Rapid senescence of day lily flowers (Hemerocallis sp. cv. Cradle Song) has been shown to be associated with a rapid disappearance of proteins. Senescence was significantly delayed by pulsing developing flowers with cycloheximide, an inhibitor of protein synthesis. A cDNA library prepared from mRNA extracted from flowers in the very early stages of senescence was probed with mRNA from flowers at different stages of opening and senescence. Characterization of senescence-specific clones, and implications for the control of senescence in this non-climacteric flower will be discussed.
Abstract
Spraying trees of ‘King of the Pippin’ and ‘Golden Delicious’ (Malus domestica Borkh.) with the substituted amino acid aminoethoxyvinylglycine hydrochloride (AVG), within 1 month of harvest delayed fruit ripening, reduced preharvest drop, and increased fruit removal force (FRF). Five sprays of 5 × 10-4 m AVG inhibited the development of the climacteric of ‘Golden Delicious’ apple fruits. Reduced biosynthesis of ethylene was probably responsible for these effects. Naphthaleneacetic acid and AVG synergistically reduced ethylene biosynthesis and warrant further investigation, especially in connection with preharvest drop.
Abstract
Senescence of sweet pea (Lathyrus odoratus L.) flowers was associated with a climacteric rise in ethylene (C2H4) production. Pretreatment for 8 min with 4 mM silver thiosulfate (STS) doubled the vase life of the flowers and enhanced opening of buds on the spike. An overnight pulse at 20°C with 4% sucrose also promoted bud opening. A combined STS and sucrose treatment improved flower quality by promoting bud opening of spikes cut with tight florets, and by delaying floret senescence and abscission in both fresh and stored flowers. Aminooxyacetic acid (AOA) was less effective than STS in extending the vase life of sweet peas.
Abstract
The watermelon [Citrullus lanatus (Thunb.) Mats, and Nak.] is a climacteric fruit when harvested at 30 to 50 days after anthesis. At 20 days the fruit is too immature and at 60 days too overmature to show this pattern. An increase in ethylene production is associated with the respiratory peak and final senescence. Initiation of increased respiration occurred about 53 days after anthesis and final senescence at 70 to 74 days, regardless of age at harvest. Optimum harvest maturity occurs at about 45 days, when the fruit is still preclimacteric.
Abstract
Postclimacteric respiration of apples (Malus pumila Mill. cv. Baldwin) decreased as peel Ca level increased from 400 to 1300 ppm. The respiratory climacteric occurred simultaneously in fruit of all Ca levels, indicating that maturation was unaffected by these Ca levels. Occurrence of bitter pit was inversely related to Ca levels. Scald, internal breakdown, and decay were more prevalent when peel Ca was below 700 ppm. Fruits were firmer after 5 months storage in 0°C air if Ca was below 700 ppm, although they were larger, yellower, and more susceptible to decay and other disorders than higher Ca fruit.
Abstract
Respiration (ml CO2/kg/hour) decreased as fruits matured in mango (Mangifera indica L. cv. Haden), avocado (Persea americana Mill. cv. unknown), and lychee (Litchi chinensis Sonn. cv. Kwai Mi). With ripening, a respiratory rise commenced in the climacteric mango and avocado, but not in the nonclimacteric lychee. Ethylene (μl/mg/hour) production in all species also decreased as the fruit matured, became undetectable, then reappeared upon fruit ripening (mango and avocado) or senescence (lychee). The possible relationship between respiration and ethylene production in the ontogeny of fruit is discussed.
Abstract
Fruits of 4 species and cultivars of guava (Psidium guaiava L. cv. Beaumont, P. cattleianum Sabine, P. cattleianum f. lucidum Degener, and P. guajava L. cv. Allahabed Safeda) were found to be climacteric in their respiratory behavior with C2H4 triggering the respiratory rise. Fruits of 4 species of Eugenia (Eugenia malaccensis L., E. cumini (L.) Druce, E. uniflora L., and E. jambos L.) exhibited typical respiratory behavior of nonclimacteric fruits including the response to exogenous C2H4 treatments. The possibility of using respiratory data as a physiological tool for taxonomic differentiation of plants is discussed.
Abstract
High temperature (40°C) for 2 and 4 days lowered the acidity of 4 cultivars of apples (Malus domestica Borkh.). The preheated fruit was firmer than the control during 2 to 4 weeks of holding at 21°. The treatment also accelerated the loss of chlorophyll from the fruit skin. The soluble solid content of the fruit was not affected. Apples after the heat treatment had a normal respiratory climacteric and normal ethylene production rates. Some feasibility of applying high temperature to improve apple quality seems to exist.
The onset of the respiratory and ethylene climacterics in Granny Smith apples is usually protracted when the fruit are held continuously at 20°C. We have found that a period of at least 4 days at 0°C stimulates ethylene production when the fruit are returned to 20°C. Once initiated ethylene production proceeds at a high rate. Data will be presented showing the pattern of ethylene production following chilling by Granny Smith apples from two commercial districts in Australia. Our data suggests that a period of chilling stimulates ACC Synthase as in Winter Pears.
Climacteric `Fuji' apples (Malus ×domestica Borkh.) were treated with water, 0.45 mmol·m–3 1-methylcyclopropene (MCP), 2 mmol·L–1 methyl jasmonate (MJ), or both MCP and MJ. Fruit were kept at 20 °C for 17 days after treatment. Ethylene production, respiration, and color change were all inhibited following MCP treatment. Ethylene production following MJ treatment fluctuated below and above that of controls, but was representative of postclimacteric apples at all times. Rates of respiration and color change were enhanced by MJ, even when fruit were previously treated with MCP. The results indicate that MJ can enhance rate of color change and respiration in apple fruit independently of ethylene action.