The mineral concentration of bearing `Mejhool' date palm (Phoenix dactylifera L.) trees was investigated with the objective of identifying the cause of browning and dieback of distal parts of the fruit-bearing strands. Tissue analyses of leaves, fruits, healthy and dead portions of fruit-bearing strands indicated that tissue browning and dieback appeared to be associated with a high concentration of certain mineral elements. A comparison of mineral concentration between healthy and dead tissue of the fruit-bearing strands showed no significant increase in K, Cu, B, Zn, and Na, but very high increases in the concentrations of P, Ca, Mg, S, Mn, and Fe. The levels of P, Ca, Mg, S, Mn, and Fe in the distal part of the fruit-bearing strand over a 3-year average were 5, 18, 12, 3, 11, and 2 times, respectively, higher than those in the healthy, proximal part of the strand. Mineral concentrations of leaves and mature fruits were determined for comparison with those in fruit-bearing strands.
Aref A. Abdul-Baki, Clyde Wilson, George E. Brown Jr., Lidia M. Carrera, Sam Aslan, Sam Cobb, and Tim Burke
Peter D. Petracek and Lymari Montalvo
`Fallglo' (Bower citrus hybrid [Citrus reticulata Blanco × (C. reticulata Blanco × C. paradisi Macf.)] × `Temple' [C. reticulata Blanco × C. sinensis L.] is an early season tangerine that is reportedly hypersensitive to ethylene exposure during degreening. The effects of ethylene exposure time, waxing, and storage temperature on `Fallglo' color were examined to assess degreening strategies. Exposure to 5 μL·L-1 ethylene for 24 or 48 hours hastened degreening, and internal ethylene levels increased following the time periods of ethylene exposure. Fruit not exposed to ethylene, or exposed for shorter periods (2 or 6 hours), degreened slowly during storage at 15.5 °C and internal ethylene levels remained low. Low-temperature storage (4.5 °C) or waxing hindered degreening after ethylene exposure but decreased water loss. Degreening after ethylene exposure was faster for fruit stored at 15.5 than 26.5 °C.
S.R. Drake, D.C. Elfving, and R.D. Gix
Pears (Pyrus communis `d'Anjou') were packed in six commercial paper wraps (dry; 3% oil; 3% oil with copper and ethoxyquin; 6% oil; 6% oil with ethoxyquin; 9% oil). After packing, the pears were placed in three different controlled atmosphere (CA) storage conditions in commercial CA rooms: 1) 1.5% oxygen (O) and 1% carbon dioxide (CO2); 2) 1.5% O2 and 3% CO2; 3) 1.5% O2 and 1% CO2 for 60 days, 4% O2 for 60 more days and finally 6% O2 for an additional 90 days. Pears were stored in CA for 120 and 210 days, with or without an additional 30 days in regular atmosphere (RA) storage to simulate shipping and handling. Objective quality evaluations were conducted after each storage period and sensory evaluations after 210 days of storage. Paper type influenced both the peel and flesh color of pears before and after ripening, but did not influence firmness, soluble solids or acid content. Subjective ratings of appearance and disorder incidence were unacceptable for pears stored in a variable atmosphere wrapped in dry or paper containing 3% oil. The disorder black speck was present only in pears wrapped in paper with 6% oil and stored in an atmosphere of 1.5% O2 and 1% CO2. Pears stored in an atmosphere of 1.5% O2 and 3% CO2 received acceptable subjective scores regardless of paper type.
Jinwook Lee, James P. Mattheis, and David R. Rudell
physiological disorders ( DeEll et al., 2003 ; DeLong et al., 2004a ; Jung et al., 2010 ; Larrigaudière et al., 2010 ; Lee et al., 2012b ; Moran and McManus, 2005 ; Zanella, 2003 ). The differential (increased or decreased incidence) impacts on disorder
Jinwook Lee, James P. Mattheis, and David R. Rudell
. (1997a) . In terms of fruit physiological disorders, cracking was expressed as fractures in the cuticle or skin which would be microscopic or easily seen, sometimes extending deep into the inner flesh. Splitting was defined as an extreme phenotype of
Araceli M. Vera-Guzman, Maria T. Lafuente, Emmanuel Aispuro-Hernandez, Irasema Vargas-Arispuro, and Miguel A. Martinez-Tellez
being erratic, and showing high variability among orchards and from year to year ( Lafuente and Zacarías, 2006 ). Likewise, the susceptibility of citrus fruit to postharvest physiological disorders may depend on the cultivar, the fruit maturity stage
The environmental and physiological causes of cracking or splitting of soft fruits and citrus as they ripen are not well understood. This paper explores factors contributing to radial cracking in tomatoes, gives suggestions for prevention of cracking, and suggests directions for future research. Fruit cracking occurs when there is a rapid net influx of water and solutes into the fruit at the same time that ripening or other factors reduce the strength and elasticity of the tomato skin. In the field, high soil moisture tensions suddenly lowered by irrigation or rains are the most frequent cause of fruit cracking. Low soil moisture tensions reduce the tensile strength of the skin and increase root pressure. In addition, during rain or overhead irrigation, water penetrates into the fruit through minute cracks or through the corky tissue around the stem scar. Increases in fruit temperature raise gas and hydrostatic pressures of the pulp on the skin, resulting in immediate cracking in ripe fruit or delayed cracking in green fruit. The delayed cracking occurs later in the ripening process when minute cracks expand to become visible. High light intensity may have a role in increasing cracking apart from its association with high temperatures. Under high light conditions, fruit soluble solids and fruit growth rates are higher. Both of these factors are sometimes associated with increased cracking. Anatomical characteristics of crack-susceptible cultivars are: 1) large fruit size, 2) low skin tensile strength and/or low skin extensibility at the turning to the pink stage of ripeness, 3) thin skin, 4) thin pericarp, 5) shallow cutin penetration, 6) few fruits per plant, and 7) fruit not shaded by foliage. Following cultural practices that result in uniform and relatively slow fruit growth offers some protection against fruit cracking. These practices include maintenance of constant soil moisture and good Ca nutrition, along with keeping irrigation on the low side. Cultural practices that reduce diurnal fruit temperature changes also may reduce cracking. In the field, these practices include maintaining vegetative cover. Greenhouse growers should maintain minimal day/night temperature differences and increase temperatures gradually from nighttime to daytime levels. For both field and greenhouse tomato growers, harvesting before the pink stage of ripeness and selection of crack-resistant cultivars probably offers the best protection against cracking. Areas for future research include developing environmental models to predict cracking and exploring the use of Ca and gibberellic acid (GA) sprays to prevent cracking.
Peter D. Petracek, Lymari Montalvo, Huating Dou, and Craig Davis
The morphology and etiology of postharvest pitting of `Fallglo' [Bower citrus hybrid (Citrus reticulata Blanco × C. reticulata Blanco × C. paradisi Macf.) × Temple (C. reticulata Blanco × C. sinensis L.)] peel were determined. The disorder was characterized by scattered collapse of the flavedo that resulted from necrosis of cells within and enveloping the oil glands. In severe cases, damage occurred in epidermal and hypodermal cells above collapsed oil glands and surrounding vascular tissues, but cells between oil glands were often undamaged. Pitting was caused by storing waxed fruit at high temperature (≥15.5 °C), but was not affected by ethylene exposure during degreening. Fruit coated with commercially available shellac- and polyethylene-based waxes pitted more than fruit coated with carnauba-based waxes. Pitting was controlled by not coating the fruit with wax or storing the fruit at low temperature (4.5 °C) within hours after wax application.
Wade J. Sperry, Jeanine M. Davis, and Douglas C. Sanders
Two crack-resistant and two crack-susceptible fresh-market tomato (Lycopersicon esculentum Mill.) cultivars were evaluated at varied soil moisture levels for physiological fruit defects and yield. Cultural practices recommended for staked-tomato production in North Carolina with raised beds, black polyethylene mulch, and drip irrigation were used. Soil moisture levels of less than −15.0, −30 to −40, and greater than −70 kPa were maintained and monitored using daily tensiometer readings. Soil moisture level had no effect on fruit cracking, blossom-end rot, zippers, or yield. However, there-were large differences among cultivars for fruit defects and total and marketable yields.
Juan Pablo Fernández-Trujillo, Gene E. Lester, Noelia Dos-Santos, Juan Antonio Martínez, Juan Esteva, John L. Jifon, and Plácido Varó
Fruit cracking (also known as growth cracks or fruit splitting) is a major physiological disorder that can cause significant economic losses in a wide variety of fruit including tomato ( Solanum lycopersicon ), cherry ( Prunus avium ), apple ( Malus