Cold Storage Treatment Research Articles

Internal quality and antioxidants content of cold-stored red sweet peppers as affected by polyethylene bag packaging and hot water treatment

Physical (weight, firmness) and compositional (sugars, organic acids, ascorbic acid, phenolic compounds and carotenoids) changes of red sweet peppers (Capsicum annuum L.) were monitored during 21 days of cold storage (at 7.5 °C); fruits were stored without packaging, packaged in low density polyethylene bags, or after hot water dipping (53 °C for 4 min) and packaging. Packaging prevented water loss, and preserved the firmness of the fresh product. Sugars (fructose and glucose) content was practically constant throughout the whole storage time, for all treatments. A moderate accumulation of citric acid was observed during storage, but no marked effects of packaging and hot water dipping on citric and malic acid content. Ascorbic acid content slightly increased in unpackaged and packaged fruits, but not in treated+packaged peppers. Hydroxycinnamics total content seemed not to be affected by cold storage, packaging or hot water treatment, whereas glycosylated flavonoids showed somewhat lowered levels during storage, particularly in the case of unpackaged and packaged+treated fruits. Regarding carotenoids content, the effect of the considered storage conditions seemed to be much smaller than that due to ripening stage. Provitamin A content showed an increasing trend in unpackaged and packaged fruits; packaged+treated peppers were characterised by a lower retention of provitamin A and a higher level of capsanthin and cucurbitaxanthin A with respect to not treated fruits. On the whole, packaging and hot water treatment did not produce noticeable adverse effects on the majority of the examined compositional quality parameters.

DEVELOPMENT OF HYPERSPECTRAL IMAGING TECHNIQUE FOR THE DETECTION OF CHILLING INJURY IN CUCUMBERS; SPECTRAL AND IMAGE ANALYSIS

Hyperspectral images of cucumbers were acquired before and during cold storage treatment as well as during subsequent room temperature (RT) storage to explore the potential for the detection of chilling induced damage in whole cucumbers. Region of interest (ROI) spectral features of chilling injured areas, resulting from cold storage treatments at 0C or 5C, showed a reduction in reflectance intensity during multi-day post-chilling periods of RT storage. Large spectral differences between good-smooth skins and chilling injured skins occurred in the 700- to 850-nm visible/NIR region. A number of data processing methods, including simple spectral band algorithms and principal component analysis (PCA), were attempted to discriminate the ROI spectra of good cucumber skins from those of chilling injured skins. Results revealed that using either a dual-band ratio algorithm (Q811/756) or a PCA model from a narrow spectral region of 733- to 848-nm could detect chilling injured skins with a success rate of over 90%. Furthermore, the dual-band algorithm was applied to the analysis of images of cucumbers at different conditions, and the resultant images showed more correct identification of chilling injured spots than PCA method. The results also suggested that chilling injury was relatively difficult to detect at the stage of the first 0 to 2 days of post-chilling RT storage, due to insignificant manifestation of chilling induced symptoms.

Available lysine content in human milk: Stability during manipulation prior to ingestion

Available lysine content is an indicator of protein quality and nutritional value of milk. Many studies have examined the effects of extraction, treatment and storage of human milk upon its components, though no references are found regarding the possible changes in milk quality as defined by its content in essential amino acids such as lysine. The present study investigates the available lysine content in human milk and the variations in lysine resulting from milk manipulation as follows: (a) Cold storage (refrigeration at 4 degrees C for 48 hours, and frozen for 15 days at -20 degrees C); (b) Thermal treatment under conditions of low (Holder)(63 degrees C/30 minutes) and high pasteurization (75 degrees C/15 seconds). The results obtained show a decrease in milk lysine concentration after storage in both refrigerated and frozen samples. Pasteurization causes a highly significant loss of available lysine. The lysine losses were greater on applying low pasteurization versus the more gentle conditions of high pasteurization. While manipulation through cold storage or thermal treatment does not affect the protein content of human milk, its protein quality is modified. When human milk must be subjected to hygienization, it is preferable to apply high temperature treatment (75 degrees C, 15 seconds) than habitual pasteurization (63 degrees C, 30 minutes).

Anthocyanins and hydroxycinnamic acids of Lambert Compact cherries ( Prunus avium L.) after cold storage and 1-methylcyclopropene treatment

Sweet cherries cv. Lambert Compact were treated with 1-methylcyclopropene (1-MCP) at 0, 180 and 360 nL/L for 2 h at 25 °C and then stored at 2–4 °C in refrigerator. Their quality was measured after 12 days of storage in terms of the contents of total and individual anthocyanins and hydroxycinnamic acids, occurrence of rot, and colour change. Colour change was monitored at three day intervals during storage in the CIE L*, a*, b* colour space. 1-MCP did not retard colour change. The contents of total and individual anthocyanins and hydroxycinnamic acids showed no correlation with the colour behaviour of the cherries. All cherries lost their initial shiny red colour on storage, regardless of the treatment. 1-MCP reduced sweet cherry rot at the highest concentration used (360 nL/L) – only 6% were rotten after 12 days in the refrigerator. This differed significantly ( P < 0.05) from untreated fruits and those treated with 180 nL/L 1-MCP which resulted on average in 14 and 20% rot (not statistically different P < 0.05), respectively. The occurrence of rot was shown to be correlated with anthocyanin accumulation, ( R = 0.62, P < 0.10). The profile of individual anthocyanins and hydroxycinnamic acids in sweet cherry was not affected neither by cold storage nor 1-MCP treatment.

SUSCEPTIBILITY OF SPANISH MELON FRUITS TO CHILLING INJURY DURING COLD STORAGE

Melon (Cucumis melo) type 'Piel de Sapo' like other members of the Cucurbitaceae, it is chilling injury (CI) sensitive. The object of this work was to analyze the chilling injury development in melon fruits, type 'Piel de Sapo' var. Sancho, under different cold storage conditions and treatments: 1-MCP, ethylene, and sucrose esters of fatty acids (SE). Melon fruits were stored at 2 and 8°C for 34 days. Sampling was performed during cold storage, before and after transfer to 20°C. Evolution of chilling injury symptoms, electrolyte leakage, ethylene and CO 2 production, ethanol and acetaldehyde, firmness, and sensorial analysis were determined. Spanish melon fruits of the Type 'Piel de Sapo' are sensitive to C.I. a temperature of 2°C, and can be conserved for 10 days with limitations. However, at 8°C it is possible to extend shelf life to 40 days with the presence of only traces of damage. Ethylene applied externally and 1-MCP protected the fruits against C.I.; however, ethylene decreased flesh firmness quickly shortering shelf life. 1-MCP temporarily delayed ripening and senescence, apparently by blocking the receptors of ethylene.

Effect of cold storage treatments and transplanting stress on gas exchange, chlorophyll fluorescence and survival under water limiting conditions of Pinus radiata stock-types

The capacity of radiata pine seedlings to overcome planting shock in wet and dry conditions and their dependence on previous history was analysed by studying post-planting resumption of gas exchange and photochemical reactions, and survival 2 months later. Even under well-irrigated soil conditions, seedlings showed the effects of stress: gas exchange was reduced, but a clear difference between soil-plugged (PR) seedlings and bare-root (BR) seedlings was observed. Drought enhanced the severity of photosynthesis deprivation. Photochemical reactions, analysed by chlorophyll a fluorescence parameters, were not affected by planting shock in conditions of available soil water, but altered dramatically when drought stress was raised, suggesting structural damage of photosynthetic machinery. Despite the dramatic sensitivity of radiata pine to water availability, rewatering produced remarkable recovery, indicating good photosynthetic components repair capacity, which depended, however, on stock quality at the moment of planting. The ability of radiata pine to cope with drought in terms of post-planting performance depended on both storage conditions and water availability at the planting site. These findings provide information for tree physiologists and foresters as to how the management of radiata pine seedlings before planting can affect post-planting performance potential under wet or dry environmental conditions.

POSTHARVEST HANDLING OF CUT KNIPHOFIA (KNIPHOFIA UVARIA OKEN 'FLAMENCO') FLOWERS

Cold storage and floral preservative treatments were evaluated in cut Kniphofia uvaria Oken ‘Flamenco’ flowering stems. Geotropic bending of the stems was strongly affected by the storage method. Stems wrapped in wet newspapers and polythene stored at 4 oC showed better postharvest performances than ‘dry’ stored stems. Cut stems were placed in floral solutions (Standard vase solution (SVS), commercial floral preservatives (Chrysal, Flora, Flower fresh), A biocide (8-HQS), a biological extract (Biovin) or in tap water as a control. Fresh weight, vase life, flower colour, soluble solid concentration, osmotic potential and water uptake were noted during the vase period. Stems treated with Flora or Flower fresh produced the longest vase life (6.90 or 6.51 d respectively). No significant differences were observed for vase life of flowers placed in 8-HQS (4.86 d) and tap water (5.25 d) vases. Flowers in SVS, Biovin and tap water increased fresh weight up to day 3 and then it decreased throughout the remaining period. In contrast, flowers in Flora, Flower fresh and 8-HQS showed continuous increase in fresh weight until senescence. However, the differences between flowers in control (tap water) and floral preservatives for fresh weight were small and nonsignificant. Results suggest that stem osmotic potential, colour and flower soluble solid concentration are important factors in determining the vase life of Kniphofia flowers. For cold storage, flower stems wrapped in wet newspapers was the better option, as it reduced geotropic bending during the storage period and maintained good flower quality during the vase period.

Influence of Plant Storage Duration on Strawberry Runner Tip Viability and Field Performance

Tissue-culture derived mother plants were established in a greenhouse suspended-gutter, nutrient-film technique growing system to evaluate runner tip productivity in the system. Effects of cultivar (`Allstar', `Chandler', `Latestar', `Northeaster', and USDA selection B 27) and duration (0, 1, or 2 months) of cold storage at 1 °C on tip viability, rooting success, and performance in fruit production were determined. The average number and weight of runner tips produced in the gutter production system, the capacity of runner tips to form cohesively rooted plug plants, and the number and length of adventitious roots produced by runner tips varied significantly among the cultivars and the three storage durations (0, 1, or 2 months). In the field, plants produced from runner tips stored for 2 months produced more runners than plants produced from freshly harvested runner tips. Crown number differed among the cultivars, but was not affected by cold storage treatment. No treatment differences were noted for the fruit harvest parameters evaluated. The results suggest that the transplants derived from mother plants grown in a greenhouse-based soilless system can be useful for annual plasticulture strawberry production in colder climates. Although long periods of cold storage of runner tips resulted in lower tip-to-transplant conversion ratios, field performance of transplants was not adversely affected. Additional research is needed to improve greenhouse strawberry production practices for increasing runner output and storage conditions that maintain the integrity of cold-stored runner tips. Without these improvements it is unlikely that soilless runner tip production will become a widely accepted technique that would replace the field nursery tip production method currently used by commercial strawberry propagators.

Evaluation of an Inoculum Production and Delivery Technique for Valdensinia heterodoxa, a Potential Biological Control Agent for Salal

Inoculum production of Valdensinia heterodoxa Peyr. (isolate PFC 3027), a foliar pathogen of salal (Gaultheria shallon Pursh.), was evaluated on various solid substrates. Incubation on salal leaf pieces resulted in the greatest number of discharged conidia, which is deemed a suitable indicator for sporulation and inoculum dispersal of V. heterodoxa. Subsequently, V. heterodoxa inoculum of two isolates (PFC 2761 and PFC 3027) was produced on salal leaf pieces using four different growth periods (0, 4, 8, or 12 days) and three different cold storage treatments (0, 4, or 8 weeks) following harvest of colonised leaf pieces. Overall, the maximum number of discharged conidia was obtained with a growth period of 4 or 8 days, whereas the effect of a cold storage treatment was inconclusive between the fungal isolates and various growth periods. Conidia discharge from salal leaf piece inoculum of V. heterodoxa (PFC 2761 and PFC 3027) applied on pot soil level resulted in 8-41% leaf damage of intact salal plants. Results from this study indicate the potential of salal plant tissue as both a growth substrate and a suitable delivery technique for V. heterodoxa to control salal.

Cultivar Variation in Response to AVG and Heat Treatments for Sustaining Apple Fruit Quality in Cold Storage

To determine if apple cultivars vary in their response to aminoethoxyvinylglycine (AVG) and heat treatment, alone or combined, postharvest ripening traits and storability of treated Lodi, Senshu, Red Delicious and Fuji have been studied. An aqueous solution of AVG was applied 4 weeks before harvest of each cultivar at 124 g·ha-1 a.i. Control and AVG-treated fruit were heated at 38 °C for 4 days. Fruit were ripened at ambient temperature immediately harvest and treatment, or after storage at 4 °C for 30 days. AVG reduced firmness loss in all but Fuji apples immediately after harvest, and that effect was maintained in Senshu and Red Delicious apples after 30 days in cold storage. All AVG-treated fruit showed a reduction in respiration rate and ethylene production immediately after harvest as well as after removal from cold storage. Heat treatment alone prevented firmness loss in Senshu and Red Delicious cultivars, and slightly reduced respiration rate of Lodi and Senshu apples. Ethylene production was clearly lower in heated compared to non-heated fruit in Senshu, Red Delicious and Fuji. After cold storage, AVG and heat treatments combined decreased flesh firmness loss of Lodi apples, reduced respiration in Lodi and Fuji apples, and highly repressed ethylene production of Red Delicious and Fuji fruit. Overall, AVG seemed to have a stronger effect on the measured ripening traits, and its combination with heat treatment improved fruit quality of cold-stored Lodi apples and reduced ethylene production the most for all but Lodi.

Plugging Date and Cold Storage Affect Strawberry Transplant Production and Performance in Annual Plasticulture

`Chandler' strawberry plants were propagated in tissue culture and grown from April to August in a protected environment to produce stolons. July-harvested daughter plants were stuck in cell packs with rooting media and placed under mist sprinklers, or cold stored at 2 °C for 42 days. Among the July transplants, some were kept in the greenhouse until field planting (14 Sept.) and others were moved into a cold room on 14 August. Daughter plant size and position on the stolon affected rooting and quality of transplants. July-harvested daughter plants that were plugged and misted after being cold stored for 42 days developed fewer roots than daughter plants plugged immediately after detaching from mother plants in July or August. In the field, transplants produced from daughter plants harvested in July and cold stored for 42 days developed more stolons than transplants from July- and August-harvested daughters that were not exposed to cold storage treatments. Larger daughter plants produced more branch crowns than did smaller daughter plants during the fall. All transplants from daughter plants harvested in July and propagated without cold treatment bloomed by November. Fruit production ranged from 521 to 703 g per plant. `Chandler' plants from daughter plants that weighed 10 g produced 10% greater yield than those that weighed &lt;1.0 g. Plants generated from daughter plants plugged in July produced 26% more fruit than those plants plugged in August. Greenhouse soilless systems can be used to grow `Chandler' mother plants for generating runner tips and transplants for the annual plasticulture in colder climates. `Chandler' plants produced in July can yield a late fall crop under high tunnels and more fruit in the spring than August-plugged transplants

Ionizing Irradiation Quarantine Treatment Against Plum Curculio (Coleoptera: Curculionidae)

Plum curculio, Conotrachelus nenuphar (Herbst), is a quarantine pest of many temperate fruits, such as pomes, Malus spp.; stone fruits, Prunus spp.; and blueberries, Vaccinium spp.; in North America east of the Rocky Mountains and a small area in Utah. There are two strains, a northern univoltine one that undergoes obligate diapause as an adult and a southern multivoltine strain that usually has facultative diapause. Current quarantine treatments for shipment to areas that do not have the pest include methyl bromide fumigation and cold storage for several weeks. The cold storage treatment may not be effective against northern strain adults in diapause. The objective of this research was to develop an irradiation quarantine treatment against plum curculio. The estimated dose to kill southern strain plum curculio adults in one day is ≈4 kGy. Diapausing northern strain plum curculios were prevented from reproducing with 40 Gy. Reproduction of southern strain plum curculios was prevented with a target dose of 80 Gy, and the dose recommended as a quarantine treatment, that would prevent adults from reproducing, is 92 Gy, the maximum absorbed dose measured when a target dose of 80 Gy was sought. At that dose, oviposition may still occur for up to 1 wk and some of the eggs may hatch, but there is no development beyond the first instar. Hosts of the plum curculio would tolerate that dose well. Immature plum curculios were prevented from reproducing with lower doses.

Ionizing irradiation quarantine treatment against plum curculio (Coleoptera: Curculionidae).

Plum curculio, Conotrachelus nenuphar (Herbst), is a quarantine pest of many temperate fruits, such as pomes, Malus spp.; stone fruits, Prunus spp.; and blueberries, Vaccinium spp.; in North America east of the Rocky Mountains and a small area in Utah. There are two strains, a northern univoltine one that undergoes obligate diapause as an adult and a southern multivoltine strain that usually has facultative diapause. Current quarantine treatments for shipment to areas that do not have the pest include methyl bromide fumigation and cold storage for several weeks. The cold storage treatment may not be effective against northern strain adults in diapause. The objective of this research was to develop an irradiation quarantine treatment against plum curculio. The estimated dose to kill southern strain plum curculio adults in one day is approximately 4 kGy. Diapausing northern strain plum curculios were prevented from reproducing with 40 Gy. Reproduction of southern strain plum curculios was prevented with a target dose of 80 Gy, and the dose recommended as a quarantine treatment, that would prevent adults from reproducing, is 92 Gy, the maximum absorbed dose measured when a target dose of 80 Gy was sought. At that dose, oviposition may still occur for up to 1 wk and some of the eggs may hatch, but there is no development beyond the first instar. Hosts of the plum curculio would tolerate that dose well. Immature plum curculios were prevented from reproducing with lower doses.

Effect of Cold Temperature Treatments on the Mortality of Eggs and Feeding Larvae of the Oriental Fruit Moth

Two cold storage treatments were evaluated against eggs, early instars, and late instars of the oriental fruit moth [Cydia molesta (Lepidoptera: Tortricidae)] a quarantine pest for Mexico of stone and pome fruit from the United States. In the first, `Delicious' apples (Malus domestica) were infested with these life stages and treated for 13 weeks in cold storage at 38 °F (3.3 °C) in replicated studies. In the second, the same life stages infesting `Delicious' apples were exposed to air temperatures slightly above freezing, 33.3 ± 0.7 °F (0.7 ± 0.4 °C), up to 7 weeks to simulate near commercial storage conditions. Weekly subsamples of the life stages were examined for survival. At 38 °F, complete mortality was obtained for eggs and early instars by the eighth week, and for late instars by the tenth week. At near freezing temperatures, eggs and early instars died by the fourth week, and late instars eliminated by the sixth week. This study demonstrated that the treatments were effective against the infesting life stages.

Mortality responses of the brownheaded and blacklyre leafrollers to controlled atmosphere and air cold storage treatments for kiwifruit

The mortality responses of the brownheaded leafroller (Ctenopseustis obliquana) and the blacklyre leafroller (Cnephasia jactatana) to controlled atmosphere cold storage (CACS) and air cold storage (CS) treatments for kiwifruit were investigated CACS (2 O2 5 CO2 at 0C) killed both leafrollers faster than CS (at 0C) The brownheaded leafroller was more tolerant of both storage treatments than the blacklyre leafroller Third and 5th instars were generally more tolerant of storage treatments than 1st instars which in turn outlived eggs This work predicts both brownheaded and blacklyre leafrollers should be completely controlled by 4 weeks CACS or 9 weeks CS

Pre- and Postharvest Effects of Lufenuron on &lt;I&gt;Epiphyas postvittana&lt;/I&gt; (Lepidoptera: Tortricidae)

First-, third-, and fifth-instar Epiphyas postvittana (Walker) were exposed to a range of lufenuron concentrations (0-200 ppm) incorporated into synthetic diet and their subsequent development and mortality responses were determined. For all instars the greatest change in mortality response occurred over lufenuron concentrations < or = 3 ppm. However, third and fifth instars displayed an increase in mortality earlier than first instars, and were more sensitive to the lower lufenuron concentrations in this range. Only first and third instars subjected to < or = 2.5 ppm lufenuron survived the 26-d exposure trial. No larvae first exposed to lufenuron as first or third instars survived to pupation if ingesting concentrations of > or = 1 and > or = 3 ppm, respectively. Consumption of lower lufenuron concentrations by these larvae delayed pupation and resulted in pupal deformity. In contrast, fifth instars subjected to 100 ppm were capable of surviving the 26-d trial period and displayed a slower progressive reduction in survival to pupation with increase in lufenuron concentration. Also in contrast to more immature stages, fifth instars exposed to lufenuron developed more rapidly to pupation than larvae not exposed to the insect growth regulator (IGR), and all resulting pupae were normal. Third instars were exposed to sublethal lufenuron concentrations (0-3 ppm) for 4 d and the fourth-instar survivors subjected to a controlled atmosphere cold storage treatment (2% O2, 2% CO2, 0.6 degree C). Larvae ingesting diet containing 0.5 ppm (and to a lesser extent 1 ppm) lufenuron required longer exposure to the postharvest treatment to achieve > or = 95% mortality than larvae not ingesting the IGR. However, the analogous mortality response of larvae exposed to 3 ppm lufenuron was comparable to the control.

Effect of a Combined Methyl Bromide Fumigation and Cold Storage Treatment on Cydia pomonella (Lepidoptera: Tortricidae) Mortality on Apples

Mortality responses of Cydia pomonella (L.) I-d-old eggs and diapausing 5th instars to methyl bromide fumigation at 24gm-3 for 2 h, followed by cold storage at a range of temperatures (0.5-10°C) were determined on ‘Red Delicious’ and ‘Cranny Smith’ apples. The l-d-old eggs were more tolerant to the combined treatment than were diapausing 5th instars. Times for 99%mortality (LT99s) in cold storage (0.5-4°C) following the fumigation treatment varied between 11.9d (0.5°C) and 12.8d (4°C) and were not significantly different. LT99s for I-d-old eggs in cold storage only varied between 19.4d (4°C) and 26.7 d (0.5°C) and were not significantly different. These results indicate that a quarantine protocol of fumigation with 24 gm-3 methyl bromide for 2 h, followed by cold storage between 0.5°C and 4°C for 25 d, provides a high level of quarantine security.

High temperature and cold storage treatments to control Indian meal moth, Plodia interpunctella (Hübner)

The temperature sensitivity of three egg ages of Plodia interpunctella (Hübner) were examined at 42–48°C heat (hot water) only treatments, 0.5–11.5°C cold storage only treatments, or combination treatments of 42 or 46°C, followed by subsequent 0–10.5°C cold storage. The 1-day-old egg was typically more tolerant of heat only treatments than the 2- and 3-day-old egg. A 99% mortality of all egg ages was achieved in 10.3 hours at 42°C which reduced to 34 minutes at 48°C. This tolerance was reversed at all cold storage temperatures and mortality was achieved quicker at lower temperatures. More than 22 days at ⩾4°C were required to achieve 99% mortality of the most tolerant 3-day-old egg, which was reduced to 19.8 days at 0.5°C for all egg ages. Heat treatments decreased the overall cold storage time required to obtain 99% mortality. Following heat treatment at 42°C, the 2- and 3-day-old eggs were more tolerant to subsequent cold storage than the 1-day-old egg. At 46°C, the 1-day-old was more tolerant to subsequent cold storage regardless of temperature. Eight days at 10.5°C following 6.5 hours at 42°C, or 7.7 minutes at 46°C, resulted in 99.9% mortality of all egg ages. Heat and cold storage may be implemented as part of the manufacturing and storage process of stored products, while also providing a safe and non-chemical method for control of P. interpunctella eggs.

Soil seed banks from coastal subarctic ecosystems of Bird Cove, Hudson Bay

Coastal ecosystems at high latitudes are exposed to physical disturbances (abrasion by ice, tides, waves, and wind) and to degradation due to the grazing activities of waterfowl. The frequency of disturbance and the regenerative capacity of plants determine the recovery potential for the plant community. Since there have been no previous soil seed bank studies of coastal subarctic ecosystems, we examined the seed bank in soil samples collected from a beach ridge, a drift zone, a sand bar and a salt marsh at Bird Cove, near Churchill, Manitoba, on the western shoreline of Hudson Bay. Seedling emergence from soil samples after four successive periods of stratification at 5°C totalled 2968 seedlings of 19 species. Mean emerged seedling densities for each ecosystem were (i) 786 seedlings/m2 (beach ridge), (ii) 699 seedlings/m2 (drift zone), (iii) 2875 seedlings/m2 (sand bar), and (iv) 39 204 seedlings/m2 (salt marsh). These densities are much higher than those for temperate coastal ecosystems and for most terrestrial, subarctic ecosystems. Ninety-seven percent of the 2772 identifiable emergents were of three ruderal species: Juncus bufonius, Senecio congestus and Spergularia marina. Juncus bufonius and S. marina are on the extreme northern limits of their ranges. These three common species were found from samples collected from all ecosystems except the beach ridge, which had no species in common with the other ecosystems and was dominated by Sagina nodosa and Saxifraga tricuspidata in its seed bank. There was little correlation between abundances of species in the seed bank and those in the aboveground vegetation except in the drift zone. Ninety-five percent of the seedlings emerged from the top 5 cm of the sand bar and salt marsh soils, whereas 91% within the drift were deeper than 85 cm. Seedling emergences increased with time and cold storage treatment; freshest samples (i.e., those with 35 days of cold storage) gave 6% of the ultimate emergence but this rose to 57% after two stratification episodes and then to 100% after three. This suggested that seed bank analysis using the emergence method should consider the germination requirements of each potential seed bank species.

Oleosins prevent oil-body coalescence during seed imbibition as suggested by a low-temperature scanning electron microscope study of desiccation-tolerant and -sensitive oilseeds

In order to clarify further the physiological role of oleosins in seed development, we characterized the oil-body proteins of several oilseeds exhibiting a range of desiccation sensitivities from the recalcitrant (Theobroma cacao L., Quercus rubra L.), intermediate (Coffea arabica L., Azadirachta indica A. Juss.) and orthodox categories (Sterculia setigera Del., Brassica napus L.). The estimated ratio of putative oleosins to lipid in oil bodies of Q. rubra was less than 5% of the equivalent values for rapeseed oil bodies. No oleosin was detected in T. cacao oil bodies. In A. indica cotyledons, oil bodies contained very low amounts of putative oleosins. Oil bodies both from C. arabica and S. setigera exhibited a similar ratio of putative oleosins to lipid as found in rapeseed. In C. arabica seeds, the central domain of an oleosin was partially sequenced. Using a low temperature field-emission scanning electron microscope, the structural stability of oil bodies was investigated in seeds after drying, storage in cold conditions and rehydration. Despite the absence or relative dearth of oleosins in desiccation-sensitive, recalcitrant oilseeds, oil bodies remained relatively stable after slow or fast drying. In A. indica seeds exposed to a lethal cold storage treatment, no significant change in oil-body sizes was observed. In contrast, during imbibition of artificially dried seeds containing low amounts of putative oleosins, the oil bodies fused to form large droplets, resulting in the loss of cellular integrity. No damage to the oil bodies occurred in imbibed seeds of Q. rubra, C. arabica and S. setigera. Thus the rehydration phase appears to be detrimental to the stability of oil bodies when these are present in large amounts and are lacking oleosins. We therefore suggest that one of the functions of oleosins in oilseed development may be to stabilize oil bodies during seed imbibition prior to germination.