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We express thanks to Dean Liere and Alex May, Syngenta Seeds, Inc., ROGERS Brand Vegetable Seeds, for supplying commercial cantaloupe cultivars, breeding inbreds and technical information. We gratefully appreciate the statistical advice and help
managing, tagging, and supplying anthesis-tagged immature and mature cantaloupe fruit; Jeanne M. Lea for volatile data analysis; and Amber D. Harts and James A. Miller for laboratory assistance. Statistical advice and support were obtained from Vicki
Transgenic Cantaloupe Charentais melons (Cucumis melo var. cantalupensis Naud. `Védrantais') exhibiting strong inhibition of ethylene production were used as a model to discriminate between ethylene-regulated and ethylene-independent ripening pathways. Compared to wild-type fruit, transgenic fruit did not undergo significant yellowing of the rind and softening of the flesh. However, these effects were completely reversed by treating transgenic fruit with 50 μL·L-1 exogenous ethylene. Pigmentation of the flesh occurred early before the onset of the climacteric and was thus unaffected by ethylene inhibition in transgenic fruit. Total soluble solids accumulated at the same rate in both types of fruit until 38 days after pollination when wild-type fruit abscissed. However, as ethylene-inhibited fruit failed to develop a peduncular abscission zone, they remained attached to the plant and accumulated higher amounts of sugars, mainly sucrose. Harvesting transgenic fruit resulted in a small but significant increase of internal ethylene associated with softening of the flesh.
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
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.
Abstract
In field studies with potatoes, cantaloupes, and tomatoes, using N sources banded in the soil, highest yields were obtained with (NH4)2SO4. Yields with urea-formaldehyde and sulfur-coated urea were similar to each other, and less than those from urea. Nitrogen absorption, as determined by NO3 - concn in the petiolar tissue or total N absorption by the entire plant, was in the same sequence as yields. Controlled-release fertilizers did not increase N absorption during late growth. About 90% of the N from (NH4)2SO4 and urea had nitrified and leached from the fertilizer band within 40 days after application. In contrast, about half of the N from urea-formaldehyde remained in the fertilizer band 120 days after application.
Abstract
Four seedbed configurations, north-sloped, south-sloped, mid-bed trenched, and standard flat-topped beds, were evaluated for influence on plant growth, development, and yield in ‘TAM Uvalde’ muskmelon (Cucumis melo L.). The most desirable growth rate and yield pattern was produced in mid-bed trenches. This configuration significantly increased early yield. Early season yield (June harvest) was 8670 kg/ha or 48% of total yield for the mid-bed trenched treatment as compared with 7170 (38%), 4730 (32%), and 3380 kg/ha (20%), respectively, for the south-sloped, standard, and north-sloped beds.
Abstract
The salt tolerance of 3 muskmelon cultivars (Cucumis melo L. cv. Top Mark, PMR 45, and Hale's Best) was determined in plots artificially salinized with NaCl and CaCl2. Marketable yield, total dry weight, vine dry weight, and total fruit weight of all cultivars decreased with increasing salinity. ‘Top Mark’, the highest yielding cultivar at low salinity, yielded least at high salinity. ‘PMR 45’ was the least affected with increasing salinity. Na and Cl in the leaves and fruit and % soluble solids in the fruit all increased with increasing salinity levels.