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Chien Yi Wang

Cucumbers (Cucumis sativus L.) and zucchini squash (Cucurbita pepo L.) were pressure-infiltrated (82.7 kPa for 3 min) with methyl jasmonate (MJ) in aqueous suspension and then stored at a chilling temperature of 5C. Control fruit were infiltrated with distilled water and handled in a similar manner. Treatment with MJ delayed the onset and reduced the severity of chilling injury symptoms in both cucumbers and zucchini squash. Analysis of polyamines in zucchini squash showed that putrescine increased with time in storage at 5C, while spermidine and spermine decreased during the same period. MJ treatment did not have an appreciable effect on putrescine, but the treated fruit maintained higher levels of spermidine and spermine than the control fruit throughout storage at 5C.

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Charles A. McClurg

Commercial producers of pumpkin (Cucurbita pepo) in the Mid-Atlantic region frequently experience losses from the fungal diseases powdery mildew (Erysiphe cichoracearum) and black rot (Didymella bryoniae). In addition to loss of fruit size in some cultivars, the diseases can result in poor-quality handles (fruit stems) and preand postharvest decay. Since the pumpkins are grown for fresh market ornamental use, their appearance, size, and quality are important in marketing strategies. Applications of recommended fungicides during the growing season, although costly, reduce losses in fruit size and quality from fungal pathogens. Subsequent storage studies have documented reduced losses and maintenance of handle quality of pumpkins treated with fungicides during the growing season. This suggests that those who want or need to store pumpkins prior to sale can evaluate costs and benefits of the program. Producers can also choose cultivars that are better suited to storage if fungicides will not be used.

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Charles A. McClurg

Commercial producers of pumpkin (Cucurbita pepo) in the mid-Atlantic region frequently experience losses of fruit size and quality from the fungal diseases powdery mildew (Erysiphe cichoracearum) and black rot (Didymella bryoniae). In addition to loss of fruit size in some cultivars, the diseases can result in poor quality handles (fruit stems) and pre- and postharvest decay. Since the pumpkins are grown for ornamental use, their appearance, size, and quality are important in marketing strategies. Applications of recommended fungicides during the growing season, although costly, reduce losses in fruit size and quality in susceptible cultivars during years in which the pathogens become established prior to fruit maturity. Larger-fruited cultivars, in general, benefit more from fungicide application than smaller-fruited types in fruit weight, although both benefit in improved handle quality. Cultivars with apparent tolerance to fungal diseases are identified for producers who choose not to use fungicides.

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R.W. Robinson and Stephen Reiners

Summer squash (Cucurbita pepo L.) cultivars were compared for ability to set parthenocarpic fruit. Some cultivars set no parthenocarpic fruit and others varied in the amount of fruit set when not pollinated. The degree of parthenocarpy varied with season, but the relative ranking of cultivars for parthenocarpy was generally similar. Cultivars with the best parthenocarpic fruit set were of the dark green, zucchini type, but some cultivars of other fruit types also set parthenocarpic fruit. A summer squash cultivar was developed that combines a high rate of natural parthenocarpy with multiple disease resistance. Yield of summer squash plants grown under row covers that excluded pollinating insects was as much as 83% of that of insect-pollinated plants in the open.

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Harry S. Paris and Rebecca Nelson Brown

Pumpkin and squash (Cucurbita L. spp.) are important cucurbit crops and are grown in almost all arable regions of the world. The three economically important species, Cucurbita pepo L., Cucurbita moschata Duchesne, and Cucurbita maxima Duchesne are highly polymorphic in fruit characteristics, inspiring much research into their inheritance. A comprehensive list of genes for Cucurbita was last published more than a decade ago. This new gene list for pumpkin and squash includes descriptions of gene interactions and the genetic background of the parents that had been used for crossing to allow easy confirmation of previous work and provide a sound foundation for further investigation. This gene list includes 79 loci for phenotypic/morphological traits and 48 polymorphic allozyme loci. Linkage and mapping are discussed.

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Harry S. Paris

Summer squash (Cucurbita pepo L.) is grown in many temperate and subtropical regions, ranking high in economic importance among vegetable crops worldwide. A native of North America, summer squash has been grown in Europe since the Renaissance. There are six extant horticultural groups of summer squash: cocozelle, crookneck, scallop, straightneck, vegetable marrow, and zucchini. Most of these groups have existed for hundreds of years. Their differing fruit shapes result in their differential adaptations to various methods of culinary preparation. Differences in flavor, while often subtle, are readily apparent in some instances. The groups differ in geographical distribution and economic importance. The zucchini group, a relatively recent development, has undergone intensive breeding in the United States and Europe and is probably by far the most widely grown and economically important of the summer squash.

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G.H. Clough, S.J. Locascio and S.M. Olson

Squash (Cucurbita pepo L. var. melopepo) was grown at two locations with different soil types as a second crop in a succession cropping study that used previously cropped polyethylene-mulched beds. Squash was produced with drip or overhead irrigation and with concurrent N-K fertilization or residual fertilizer from the previous crop. Tissue mineral concentration responses to irrigation method were variable; in early fruit, N and K concentrations were higher with overhead than for drip, but leaf Ca and Mg concentrations were higher with drip than with overhead irrigation. Concentrations of N and K were higher with concurrent than with residual fertilization and increased with an increase in application rate. In contrast, concentrations of P, Ca, and Mg decreased with concurrent fertilization and an increase in application rate.

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Harry S. Paris

The fruits of Cucurbita pepo cv. Table Queen are light green when young, turn dark green by intermediate age (15-18 days past anthesis) and remain dark green through maturity. Three major genes are known to affect developmental fruit color intensity in C. pepo: D, 1-1, and 1-2. Table Queen was crossed with cv. Vegetable Spaghetti and with tester stocks of known genotype in order to determine the genetic basis of its developmental fruit coloration. The results from filial, backcross. and testcross generations suggest that Table Queen carries gene D, which confers dark stem and fruit color from intermediate fruit age through maturity. Table Queen also carries L-2. which confers Light Type 2 (a pattern of grayish green hue) fruit color from intermediate age, but D is epistatic to L-2. The genotype of Table Queen is D/D 1-1/1-1 L-2/L-2. Clear-cut results were not obtained -- regarding the genetic basis of the retention of green color through maturity of Table Queen fruits.

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William B. Evans, Kenneth W. Hood, Peter M. Hudson and Keri L. Paridon

Yield and economics of vegetable crops are being evaluated in non-adjacent organic (OG) and nonorganic (NOG) vegetable production field areas in Crystal Springs, Mississippi. Each production area has six sections in which crops are rotated over several seasons and years. Production techniques and management are as similar in timing and methodology as possible between the systems without compromising either system. Production methods, timing, and costs are recorded for each operation. These are combined with yield data to create budgets and estimated returns for each production system/crop combination. When possible, harvested produce is marketed by a cooperating grower-retailer at a local mid- to up-scale farmers market. Three years into the study, positive returns have been found for several crops including potato (Solanum tuberosum L.), lettuce (Latuca sativa L.), summer squash (Cucurbita pepo L.), cucumber (Cucumis sativa L.), and others. Marketable new potato yields in 2005 were under 10,000 lb/acre for Yukon Gold and Red Lasoda in either production system. Estimated net returns, based on an actual $2.00/lb market price, were positive for all system/cultivar combinations although final budget numbers are not firm. Significant differences in yield among cultivars were seen in potato, lettuce, summer squash, and cucumber. Organic production budgets for other crops in the study are also being developed.

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S. Alan Walters, Scott A. Nolte and Bryan G. Young

The influence of `Elbon', `Maton', and `Wheeler' winter rye (Secale cereale) with or without herbicide treatments on weed control in no-tillage (NT) zucchini squash (Cucurbita pepo) was determined. `Elbon' or `Maton' produced higher residue biomass, greater soil coverage, and higher weed control compared with `Wheeler'. Although winter rye alone did not provide sufficient weed control (generally <70%), it provided substantially greater redroot pigweed (Amaranthus retroflexus) and smooth crabgrass (Digitaria ischaemum) control (regardless of cultivar used) compared with no winter rye at both 28 and 56 days after transplanting (DAT). No effect (P > 0.05) of winter rye cultivar on early or total squash yield was detected. Although applying clomazone + ethalfluralin to winter rye residues improved redroot pigweed control compared with no herbicide, the level of control was generally not adequate (<85% control) by 56 DAT. Treatments that included halosulfuron provided greater control of redroot pigweed than clomazone + ethalfluralin, and redroot pigweed control from halosulfuron treatments was similar to the weed-free control. However, regardless of year or cover crop, any treatment with halosulfuron caused unacceptable injury to zucchini squash plants which lead to reduced squash yield (primarily early yields). Insignificant amounts of squash injury (<10% due to stunting) resulted from clomazone + ethalfluralin in no-tillage plots during either year. Treatments with clomazone + ethalfluralin had early and total yields that were similar to those of the weed-free control, although this herbicide combination provided less weed control compared with the weed-free control.