Abstract
A method is presented to calculate net heat gain per unit time (G) for normal (N) and for whitewashed (W) cantaloupe fruits (Cucumis melo, L., var. reticulatus Naud.) exposed to direct solar radiation. Calculations of G were based on pulp temp. G of the W fruits averaged 80% of that for the N fruits during warming. Values of G can aid in evaluating the effectiveness of radiation-reflective materials that protect cantaloupe fruits from sunburn, a major cause of culls and market quality losses. Maximum pulp temp about 1 mm below the surface reached 49°C for the N and 42° for the W fruit. Maximum ambient air temp was 43°C.
Abstract
Applications of 2-chloroethylphosphonic acid to field grown cantaloupes resulted in yellowing of leaves, early abscission, apparent ripening of immature melons and increased total and marketable yields of full-slip melons. The percentage of soluble solids was slightly lower in treated melons.
Abstract
Gas samples from the central cavities of 3 cultivars of muskmelon fruits (Cucumis melo L.) were resolved by gas chromatography into at least 12 organic volatile fractions. Harvesting of ‘Top-Mark5 and ‘PMR-455 cantaloupe up to 12 days before normal abscission did not reduce the final concentration of volatiles attained. Production of volatiles by cantaloupe was inhibited while still attached to the parent plants, but no evidence for inhibition by the parent plant was obtained in ‘Honey Dew’, nor was the final concentration of volatiles reduced by early harvest. High concentrations of exogenous ethylene applied to harvested melons accelerated the onset of production of the organic volatiles but did not significantly affect their ultimate concentrations. Exogenous ethylene altered the relative amounts of at least 2 fractions. The production of volatiles is closely coordinated with the other aspects of ripening, but the control mechanisms appear to be different.
Abstract
U. F. breeding lines G 508, G509, G510, G511 and G515 are short internode muskmelons (cantaloupes) Cucumis melo L. that are being released as germplasm for breeding purposes (Fig. 1). The recessive dwarf character from a short internode line (MCa 66-18-14) obtained from J. L. Bowers, Arkansas Agricultural Experiment Station, was introduced into disease-resistant Florida breeding lines and several commercial cultivars.
Several postharvest quality parameters of cantaloupe fruit were grown under different organic and mineral fertilization schemes We evaluated a Laguna hybrid (Asgrow) cantaloupe grown under a design of blocks completely randomized, with three fertilizer treatments corresponding to: T1, goat manure; T2, simple fertilization; T3 mixed fertilization, with six replications each. The fruits were mature-harvested and stored in a room with an average temperature of 18°C for posterior laboratory analysis. The results showed different effects of the treatments on the following parameters: total soluble solids, diameter of the fruits, and thickness of the pulp, and showed no effects on consistency of fruits, cavity, dry matter, and fresh weight. All these parameters decreased during the period of storage. The organic manure treatments showed the best values of most of the evaluated parameters.
A whitefly trap recently developed by Chu and Henneberry was tested in a cantaloupe field at the University of Arizona Maricopa Agricultural Center in 1995. The trap was compared with a 3 × 5-inch yellow sticky card trap, a commercial dome trap, and the leaf-turn sampling method. Results showed that the new whitefly trap effectively caught adults in cantaloupes. Numbers of adults increased as whitefly adult population densities increased during the season. Numbers of adults caught by the new whitefly trap were comparable to numbers of adults caught with the commercial dome trap and to a lesser extent the counts of adults determined by leaf-turn sampling method. Results with the new trap were not comparable to adults caught with yellow sticky card traps.
Abstract
Near ultraviolet radiation appears to be largely responsible for solar injury (SI) and vein tract browning (VTB) of cantaloupes (Cumis melo L., Reticulatus group, cv. PMR 45) grown under field conditions in the San Joaquin Valley of California. Incidence and severity of SI were substantially reduced when near UV flux impinging on the fruits at solar noon was reduced to 21 Wm-2 or less and especially when wavelengths below 320 nm were excluded by the use of plastic UV filters. VTB was reduced when UV flux was 12 Wm-2 or less or when wavelengths below 320 nm were excluded. In cantaloupes, near UV appears to directly induce SI but to indirectly induce VTB, a postharvest disorder, by accelerating aging of surface tissues.
Fresh-cut melons in many consumer-ready packages are notorious for “wetting” and accumulation of standing juices. These conditions likely create undesirable flavor and aroma changes. We initiated a study to investigate flavor changes in stored fresh-cut cantaloupe. One objective was to optimize solid phase microextraction (SPME) to evaluate organoleptic compounds. Static head-space SPME analyses were performed on fresh-cut cantaloupe cubes (≈2.5 mm, 5 mm, or 2.5 cm), expressed juice, and homogenized slurries. SPME fiber (100 μm PDMS vs. 75 μm Carboxen/PDMS) exposure time (5, 7.5, 10, 12.5, 15, 17.5, 20 min) was evaluated at 40 °C with various head-space: product ratios, plus or minus NaCl to produce typical chromatograms. Fibers were desorbed in an HP5890 GC with a DB-624 or DB-5 column for 45-min runs and an HP6890 GC (DB-5) equipped with a 5973 MS detector for 35-min runs. Albeit qualitative, the best chromatograms were obtained with 7-ml slurries, stirred with NaCl, exposed to a 10 0μm PDMS SPME fiber for 12.5 min. The 100 μm PDMS fiber produced better chromatograms considering the fact that many important flavor volatiles are low-molecular-weight polar esters and alcohols. These conditions were subsequently used to analyze numerous fresh-cut cantaloupe samples stored various times (0 to 9 days). Over 100 peaks were identified, many of which changed through storage and some are suspected as probable agents responsible for undesirable flavor changes. Our analyses are progressing in an attempt to authenticate compounds associated with flavor-related changes in numerous fresh-cut cantaloupe varieties from various growing regions.
We have generated transgenic Cantaloupe Charentais melons expressing an ACC oxidase antisense gene in which ethylene production was reduced to less than 1% as compared to control untransformed fruits. As a consequence, some aspects of the ripening process were strongly inhibited (aroma volatiles production, chlorophyll and cell wall degradation, pigmentation of the rind, activation of peduncular abscission zone) while others remained unchanged (coloration of the flesh), allowing us to distinguish between ethylene-dependent and ethylene-independent pathways. Some postharvest characteristics of the transgenic fruit are described in terms of expression of ripening-related genes, respiratory behavior, and biochemical composition. Data also are presented showing that exogenous ethylene treatments could reverse the antisense phenotype.
Trenched beds covered with plastic mulch was used to capture and retain precipitation for dryland cantaloupe production. Two trenches were formed in the fall in raised beds. Plastic mulch was laid over the beds and slitted at ca. 1 meter intervals over the trenches. Soil was placed over the slits, conforming the plastic to the shape of the trenches and channeling precipitation into the beds. Cantaloupes were seeded in the spring and grown with no supplemental irrigation. Planting moisture was significantly greater under the capture system than in unmulched beds. Seedling emergence time was reduced from 18 to 6 days and vine growth in the first 6 weeks was almost doubled. Total and marketable yields were doubled and fruit size significantly increased when water was limiting. Elevated soil temperatures under the mulch enhanced plant growth and yield even when moisture was not limiting. Combining a moisture capture system with supplemental irrigation could allow commercial production of cucurbit crops under limited water conditions in semi-arid areas.