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Abstract

Telone (10, 20, 30 gal/acre) and Nemagon (1, 2, 3 gal/acre) were applied to the soil one week before planting of carrots. Compared to the untreated controls, the roots of the treated plants had a significantly higher content of total carotene, β-carotene and total sugars and a lower rate of respiration.

Open Access

Preclimacteric avocado [Persea americana (Mill.) cv. Hass] fruit or fruit disks as well as fruit harvested in either June (midseason) or August (late season) and partially ripened were kept in air (21% O2 + 78% N2), 20% CO2 + 17% O2 (63% N2), or 40% CO2 + 13% O2 (47% N2) at either 10 or 20 °C. Ethylene production by preclimacteric fruit was completely inhibited during CO2 exposure, whereas there was only partial inhibition of ethylene production when partially ripened fruit were exposed. Compared to the fruit stored in air, O2 uptake of fruit stored in 20% CO2 was decreased by 20%, whereas the fruit stored in 40% CO2 showed 25% more O2 uptake than air-stored fruit. Fruit subjected to a storage regime of 40% CO2 at 10 °C followed by 2 d in air had the best visual quality. In general, climacteric fruit treated with 20% CO2 at 10 °C showed increased pyruvate dehydrogenase (PDH) activity and decreased cytochrome oxidase (CytOx) activity. Fruit stored in 40% CO2 had reduced CytOx activity compared to air-stored fruit, and PDH activity was variable depending on the harvest season of the fruit. Our results show that the effect of elevated CO2 on a given enzyme depends on concentration of CO2, duration of exposure, physiological state of the fruit, and type of tissue exposed.

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Abstract

Soil fumigations with Telone (1,3-dichloropropene and other chlorinated hydrocarbons) at the rates of 10, 20, and 30 gal/A and Nemagon (1,2-dibromo-3-chloropropane) at the rates of 1, 2, and 3 gal/A, one week before planting carrot and sweet corn seeds brought about significant increases in the content of total carotenes, β-carotene, and total sugars in carrots and the total carotenoids in sweet corn seeds and decreases in respiratory rates of the carrot roots.

Open Access

respiratory and ethylene peaks of P. schiedeana (550 mL CO 2 /kg·h −1 and 880 μL C 2 H 4 /kg·h −1 , respectively) were at least threefold and ninefold higher, respectively, than those reported for avocados ( Kader and Arpaia, 2009 ) and also higher than

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short shelf life. Guava is a climacteric fruit exhibiting respiratory and ethylene peaks, which causes the guava to rapidly achieve senescence ( Nakasone and Paull, 1998 ). This makes the fruit inappropriate for consumption after a short period of time

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environmental impacts, including ozone depletion, smog, acidification, eutrophication, carcinogenic or non-carcinogenic human toxicity, respiratory effects, ecotoxicity, and fossil fuel depletion [ U.S. Environmental Protection Agency (USEPA), 2008 ]. These are

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transient) increase in SDH activity, which allows for a higher rate of conversion of the available sorbitol into fructose, thereby allowing the fruit to meet its immediate and high respiratory demand ( Lakso et al., 1999 ). Hence, the effects of shading on

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’ apples ( de Castro et al., 2007 ). However, inconsistencies and year-to-year variation in the effects of delayed CA establishment for alleviating certain storage disorders in apples have also been documented ( Argenta et al., 2000 ; DeEll and Ehsani

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Abstract

The effects of chilling ‘Hass’ avocado fruit at 0° or 5°C on the respiratory rates, rates of ethylene production, ripening, and chilling injury symptoms at 20° were compared with the same responses of fruit exposed to a nonchilling temperature (10°) and fruit placed directly at 20°. Fruit held at 10° for 2 weeks were beginning the climacteric and ripened after about 4 days at 20°. Longer exposures at 10° resulted in ripe or overripe fruit. Fruit held for 2 weeks at 0° or 5° displayed normal climacteric patterns and ethylene production at 20°, and developed no significant chilling injury symptoms. Exposures of 4 and 6 weeks at 0° or 5° resulted in the development of chilling injury symptoms, abnormal ripening, atypical respiratory rate patterns, and reduced ethylene production rates which peaked after 2 days at 20° and showed a declining rate thereafter, with no increase in the rate of ethylene production associated with fruit softening.

Open Access

A strong association is implicit between mitochondrial function and the energy demands of cells responding to stress. Yet, the dynamics of this organelle-cellular dependency have been difficult to resolve. This study examines a new diagnostic parameter namely, mitochondrial maintenance and self-restoration as exhibited by the course of respiratory functions (states 3 and 4 respiratory rates, respiratory control) of mitochoudria extracted during and after exposure of intact `Hass' avocado (Persea americana) fruit to different stress atmospheres: anoxia (100% N2) or high (25% and 75%) CO2 for varying durations. Comparisons are made with direct exposure of the mitochondria themselves to similar atmospheres. In general, exposure of the fruit to CO2 rich atmospheres enhanced the capacity of their mitochondria to restore energy-linked functions whereas anoxia caused irreparable damage. The physiological (climacteric) state of the fruit also affected the stress capacity of the mitochondria contained therein, anaerobiosis being more harmful to mitochondria in riper fruit. In contrast to their effects in vivo, in vitro anoxia appeared to sustain mitochondrial energy-linked functions, whereas high CO2 was clearly harmful. These and other observations are discussed in the context of mitochondrial self-restoration or homeostasis and its relevance to postharvest stress-atmosphere storage for purposes such as pathogen suppression or insect control.

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