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Abstract

Changes in respiration, ethylene production, firmness, pectolytic enzyme activity and carotenoid accumulation during ripening were monitored in fruit of a segregating population of the non-ripening (nor) mutant of tomato (Lycopersicon esculentum Mill.). In fruit from mutant (nor/nor) plants, no respiratory or ethylene climacteric was observed, firmness declined very slowly with only trace levels of polygalacturonase present in mature fruit and phytoene, β-carotene and neurosporene were the major carotenes. In very old fruit (120 days’ post-anthesis), lycopene and β-carotene were the predominant carotenoids, however lycopene content was less than 10% of normal.

Ripening of fruit from heterozygous (nor+/nor) plants was delayed and occurred more slowly than for normal (nor+/nor+ ) fruit. The respiratory climacteric was partially suppressed, peak ethylene production was one-sixth of normal, fruit softening was retarded, and polygalacturonase activity was lower at comparable maturity stages. Fruit from heterozygous (nor+nor) plants accumulated lycopene, gamma-carotene, phytofluene, and phytoene at a slower rate, but β-carotene accumulation was similar to normal. A mechanism for action of nor in control of ripening is proposed.

Open Access

In this article, we describe two melon ( Cucumis melo L.) breeding lines with the genetic background of a traditional nonclimacteric inodorus cultivar that show fruit characteristics similar to climacteric types. The breeding lines described

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We have investigated the effects of different O2 concentrations on the onset of the climacteric rise in C2H4 evolution and subsequent ripening of `Gala' apples. The data show that the effect of low O2 on the timing of the onset of the C2H4 climacteric is saturable in that for low O2 to retard the onset of the rise in C2H4 evolution its concentration must be decreased below 8%. Further, the results suggest that the retarding effects of low O2 on the onset of ripening cannot be ascribed to the inhibitory effects of low O2 on the action of the low levels of C2H4 evolution by preclimacteric apples. The results concerning the rate of C2H4 evolution and accumulation of the ACC-oxidase protein show that application of low O2 after the initiation of the climacteric rise in C2H4 is not as effective in delaying senescence as when it is imposed early, i.e., at the preclimacteric stage.

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climacteric to nonclimacteric varieties ( Ezura and Owino, 2008 ; Saladie et al., 2015 ). Climacteric melons, such as those of the Cantalupensis group, exhibit a sudden rise in respiration accompanied by an autocatalytic ethylene synthesis at the onset of the

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Authors: , , and

Ethylene evolution and ACC levels were determined throughout the growth and development of peach fruit (Prunus persica L. Batsch cv. Redhaven). In the four stages of growth (I, II, III, IV), as indicated by weekly monitoring of fresh (FW) and dry (DW) weight accumulation, ethylene biosynthesis in whole fruit decreased during FWI and remained almost undetectable during FWII and FWIII. In pericarp disks, ethylene evolution followed the same trend, although a peak at 78 days after full bloom and a slight increase before the onset of the climacteric were observed. The high rates of ethylene evolution were associated with a concurrent increase in ACC content. Enhancement of ACC synthase and ethylene-forming enzyme (EFE) activities was responsible for the peak of ethylene evolution detected before the beginning of FWIII and DWIII. At the climacteric, which occurred at the FWIII-FWIV transition, sequential events were observed in different fruit tissues. An increase of ethylene production in the mesocarp preceded the onset of the climacteric rise in whole fruit. The high amount of ethylene detected during the climacteric appeared to be related to increased EFE activity in the epicarp. Chemical name used: 1-aminocyclopropane-1-carboxylic acid (ACC).

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Fruit of `Redchief Delicious' apple [Malus sylvestris (L) Mill. var. domestica (Borkh.) Mansf.] were harvested 1 week before the climacteric (harvest 1), at the onset of the climacteric (harvest 2), and 1 week after the onset of the climacteric (harvest 3). Fruit were stored at 0, 5, 10, 15, or 20 °C and were treated with 0.7 μL·L-1 1-MCP on a once-per-week, once-per-2-week, once-per-month, and once-per-year basis or were left nontreated. The initial 1-MCP treatment was at 20 °C and subsequent applications were at storage temperatures. The compound slowed softening at all temperatures relative to nontreated fruit, however as temperature decreased, the benefits of 1-MCP application became less pronounced. Effectiveness of 1-MCP declined slightly as harvest maturity increased. Efficacy of 1-MCP treatment increased with greater frequency of application at 5, 10, 15, and 20 °C, but not at 0 °C. Fruit stored without refrigeration (20 °C) for more than 100 days did not soften significantly when treated once per week with 1-MCP. However, decay was a significant problem for treated and nontreated fruit stored at temperatures >5 °C; 1-MCP application reduced, but did not prevent decay. Rate of decline in titratable acidity increased with storage temperature and 1-MCP had no significant effect on retarding the decline in acid content. Minimal (Fo) and maximal (Fm) chlorophyll fluorescence was altered markedly by 1-MCP application, but the ratio of (Fm-Fo)/Fm was only slightly affected. The most effective 1-MCP treatment frequency was once per week and, at all elevated temperatures (5, 10, 15, and 20 °C), slowed loss of firmness to a greater extent than refrigeration (0 °C) alone. Application of 1-MCP resulted in greater retention of firmness than controlled atmosphere (CA) with O2 and CO2 at 1.5 kPa and 3 kPa, respectively. Data suggest that 1-MCP application, has the potential to reduce reliance on refrigeration and CA storage for maintaining firmness of `Redchief Delicious' apple, especially for relatively short storage durations (<50 days) when fruit are harvested within a week of the ethylene climacteric. Chemical name used: 1-methylcyclopropene (1-MCP).

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Bell peppers (Capsicum annuum L.) are classified as nonclimacteric fruits while some hot peppers have been reported as climacteric. Responses of peppers to exogenously applied ethylene-releasing compounds suggest ethylene involvement in the ripening process. Ethylene production and respiration rates in 13 cultivars of pepper: `Camelot', `Cherry Bomb', `Chiltepin', `Cubanelle', `Banana Supreme', `Habanero', `Hungarian Wax', `Mesilla', `Mitla', `Savory', `Sure Fire', `Tabasco', and `King Arthur' were studied under greenhouse and field conditions. Fruit from each cultivar were harvested at different maturity stages determined by color, ranging from mature-green to full red-ripe. Carbon dioxide and ethylene production were measured by gas chromatography. Both variables were significantly different among maturity stages for all cultivars. Respiration rates were between 16.5 and 440.3 mg·kg-1·h-1 CO2. Ethylene production ranged from 0.002 to 1.1 μL·kg-1·h-1. Two patterns of CO2 production were identified: higher CO2 production for mature-green fruit with successive decreases for the rest of the maturity stages or lower respiration rates for mature-green fruit with an increase in CO2 production either when fruit were changing color or once fruit were almost totally red. A rise in CO2 production was present for most cultivars. Ethylene evolution increased significantly at maturity or before maturity in all cultivars except `Cubanelle' and `Hungarian Wax'. Respiration rates and ethylene production were significantly different among cultivars at the mature-green and red stages.

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Abstract

Influences of rootstocks on ‘Goldspur Golden Delicious’ apple (Malus domestica Borkh.) respiration rate, ethylene evolution, skin color, firmness, internal color, soluble solids content (SSC), acidity, carbohydrate, and mineral content were evaluated over an extended harvest and after cold storage. At first harvest, fruit from trees on seedling rootstock entered the climacteric (as determined by ethylene evolution) first (after 10 days) followed by fruit from M.26 trees, while apples from trees on MM.111 required 16 days. After 60 days in storage, CO2 and ethylene production were greatest for apples from trees on MM.111 rootstock. Fruit from trees on M.26 developed more external color, contained more acids, had a higher SSC, and appeared to mature between apples grown on the other two rootstocks. Fruit from trees on M.26 were firmer than those on MM.111. Apples from trees on seedling rootstock contained less fructose, glucose, and sucrose than apples from M.26 or MM.111. Calcium content was highest in fruit from trees on M.26.

Open Access

`Galia' (Cucumis melo var. reticulatus L. Naud. `Galia') melons exhibit relatively short postharvest longevity, limited in large part by the rapid softening of this high quality melon. The present study was performed to characterize the physiological responses of `Galia' fruit harvested at green (preripe) and yellow (advanced ripening) stages and treated with 1-methylcyclopropene (1-MCP) before storage at 20 °C. Treatment with 1.5 μL·L-1 1-MCP before storage delayed the climacteric peaks of respiration and ethylene production of green fruit by 11 and 6 d, respectively, and also significantly suppressed respiration and ethylene production maxima. Softening of both green and yellow fruit was significantly delayed by 1-MCP. During the first 5 d at 20 °C, the firmness of green control fruit declined 66% while 1-MCP-treated fruit declined 46%. By day 11, firmness of control and 1-MCP-treated green fruit had declined about 90% and 75%, respectively. The firmness of control yellow fruit stored at 20 °C declined 70% within 5 d while 1-MCP-treated fruit declined 30%. The 1-MCP-induced firmness retention was accompanied by significant suppression of electrolyte leakage of mesocarp tissue, providing evidence that membrane dysfunction might contribute to softening of `Galia' melons. The mesocarp of fruit harvested green and treated with 1-MCP eventually ripened to acceptable quality; however, under the treatment conditions (1.5 μL·L-1 1-MCP, 24 h) used in this study, irreversible suppression of surface color development was noted. The disparity in ripening recovery between mesocarp versus epidermal tissue was considerably less evident for fruit harvested and treated with 1-MCP at an advanced stage of development. The commercial use of 1-MCP with `Galia'-type melons should prove of immense benefit in long-term storage and/or export situations, and allow for retention of quality and handling tolerance for fruit harvested at more advanced stages of ripening.

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External color, length, diameter, fresh weight, C02 production, internal C2HA concentration, flesh firmness, soluble solids concentration (SSC), flesh color, and seed cavity diameter were measured during fruit growth and maturation of seven melon cultivars (Cucumis melo L., Inodorus Group, Naud. cv. `Amarelo', `Golden Beauty Casaba', `Honey Dew', `Honey Loupe', `Juan Canary', `Paceco', and `Santa Claus Casaba') of known age. There was no increase in C02 production either during ripening (e.g., loss of firmness and increased SSC) or with increasing C2H4 levels in fruit from any of the seven cultivars. There was a significant decline in respiration only at the second sampling date, which ranged from 14 to 18 days after anthesis. Respiration measured 1 week later was substantially higher and was followed by a general decline. This post 14- to 18-day rise in respiration was not a climacteric since it occurred well in advance of other ripening characteristics, e.g., loss of firmness, increase in SSC, or rise in internal C2H4. The increase in internal C2H4. coincided with or followed attainment of full fruit size, while flesh softening and the rapid rise in SSC preceded the rise in internal C2H4, concentration. Respiration declined from 67 to 18 ml CO2/kg per hour by day 43 in all cultivars, except `Honey Dew' and `Honey Loupe'. Respiration in `Honey Loupe' remained above 23 ml CO2/kg per hour and showed a rise to 32 ml/kg per hour on day 53. Respiration in `Honey Dew' did not fall below 18 ml CO2/kg per hour until day 53. As with internal C2H4 levels, there was no correlation between changes in and any marked change in the other signs of ripening that were measured.

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