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Abstract
Adequate taxonomic or horticultural classifications of pineapple cultivars have not been devised. Hume and Miller’s groups as modified by Py and Tisseau form a good basis but do not emphasize the value of the totally spineless cultivars. Another group, “Maipure,” is proposed at this time.
Abstract
Honey bees from commercial apiaries placed in a macadamia nut orchard increased nut yields in 2 of 3 cultivars tested.
Three experiments were performed to characterize the physiological responses of an Eastern United States shipper muskmelon (Cucumis melo L. var. reticulatus ‘Athena’) harvested preripe (¼ slip) and during ripening (half-slip, full-slip) to 1 μL·L−1 1-methylcyclopropene (1-MCP), a potent ethylene antagonist effective at significantly extending the time required for climacteric fruit to complete ripening. In the first experiment, preripe fruit were treated with 1-MCP (18 hour, 20 °C) before storage at 15 °C. Softening of preripe ‘Athena’ was significantly suppressed in response to 1-MCP, with firmness of control and 1-MCP–treated fruit declining ≈50% and ≈36% through 12 and 18 days of storage at 15 °C, respectively. By 21 days of storage, firmness of 1-MCP–treated remained near 70 N, minimally within the upper range of whole-fruit firmness values considered acceptable for consumption (50–75 N). Fruit treated with 1-MCP exhibited significantly lower ethylene production, respiratory rates, and electrolyte leakage throughout storage. In a second experiment, muskmelon were treated with 1-MCP (18 hours, 20 °C) at progressively advanced stages of ripening (half- and full-slip stages). Softening was significantly suppressed in half-slip fruit, declining ≈64% and ≈23% in control and 1-MCP–treated fruit, respectively, during 16 days of storage at 15 °C. Advanced-ripening, full-slip fruit were similarly affected, softening ≈60% and ≈25% in control and 1-MCP–treated fruit, respectively, during 10 days at 15 °C. In a third experiment designed to simulate possible commercial handling protocols, full-slip muskmelon were treated with 1-MCP (24 hours, 10 °C) and held at 10 °C for 5 days before transfer to 20 °C. Mesocarp firmness of 1-MCP and control fruit within 2 days of transfer to 20 °C had decreased ≈40% and ≈54%, respectively, compared with values at the start of the experiment. After an additional 2 days at 20 °C, the mesocarp tissue of the respective treatments had softened 42% and 70%. Fruit treated with the ethylene antagonist showed significantly delayed incidence of surface decay and sunken regions compared with control fruit.
This study was performed to characterize the physiological responses of tomato (Lycopersicon esculentum L.) fruit harvested at either 10% to 30% or 30% to 60% color change and treated with two forms of 1-methylcyclopropene (1-MCP). Tomato fruit were treated either by submersion for 1 min in 1-MCP aqueous solution at the ambient temperature or by exposure for 12 h at 20 °C in air with 1-MCP gas, then stored at 20 °C. The concentrations (1.0, 5.0, or 10.0 μL·L-1) in 1-MCP aqueous solution were achieved through addition of 0.5, 2.5, or 5.0 g of AFxRD-300 powder (2.0% formulation, Agro-Fresh, Inc.) to 10 L of the de-ionized water, following manufacturer's instructions. 1-MCP (0.5 μL·L-1) gas in a 174-L container was achieved through addition of 0.22 g of SmartFresh® powder (0.14% formulation, Agro-Fresh, Inc.) to 100 mL of tap water. Both forms of 1-MCP significantly delayed ripening of fruit at the two initial ripeness stages, as noted by a significant delay in fruit softening and peel color change. The firmness of 30% to 60% color change tomatoes was significantly retained in response to gaseous or aqueous 1-MCP. Control fruit softened rapidly and reached the minimum marketable firmness value (about 5 N) within 8 days of storage at 20 °C, whereas fruit treated with gaseous 1-MCP (0.5 μL·L-1) or aqueous 1-MCP (1.0 or 5.0 μL·L-1) reached the same stage after 16, 20, or 24 days, respectively. Firmness retention was also highly significant for 10% to 30% color change tomatoes treated with both forms of 1-MCP. The highest concentration of aqueous 1-MCP (10.0 μL·L-1) did not result in a further delay in ripening compared with treatment at 5.0 or 1.0 μL·L-1 1-MCP.
Abstract
Three rabbiteye blueberry (Vaccinium ashei Reade) plantations of different ages were surveyed in north Florida to determine the type and extent of mycorrhizal colonization. Ascocarps of an ectendomycorrhizal fungus, Elaphomyces persoonii Vitt., were found attached to the root of V. fuscatum Ait., a common wild blueberry. This fungus was identical morphologically to that isolated from roots of rabbiteye blueberry. Mycorrhizal colonization was greatest at the 8- and 18-year-old plantations, where at least 50% of the roots were colonized, and least at the 4-year-old planting and on 2-year-old bushes in the nursery. The greatest number of ascocarps was found in the wild near the most heavily colonized plantation. Soil P was highest at the 4-year-old and lowest at the 18-year-old planting. No monthly variation in the amount of mycorrhizal colonization was observed thoughout the year at the oldest site. Inoculum potential of ectendomycorrhizal fungi in the surrounding land, age of the planting, and P content of the soil appear to influence the extent of colonization of cultivated rabbiteye blueberry.
‘Honeycrisp’ apples are susceptible to bitter pit, a physiological disorder that impacts peel and adjacent cortex tissue. ‘Honeycrisp’ is also susceptible to chilling injury (CI) that can be prevented by holding fruit at 10 to 20 °C after harvest for up to 7 days. This temperature conditioning period reduces CI risk but can enhance bitter pit development. Previous research demonstrated a controlled atmosphere (CA) established during conditioning can reduce ‘Honeycrisp’ bitter pit development without inducing other physiological disorders. The objective of this research was to evaluate the duration of CA needed to reduce bitter pit development. Experiments were conducted in 2014, 2016, and 2017 with fruit obtained from commercial orchards in Washington State and, in 2017 only, Ontario, Canada. Half the fruit were treated with 42 µmol·L−1 1-methycyclopropene (1-MCP) for 24 hours at 10 °C immediately following harvest. The untreated fruit were held at the same temperature (10 °C) in a different cold room. Following 1-MCP treatment, all fruit were conditioned at 10 °C for an additional 6 days, then fruit was cooled to 2.8 °C. During conditioning, fruit were held in air or CA (2.5 kPa O2, 0.5 kPa CO2) established 1 day after harvest, for 1 to 8 weeks, then in air. All fruit were removed from cold storage after 4 months and then held 7 days at 20 °C. Fruit from most orchards/years stored in CA developed less bitter pit compared with fruit stored continuously in air. CA during conditioning also reduced poststorage peel greasiness but CA for 2 weeks or longer enhanced cortex cavity development in some orchard lots. Treatment with 1-MCP did not reduce bitter pit but enhanced development of peel leather blotch and core browning for some orchards/years. 1-MCP–treated fruit slowed the loss of soluble solids content, titratable acidity, and reduced internal ethylene concentration. Results suggest the potential for postharvest management of bitter pit development in ‘Honeycrisp’ apples by CA established during conditioning with minimal development of other postharvest disorders.
Abstract
A germplasm release representing 8 selections of Salpiglossis sinuata L. (velvet flower), all free of the cleistogamous character which inhibits corolla development, is being made by the Purdue University Agricultural Experiment Station. Five of the selections are diploid (2n = 44) and 3 are tetraploid (2n = 88).
‘Royal Gala’ apples [Malus domestica (Borkh.) Mansf.]can develop postharvest disorders such as flesh browning, senescent breakdown, peeling, cracking, or shriveling during and after cold storage. The objective of this study was to examine the effects of storage temperature and a range (0, 0.25, 0.5, or 1 µL·L−1) of 1-methylcyclopropene (1-MCP) concentrations on fruit quality attributes and incidence and severity of physiological disorders during and after cold storage. Storage temperature differentially affected internal ethylene concentration (IEC), fruit circumference, and cortex color. 1-MCP treatment resulted in significant effects on fruit quality attributes and severity of physiological disorders, regardless of storage temperature. Incidence and severity of diffuse flesh breakdown (DFB), shriveling, cracking, and peeling were highest in control fruit stored but radial stem-end flesh breakdown (RSFB) only primarily in 1-MCP-treated fruit. Incidence of RSFB was highest following storage at 0.5 °C compared with 3 °C. 1-MCP treatment had the most influence on disorder incidence/severity or quality attributes, while treatment concentration of 1-MCP was not significant. Overall, the results indicate that 1-MCP treatment can reduce the incidence of ‘Royal Gala’ DFB but may enhance sensitivity to RSFB, when fruit are stored at 0.5 or 3 °C. Incidence of DFB and RSFB are influenced differentially by storage temperature or by 1-MCP treatment, respectively, indicating they may be different disorders.
‘Royal Gala’ apple [Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.] fruit can be susceptible to the development of postharvest disorders such as flesh breakdown and cracking (splitting) during and after cold storage. The objective of this research was to investigate fruit size and 1-methylcyclopropene (1-MCP) treatment effects on fruit physiological attributes and incidence and severity of storage disorders in ‘Royal Gala’ apples held in cold storage. In 2011, fruit segregated at harvest into two groups based on size (120 to 175, 250 to 350 g/fruit) were stored in air at 0.5 °C for 6 months and then at 20 °C for 7 days. In 2012, fruit were sorted into four groups (less than 200, 200 to 240, 241 to 280, and greater than 280 g/fruit), treated with 0 or 1 μL·L−1 1-MCP for 12 hours, and then stored in air at 0.5 °C for 3 or 6 months. Storage disorders were only detected at 6 months, regardless of 1-MCP treatment. In both control and 1-MCP-treated fruit, flesh breakdown incidence increased with fruit size, whereas severity was less associated with size. The progression of flesh breakdown developed in overall cortex tissue of control fruit but only detected in the stem-end tissue of 1-MCP-treated fruit. Internal ethylene concentration (IEC) decreased and CO2 production increased with increased fruit weight; however, 1-MCP-treated fruit had low IEC regardless of weight. Cortex tissue lightness (L*) increased with fruit size irrespective of tissue localization (stem end, equatorial, calyx end) at harvest. During 6 months’ storage, L* decreased with increased fruit size in controls but not 1-MCP-treated fruit. Fruit fresh weight loss increased with fruit size and storage duration, more so in controls when compared with 1-MCP-treated fruit. Furthermore, fruit circumference increased during storage with fruit size only for control fruit. These physical changes are associated with susceptibility of large fruit to flesh breakdown more so than small fruit. Reduced flesh breakdown incidence, progression of symptoms from the stem end into the cortex, and symptom severity in 1-MCP-treated fruit may indicate flesh breakdown is related to fruit ripening and senescence.