Post-harvest physiology of waratah inflorescences (Telopea speciosissima,Proteaceae)

The post-harvest development and senescence of cut waratah inflorescences (Telopea speciosissima R.Br.) held at 20° C is described. Individual flowers of the raceme opened and after 4 or more days the perianth abscised, wilted and changed color from bright red to blue-red. The end of vase life was defined as a readily discernible wilting and blueing of either flowers or of the bracts which subtend the inflorescence. During vase life the fresh weight, water content and anthocyanin concentration of both flowers and bracts decreased. Water uptake by the whole inflorescence decreased, the cumulative nett water loss increased and the fresh weight of the inflorescence decreased. Ethylene production by flowers increased to a maximum and then declined, while the low ethylene production by bracts slowly decreased. Vase life was extended from 7.9 to 11.7 days when the vase water was treated with chlorine bactericide (sodium dichloroisocyanurate, 25 mg l⁻¹ available Cl). This increased vase life was accompanied by increased water uptake, decreased nett water loss, and a slower rate of decrease in flower and bract fresh weight and water content. Vase life was also extended by early harvest, when 6% of individual flowers were open rather than 48%. It was concluded that decreased water uptake and flower abscission were the major physiological factors which limited vase life.     

Fruit quality and respiration of ‘McIntosh’ apples in response to ethylene,very low oxygen and carbon dioxide storage atmospheres

Storage of ‘McIntosh’ Apples (Malus domestica Borkh.) in a controlled atmosphere (CA) with very low O₂ (1.5% CO₂ + 1.0% O₂, 2.8°C) retained greater fruit firmness and titratable acids during storage and during subsequent air storage than apples stored in conventional CA (5.0% CO₂ + 3.0% O₂, 2.8°C). The rate of firmness loss during subsequent 0°C air storage decreased with length of storage in CA. Storage of apples in very low O₂ for 40 or 80 days decreased the rate of firmness loss in subsequent 0°C air storage as compared to the rate of firmness loss in conventional CA fruit, but the rate of firmness loss in 0°C air storage subsequent to 160 or 320 days of conventional CA was significantly less than the loss in similar fruit stored in very low O₂ atmospheres.A modified atmosphere with 1.0% O₂ decreased the rate of C₂H₄ accumulation in storage, and fruit production of both C₂H₄ and CO₂ after storage opening in comparison with similar fruit in conventional CA. The accumulation of C₂H₄ in storage chambers was increased with increasing O₂ levels, but the rate of increase depended upon the CO₂ level. C₂H₄ storage accumulation was stimulated by the presence of CO₂ at 0.5% O₂, but was suppressed by CO₂ when 3.0% O₂ was maintained.Retention of fruit firmness and titratable acids in apples stored in 1.5% CO₂ + 1.0% O₂ were insensitive to very low (0.231 ml l^?1) or very high (2440 ml l^?1) C₂H₄ levels in storage. Scrubbing C₂H₄ (0.304 ml l^?1) from chambers held at 5.0% CO₂ + 3.0% O₂ resulted in significantly firmer fruit after storage, but this effect was not significant after shelf life of 7 days at 20°C.     

Factors affecting the vase life of fronds of maidenhair fern

Cut fronds of maidenhair fern (Adiantum raddianum), which last only 3 days in DI water, were used as a model system to study factors affecting the vase life of cut greens. Solutions containing 25 mg 1^?1 Ag⁺ increased vase life 5-fold. Other biocides (8-hydroxyquinoline citrate, a quaternary ammonium compound, or 8-hydroxyquinoline citrate + NaOCl) had little effect on vase life, while inhibitors of ethylene (C₂H₄) production (Co²⁺, aminooxyacetic acid) increased vase life. Wound C₂H₄ production by the cut ends of the stipes declined during the first 2 h after cutting. The hypothesis that this C₂H₄ is the cause of the brief vase life of maidenhair fern is discussed.     

Author index

Open carnation (Dianthus caryophyllus L.) flowers survived storage at ?3°C for 20 days if previously pulsed with 6% dimethylsulfoxide (DMSO) and 20% sucrose. However, vase life after removal was only 1 day. With 15 days storage, such flowers were acceptable for 7.5 days. With DMSO alone, the possible freezing time was shorter than with sucrose alone. A 5% solution of DMSO increased longevity compared to the water control when flowers were not stored.     

The Response of Carnations (Dianthus Caryophyllus) to Ethylene

Carnation flowers were treated with ethylene and then transferred to ethylene-free air at 65° F. (18·3° C.) and the effect on senescence observed. Short exposures (0.2 p.p.m. for 6 hrs.) gave no visible response; the same concentration for 48 hrs. in the absence of CO₂ caused irreversible wilting. The response of flowers to intermediate concentrations is described.

Accumulation of carbon dioxide during the ethylene treatment delayed ethylene-induced senescence. Carbon dioxide (2–3%) or ethylene oxide (0·1–0·2%) was sufficient to prevent damage by 0·2 p.p.m. ethylene and also suppressed the surge of endogenous ethylene which accompanies wilting of petals by exogenous ethylene. Respiration was increased 25–40% by toxic doses of ethylene. The surge in endogenous ethylene which occurs at senescence may be suppressed by accumulation of carbon dioxide or depletion of oxygen, the threshold concentration being about 4% for each gas. An increase in the rate of leakage of solutes occurred at senescence and when petal tissue broke down.

The results of these investigations are discussed in relation to the problem of storage of flowers.     

Genetic improvement of vase life of carnation flowers by crossing and selection

We used conventional cross-breeding techniques to develop many carnation lines with long vase life and either low ethylene production or low ethylene sensitivity. Two cycles of selection and crossing to improve vase life led to a 3.6-day increase in mean vase life. All 39 selected lines had significantly longer vase life than the control cultivar, ‘White Sim’. In particular, second-generation lines 63-3, 63-12, 66-15, and 63-41 had a mean vase life of more than 15 days without chemical treatment. Measurements of ethylene production indicated that flowers of all second-generation selected lines had a greatly reduced capacity to produce ethylene. We screened three lines (515-10, 64-13, and 64-54) with low ethylene sensitivity. Evaluation by exposure to ethylene at high concentration showed that 64-13 and 64-54 were less sensitive to ethylene than ‘Chinera’, which is known for it low sensitivity. The vase life of these low-sensitivity lines was about twice that of ‘White Sim’. The extended vase life of selected lines was related to low ethylene production at flower senescence rather than to degree of ethylene sensitivity in young flowers. Ethylene sensitivity decreased with the age of the flower in many selected lines. The results clearly show that vase life of carnation flowers can be extended by crossing and selection.     

Changes in Ripening Behaviors of 1-MCP-Treated ‘d’Anjou' Pears After Storage

Abstract

1-Methylcyclopropene (1-MCP), an ethylene action inhibitor, was applied to ‘d’Anjou' pears (Pyrus communis L.) at 20°C between 2 and 5 days after harvest. Scald of ‘d’Anjou' pears was completely controlled by 1-MCP at a concentration between 0.05 and 0.3 µl l1 after a prolonged cold storage plus 7 days of exposure to an environment with or without 500 µl l1 ethylene at a temperature of 20°C or 25°C. 1-MCP inhibited the biosyntheses of α-farnesene and its oxidative products (conjugated trienes) and thus controlled scald. However, fruit treated with the above concentrations of 1-MCP did not ripen normally in an environment with or without ethylene. Ethylene production and fruit softening of 1-MCP-treated ‘d’Anjou' pears were inhibited during 7 and 15 days at 20°C. ‘d’Anjou' fruit treated with 0.01 and 0.02 µl l¹ 1-MCP ripened normally on day 7 at 20°C after 3 months of cold storage at ? 1°C, and ripened fruit did not develop any incidence of scald. Untreated fruit developed substantial scald. After 4 months of storage or longer, both untreated fruit and fruit treated with 0.01 and 0.02 µl l 1 1-MCP developed an unacceptable incidence of scald upon ripening. Thus, use of other scald control methods may be necessary in addition to treatment with a low dosage of 1-MCP to insure both normal ripening and scald control for d'Anjou pear fruit from the Mid-Columbia district.     

Temperature,ethylene and the postharvest performance of cut snapdragons (Antirrhinum majus)

The effects of temperature and ethylene on the quality of snapdragon flowers (Antirrhinum majus L. cvs. ‘Potomac Pink’ and ‘Rocket’) after harvest were investigated. The flowers were stored dry or wet at 6 temperatures ranging from 0 to 12.5 °C for 5 days. Vase life and gravitropic bending were measured at 20 °C after storage. Respiration rates of flowers at 8 different temperatures (0, 2.5, 5, 7.5, 10, 12.5, 15 and 20 °C) were measured continually using a computerized system. The respiration of cut snapdragon flowers increased exponentially as the temperature increased from 0 to 20 °C, with a mean Q₁₀ of 2.6. The vase life of flowers of the ‘Potomac Pink’ cultivar stored dry at 0 °C was 10.8 days, similar to that of freshly harvested controls (10.6 days), and 4.4 days longer than that of flowers stored at 7.5 °C. When spikes were placed horizontally at 20 °C, growth became negatively gravitropic within 20 min. Bending was significantly higher than controls (stored vertically) in all flowers stored horizontally at temperatures above 5 °C. Vase life of flowers stored for 5 days at a range of temperatures then placed in an interior environment was directly correlated with respiration rate at the storage temperature. Wet storage of cut snapdragon flowers reduced the loss of quality at storage temperatures above 5 °C but the vase life of flowers stored in water at 12.5 °C was less than half that of flowers stored dry at 0 °C. Ethylene treatment caused 100% floret abscission which was prevented by pre-treatment either with 1-methycyclopropene (1-MCP) or with silver thiosulfate (STS), but neither of these inhibitors prevented gravitropic bending.     

Ethylene Production During Senescence of Flowers

A method of determining ethylene production by detached flowers is described. A surge of ethylene has been shown to accompany the wilting of carnation flowers at the end of senescence. This surge is independent of fungal infection and it is concluded that in the infected flower the major source of ethylene production is the host tissues.

A similar surge of ethylene production has been observed when the inflorescence wilts on the plant between 20 and 40 days from flower opening.

At temperatures above 7·2° C. (45° F.) the ethylene surge was accompanied by collapse of the petals and rapid loss of water. Cut flowers kept continuously below 7·2° C. slowly declined in weight, the petals became flaccid and ethylene production was negligible. Infection of the flowers with fungus did not materially alter the effect of temperature on the ethylene production.     

Pollination-induced oxidative stress in floral organs of Cymbidium pendulum (Roxb.) Sw. and Cymbidium aloifolium (L.) Sw. (Orchidaceae): A biochemical investigation

A perusal of literature showed that a little is known about the metabolic changes related to senescence in orchid flowers. It was observed that unpollinated flowers of Cymbidium pendulum (Roxb.) Sw. remained fresh for 20 days and senesced within 8 days after pollination (DAP), while that of Cymbidium aloifolium (L.) Sw. took 18 days when unpollinated but showed senescence in 7 DAP. A higher level of electrolyte leakage was recorded in all the floral organs of pollinated flowers in both the species. There was a concomitant increase in levels of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂); indicators of oxidative damage, in all the organs for both the species. Ascorbic acid, on the other hand, decreased significantly. Higher amount of electrolyte leakage, MDA and H₂O₂ content were recorded in C. pendulum as compared of the other species while the ascorbic acid, on the other hand, was observed to be decreased and this decrease was more in C. pendulum than C. aloifolium suggesting a higher oxidative damage to the floral organs in the former species than the latter. TIBA, i.e. tri-iodobenzoic acid (an auxin inhibitor; 0.25 μM) and silver nitrate (ethylene inhibitor; 0.25 μM) application to pollinated flowers partially prevented the elevation of oxidative damage and consequently senescence suggesting the involvement of these hormones in governing these changes in orchid flowers. Comparatively, AgNO₃ was more effective than TIBA in delaying senescence.     

Extension of shelf life of tuberose flowers using a combination of gamma irradiation and generally regarded as safe (GRAS) preservatives and assessment of antimicrobial potency of senesced flowers

Tuberose cut flowers, available as loose flowers, were treated with gamma (γ) irradiation and generally regarded as safe (GRAS) preservative solutions for extension of shelf life. The flowers were packaged in low-density polyethylene bags, heat sealed and stored at 23 ± 2°C, 80% relative humidity (RH) and 4 ± 1°C, 40% RH, respectively. The flowers stored at these two temperature regimes were subjected to sensory evaluation and biochemical analyses. From these assessments, the longest shelf life of tuberose flowers was found to be 8 days at 23 ± 2°C, 80% RH (compared to 4 days for control) and 24 days at 4 ± 1°C, 40% RH (compared to 8 days for control) using combination treatment of low dose γ-irradiation (0.02 kGy) and preservative solutions (4% sucrose and 0.02% CaCl₂). Ethanolic extract of tuberose flowers of the most shelf stable set (stored at 4 ± 1°C), i.e. at the end of 24 days, showed antimicrobial potency against the common skin pathogen Staphylococcus aureus (ATCC 25923 and MDR strains), suggesting utility of the senesced tuberose flowers for therapeutic applications. This preservation technique would promote export of tuberose flowers by extension of their shelf lives and allow utilization of these flowers, post senescence.     

Effects of duration of exposure to ethylene on dormancy release in freesia corms

The exposure of freesia corms to ethylene (C₂H₄) at ca. 10 μl/l air for only 5 h was sufficient to promote sprouting, either under a closed system in which corms were treated in a sealed space of 3–10 1 or under a flow system in which corms were exposed to a continuous flow of air containing C₂H₄. Under the closed system, little change in corm response to C₂H₄ was found with increasing duration of exposure from 5 to 48 h, and the C0₂ concentration reached nearly 4% after 48 h. On the other hand, under the flow system, in which CO₂ did not accumulate above 0.1%, the promotive effect of C₂H₄ was diminished by extended exposure from 5 to 48 h.Repeated treatment with C₂H₄ for 23 h daily on 4 successive days resulted in the lowering of the promotive effect as compared with a single treatment, but repeated application of C₂H₄ for 5 h daily showed the same effect as a single application and gave a high sprouting rate similar to smoke treatment, independent of ambient temperature ranging from 25 to 35° C.Corms exposed to C₂H₄ for 5 h daily, or to smoke for 4 days, exhibited a better chilling response and advanced flowering.     

Guazatine control of sour rot in lemons,oranges and tangors under various storage conditions

Guazatine (1-17-diguanidino-9-aza-heptadecane acetate) was compared with sodium orthophenylphenate (SOPP), sec-butylamine (2-AB), benomyl and tridemorph for the control of citrus sour rot (Geotrichum candidum) under local marketing, export, and ethylene (C₂H₄) degreening storage conditions. Guazatine at 25–125 mg/l gave better control than 20 g/l SOPP, 10 g/l 2-AB and 250 mg/l benomyl in artificially inoculated ‘Eureka’ lemons stored at 27° C and high humidity for 6 days. At 500 mg/l, guazatine gave better control than 20 g/l SOPP, 10 g/l 2-AB or 500 mg/l benomyl in dip-inoculated ‘Eureka’ lemons, treated and packaged as for export and stored at 7° C for 2 or 10 weeks. At 250 mg/l, guazatine provided better control than 20 g/l SOPP, 5 g/l 2-AB, 250 mg/l benomyl or 1000 mg/l tridemorph in artificially inoculated ‘Washington’ navel oranges held for 4 days under degreening-conditions of 27° C and 90% RH with added C₂H₄.     

Interaction of ethylene concentration and storage temperature on postharvest life of the green vegetables pak choi,broccoli, mint,and green bean

Reducing ethylene levels around produce delays the senescence of fruit and vegetables and therefore has the potential to reduce the need for refrigeration during transport and storage, which would result in substantial energy savings. In this study four non-climacteric green vegetables were stored at 0, 5, 10, and 20°C in an atmosphere containing 0.001, 0.01, 0.1, and 1.0 μL L^?1 ethylene. The results showed that the postharvest life, as determined by consumer acceptance criteria of yellowing for pak choi and broccoli, leaf abscission for mint, and pod softening and chilling injury for green bean, increased as the temperature and ethylene concentration decreased. Regression equations generated from the storage data allowed for the calculation of the temperature and ethylene levels required for any nominated postharvest life. Using a 14-day postharvest life as an example, storage in ethylene at 0.001 μL L^?1 would allow a storage temperature of about 10°C for pak choi, broccoli, and mint and about 18°C for green bean, temperatures well above the current recommendations of 0 to 5°C.     

Effects of controlled atmosphere,edible coating,and 1-methylcyclopropene on improving storage quality of ‘Bartlett’ pears after long-term storage

Recent trends towards greater fresh market use of ‘Bartlett’ pears has increased the need to extend its storage life to prolong the packing and marketing season in the United States Pacific Northwest region. Sixteen and 38%, respectively, of control fruit developed senescence disorders following 5 and 6 months of storage at ?1.1°C. Commercial standard controlled atmosphere (CA) conditions (O₂ at 1.5 kPa and CO₂ < 1 kPa) or edible coating (Semperfresh?, SF) prevent the appearance of senescence disorders for 5 months, but 9% and 16% of fruit, respectively, developed senescence disorders after 6 months. The combination of CA+SF completely inhibited senescence disorders for 6 months. Treatment with CA and SF, alone or in combination, maintained high-storage quality and developed ripening capacity with characteristic melting texture during storage. Senescence disorders were inhibited for 6 months by 0.3 µL l^?1 1-methylcyclopropene (1-MCP), alone or combination with CA or CA+SF. In part these pears developed ripening capacity after 6 months of storage. The combination of CA+SF+1-MCP maintained the highest storage quality with dark green colour and hard firmness, which might be associated and proportional with reductions in ethylene synthesis and respiration rate after long-term storage.     

Influence of ethanol on ethylene biosynthesis and flower senescence of cut carnation

Ethanol in the holding-solution inhibited climacteric ethylene (C₂H₄) biosynthesis and decreased the respiration rate 60% during a 7-day period in cut carnation flowers. Conversion of 1-aminocyclopropane-1-carboxylic acid (ACC) to C₂H₄ was inhibited by adding ethanol to the holding-solution. Simultaneously, ACC-induced senescence in carnation flowers was inhibited by ethanol. Ethanol was the most effective alcohol in delaying carnation flower senescence of the tested series methanol, ethanol, propanol, tert-butanol and n-butanol. Ovary development was also inhibited in carnation flowers by ethanol. The senescence of Easter lily flowers (Lilium longiflorum) and tulip flowers (Tulipa gesneriana) was not delayed by ethanol.     

Changes in the contents of phenolic substances,phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) accompanying chilling-injury of eggplant fruit

The mechanism of browning, which is a typical chilling-injury of eggplant fruit (Solanum melongena L.), was investigated by determining the changes of phenolic substances, phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) either during storage at 1°C or after exposing fruit to low temperature for various periods.Chlorogenic acid and its isomer, the main substrates for browning, were isolated from eggplants by column and paper chromatography. R_f values and various color reactions of the above acids were compared with those of authentic chlorogenic acid.After 2 days of cold storage at 1°C, when browning was initiated, chlorogenic acid content decreased to less than half that of the initial day, rose to a maximum after 4 days, and then decreased rapidly.PAL activity increased to a peak after 2 days at 1°C, then decreased over 10 days as browning increased. TAL activity also increased after transfer from 1°C to 20°C.It is suggested that rapid turn-over of chlorogenic acid occurs in the early stage of cold storage of eggplant fruit, and development of browning is closely related to chlorogenic acid, PAL and TAL.     

乙烯对‘洛阳红’牡丹切花开放衰老进程及内源乙烯生物合成的影响

 以开花指数为1级的‘洛阳红’牡丹切花为试材,研究了外源乙烯和乙烯作用抑制剂1-甲基环丙烯（1-MCP）处理对其采后开花衰老进程中开花指数、花径增大率、瓶插寿命、内源乙烯生成量及乙烯生物合成关键酶ACC合成酶（ACS）和ACC氧化酶（ACO）活性的影响,从乙烯生物合成角度探讨了乙烯对其采后开花衰老的调节机理。结果表明,10 μL·L^-1乙烯处理6 h明显加快了‘洛阳红’花朵开放进程,缩短了切花的瓶插寿命,并促使其在盛开后出现严重落瓣;1.0 μL·L^-1 1-MCP处理6 h则延缓了花朵开放,延长了瓶插寿命,但却影响了部分切花的充分开放;内源乙烯的生成分别受乙烯和1-MCP处理的促进和抑制,与切花的开放衰老进程密切相关。不同处理后ACS、ACO酶活性分析表明,ACS活性变化与内源乙烯的生成相联系,是影响牡丹切花开放衰老进程的主要因子,这与目前得出的ACS是植物乙烯生物合成限速酶的研究结果相一致。     

Effects of exposure of bulbs to smoke and ethylene on flowering of Narcissus tazetta cultivar ‘Grand Soleil d'Or’

Bulbs of ‘Soleil d'Or’, exposed to smoke generated from smouldering wood and fresh leaves for several hours on each of 4 consecutive days during storage, produced flowers earlier and at a higher rate, even when using bulbs which were too small to flower using normal methods. The smoked bulbs showed an earlier start of floral initiation and faster development. A temperature of 25°C was optimal for storage. Application of ethylene also gave similar promotive effects when repeated 4 times at 10 μl 1^?1 for 1–5 h per day. Longer exposure to ethylene or smoke was less effective or had no promotive effect.     

Changes in ripening behavior of ‘d'Anjou’ pears (Pyrus communis L.) after cold storage

‘d'Anjou’ pear fruit, harvested at optimum maturity with flesh firmness of 6.8 kg, were stored at ?1.1°C. Fruit were ripened at 20°C for 15 days following storage for 1–8 months. Dessert qualities were evaluated organoleptically on Day 10 of each ripening period. Changes in fruit firmness, extractable juice, titratable acids, solubl solids, respiration, ethylene production and internal ethylene were determined daily during each ripening period. Fruit firmness declined continually from 6.8 kg at harvest to 4.5 kg after 8 months of storage. Fruit stored for 2–8 months softened with a similar pattern during a 15-day ripening period at 20°C, while fruit stored for 1 month softened at a slower rate during ripening to 3.2 kg, with a coarse and dry texture after 15 days at 20°C. Fruit stored for 2–4 months ripened with the desirable buttery and juicy texture, while those stored for more than 5 months ripened with a coarse or mealy and dry texture. The buttery and juicy texture was highly correlated with a lower extractable juice, which could be used for quantitative determination of storage life based on ripened fruit quality. Changes in titratable acids and soluble solids during each ripening period were not associated with changes in dessert qualities of the ripened pears. Rates of respiration, ethylene production and internal ethylene during ripening at 20°C varied with duration of storage, but were not associated with changes in dessert qualities of the ripened fruit.