dates, and a rapid increase in autocatalytic ethylene production was not always apparent. The starch pattern index, soluble solids content, titratable acidity and firmness also appear to have limited use as harvest indices. Development of soggy breakdown and soft scald is associated with later harvest dates and storage of fruit at temperatures of 0 to 0.5 °C compared with higher storage temperatures. It is recommended that `Honeycrisp' be stored at 3 °C, although storage disorders still can occur at this temperature if fruit are harvested late. In addition, greasiness development may be worse at higher storage temperatures.
Christopher B. Watkins, William J. Bramlage, and Belinda A. Cregoe
To examine the hypothesis that superficial scald of apple (Malus domestics Borkh.) is a chilling injury, `Granny Smith' apples were stored at temperatures ranging from 0 to 20C, temperature-conditioned before storage, and warmed during storage. Fruit stored at 0 or 4C developed supeficial scald. At 10C, surface defects occurred but they were not typical symptoms of scald, and at 15 or 20C no symptoms developed. Accumulation of α-1 faroesene and conjugated trienes in fruit peel correlated with increasing ethylene production, which was greater at higher temperatures. However, concentrations of conjugated trienes were highest at 0 and 4C. When fruit were kept at 10C for 5 or 10 days before storage, scald development after storage was not reduced. An interruption of 0C storage with a single warming period at 10 or 20C reduced scald development after 25 weeks of storage, maximum reduction occurring when fruit were warmed for 3 to 5 days at 20C after 1 to 4 weeks at 0C. Amelioration of scald declined as time at 0C before warming increased. Diphenylamine application after the same intervals at 0C, instead of warming, also was less beneficial as time before treatment increased. α-Farnesene and conjugated trienes increased during warming, but at the end of storage (when scald was developing) the conjugated triene concentrations in peel were reduced in fruit that had been warmed. Warming slightly increased yellowing, softening, and greasiness of fruit after storage, We conclude that chilling induced superficial scald on `Granny Smith' apples.
Kathleen Delate, Andrea McKern, Robert Turnbull, James T.S. Walker, Richard Volz, Allan White, Vincent Bus, Dave Rogers, Lyn Cole, Natalie How, Sarah Guernsey, and Jason Johnston
fitted with a miniature infrared CO 2 transducer, using O 2 -free N as the carrier gas (40 mL·min −1 ). Greasiness of apple peel was determined by a tactile measurement and rating system ( Brookfield, 1999 ) of 0 point (no greasy peel), 1 point (slight
James P. Mattheis, David R. Rudell, and Ines Hanrahan
, cavitation, soft scald, soggy breakdown, and greasiness) were reported as incidence. Bitter pit was identified as surface lesions <5 mm in diameter with underlying brown, corky tissue. Irregularly shaped peel areas of rough, brown tissue >5 mm were considered
Magdolna Tóth, Gitta Ficzek, Ildikó Király, Szilvia Kovács, Mária Hevesi, Júlia Halász, and Zsolt Szani
shape with a moderately ribbed surface ( Fig. 2 ), average height of 7.8 cm, average diameter of 8.4 cm, ratio of height vs. diameter of 0.93, moderate greasiness on the surface, and medium size and density of lenticels. The ground color of the fruits is
Jennifer R. DeEll, Jennifer T. Ayres, and Dennis P. Murr
improve many physiological characteristics of apples, such as reduced ethylene production and respiration, enhanced fruit firmness and acidity retention, and reduced peel greasiness and various physiological disorders ( Blankenship and Dole, 2003 ; DeEll
Jennifer R. DeEll and Behrouz Ehsani-Moghaddam
cultivars) cannot be expected to occur quickly in ‘Honeycrisp’. There was no significant effect or little consistent effect of preharvest 1-MCP treatments on SSC ( Tables 2 and 3 ). In addition, there were no notable differences in peel greasiness