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Jinwook Lee and Kenneth W. Mudge

Variation in ginsenoside content was investigated as a function of population/genotype, plant organ, and age using four geographically isolated wild populations and one landrace population of american ginseng (Panax quinquefolius L.). The contents of individual and total ginsenosides were affected by the main and two-way interactions between population, organ, and age. Ginsenoside Re was not detected in roots of the wild population plants but was found in leaves and in both organs of the landrace population. A positive relationship between root age and total root ginsenosides was detected in two wild populations. Individual root ginsenosides were highly correlated with certain leaf ginsenosides in wild populations rather than in landrace populations. Therefore, the results suggest that certain leaf ginsenosides would be applied for potential biomarkers to estimate individual root ginsenosides. Principal component analysis (PCA) scores plot indicates that all wild populations were segregated from the single landrace population. However, cluster analysis indicates that differences existed between organs, and between the wild and landrace populations. Overall, the result suggests that the variation of individual and total ginsenoside contents would be influenced by a combination of population, plant organ, and root age.

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Jinwook Lee, James P. Mattheis and David R. Rudell

‘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.

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Jinwook Lee, James P. Mattheis and David R. Rudell

‘Royal Gala’ apples can be susceptible to the incidence of fruit cracking and senescent flesh breakdown during cold storage. Because the development of these physiological disorders in other cultivars can be influenced by humidity during storage, the objective of this study was to evaluate the effect of high storage humidity on fruit quality attributes and incidence of physiological disorders in cold-stored ‘Royal Gala’ apples. Fruit obtained from a commercial orchard were kept in cardboard boxes with or without a perforated polyethylene liner during and after cold storage. High storage humidity induced by the perforated polyethylene liner reduced fresh weight loss but enhanced the change of fruit circumference after cold storage. High storage humidity contributed the most reduction of cortex lightness (L*) and hue angle (h o) in stem-end cortex tissues during shelf life. Fruit stored with liners had reduced internal ethylene concentration (IEC) and outer cortex firmness after removal from storage compared with control fruit. Furthermore, high storage humidity prevented shriveling but provoked fruit cracking. The incidence and severity of flesh breakdown were further aggravated during shelf life, compared with cold storage, regardless of a liner application. Overall, maintaining high storage humidity by applying a perforated polyethylene liner can contribute to delaying fresh weight loss, reducing IEC, and preventing fruit shriveling but can enhance cortex tissue browning, loss of flesh firmness, and incidence of fruit cracking during cold storage and shelf life.

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Jinwook Lee, James P. Mattheis and David R. Rudell

‘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.

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Jinwook Lee, In-Kyu Kang, Jacqueline F. Nock and Christopher B. Watkins

The effects of preharvest and postharvest treatments of 1-methylcyclopropene (1-MCP) in combination or alone on fruit quality and the incidence of physiological disorders during storage of ‘Fuji’ apples [Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.] at 20 and 0.5 °C were investigated. Preharvest 1-MCP (Harvista) treatments were applied 4 or 10 days before harvest (DBH), and then fruit were either untreated or treated with 1-MCP (SmartFresh) postharvest. Fruit were stored at 20 °C for up to 4 weeks or at 0.5 °C for up to 36 weeks. At harvest, starch pattern indices and watercore incidence and severity were lower in fruit with preharvest 1-MCP treatment applied 10 DBH than in untreated fruit and in fruit treated 4 DBH. At 20 °C, the combination of preharvest and postharvest 1-MCP treatments reduced the internal ethylene concentration (IEC) more than preharvest 1-MCP treatment alone, but not to a greater extent than postharvest 1-MCP treatment alone. Greasiness and watercore were reduced more by the combination of preharvest and postharvest 1-MCP treatments than by either treatment alone. However, preharvest and postharvest 1-MCP treatments, in combination or alone, did not consistently affect flesh firmness, titratable acidity (TA), soluble solids concentration, color a* values, or incidences of flesh browning, core browning, and stem-end flesh browning. At 0.5 °C, the combination of preharvest and postharvest 1-MCP treatments inhibited IECs and maintained firmness and TA more than no treatment or preharvest 1-MCP treatment alone. However, there was a lesser extent of differences than there was with postharvest 1-MCP treatment alone. Incidences of physiological disorders were not consistently affected by the preharvest and postharvest 1-MCP treatments. Overall, the results suggested that the preharvest 1-MCP treatment positively affected fruit quality attributes compared with no treatment during shelf life and long-term cold storage, but not as effectively as a combination of preharvest and postharvest 1-MCP treatments.