`Elegant Lady', `O'Henry' and `September Sun' peaches [(Prunus persica (L.) Batsch (Peach Group)] and `Summer Bright' and `Summer Grand' nectarines [(Prunus persica (L.) Batsch f. nucipersica (Nectarine Group)] heated to a seed surface temperature of 47.2 °C over a period of 4 hours developed mealy flesh sooner and to a much greater extent than nonheated fruit following cold storage at 5 °C for 1 to 3 weeks. Exo- and endopolygalacturonase activities were reduced following 3 to 4 hours of heating and may have been responsible for the increased mealiness. Mealiness often developed in defined regions rather than throughout the entire fruit. Comparison of juicy and mealy regions within individual fruit revealed that mealy regions contained 65% and 86% less exo- and endopolygalacturonase activity, respectively, than juicy regions, whereas pectinmethylesterase activity was unchanged. Extractable protein was reduced by >50% in the mealy regions of the fruit. Intermittent warming periods of 24 hours at 20 °C at weekly intervals during storage at 5 °C were less effective in reducing mealiness in heat-treated than in control fruit. It is important that future work with heat treatments and stone fruit closely monitor potential effects on this disorder to avoid loss of market quality following treatment.
David M. Obenland and Tanya R. Carroll
`Bartlett' pears were harvested from four commercial orchards at their optimum harvest date and 3 or 7 days later (depending on grower orchard). Samples were held for 3 or 7 days before stored in cold storage and two controlled-atmosphere conditions: 1) cold storage at 1C; 2) regular CA storage (2.5% O2 + 1.0% CO2 at –1C); 3) low-oxygen CA (1.0% O2 + 0.2% CO2 at –1C). After 2 months of cold and CA storage, pears showed that postharvest prestorage holding temperature, affected the rate of change in weight loss, firmness, ground color, and senescent breakdown. After 4 months of CA storage, `Bartlett' pears maintained their quality at about 53–58 N of firmness. Firmness loss, peel ground color change, and senescent breakdown of `Bartlett' pears were affected by the holding temperature and the length of the holding period between harvest and storage. In conclusion, pear quality was reduced depending on the holding temperature and holding period between harvest and storage. CA storage maintained better pear quality than cold storage. Fast oxygen pulldown in order to establish CA condition sooner was essential to maintain better pear quality.
Mary Lewnes Albrecht and Jerald T. Lehmann
Greenhouse- and field-produced plants of Asclepias tuberosa L., butterfly flower, were forced in the greenhouse under various daylengths to produce flowering plants for the florist industry. Examined were post-production cold storage temperature (4.5 and 10C) and period (12, 14, and 16 weeks), forcing daylength (9, 13, 15, or 17 hours), plant-production scheme (greenhouse- vs. field-produced), and planting depth (exposed crowns or crowns planted 1.3 cm below the medium surface). When forced under a 9-hour daylength, blind shoots and aborted flower buds were prevalent. When daylengths exceeded 13 hours, using night interruption, the time to produce a marketable plant was reduced from 71 days to 61 days for 18-month-old greenhouse-produced plants. Daylength of 17 hours delayed flowering of field-produced liners by 15 days in comparison to those forced under 13-hour daylength. Greenhouse-produced plants stored at 10C did not sprout when brought into the forcing greenhouse held at 17/25C (night/day). Field-produced plants, when greenhouse-forced, had fewer flowers per inflorescence (88 to 94 flowers) than greenhouse-produced plants (79 to 87 flowers).
Michelle L. Jones, Kenneth K. Cochran, Gary A. Anderson, and David C. Ferree
Deciduous holly branches were visually rated over a period of 5 weeks to evaluate differences in display life between various cultivars of winterberry (Ilex verticillata) and japanese winterberry (I. serrata) x winterberry. Holly branches were naturally defoliated and the postharvest performance of the cut branches was therefore based on the quality and longevity of the fruit. Chemical treatments including floral preservative, floral preservative plus silver, and anti-transpirant were also evaluated. `Bonfire' and `Sunset' had the highest ratings for marketability based on the longevity and quality of their fruit. `Bonfire' and `Winter Red' had the highest fruit density per stem. Treatment with floral preservatives significantly increased the display life of holly branches. Preservative plus silver delayed deterioration later in the study, presumably by delaying the senescence of the fruit. Anti-transpirant treatment did not decrease solution uptake by the holly stems. Cold storage of dry branches at 0.00 ± 1.11 °C (32.0 ± 2.0 °F) did not significantly reduce branch display life if held for 23 days or less. Cut branches of all cultivars had a longer display life when stuck in sand and left outdoors in a lath house than when rated in vase solutions indoors. This study indicates that deciduous holly branches provide an attractive alternative cut branch for both interior and outdoor holiday displays.
R.E. Byers, D.H. Carbaugh, and L.D. Combs
92 POSTER SESSION 10 (Abstr. 105–119) Postharvest Physiology/Storage/Food Science Tuesday, 25 July, 1:00–2:00 p.m.
Rick M. Bates and Alexander X. Niemiera
Two-year-old Washington hawthorn (Crataegus phaenopyrum Med.) and Norway maple (Acer platanoides L.) seedlings were subjected to varying cold storage durations and four storage treatments: whole plant covered in polyethylene bags, shoots exposed, roots exposed, and whole plant exposed. After storage, half the seedlings were immediately plant and half received a 12-hour desiccation treatment before transplanting. Root growth potential (RGP), time to budbreak, and marketability were measured. With the root covered treatments, Norway maple RGP increased while Washington hawthorn RGP decreased with increased cold storage duration. RGP for both species remained low throughout storage for treatments exposing roots. The 12-hour desiccation treatment reduced RGP for both species with hawthorn being more affected than maple. Days to budbreak for both species decreased with increased storage time for whole plant covered treatments but increased for both species when stored with exposed roots. Maple marketability for root covered treatments was high for most storage durations. Hawthorn marketability was generally low except for the whole plant covered treatment during the first 6 weeks of storage. For the respective storage durations, hawthorn RGP, time to budbreak and marketability values for the shoots exposed treatment were similar to the root exposed treatments. In contrast, values for the shoots exposed treatment were similar to the whole plant covered treatment for maple. There was a high positive correlation between RGP and marketability for both species.
Mariya Khodakovskaya, Richard McAvoy, Hao Wu, Jeanne Peters, and Yi Li
Chill injury and leaf senescence occur in plants held in prolonged cold, dark storage. To increase tolerance to these conditions, Nicotiana alata and N. tabacum were transformed with either the FAD7 or IPT genes under the control of a cold-inducible promoter (cor15a). FAD7 encodes for omega-3-fatty acid desaturase and was used to resist cold-stress. IPT encodes the cytokinin-pathway enzyme isopentenyl transferase and was used to delay senescence. Independent FAD7 and IPT lines were crossed to produce double transgenic seed. Seedlings from single transgenic (cor15a-IPT or cor15a-FAD7) lines, double transgenic lines, and the wild-type were exposed to prolonged cold, dark conditions. After 3 months in the dark at 2 °C, survival of independent double transgenic N. tabacum lines ranged up to 80% to 90%. However only 40% of FAD7 seedlings survived, 10% of IPT seedlings survived, and no wild-type plants survived. Double transgenic N. alata seedlings average 90% survival under similar conditions and RT-PCR revealed expression of both the IPT and FAD7 genes. Omega-3-FAD enzyme activity increases desaturation in chloroplast membrane fatty acids. When exposed to prolonged cold, the molecular fraction of polyunsaturated fatty acids (18:3 and 16:3) in leaves of wild-type N. alata decreased while monounsaturated (16:1 and 18:1) and saturated fatty acid species (16:0 and 18:0) increased dramatically. In double transgenic N. alata lines exposed to prolonged cold, the molecular fraction of 18:3 and 16:3 increased, while the 16:0 and 18:0 species decreased dramatically compared to nonchilled double transgenic plants.
Valeria Sigal Escalada* and Douglas D. Archbold
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.
Wenting He, Weiming Guo, and Zhongchun Jiang*
Effects of two pretreatments, i.e., ultrasonic wave (UW) and ultrasonic wave plus preservative solution (UW+PS), on water conditions of flower stem and membrane stability of petals in Nymphaea tetragona during 6-d cold wet storage. Compared with no pretreatment control, the two pretreatments prolonged the vase life and improved water conditions of the cut flower during cold storage to different degrees. Fresh weight of flower stems and relative water content of petals increased during cold storage. The water utilization efficiency of flower stem and water potential in different parts of flower stem were improved significantly as a result of the pretreatments. Although both pretreatments helped the cut flowers maintain favorable water relations, the effects of UW + PS combined pretreatment were better than UW pretreatment alone. In addition, UW and UW+PS inhibited the increase in the contents of lipid peroxidation product malondialdehyde (MDA) and superoxide anion in petals. UW + PS promoted superoxide dismutase (SOD) and catalase (CAT) activities in petals during cold storage to a greater degree than did UW.
Jan E.P. Debaene and I.L. Goldman
Raw onion extract contains organosulfur compounds that prevent aggregation of platelets in human blood plasma and influence onion pungency. An increase in antiplatelet activity has the potential of reducing cardiovascular diseases. Accumulating organosulfur compounds directly influences pyruvic acid concentrations and may determine antiplatelet activity. Organosulfur compounds are volatile and may change concentration during storage. A study was conducted to evaluate antiplatelet activity, pyruvic acid content, and percent solids during cold storage. Two low-pungency lines (8155B and Exhibition) and two high-pungency (W420B and W434B) lines were grown in replicated plots at two Wisconsin locations in 1994 and 1995. Bulbs were evaluated for antiplatelet activity, percent solids, and pyruvic acid content at 40-day intervals after onion harvest. We found significant differences for antiplatelet activity and pyruvic acid content among dates of sampling and lines. Averaged over lines antiplatelet activity increased by 73% and 29% over 160 days in storage during the 1994–95 and 1995–96 storage seasons, respectively. Mean pyruvic acid concentrations increased 27% for the 1994–95 storage season and decreased 27.5% for the 1995–96 storage season. There were no significant changes for solids during storage for both years. These data indicate that antiplatelet activity increases during storage, which may be beneficial for human health. Since onions are often stored for long periods of time before sale, an increase in antiplatelet activity may be an added benefit for this crop.