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BACKGROUND Under-Skin Browning (USB) is a physiological skin disorder that significantly reduces quality of ?Honey Gold? mango (HG) fruit. Relationships between potential causative factors (vibration, holding temperature, sap) and expression factors (enzymes activities, phenolic concentration, anatomy) were investigated. RESULTS USB incidence was 2.6?3.6-fold higher in ripe HG fruit vibrated for 3?18?h at 12 °C to simulate transport damage and held then at 12 °C for 8?days compared to control fruit held under the same conditions. USB severity of fruit lightly abraded with sand paper to simulate physical damage and artificially induce USB was higher in fruit held at 10 °C than at 6?8 °C or 12?13 °C for 6?8?days. Compared to non-affected skin, USB-affected tissue had a 7.4% increase in total phenolics concentration. However, polyphenol oxidase (PPO) and peroxidase (POD) activities decreased by 19%. Anatomical similarities were observed between USB symptoms and sapburn caused by spurt sap or terpinolene (a major sap component) to abraded skin areas. Incidence of sapburn was higher in abraded fruit held at 12 °C than at 20 °C. CONCLUSION Holding HG mango fruit at 10 °C can intensify USB. Activities of PPO and POD appear not to be regulatory factors in USB expression in HG. Sap components may be involved in USB expression under conducive postharvest conditions. ? 2021 Society of Chemical Industry.

The mango cultivar 'Honey Gold' (HG) was developed in Queensland, Australia. Ripe defect-free HG fruit are characterized by bright yellow skin with red blush on their sun-exposed shoulders. HG mangoes are mostly grown from the Northern Territory down though Queensland into northern New South Wales (nNSW). As with many mango cultivars, HG suffers from a range of skin disorders. However, HG mango fruit grown in nNSW almost uniquely express a blotchy 'skin reddening' disorder that detracts from their visual appeal. The non-uniform reddening, which can encompass 'red lenticels', appears to be a host defense response. Causal agents of the reddening disorder are currently elusive. There may be a range of pre- and postharvest abiotic and/or biotic stresses, and they could be additive. A number of physical and chemical treatments were applied pre- or postharvest with a view to either suppress (i.e., prevent) or enhance (i.e., mask) uneven skin reddening. The physical treatments included preharvest fruit bagging and post-harvest exposure to different wavelengths of light. These physical treatments are considered in this paper. The chemical treatments included known modulators of host defense and ethylene responses. Those treatments are not reported in this short paper. However, among the full suite of treatments tested, one only notably influenced skin reddening. In this case, postharvest exposure to blue light increased reddening. Future research with HG will build on this initially promising finding.

Lenticel discoloration (LD), under-skin browning (USB) and resin canal disorder (RCD) are three important fruit skin disorders of concern to the Australian mango industry. They result in downgrading of fruit quality and loss of market confidence. LD is confined to the discoloration of lenticels on the fruit skin. USB is a sub-surface spreading grey-brown lesion that may only become evident in the marketplace. RCD is a dark brown discoloration of the finely branched pattern of ramifying sub-surface resin canals. These three browning disorders were compared and contrasted at the cellular level by light microscopy after free-hand sectioning. Discoloured lenticels on the surface of 'Honey Gold' mango fruit typically appeared as small round spots comprised of a dark brown centre surrounded by a white corona. Non-coloured lenticels were visible as small round spots surrounded by a white corona. In cross-section, there was browning of cells surrounding the cavity of discoloured lenticels. Nonetheless, there was no such browning in non-coloured lenticels. USB symptoms in 'Honey Gold' fruit were evident as dark-brown cells in the tissue surrounding the resin ducts. In contrast, RCD, which was evident in 'Kensington Pride' mango fruit, was characterised by browning of the lumen of resin ducts. Accordingly, LD, USB and RCD involve different browning biology processes at the cell and tissue levels. A greater understanding of symptom development and expression could aid in informed management of these physiological disorders.

Refrigerated containers are used to transport mangoes over long distances. In Australia, mangoes grown in northern tropical production areas for the domestic market are transported by road and/or rail for up to 4000 km to southern ripening centres. There is no other viable option for growers to ripen their fruit. A current project is investigating sustained ethylene release systems for ripening mango fruit in road transport containers over an in-transit period of up to 4 days. This approach could potentially provide an alternative cost-effective ripening strategy for the mango industry. Studies have been and will be performed using shipments of 'B74' and 'Honey Gold' mango fruit, respectively, in refrigerated road containers. In-container environment monitoring, fruit shelf life and quality evaluation at outturn are carried out. Corresponding laboratory experiments that simulate transit are also to be conducted with a view to modelling mango fruit responses to in-transit conditions.

Resin canal discoloration (RCD) is a quality defect that reduces the visual appeal and marketability of mango fruit. Market reports of RCD have increased recently, particularly for 'Kensington Pride' fruit produced in the Northern Territory, Australia. Anecdotal observations by mango growers suggest that early fruit harvest maturity, rain before harvest and handling conditions may be associated with RCD. In the current study, we completed a series of preliminary experiments with 'Kensington Pride' fruit to characterise RCD symptom development and to identify potential contributing factors. RCD was seldom present in hard green-mature fruit at harvest. The defect was first visualised as lightly discoloured resin canals in partially ripe fruit. The severity of RCD symptoms steadily increased as fruit developed from firm-ripe to eating-ripe. The incidence of RCD was 42-52% higher for fruit picked early in the season at KLEINERDAN13% dry matter content (DMC) than for those harvested 2-4 weeks later at 15-17% DMC. Harvesting fruit within 12 h of a 14-mm rainfall event resulted in 45% higher RCD incidence than in fruit picked after 60 h of sustained dry weather. The incidence of RCD varied from 0 to 45% for fruit from nine orchards in the Northern Territory when harvested and ripened directly off the tree. RCD incidence was threefold higher in the same fruit that were exposed to commercial handling and interstate transport. Overall, these observations suggest that RCD is a complex disorder that occurs when field conditions result in sensitised fruit that may express the defect when exposed to postharvest handling practices.

1-Methylcyclopropene (1-MCP) has been a useful tool to extend the postharvest life of ‘Bartlett’ pears, but fruit response can be highly variable due to competition with ethylene. Application of liquid 1-MCP after harvest was tested to determine its efficacy as compared with gaseous 1-MCP. Fruit harvested from Sacramento and Lakeport, California at early-, mid- and late- commercial harvest maturity were treated with 0.6 μL L−1 gaseous 1-MCP at 0 °C for 24 h or dipped for 0, 15, 30, 45 or 60 s in 250, 500, 750 or 1000 μg L−1 1-MCP in four experiments across three years of study. After treatment, pears were exposed to ethylene or kept in cold storage at 1 °C for 5 weeks before ripening at 20 °C. Treatment with liquid 1-MCP delayed pear ripening as evidenced by delayed softening for a minimum of 6 d compared to the control fruit, delayed the increase in respiration and ethylene production rates, and reduced respiration and ethylene production rates. Treatment was effective in a concentration- and dip time-dependent manner. Overall, dipping in 1000 μg L−1 liquid 1-MCP for 60 s was the most consistent treatment among years and locations; however, the resulting time to ripen at 20 °C could be too long for some commercial applications. Treatment at 500 μg L−1 liquid 1-MCP is recommended for ‘Bartlett’ pears as this dose controls the ripening process, and provides consistent response for mid- and late-maturity fruit. A postharvest evaluation of a liquid formulation of 1-MCP provided a more consistently effective treatment for ‘Bartlett’ pears (Pyrus communis) than the current gaseous treatments.

‘B74’ mango is a recently commercialised cultivar in Australia, with an appealing skin colour and firm fibreless flesh. However, fruit can develop lenticel discolouration (LD) after harvest, with loss of commercial value, especially after γ-irradiation as a disinfestation treatment. We hypothesised that postharvest practices could increase fruit sensitivity to LD and tested that by sequentially sampling fruit between the orchard and the end of the packing line over two seasons, followed by ripening without and with irradiation treatment. Exposure of 441–610 Gy γ-irradiation significantly increased the severity of LD by 6.8-fold in commercially picked and packed ripe fruit, reducing the proportion of marketable fruit from 98% to 2%, compared to irradiated fruit harvested directly from the trees and not exposed to de-sapping solution and packing operations. Also, LD increased progressively as the fruit passed through the harvesting and packing processes, and exposure to only bore water increased LD ...

'Honey Gold' is an Australian mango cultivar with attractive skin colour and good flavour when ripe. Under-skin browning (USB) is a disorder that develops on 'Honey Gold' fruit after harvest. The disorder is usually not evident until fruit reach the wholesale market. Thus, fruit often need re-packing at the markets, causing considerable wastage and financial loss. Previous research suggested that USB results from an interaction between physical pressure (i.e., mechanical stress) and low temperature (i.e., physiological stress) during transport and distribution. To address this issue, fruit from three farms in the Northern Territory were either cooled to 13°C within 10 h of harvest, or held at 18-20°C for 1-2 days before cooling to 13°C. The fruit were packed within commercial fibreboard trays in either standard plastic liners, a 'softer' liner to potentially minimise fruit damage, or were individually wrapped in plastic or bubble wrap to prevent any damage. The fruit were then palletised and transported for three days to southern Australia in a refrigerated truck. Delaying cooling after harvest for two days reduced the incidence of USB by 52-85%. As compared to using standard liners and cooling immediately after harvest, the proportion of fruit with USB decreased from 25 to 3% when fruit packed with soft liners were held at 18-20°C for two days before cooling at 13°C and transporting. These findings show that reducing the risk of vibration damage by using soft liners in combination with a delay in temperature reduction after harvest can significantly reduce USB in commercial practice.

γ-Irradiation doses of 0.5 (target) and 1.0 (high) kGy were applied as insect disinfestation treatments to 'Kensington Pride' mango fruit. The effects of these treatments on fruit physicochemical properties and aroma volatile production were investigated and compared to non-irradiated controls. There were no significant effects of the irradiation treatments on flesh total soluble solids content. However, the loss of green skin colour usually associated with fruit ripening was inhibited by irradiation at both 0.5 and 1.0 kGy by approximately 32 and 52%, respectively, relative to non-irradiated fruit. Fruit exposed to 0.5 and 1.0 kGy exhibited a 58 and 80% reduction in emission of a-terpinolene volatiles, respectively. Thus, γ-irradiation at 0.5 and 1.0 kGy can have an adverse effect on 'Kensington Pride' mango fruit aroma volatile production and skin colouration.

Lenticel discolouration (LD) is a common disorder of mango fruit around the world. It results in poor appearance and disappointment of consumers. LD is exacerbated by treatment of mango fruit with gamma irradiation for insect disinfestation. The issue is problematic on the relatively new mango cultivar 'B74' and may represent an oxidative browning process. With a view to reducing irradiationinduced LD on 'B74', postharvest wax (one and three layers; 75% carnauba wax) and antioxidant (100 mM ascorbic acid, 100 mM calcium chloride, 10, 50 and 100 mM calcium ascorbate) dip treatments were investigated. Treatment of green mature fruit with three layers of wax prior to exposure to 557 Gy gamma irradiation reduced LD by 40% relative to the non-waxed control. However, the fruit failed to ripen properly as evidenced by delayed skin colour change, retarded softening and increased skin browning as compared to the controls and fruit coated with one layer of wax. Treatment with one layer of wax did not reduce LD. Mechanistically, the responses suggest that air exchange plays a pivotal role in LD. A lowered oxygen concentration in the lenticels may reduce the disorder after irradiation treatment. Postharvest treatments with the various antioxidants failed to reduce LD. Rather, all antioxidant treatments at the test concentrations, except calcium chloride, significantly increased skin browning.

'B74' mango fruit are sensitive to lenticel discolouration (LD). Exposure of the fruit to water during production and postharvest handling can increase LD. We propose that water infiltration into the lenticel cavity increases turgor in adjacent cells that leads to tissue strain, cellular stress and defence, and enzymatic browning. In the current study, we tested the efficacy of pre-harvest fruit bagging and coating treatments to reduce water infiltration and LD. Individual fruit on 'B74' trees at a commercial orchard were covered with a white paper bag, or coated with either 5% RainGard™ (a cracking suppressant), or 5% Raynox® (a carnauba wax-based coating) at two months before harvest. RainGard™ and Raynox® were re-applied to fruit at one month and one day before harvest. Additional fruit were coated with 2.5% Natural Shine™ TFC210 (a carnauba wax-based coating) at one day before harvest. The fruit were harvested, dipped in a detergent and a fungicide, and brushed. They were exposed to 10 μL L-1 ethylene at 20°C and allowed to ripen. The result showed that bagging and coating with Natural Shine™ TFC210 were the most effective treatments. They reduced LD on 'B74' fruit by 30-55% and 39-43% at the green mature and full ripe colour stages, respectively, as compared to the non-bagged and non-coated control. Pre-harvest bagging and coating treatments did not affect fruit firmness and lenticel morphology.

The ethylene biosynthesis inhibitor, 1-methylcyclopropene (1-MCP), has been commercially used to extend the storage life of European pear fruit and to allow shipment to distant markets. However, the influence of 1-MCP on the ability of fruit to ripen to an acceptable sensory quality has not been investigated in 'Bartlett' pear, one of the most aromatic of pear fruit. In the current study, early-, mid- and late-season 'Bartlett' pear fruit were treated with 0.6μLL-1 1-MCP at 0°C for 24h, 100μLL-1 ethylene at 20°C for 24h, or untreated before immediate transfer to 20°C for ripening until eating soft (13N firmness). Fruit from each treatment were subjected to objective and sensory quality evaluation once ripe. Sensory quality showed differences related to harvest maturity; the importance of harvest maturity depended on the treatment. Treatment with 1-MCP effectively slowed fruit ripening and therefore extended postharvest life, but also resulted in fully ripened pears with more desirable sensory traits, as compared with ethylene-treated and untreated pears. The enhanced sensory quality was related to higher sweetness, juiciness and pear aroma and reduced fermented aroma, gritty texture and tart taste. In addition, the sensory profiles of 1-MCP-treated pears were more stable among fruit from the three harvest dates than the ethylene-treated pears, which exhibited very different sensory profiles between early- and late-season fruits. © 2015 Elsevier B.V.

The effect of a pre-shipment hypochlorite treatment on botrytis incidence was evaluated in a large number of rose cultivars and under different long-term storage conditions. Application parameters, stability and sources of hypochlorite were investigated. Irrespective of the type of packaging and shipment conditions, roses that received a pre-shipment treatment with 100 to 150 mg/L hypochlorite showed a significantly decreased botrytis incidence compared to non-hypochlorite treated roses. The hypochlorite treatment generally was more effective than a comparable treatment with commercial fungicides. Dipping the flower heads for approximately one second in a hypochlorite solution was more effective than spraying the heads. In few cases minor hypochlorite-induced damage on the petal tips was observed at higher concentrations (>200 mg/L). Apart from the effect on botrytis incidence, the treatment resulted in reduced water loss that may have an additional beneficial effect on the eventual flower quality. It is concluded that, apart from other obvious measures to reduce botrytis incidence (prevention of high humidity at the flower heads) a pre-shipment floral dip in 100 to 150 mg/L hypochlorite from commercial household bleach is an easy and cost effective way to reduce botrytis incidence following long term storage/transportation of roses.

Background The capacity of European pear fruit (Pyrus communis L.) to ripen after harvest develops during the final stages of growth on the tree. The objective of this study was to characterize changes in ‘Bartlett’ pear fruit physico-chemical properties and transcription profiles during fruit maturation leading to attainment of ripening capacity. Results The softening response of pear fruit held for 14 days at 20 °C after harvest depended on their maturity. We identified four maturity stages: S1-failed to soften and S2- displayed partial softening (with or without ET-ethylene treatment); S3 - able to soften following ET; and S4 - able to soften without ET. Illumina sequencing and Trinity assembly generated 68,010 unigenes (mean length of 911 bp), of which 32.8 % were annotated to the RefSeq plant database. Higher numbers of differentially expressed transcripts were recorded in the S3-S4 and S1-S2 transitions (2805 and 2505 unigenes, respectively) than in the S2-S3 transition (2037 unigenes). High expression of genes putatively encoding pectin degradation enzymes in the S1-S2 transition suggests pectic oligomers may be involved as early signals triggering the transition to responsiveness to ethylene in pear fruit. Moreover, the co-expression of these genes with Exps (Expansins) suggests their collaboration in modifying cell wall polysaccharide networks that are required for fruit growth. K-means cluster analysis revealed that auxin signaling associated transcripts were enriched in cluster K6 that showed the highest gene expression at S3. AP2/EREBP (APETALA 2/ethylene response element binding protein) and bHLH (basic helix-loop-helix) transcripts were enriched in all three transition S1-S2, S2-S3, and S3-S4. Several members of Aux/IAA (Auxin/indole-3-acetic acid), ARF (Auxin response factors), and WRKY appeared to play an important role in orchestrating the S2-S3 transition. Conclusions We identified maturity stages associated with the development of ripening capacity in ‘Bartlett’ pear, and described the transcription profile of fruit at these stages. Our findings suggest that auxin is essential in regulating the transition of pear fruit from being ethylene-unresponsive (S2) to ethylene-responsive (S3), resulting in fruit softening. The transcriptome will be helpful for future studies about specific developmental pathways regulating the transition to ripening. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1939-9) contains supplementary material, which is available to authorized users.

Significant interactions have been demonstrated between production factors and postharvest quality of fresh fruit. Accordingly, there is an attendant need for adaptive postharvest actions to modulate preharvest effects. The most significant preharvest effects appear to be mediated through mineral nutrition influences on the physical characteristics of fruit. Examples of specific influencers include fertilisers, water availability, rootstock, and crop load effects on fruit quality attributes such as skin colour, susceptibility to diseases and physiological disorders, and fruit nutritional composition. Also, rainfall before and during harvest can markedly affect fruit susceptibility to skin blemishes, physical damage, and diseases. Knowledge of preharvest-postharvest interactions can help determine the basis for variability in postharvest performance and thereby allow refinement of postharvest practices to minimise quality loss after harvest. This knowledge can be utilised in predictive management systems. Such systems can benefit from characterisation of fruit nutritional status, particularly minerals, several months before and/or at harvest to allow informed decisions on postharvest handling and marketing options. Other examples of proactive management practices include adjusting harvesting and packing systems to account for rainfall effects before and/or during harvest. Improved understanding of preharvest-postharvest interactions is contributing to the delivery of consistently higher quality of fruit to consumers. This paper focuses on the state of knowledge for sub-tropical and tropical fruits, in particular avocado and mango.

Low temperature (LT) treatments enhance ethylene production and ripening rate in the European pear (Pyrus communis L.). However, the underlying molecular mechanisms are not well understood. This study aims to identify genes responsible for ripening enhancement by LT. To this end, the transcriptome of 'Bartlett' pears treated with LT (0°C or 10°C for up to 14 d), which results in faster ripening, and control pears without conditioning treatment was analyzed. LT conditioned pears reached eating firmness (18N) in 6 d while control pears took about 12 d when left to ripen at 20°C. We identified 8,536 differentially expressed (DE) genes between the 0°C-treated and control fruit, and 7,938 DE genes between the 10°C-treated and control fruit. In an attempt to differentiate temperature-induced vs. ethylene-responsive pathways, we also monitored gene expression in fruit sequentially treated with 1-MCP then exposed to low temperature. This analysis revealed that genes associated with jasmonic acid biosynthesis and signaling, as well as the transcription factors TCP9a, TCP9b, CBF1, CBF4, AGL24, MYB1R1, and HsfB2b could be involved in the LT-mediated enhancement of ripening independently or upstream of ethylene.

Reported herein is a high throughput method to quantify in a single analysis the key volatiles that contribute to the aroma of commercially significant mango cultivars grown in Australia. The method constitutes stable isotope dilution analysis (SIDA) in conjunction with headspace (HS) solid-phase microextraction (SPME) coupled with gas-chromatography mass spectrometry (GCMS). Deuterium labelled analogues of the target analytes were either purchased commercially or synthesised for use as internal standards. Seven volatiles, hexanal, 3-carene, α-terpinene, p-cymene, limonene, α-terpinolene and ethyl octanoate, were targeted. The resulting calibration functions had determination coefficients (R2) ranging from 0.93775 to 0.99741. High recovery efficiencies for spiked mango samples were also achieved. The method was applied to identify the key aroma volatile compounds produced by ‘Kensington Pride’ and ‘B74’ mango fruit and by ‘Honey Gold’ mango sap. This method represents a marked improvement over current methods for detecting and measuring concentrations of mango fruit and sap volatiles.

The efficacy of several proprietary plastic pallet cover systems to maintain strawberry (Fragaria ×ananassa) fruit quality during commercial shipment was determined. ‘Albion’ fruit were harvested from farms near Watsonville, CA. Fruit in vented plastic clamshells were palletized and forced-air cooled to 33–35 °F. Different cover systems (CO2 West, PEAKfresh, PrimePro, Tectrol) were placed over the pallets. Pads that released carbon dioxide (CO2) gas were placed inside the CO2 West cover. The Tectrol cover was sealed to the pallet base, a partial vacuum was applied, and pressurized CO2 gas was injected inside. The systems other than Tectrol remained open at the base. Six separate shipments of palletized fruit were transported in refrigerated (32–39 °F) truck trailers to distribution centers in either Florida or Georgia in 2.3–4.7 days. CO2 concentrations within pallets at the beginning and end of transport were highest (11% to 16%) in the sealed Tectrol system and relatively low (0.06% to 0.30%) in the open CO2 West, PEAKfresh, and PrimePro cover systems. Relative to noncovered control fruit, which lost 0.8% fresh weight during shipment, the pallet covers reduced the transport-related weight loss by 38% to 52%. The incidence of fruit decay was low (1.0% to 1.4%) after transport but increased substantially following a 2-day shelf life at 68 °F. However, fruit from the Tectrol pallets exhibited significantly less decay (36%) after shelf life than the CO2 West (39%), noncovered control (41%), PrimePro (42%), and PEAKfresh (43%) pallets. Fruit sensory quality was unaffected by the different pallet cover systems. Our findings show that transporting strawberries in the sealed Tectrol pallet cover system, in which CO2 concentrations were elevated to 11% to 16%, was most effective in complementing current low temperature management practices to maintain fruit quality.

Exposure to 0.1, 1.0, or 10 μL·L−1 ethylene for 4 days at 21 °C reduced the display life of 17 commonly traded potted foliage plant genotypes (Aglaonema ‘Mary Ann’, Anthurium scherzerianum ‘Red Hot’ and ‘White Gemini’, Aphelandra squarrosa ‘Dania’, Chlorophytum comosum ‘Hawaiian’, Codiaeum variegatum pictum ‘Petra’, Dieffenbachia maculata ‘Carina’, Dracaena marginata ‘Bicolor’ and ‘Magenta’, Euphorbia milii ‘Gaia’, Euphorbia splendens ‘Short and Sweet’, Ficus benjamina, Polyscias fruticosa ‘Castor’, Radermachera sinica ‘China Doll’, Schefflera elegantissima ‘Gemini’, Schefflera arboricola ‘Gold Capella’, Spathiphyllum ‘Ty's Pride’). Ethylene treatment hastened leaf and bract abscission or senescence. The responsiveness of plants to ethylene varied considerably; six genotypes were sensitive to 0.1 μL·L−1 ethylene, whereas three genotypes required exposure to 10 μL·L−1 ethylene to trigger visible injury. Four genotypes (Asplenium nidus, Chamaedorea elegans ‘Neathe Bella’, Hedera helix ‘Chicago’, Syngonium podophyllum ‘White Butterfly’) included in our study were insensitive to ethylene. Treating Aglaonema ‘Mary Ann’, Polyscias fruticosa ‘Castor’, and Schefflera arboricola ‘Gold Capella’ plants with 0.9 μL·L−1 1-methylcyclopropene (1-MCP, provided as EthylBloc™), a gaseous ethylene-binding inhibitor, for 4 to 5 h at 21 °C reduced the deleterious effects of ethylene. The release of 1-MCP from two sachets containing EthylBloc™ into a single shipping box also protected Aphelandra squarrosa ‘Dania’, Euphorbia milii ‘Gaia’, Polyscias fruticosa ‘Elegans’, and Schefflera arboricola ‘Gold Capella’ plants from ethylene injury after simulated transport. Our data reveal the genetic variation in ethylene sensitivity among potted foliage plants and highlight genotypes that benefit from 1-MCP treatment.

Thidiazuron (N-phenyl-N'-1,2,3-thiadiazol-5-ylurea, TDZ), a non-metabolized phenyl urea compound with cytokinin-like activity, is a potent inhibitor of leaf senescence in cut flowers. In the present study, we determined the potential for TDZ to delay both leaf and flower senescence on cut iris 'Discovery' stems. We found that a postharvest pulse with 200, 500 or 1000 μM TDZ for 6, 12 or 24 hours at 20°C prevented leaf yellowing and extended flower life by 0.6-1.5 days (12-34%) relative to control (0 μM TDZ) stems. Treatment with TDZ also increased the length of shoots on which flowers develop by 0.7-2.5 cm (8-30%) over control stems. The benefits of TDZ treatment were maintained even when flowers were held dry for 3 days at 0°C after pulsing. Treating flowers with 500 μM TDZ in combination with 350 mg/L GA 3 further increased floral shoot growth and led to more complete flower opening. The extension in flower life may be a direct effect of TDZ treatment in delaying floral senescence or a reflection of improved carbohydrate supply from leaf tissues. Our findings highlight the potential use for TDZ as a postharvest pulse treatment to improve the opening and longevity of iris flowers.

As the flowers of Nicotiana mutabilis open and senesce, their petals show a striking color change from white through pink to red. This was associated with an increase in chalcone synthase ( CHS ) gene expression and a substantial rise in petal anthocyanin content. It was also accompanied by up-regulation of 1-aminocyclopropane-1-carboxylic acid oxidase ( ACO ) transcripts and elevated rates of ethylene production at the onset of petal wilting. Emission of the fragrant monoterpenoid volatiles 1,8-cineole, linalool, and terpineol also increased as petals developed pink coloration. The increase in volatile emission was preceded by a rise in monoterpene synthase ( MTS ) gene expression. Transcripts of a homologue of SAG12 , a senescence-associated gene encoding a cysteine protease, began to accumulate in petals 3 days prior to visible wilting. Exposure of newly opened white flowers to 1 μL L −1 ethylene accelerated petal coloration, wilting, and induction of SAG12 expression by ca. 1 day while treatment with 500 nL L −1 1-methylcyclopropene (1-MCP), an inhibitor of ethylene action, retarded these processes. The numerous genetic and experimental tools available for tobacco can readily be applied to this close relative, which therefore provides an interesting new model for studying ethylene-mediated flower senescence.

Natural variation in the postharvest quality and longevity of ornamental plants can often be related to differences in their response to ethylene. In the present study, we determined the postharvest performance and ethylene sensitivity of cut flowers from 38 cultivated Hybrid Tea rose genotypes. The vase life of the cultivars varied considerably from 4.5 to 18.8 days at 21 °C. There was also substantial variation in the degree of flower opening among genotypes. Exposure to 1 μL·L−1 ethylene for 24 h at 21 °C reduced the longevity of 27 cultivars by 0.8 to 8.4 days (18% to 47%) by accelerating petal wilting and abscission. Ethylene treatment also significantly reduced rates of flower opening in 17 sensitive cultivars and in six cultivars that showed no ethylene-related reduction in vase life. Five cultivars showed no reduction in vase life or flower opening in response to ethylene exposure. Pre-treating stems with 0.2 mm silver thiosulfate liquid or 0.9 μL·L−1 1-methylcyclopropene (1-MCP) gas for 16 h at 2 °C reduced the deleterious effects of ethylene. The release of 1-MCP from two sachets containing EthylBloc™ into individual shipping boxes also protected flowers against ethylene applied immediately after a 6-d commercial shipment. The duration of protection afforded by the 1-MCP sachet treatment was greatest when flowers were maintained at low temperature.

GA3 Iris Postharvest Sucrose Thidiazuron TDZ Vase life abstract The marketability of Dutch iris (Iris × hollandica) cut flowers is limited by their short display life and frequent failure to open fully. We tested the ability of thidiazuron (TDZ), a phenyl-urea compound with cytokinin-like activity, to improve iris flower opening and longevity. A postharvest pulse with 0.2-1 mM TDZ for 6-24 h at 0 or 20 ◦ C extended the vase life of flowers by up to 1.5 d relative to control (0 mM TDZ) stems in water. TDZ treatment also stimulated growth of the pedicel and ovary by up to 2.5 cm that, in turn, led to more complete opening of flowers. Inclusion of 1 mM gibberellic acid (GA3) in the TDZ pulsing solution did not extend vase life further but did increase flower shoot elongation by an additional 1.0 cm. Provision of 20% sucrose with the TDZ plus GA3 treatment had an additive effect, increasing vase life and shoot growth by a further 0.8 d and 1.0 cm, respectively. Pulsing stems with this combined treatment prior to storing flowers dry for 14 d at 0 ◦C provided maximum flower opening and display life after storage. Treatment with 0.5 mM TDZ stimulated a significant increase in ethylene production by flowers during their opening.

Botrytis cinerea is a fungal pathogen that greatly reduces the postharvest quality of rose flowers. A posthar- vest dip in 200 LL −1 sodium hypochlorite (NaOCl) for 10 s at 20 ◦C provided the greatest control of B. cinerea on 'Akito' and 'Gold Strike' flowers. NaOCl derived from Clorox ® Ultra household bleach solu- tion was more effective than laboratory grade NaOCl in reducing disease symptoms. Lowering the pH of the NaOCl solution from pH 9.7 (unadjusted) to pH 7.0 greatly improved its efficacy. Treating 'Gold Strike' flowers in this pH-adjusted NaOCl solution was more effective in reducing the level of infection on petals than postharvest dips in the conventional fungicides Medallion®, Phyton®, Switch® and Vangard®. Applying NaOCl prior to a 3- or 10-d commercial shipment also provided the most consistent disease control for a wide range of rose cultivars as compared to conventional fungicides. Of particular interest, the efficacy of NaOCl and Phyton ® was greatest when these compounds were applied to 'Gold Strike' flowers after incubation at 20 ◦C and 90% RH for 6-9 h. Our findings highlight NaOCl as a promising new candidate for the control of B. cinerea on rose flowers.

Cut waxflower (Chamelaucium spp. and hybrids) stems bear numerous small attractive flowers. However, unsightly flower abscission often occurs during their postharvest handling. A range of possible causes of this symptom were initially investigated, including exogenous ethylene, water deficit stress, physical injury, and pathogen infection. Ultimately, the flowers proved to be particularly susceptible to Botrytis cinerea. This cause was not initially obvious because ethylene mediated abscission was elicited by Botrytis infection before disease became evident. Airborne conidia of Botrytis are typically dispersed in the field before harvest. They require cool temperatures and, ideally, free water to germinate. Such conditions are common during handling after harvest. Botrytis can infect all organs of waxflower flowers. Under ideal incubation conditions, flower abscission occurs within 2-4 days. Flower fall occurs at least 1 day before tan coloured lesions appear. A further 1-2 days are required before superficial mycelia and conidiophores form and sporulation occurs. Heavily infected flowers become water-soaked and turn dark brown. Postharvest flower abscission in waxflower can be prevented by treatment with anti-ethylene agents, including silver thiosulphate and, to a lesser degree, 1-methylcyclopropene. However, through better understanding the host-pathogen interaction, opportunities exist to directly address the cause of the problem as opposed to the initial symptom. Fungicides are effective in suppressing Botrytis-elicited flower fall, but their use is falling from favour. In this general context, the waxflower-Botrytis pathosystem constitutes a potentially useful 'model system' for further investigation of pathogen elicited flower abscission at physiological, cellular, biochemical, and molecular levels.

The most traditional first step after harvesting flowers is to place the cut stems into water or a postharvest solution. Although this step is thought to reduce desiccation, and thereby extend postharvest life, there has been no detailed study of this hypothesis. We harvested rose flowers from commercial farms near Bogota, Colombia and Quito, Ecuador. Flowers were either hydrated as per conventional practice, or not provided with immediate postharvest hydration. They were then processed and transported to Davis, California, following standard commercial practices. Despite substantial loss of water during transport, dry-handled flowers rehydrated fully, and performed at least as well in the vase as flowers handled according to the standard protocol. Our data suggest that the value of immediate hydration of harvested flowers should be carefully examined, not only for roses, but for other important species.

Application of low concentrations of thidiazuron (N-phenyl-N’-1,2,3thiadiazol-5-yl urea, TDZ) has been shown to be a very effective means of delaying leaf yellowing in cut flowers such as alstroemeria, stock, lilies and tulips. We examined the possible use of this compound for delaying leaf yellowing in a range of potted plants, including geranium, freesia, Ornithogalum, and Euphorbia fulgens. Spray treatments with 2 to 10 µM TDZ at the end of the production cycle had significant, sometimes spectacular effects on the postharvest performance of most species studied. In addition to a considerable delay in leaf yellowing and/or abscission in most species tested, TDZ application improved display performance in a number of species. In geranium, for example, the individual florets on TDZ-treated plants had a significantly longer life than those on control plants. In E. fulgens, flowers lasted longer, and more flowers opened on the TDZ-treated plants. Our results indicate significant potential for TDZ as a tool to improve the postharvest life of potted flowering and foliage plants.

Wounding of plants is a widespread stress in nature. Physical damage frequently occurs during harvesting, handling and marketing of fresh produce. Phenylalanine ammonia-lyase (PAL) is a key enzyme involved in plant wound related phenylpropanoid metabolism while heat shock proteins (HSPs) are involved in abiotic, including wounding, and biotic stress responses in plants. However, little is known about postharvest expression at gene and protein levels of PAL and HSPs in wounding (fresh-cut) fruits. In the present study, expression patterns of PAL and HSPs in fresh-cut and intact banana fruit pulp were characterized by Northern and Western blot analyses. Cuting enhanced Ma-PAL2 mRNA accumulation, new PAL protein synthesis, and PAL activity; thereby resulting in accumulation of total phenolics. HSP70 protein and Ma-HSP70-2 transcript were constitutively expressed and were not affected by cutting. However, Ma-HSP70-1 transcript levels increased in fresh-cut pulp tissue at 2–18 h after cutting. Ma-sHSP-1-CI, Ma-sHSP-3-CII, Ma-HSP90, and Ma-HSP101 transcripts also accumulated in fresh-cut tissues at 2–18 h after cuting, but Ma-sHSP-2-CI did not accumulate. Accumulation of sHSP (HSP17.6), HSP90 and HSP101 proteins exhibited the same pattern of expression as their mRNA. There was no evidence of a possible suppressive effect of HSPs synthesis on PAL protein accumulation. Thus, PAL, sHSP, HSP90 and HSP101 were regulated by cutting both at translational and transcriptional levels while HSP70 (Ma-HSP70-1) was regulated by cutting only at transcription level.

The accumulation of bacteria in vase water is often associated with premature senescence in many cut flower species. In the present study, we tested the efficacy of aqueous chlorine dioxide (ClO2) to extend flower display life by preventing the build-up of bacteria in vase solutions. The addition of 2 or 10 μL L−1 ClO2 to clean deionized water extended the vase life of Alstroemeria peruviana ‘Senna’, Antirrhinum majus ‘Potomic Pink’, Dianthus caryophyllus ‘Pasha’, Gerbera jamesonii ‘Monarch’, Gypsophila paniculata ‘Crystal’ and ‘Perfecta’, Lilium asiaticum ‘Vermeer’, Matthiola incana ‘Ruby Red’ and Rosa hybrida ‘Charlotte’ flowers by 0.9–13.4 d (7–77%) relative to control (i.e. 0 μL L−1 ClO2) stems. The beneficial effects of ClO2 treatment were associated with a reduction in the accumulation of aerobic bacteria in vase water and on cut surfaces of flower stems. ClO2 treatment was also effective in maintaining or extending the vase life of A. majus ‘Potomic Pink’, Dendrathema × grandiflorum ‘Albatron’, G. paniculata ‘Perfecta’ and M. incana ‘Ruby Red’ flowers even when stems were placed into water containing 1011 CFU L−1 bacteria. The efficacy of 10 μL L−1 ClO2 in vase water containing 0.2 g L−1 citric acid and 10 g L−1 sucrose to extend the display life of G. jamesonii ‘Lorca’ and ‘Vilassar’ flowers was equal to or greater than other tested biocides (i.e. aluminum sulfate, dichloroisocyanuric acid, 8-hydroxyquinoline sulfate, Physan 20™, sodium hypochlorite). Taken collectively, the results of the present study highlight the potential of aqueous ClO2 for use as an alternative antibacterial agent in flower vase solutions.

The woody resurrection plant Myrothamnus flabellifolia has remarkable tolerance to desiccation. Pyro-sequencing technology permitted us to analyze the transcriptome of M. flabellifolia during both dehydration and rehydration. We identified a total of 8287 and 8542 differentially transcribed genes during dehydration and rehydration treatments respectively. Approximately 295 transcription factors (TFs) and 484 protein kinases (PKs) were up- or down-regulated in response to desiccation stress. Among these, the transcript levels of 53 TFs and 91 PKs increased rapidly and peaked early during dehydration. These regulators transduce signal cascades of molecular pathways, including the up-regulation of ABA-dependent and independent drought stress pathways and the activation of protective mechanisms for coping with oxidative damage. Antioxidant systems are up-regulated, and the photosynthetic system is modified to reduce ROS generation. Secondary metabolism may participate in the desiccation tolerance of M. flabellifolia as indicated by increases in transcript abundance of genes involved in isopentenyl diphosphate biosynthesis. Up-regulation of genes encoding late embryogenesis abundant proteins and sucrose phosphate synthase is also associated with increased tolerance to desiccation. During rehydration, the transcriptome is also enriched in transcripts of genes encoding TFs and PKs, as well as genes involved in photosynthesis, and protein synthesis. The data reported here contribute comprehensive insights into the molecular mechanisms of desiccation tolerance in M. flabellifolia.

SummaryExperiments were conducted to evaluate the effects of anoxia treatments on banana fruit ripening. Pre-climacteric banana fruit were exposed to pure N2 for 0, 6, 9, 12 or 24 h, then stored for up to 3 weeks at 20°C and approx. 90% relative humidity. Changes in peel colour, fruit firmness and post-harvest life were evaluated. Ripening was inhibited most effectively in fruit exposed to N2 for 9 h. Furthermore, exposure of banana fruit to pure N2 gas for 9 h reduced the rates of ethylene production and respiration, as well as the activities of polygalacturonase and pectin methyl esterase. These results suggest that anoxia treatment is a feasible technology to inhibit ripening and extend the shelf-life of banana fruit.

Previous investigations with 1-methylcyclopropene (1-MCP) on avocado (Persea americana Mill.) fruit have focussed mainly on improving storage life by reducing the severity of disorders causing discolouration of the flesh. Development of 1-MCP and ethylene treatments, which also help control the time to reach the eating ripe stage, may confer additional practical benefits. In this context, the current study investigated the potential of 1-MCP to accurately manipulate ripening of non-stored 'Hass' avocado fruit by treatment before or after ethylene and at different times during ripening. To investigate this, 500 nL L-1 1-MCP was applied within 1 day after harvest, followed by ethylene 0-14 days after 1-MCP. In addition, fruit were treated with ethylene, then 1-MCP 0-8 days after ethylene. Treatment of fruit with 500 nL L-1 1-MCP for 18 h at 20 degreesC provided the maximum effect by increasing the days from harvest to ripe (DTR) from 8 (with no 1-MCP) to 20. Fruit treated with 500 nL L-1 1-MCP for 18 h at 20 degreesC remained insensitive to 100 muL L-1 ethylene applied between 0 and 14 days after 1-MCP for 24 h at 20 degreesC. Ripening of fruit exposed to 100 muL L-1 ethylene for 24 h at 20 degreesC could be delayed by up to 3.3 days by applying 500 nL L-1 1-MCP for 18 h at 20 degreesC up to 2 days after ethylene treatment. However, once the fruit started to soften (sprung) there was little effect of 1-MCP on DTR, compared with no 1-MCP. 1-MCP treatment was associated with increased severity of body rots (caused mainly by Colletotrichum spp.) and stem-end rots (caused mainly by Dothiorella spp.), which was likely due to the increased DTR in these treatments. Significant differences in disease severity were found between orchards (replications), with replicates with low disease severity being less affected by 1-MCP treatment. These results indicate that 1-MCP can delay ripening, but careful sourcing of fruit is required to reduce the risk of diseases in ripe fruit. There is some capacity to delay ripening using 1-MCP after ethylene. There is little potential to control ripening using ethylene after treatment with 500 nL L-1 1-1-MCP, but lower concentrations may be more effective. (C) 2004 Elsevier B.V. All rights reserved.

Postharvest flower abscission is an ethylene-mediated process that can reduce the marketability of cut Chamelaucium Desf. (Myrtaceae) flowers. The sensitivity of 51 Chamelaucium cut flower genotypes to ethylene was evaluated. Sensitivity varied among genotypes both between and within different species and crosses. C. uncinatum x C. micranthum cv. 'Sweet Georgia' and C. uncinatum cvv. 'Early Nir', 'Paddy's Late', 'Purple Pride', 'CWA Pink' and 'Early Hard' flowers were highly sensitive to ethylene. These genotypes shed 10 % of their flowers in response to a 12 h treatment with < 0.01 microlitres l-1 ethylene at 20 degrees C. In contrast, C. megalopetalum 'Winter White' and 'Iceberg' flowers were insensitive to ethylene even at 100 microlitres l-1 for 12 h at 20 degrees C. Sensitivity to ethylene varied between harvests during the flowering season and for the same genotypes harvested from different farms. Sensitivity of C. uncinatum cv. 'Purple Pride' flowers to treatment with 1 microlitres l-1 ethylene also decreased towards the end of vase life in association with slight dehydration. Variation in ethylene-induced abscission responses highlights the need to screen flowers from multiple harvests and varying growing conditions when assessing ethylene sensitivity. Screening genotypes for ethylene sensitivity should facilitate selection of Chamelaucium species with greater durability for export handling.

SummaryExposure to ethylene gas elicits flower abscission from cut stems of Geraldton waxflower (Chamelaucium uncinatum Schauer). Ethylene response rates in plants are mediated by temperature. At 20°C, flower abscission from waxflower ‘Purple Pride’ occurred upon 12 h exposure to 1 µ11–1 ethylene. This ethylene treatment did not cause flower abscission at either 10 or 2°C. Moreover, flowers held at 2°C were insensitive to 48 h exposure to 1, 10 and 100 µ11–1 ethylene. However, increasing the duration of treatment with 1 µ11–1 ethylene at 10 and 2°C to 48 and 144 h, respectively, induced flower abscission. When flowers were held at 20°C in air without exogenous ethylene following continuous exposure to 1 µ11–1 ethylene at 2°C, the duration required to elicit flower abscission was reduced from 144 to 72 h. Collectively, these responses show that maintaining harvested waxflower at low temperature (e.g. 2°C) is an effective means to minimise ethylene-mediated flower abscission.

Elevated temperatures experienced by harvested fruit can modulate theirripening. Moreover, heat treatments can be applied to reduce susceptibility tolow temperature disorders and to help control pests and diseases. Theethylene-binding inhibitor 1-methylcyclopropene (1-MCP) was used to investigatethe ethylene-mediated softening response of banana fruit exposed to elevatedtemperatures. A preliminary experiment was conducted to determine levels ofhightemperature (30–50 °C) imposed for a short periodof time that did not cause skin scald. The softening response of Williamsbananafruit treated with 1-MCP at various temperatures and durations wascharacterisedin subsequent experiments. Exposure of fruit to hot air for 60 minat 45 °C or for 30 min at50 °Ccaused 30–40% peel scald. The peel was not visibly damaged forfruit treated at 40 °C for up to 60 min.Softening of fruit treated with 1-MCP for 12 h at25 °Cand then held for 7 days at 30, 35 or 40 °C wasinhibited in proportion to increasing concentration over the range 0.01–1μl/l 1-MCP. However, softening was progressively enhanced withincreasing holding temperatures from 30–40 °Cand/or time from 1–7 days, although fruit treated with the higher 1-MCPconcentrations of 1 and 10 μl/l were comparatively lessresponsive to heat. Although banana fruit held at30–40 °Cdid not de-green, their increased softening at elevated temperatures andinhibition of this response by 1-MCP suggest that heat enhances synthesis ofnewethylene sites which mediated banana fruit softening.

The role of abscisic acid (ABA) in banana fruit ripening was examined with the ethylene binding inhibitor, 1-methylcyclopropene (1-MCP). ABA (0, 10(-5), 10(-4), or 10(-3) mol/L) was applied by vacuum infiltration into fruit. 1-MCP (1 µL/L) was applied by injecting a measured volume of stock gas into sealed glass jars containing fruit. Fruit ripening, as judged by ethylene evolution and respiration associated with color change and softening, was accelerated by 10(-4) or 10(-3) mol/L ABA. ABA at 10(-5) mol/L had no effect. The acceleration of ripening by ABA was greater at 10(-3) mol/L than at 10(-4) mol/L. ABA-induced acceleration of banana fruit ripening was not observed in 1-MCP treated fruit, especially when ABA was applied after exposure to 1-MCP. Thus, ABA's promotion of ripening in intact banana fruit is at least partially mediated by ethylene. Exposure of ABA-treated fruit to 0.1 µL/L ethylene for 24 h resulted in increased ethylene production and respiration, and associated skin color change and fruit softening. Control fruit (no ABA) was unresponsive to similar ethylene treatments. The data suggest that ABA facilitates initiation and progress in the sequence of ethylene-mediated ripening events, possibly by enhancing the sensitivity to ethylene.

The effect of the new anti-ethylene compound 1-methylcyclopropene (1-MCP) in combination with polyethylene bags on the ripening of harvested banana fruit was investigated. 1-MCP treatment delayed peel colour change and fruit softening, and extended shelf life in association with suppression of respiration and C2H4 evolution. Banana fruit ripening was delayed when exposed to 0.01-1.0 mu l 1-MCP/l for 24 h, and increasing concentrations of 1-MCP were generally more effective for longer periods of time. Similar results were obtained with fruit sealed in polyethylene bags (0.03 mm thick) containing 1-MCP at various concentrations, but longer delays in ripening were achieved. The greatest longevity of about 58 days was realised by packing fruit in sealed polyethylene bags with 1-MCP at either of 0.5 or 1.0 mu l/l. Analyses of C2H4 and CO2 concentrations within polyethylene bags confirmed that 1-MCP suppressed both C2H4 evolution and respiration. Thus, application of 1-MCP in combination with the use of polyethylene bags can greatly extend the postharvest life of banana fruit. (C) 1999 Elsevier Science B.V. All rights reserved.

International audience; In determining vase life (VL), it is often not considered that the measured VL in a particular experiment may greatly depend on both the preharvest and evaluation environmental conditions. This makes the comparison between studies difficult and may lead to erroneous interpretation of results. In this review, we critically discuss the effect of the growth environment on the VL of cut roses. This effect is mainly related to changes in stomatal responsiveness, regulating water loss, whereas cut flower carbohydrate status appears less critical. When comparing cultivars, postharvest water loss and VL often show no correlation, indicating that components such as variation in the tissue resistance to cavitate and/or collapse at low water potential play an important role in the incidence of water stress symptoms. The effect of the growth environment on these components remains unknown. Botrytis cinerea sporulation and infection, as well as cut rose susceptibility to the pathogen are also affected by the growth environment, with the latter being largely unexplored. A huge variability in the choices made with respect to the experimental setup (harvest/conditioning methods, test room conditions and VL terminating symptoms) is reported. We highlight that these decisions, though frequently overlooked, influence the outcome of the study. Specifications for each of these factors are proposed as necessary to achieve a common VL protocol. Documentation of both preharvest conditions and a number of postharvest factors, including the test room conditions, is recommended not only for assisting comparisons between studies, but also to identify factors with major effects on VL. (c) 2012 Elsevier B.V. All rights reserved.

CONTENTS 19.1 Introduction 491 19.2 CA and MA Storage of Cut Flowers and Greens 49319.2.1 Anthurium 493 19.2.2 Carnation 494 19.2.3 Daffodil 495 19.2.4 Gladiolus 495 19.2.5 Rose 496 19.2.6 Foliage Plant Species 49619.3 CA and MA Storage of Bulbs 496 19.3.1 Lily 496 19.3.2 Tulip 49719.4 CA and MA Storage of Vegetative Cuttings 498 19.5 CA and MA Storage of Potted Ornamental Plants 498 19.6 CA and MA Treatments for Pest and Disease Control 498 19.7 Biotic and Abiotic Factors Affecting the Efficacy of CA and MA Treatments....... 500 19.8 Future Research Needs and Commercial Applications 502 19.9 Conclusions 503 References 503Ornamental plants and their detached organs (e.g., bulbs, cut flowers) are among the most highly perishable horticultural commodities traded internationally (Reid, 2002). High rates of respiration and transpiration, sensitivity to ethylene, and=or low natural resistance to disease-causing organisms (e.g., Botrytis cinerea) often limit the postharvest life of ornamentals (Elad, 1988; Reid, 2002). Extending the time that these products can be stored would provide an opportunity to use less expensive surface (e.g., truck, boat) transport than the current costly reliance on airplanes to supply international markets. Developing appropriate methods of storing ornamentals, particularly cut flowers, could also facilitate product accumulation and distribution for more profitable marketing on special days (e.g., Valentine’s Day, Mother’s Day) when demand for these commodities often exceeds supply. Storing ornamental plants at low but nonchilling and nonfreezing temperatures isan effective method for extending postharvest life (Halevy and Mayak, 1981). LowTABLE 19.1Published Studies that Have Evaluated Responses of Ornamental Plants and Their Detached Organs to CA and MA Treatmentstemperatures reduce rates of respiration, ethylene production and sensitivity, and metabolic reactions associated with tissue senescence (Barden and Hanan, 1972; Maxie et al., 1973). Maintaining ornamental commodities at constant optimal storage temperatures also prevents condensation from developing on tissues and thereby reduces the related development of fungal pathogens (Reid, 2002). A range of chemical treatments including antiethylene agents (e.g., silver thiosulfate [STS]), hormones (e.g., cytokinins) and fungicides (e.g., iprodione) are also used to maximize the postharvest life of ornamentals (Halevy and Mayak, 1981). Exposure to atmospheres of reduced O2 and=or elevated CO2 concentrations is anadditional strategy with potential to maintain the postproduction longevity of ornamentals. Storage under such an appropriate controlled atmosphere (CA) or within packaging in which a beneficial modified atmosphere (MA) develops is an effective means for extending the postharvest longevity of various fruits (e.g., apple, pear) and vegetables (e.g., broccoli) (Kader et al., 1989). The benefits of CA principally arise from associated reductions in rates of respiration, ethylene production and response, and oxidative processes (Beaudry, 1999). CA treatments can also aid in reducing pest infestations (e.g., arthropods) and disease infections (e.g., Botrytis) of harvested commodities (El-Goorani and Sommer, 1981; El-Kazzaz et al., 1983). In contrast to fruits and vegetables, effects of CA storage and MA packaging (MAP) on ornamentals have been less extensively and intensively studied. Thus, relatively few ornamental plant species have been tested for beneficial effects of CA and MA treatments (Table 19.1). Nonetheless, early studies on CA storage of cut flowers date back to 1930 (Thornton, 1930). Some interesting studies have also evaluated hypobaric storage, whereby a reduction in atmospheric pressure reduces the partial pressure of O2 and other gases (e.g., ethylene) and can extend the longevity of ornamentals (Dilley et al., 1975; Staby et al., 1982). The principles and effects of CA and MA treatments on ornamentals have previouslybeen well documented by Halevy and Mayak (1981), Eisenberg (1985), Goszczynska and Rudnicki (1988), and Zagory and Reid (1989). This chapter aims to highlight specific examples of ornamental species that have responded favorably to CA and MA in terms of extended storage life, including reduced insect pest and fungal pathogen problems. Key biotic and abiotic factors affecting the efficacy of CA treatments and opportunities for future study and commercial development are also discussed.

Premature and rapid ripening are two ethylene-related postharvest problems of banana fruit. Ethylene binding inhibitors such as diazocyclopentadiene (DACP) delay fruit ripening, even when applied at late stages [2]. However, constraints prohibit commercial use of DACP [2]. 1-Methylcyclopropene (1-MCP), an alternative and irreversible ethylene binding inhibitor, prevents fruit ripening [1]. This study investigated effects of 1-MCP applied before or after ethylene gasing.

Ethylene elicits floral organ abscission from cut inflorescences of some Australian Proteaceae [1]. A novel ethylene binding inhibitor, 1-methylcyclopropene, prevents abscission for a number of ornamentals [2, 3]. The efficacy of 1-MCP in preventing ethylene-induced floral organ abscission from Australian Proteaceae was determined.

Postharvest longevity of some cut flowers is shortened by exposure to ethylene gas. Adverse effects of ethylene may be prevented by treatment with 1-methylcyclopropene (1-MCP) gas. Responses of 14 different native Australian cut flowers to 1-MCP and ethylene applied at concentrations of 10 nL·L-1 and 10 μL·L-1, respectively, were examined. Each gas was applied alone for 12 hours at 20 °C and they were also applied in series. Vase lives of Ceratopetalum gummiferum, Chamelaucium uncinatum, Grevillea `Kay Williams' and `Misty Pink', Leptospermum petersonii, Telopea `Shady Lady', and Verticordia nitens were reduced by ethylene treatment. Treatment with 1-MCP generally protected these cut flowers against subsequent exposure to ethylene. The 1-MCP treatment usually did not extend their vase lives in the absence of exogenous ethylene.

The postharvest longevity of fresh-cut flowers is often limited by the accumulation of bacteria in vase water and flower stems. Aqueous chlorine dioxide is a strong biocide with potential application for sanitizing cut flower solutions. We evaluated the potential of chlorine dioxide to prevent the build-up of bacteria in vase water and extend the longevity of cut Matthiola incana `Ruby Red', Gypsophila paniculata `Crystal' and Gerbera jamesonii `Monarch' flowers. Fresh-cut flower stems were placed into sterile vases containing deionized water and either 0.0 or 2 μL·L–1 chlorine dioxide. Flower vase life was then judged at 21 ± 0.5 °C and 40% to 60% relative humidity. Inclusion of 2 μL·L–1 chlorine dioxide in vase water extended the longevity of Matthiola, Gypsophila and Gerbera flowers by 2.2, 3.5, and 3.4 days, respectively, relative to control flowers (i.e., 0 μL·L–1). Treatment with 2 μL·L–1 chlorine dioxide reduced the build-up of aerobic bacteria in vase water for 6 to 9 days of vase life. For example, addition of 2 μL·L–1 chlorine dioxide to Gerbera vase water reduced the number of bacteria that grew by 2.4- to 2.8-fold, as compared to control flower water. These results confirm the practical value of chlorine dioxide treatments to reduce the accumulation of bacteria in vase water and extend the display life of cut flowers.

The vase life of many cut flowers is often limited by bacterial occlusion of stem bases. In this study, we tested the efficacy of a novel antimicrobial agent, aqueous chlorine dioxide (ClO2), to extend the longevity of cut Gerbera flowers by reducing the number of bacteria in vase water. Commercially mature and freshly cut Gerbera jamesonii `Monarck' flowers were placed into clean vases containing deionized water and 0, 2, 5, 10, 20, and 50 μL·L-1 ClO2. Stems were then maintained in solutions at 21 ± 0.5 °C and 42 ± 11% relative humidity until the end of vase life. Inclusion of 2, 5, and 10 μL·L-1 ClO2 in vase water had beneficial effects on flower longevity. For instance, treatment with 5 and 10 μL·L-1 ClO2 extended flower longevity by 1.4-fold or 3.7 days, as compared to control flowers (0 μL·L-1 ClO2). In contrast, exposure to the higher concentrations of 20 and 50 μL·L-1 ClO2 did not extend flower vase life. Relative to control flowers, treatment with 10 μL·L-1 ClO2 delayed the onset of detectable bacterial colonization of vase solutions from day 3 to day 6 of vase life. However, this ClO2 treatment did not reduce the number of bacteria that subsequently accumulated in vase water as compared to control flowers. Treatment with 10 μL·L-1 ClO2 also increased rates of solution uptake by stems and reduced the loss of flower fresh weight over time. These results highlight the potential use of ClO2 treatments to extend the postharvest longevity of Gerbera flowers.

Postharvest abscission of Geraldton waxflower (Chamelaucium uncinatum Schauer) flower buds and flowers is ethylene-mediated. Exposure of floral organs to exogenous ethylene (1 mu L L-1) for 6 h at 20 degrees C induced separation at a morphologically and anatomically distinct abscission zone between the pedicel and. oral tube. Flower buds with opening petals and flowers with a nectiferous hypanthium were generally more responsive to exogenous ethylene than were flower buds enclosed in shiny bracteoles and aged (senescing) flowers. The anatomy of abscission-zone cells did not change at sequential stages of floral development from immature buds to aged flowers. The zone comprised a layer of small, laterally elongated-to-rounded, closely packed and highly protoplasmic parenchyma cells. Abscission occurred at a two- to four-cell-wide separation layer within the abscission zone. The process involved degradation of the middle lamella between separation layer cells. Following abscission, cells on both the proximal and distal faces of the separation layer became spherical, loosely packed and contained degenerating protoplasm. Central vascular tissues within the surrounding band of separation layer cells became torn and fractured. For flower buds, bracteoles that enclose the immature floral tube also separated at an abscission zone. However, this secondary abscission zone appeared less sensitive to ethylene than the primary ( central). oral-tube abscission zone as bracteoles generally only completely abscised when exposed to 10 mu L L-1 ethylene for the longer period of 24 h at 20 degrees C. The smooth surfaces of abscised separation-layer cells suggest that hydrolase enzymes degrade the middle lamella between adjacent cell walls.

Intracellular inclusions in the pedicel and calyx-tube tissues of Chamelaucium uncinatum Schauer (Myrtaceae) flowers are irregular in shape. They were shown, by polarised light and scanning electron microscopy, to be birefringent 8.9–29.5 μm druse (i.e. aggregate) crystals. Energy-dispersive X-ray spectroscopy showed that these crystals were predominantly composed of calcium. Histochemical and acid-solubility tests indicated that the crystals were calcium oxalate. Raman microprobe spectroscopy was used to confirm this chemical identity. The calcium oxalate crystals were located in xylem-vessel lumens and also in parenchyma cells adjacent to vascular tissues. Thus, the crystals may function to regulate soluble calcium concentrations in C. uncinatum tissues near sites where calcium is unloaded from the xylem.

The potential for the ethylene binding inhibitor, 1-methylcyclopropene, to delay ripening of ‘Hass’ avocado, ‘African Pride’ custard apple, ‘Kensington Pride’ mango and ‘Solo’ papaya was examined. Fruit were gassed with 25 µL/L 1-methylcyclopropene for 14 h at 20°C, followed by treatment with 100 µL/L ethylene for 24 h, and then ripened at 20°C. Ethylene treatment alone generally halved the number of days for fruit to reach the ripe stage, compared with untreated fruit. 1-Methylcyclopropene treatment alone increased the number of days to ripening by 4.4 days (40% increase), 3.4 days (58%), 5.1 days (37%) and 15.6 days (325%) for avocado, custard apple, mango and papaya, respectively, compared with untreated fruit. Applying 1-methylcyclopropene to the fruit before ethylene prevented the accelerated ripening normally associated with ethylene treatment, so that the number of days to ripening for fruit treated with 1-methylcyclopropene plus ethylene was similar to the number of days to ripening for fruit treated with 1-methylcyclopropene alone. 1-Methylcyclopropene treatment was associated with slightly higher severity of external blemishes in papaya and custard apple, slightly higher rots severity in avocado, custard apple and papaya, and at least double the severity of stem rots in mango, relative to fruit not treated with 1-methylcyclopropene. Thus, 1-methylcyclopropene treatment has the potential to reduce the risk of premature ripening of avocado, custard apple, mango and papaya fruit due to accidental exposure to ethylene. However, additional precautions may be necessary to reduce disease severity associated with 1-methylcyclopropene treatment.

Summary. Treatment of cut flowering Boronia heterophylla (red boronia) stems with 10 L ethylene/L for 72 h at 20°C induced flower senescence and abscission, and thereby reduced stem fresh weight and vase life. Pre-treatment with 1-methylcyclopropene (1-MCP) reduced these ethylene effects. Treatment of B. heterophylla with 10 L ethylene/L for a shorter 12 h period at 20°C did not affect vase life. Rates of endogenous ethylene production by B. heterophylla flowers increased in association with wilting during flower senescence.