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Rhizomes of Oxalis adenophylla Gillies and bulbs of Ipheion uniflorum Raf. were planted and wet- or dry-stored at 5 °C for 0, 6, 10, 14, or 18 weeks, before being placed in a greenhouse. Regardless of moisture regime, foliage emergence and time to flower decreased for both species with increasing duration of cooling. Wet-stored bulbs/rhizomes within a cooling treatment required less time to foliage and flower emergence when compared with the corresponding dry-storage period. About 10 weeks of 5 °C was optimum for both species.

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Five members of the Proteaceae and 13 Australian native cut flower cultivars were stored for 35 days under standard conditions at 1C to assess their ability to withstand long-term storage and transport. Protea cynaroides L., Leucadendron `Silvan Red', Leucospermum `Firewheel', Thryptomene calycina (Lindl.) Stapf., Telopea speciosissima R. Br., and Verticordia grandtiflora Endl. retained a vase life of at least 7 days after 21 days of storage. Leucospermum cordifolium Salisb. ex Knight, Protea neriifoli R. Br., Chamelaucium uncinatum `Alba', C. uncinatum `Purple Pride', Verticordia monadelpha Turcz., Verticordia plumosa (Desf.) Druce, and Verticordia nitens (Lindl.) Schau. suffered a decline in vase life ranging from 31% to 100% after 14 to 21 days of storage. Species of Verticordia and Chamelaucium were particularly susceptible to fungal infection. Anigozanthos pulcherrimus Hook. and the Anigozanthos cultivars Ruby Delight, Bush Harmony, Bush Haze, and Gold Fever all showed a significant reduction in vase life after 14 days of storage compared with unstored controls.

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148 POSTER SESSION 17 (Abstr. 120–133) Postharvest Physiology/Storage/Food Science Wednesday, 26 July, 1:00–2:00 p.m.

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The relationships between cellular characteristics of cortical tissue and changes in texture during storage under controlled atmosphere (CA, 3% O2 + 3% CO2) or air at 0C were studied. The cultivars used were `Delicious', `Cortland', `Honeycrisp' and its parents, `Honeygold' and `Macoun'. The force needed to break a 7-mm cylinder of apple flesh (breaking force) was greatest for `Delicious' and `Honeycrisp'. Scanning electron microscopy demonstrated that tissues of firm-fleshed cultivars (`Honeycrisp' and `Delicious') fractured through cells, while that of soft-fleshed cultivars (`Cortland', `Honeygold', and `Macoun') fractured between cells. `Honeycrisp' had fewer cells/100 cm2 than the other cultivars. After 9 months of storage, breaking force, cell size, and K+/Ca2+ decreased, while cell number/100 cm2, Ca2+ content, and K+ content increased for all cultivars. Cell number/100 cm2 was significantly less and breaking force was significantly greater for tissue from CA than air-stored fruit.

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The development of ethylene preconditioning treatments for kiwifruit have made it possible to deliver ripe kiwifruit to consumers early in the season. We report on how maturity and length of storage time affect the ripening responses of kiwifruit [Actinidia deliciosa (A Chev) Liang et Ferguson cv Hayward] preconditioned with 100 ppm ethylene at 0°C for 24 hours and ripened for 10 days at 20°C. Kiwifruit freshly harvested at weekly intervals continued to soften faster in response to ethylene preconditioning compared to air controls for at least 5 weeks following commercial harvest. In contrast, kiwifruit commercially harvested and stored at 0°C for more than 2 weeks no longer responded to low-temperature ethylene preconditioning. However, kiwifruit stored more that 5 weeks were still responsive to exogenous ethylene and softened faster when exposed to continuous ethylene at either 0 or 20°C. Kiwifruit had relatively high respiration rates 1 days after transferring from 0 to 20°C, which quickly dropped to base levels within 1 day. Fruit stored >1 week at 0°C always had higher initial respiration than freshly harvested fruit on transfer to 20°C, and ethylene preconditioning increased initial respiration of freshly harvested fruit but had less of an effect on initial respiration of stored fruit. Plotting firmness against individual fruit's respiration and ethylene production revealed a distinct rise in respiration and ethylene production only after fruit softened to <6.5 N. Preconditioning fruit at 0°C did not significantly alter the timing of the climacteric respiration or ethylene peaks.

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Several intermittent 13C warming treatments were applied to `Primofiori' lemons (Citrus limon Burn) stored at 2 or SC. Fruit stored at 13C were treated with 10%, 2090, or 30% CO2 for 24 hours at weekly intervals. Reduction in decay and physiological disorders was best with two cycles of 2 weeks at 2C and 2 weeks at 13C and relative humidity >95 %. Under this storage condition, soluble solids concentration, pH, titratable acidity, and reducing sugars did not change relative to values at harvest, but the concentration of ascorbic acid increased and that of nonreducing sugars decreased in relation to harvest values. Carbon dioxide treatments did not prevent the development of alternaria (Alternaria citri Ell. & Pierce) rot and red blotch disorder, but effectively prevented the development of membranosis, rind pitting, and oleocellosis.

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on the effects of storage or germination temperature on germination rates of stonecrop species. Bonde (1965) showed that lanceleaf sedum ( Sedum lanceolatum ) seed germinated at 92.5% using growth chambers set at 18 °C. Widow’s cross sedum ( Sedum

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Preclimacteric `Golden Delicious' apples (Malus domestica Borkh.) were stored at 0 °C in: air; air + 5% CO2; 2% O2 + 98% N2; or 2% O2 + 5% CO2 + 93% N2, and sampled monthly for 4 months to investigate the mechanism(s) by which reduced O2 and/or elevated CO2 atmospheres inhibit C2H4 biosynthesis. Ethylene biosynthesis rates and in vitro ACS activity were closely correlated in all treatments, while in vitro ACO activity significantly increased over time regardless of the treatment. Only a small amount of C2H4 biosynthesis inhibition by lowered O2 and/or elevated CO2 atmospheres could be accounted for by suppressed induction of ACO activity. Western blot analysis demonstrated that apples held for 2 months in lowered O2 and/or elevated CO2 atmospheres had significantly reduced abundance of ACO protein, compared to fruit held in air. Northern blot analysis of ACS and ACO transcript abundance revealed that reduced O2 and/or elevated CO2 atmospheres delay induction and reduce the abundance of both transcripts. Reduced O2 and/or elevated CO2 atmospheres reduce C2H4 biosynthesis by delaying and suppressing expression of ACS at the transcriptional level and by reducing the abundance of active ACO protein. Chemical names used: 1-aminocyclopropane-1-carboxylic acid (ACC), ACC synthase (ACS), ACC oxidase (ACO), ethylene (C2H4), S-adenosylmethionine (AdoMet).

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Abstract

The capacity of ‘Eldorado’ pears to ripen increased dramatically after 4 weeks of exposure to 0°C and was associated with the synthesis of ethylene by pear tissue. Endogenous levels of ACC and internal ethylene were low after harvest, but increased rapidly after 4 weeks at 0°. Exposure to 0° for 4 weeks also resulted in an increase in soluble polyuronide during subsequent ripening at 20°. In contrast, after 9 months at 0°, soluble polyuronide content showed little increase when pears were transferred to 20°, and fruit failed to soften normally even though ACC content, internal ethylene concentration, ethylene evolution, and respiration remained relatively high. The content of arabinose, galactose, and rhamnose residues in cell walls decreased substantially during the ripening period after 4 weeks or longer at 0°. These cell wall neutral sugars decreased during ripening, even after 9 months of storage at 0°, while firmness and soluble polyuronide showed little change after fruit were transferred to 20°. These data indicate that the failure of pears to soften normally at 20° after prolonged storage at 0° is not related to ethylene synthesis or to changes in cell wall noncellulosic neutral sugar content, but is probably associated with mechanisms of polyuronide solubilization. Chemical name used: 1-aminocyclopropane-1-carboxylic acid (ACC).

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Abstract

‘Thompson Seedless’ fruits from vines that received gibberellin or auxin treatment were separated into different maturity classes and stored at 0° for 98 days. Samples were withdrawn at about monthly intervals and soluble solids, total acidity, malic acid, arginine and proline were measured. Fruits with differing soluble solids concn had the same soluble solids content per berry. After 30 days of storage, the soluble solids concn and total acidity of non-GA3 treated fruits began to increase, probably as a result of water loss. Malic acid concn and content increased for 30 days in storage, remained stable for the next 28 days, and then decreased during the remainder of the storage period. The amino acids, arginine and proline, remained relatively constant during the 1st 58 days of storage and then increased greatly both in concn and content.

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