Yellow Squash Research Articles

SENSORY COMPARISON OF PREPARED FROZEN VEGETABLES PROCESSED BY MICROWAVE AND CONVENTIONAL METHODS OF BLANCHING

Four vegetables (green beans, yellow squash, purple hull peas, and mustard greens) were processed for freezing by steam, hot water, and microwave blanching. Blanched vegetables were chilled, packaged and stored at – 18°C for 3 months. Each vegetable was prepared and subjected to quantitative descriptive analysis and preference testing by a trained eight‐member panel. The effects on texture, colour and flavour are described.

Plant tissue-based bioselective membrane electrode for glutamate

A novel potentiometric membrane electrode with selective response to L-glutamate over the 2 × 10 -4–1.3 × 10 -2 M concentration range is constructed by immobilizing slices of yellow squash tissue at a CO 2 gas sensor. This system represents the first successful use of intact plant materials as biocatalysts in the construction of bioselective potentiometric membrane electrodes; as a result, the range of future possibilities may be greatly extended. The glutamate-sensing electrode combines excellent selectivity characteristics over some 25 possible interferences tested, good reproducibility, and a useful lifetime of 7 days in aqueous samples.

Mechanisms of Resistance to Sulfur Dioxide in the Cucurbitaceae

The relative resistance of four cultivars of the Cucurbitaceae (Cucumis sativus L. cv. National Pickling, and inbred line SC 25; Cucurbita pepo L. cv. Prolific Straightneck Squash, and cv. Small Sugar Pumpkin) to SO(2) was determined. According to plots of the degree of exposure to SO(2) (which depends on the SO(2) concentration and the duration of the exposure), there is an 8-fold difference in resistance to this toxic gas among these cultivars. However, if the degree of injury is plotted as a function of the amount of SO(2) absorbed, all four cultivars appear similarly sensitive to the gas. We conclude that the principal reason for special and varietal differences in resistance among these cultivars is the relative rate of absorption of the gas. The densities of stomata on the upper and lower surfaces of leaves did not differ sufficiently between cultivars to account for the differences in absorption rates. It remains to be determined whether the differences in rate of SO(2) absorption reflect differences in stomatal activity.Resistance of individual leaves changes with position on the plant axis (age of the leaf). There exists a gradient of decreasing resistance from the apex downward. This resistance gradient cannot be accounted for by differences in rates of SO(2) absorption. We infer the existence of a biochemically based, developmentally controlled resistance mechanism which functions after SO(2) has entered the leaf. Biochemical comparisons of old and young leaves with such differences in resistance should be helpful in determining the biochemistry of SO(2) toxicity.

Reflective Film Mulches, Millet Barriers, and Pesticides: Effects on Watermelon Mosaic Virus, Insects, Nematodes, Soil-borne Fungi, and Yield of Yellow Summer Squash1

Abstract Field studies were conducted in 1973 and 1974 to determine the effects of various reflective film mulches, vegetal barriers of millet (Pennisetum americanum (L.) K. Schum), and soil- and foliar-applied pesticides on yields and control of the watermelon virus complex (WMV), insects, nematodes, and soil-borne pathogens affecting yellow summer squash (Cucurbita pepo var melopepo L. Alefi, ‘Dixie’). All film mulches used (aluminum; white and blue plastic; brown paper) significantly reduced WMV in both fruits and plants. The millet barrier caused a significant reduction in WMV infected plants. In 1974, the systemic insecticide, carbofuran (Furadan) and/or sprays of mineral oil, significantly reduced WMV in non-mulched plots. Brown paper mulch significantly increased infestation of pickleworms, Diaphania nitidalis (Stoll) and all mulches significantly reduced infestations of serpentine leafminers, Liriomyza munda Frick. Leafminers were also controlled with carbofuran. Film mulches had no significant effect on populations of plant-parasitic nematodes and plant-pathogenic fungi. Both groups of pests were controlled with DD-MENCS (a mixture of 1,3-dichloropropene, 1,3-dichloropropane, methylisothiocyanate), but not with carbofuran or sodium azide. Film mulch increased squash yield 70 to 610% over the unmulched control. Plants in non-fumigated plots covered with aluminum and white plastic mulches produced significantly greater yields than plants in plots covered with blue plastic and brown paper mulches. Soil pesticides significantly increased yields over the non-fumigated control, and, averaged across main plots, DD-MENCS = DD-MENCS + carbofuran > carbofuran + sodium azide > sodium azide = nontreated check. The effects of film mulch were greatest in the non-fumigated check. Conversely, the effects of soil fumigation were negligible under film mulch and one could be substituted for the other.

Effect of Petiole Anoxia on Phloem Transport in Squash

Translocation of (14)C-labeled assimilates in Early Prolific Straightneck squash (Cucurbita melopepo torticollis Bailey) through a 15-centimeter oxygen-deficient zone of the petiole was studied as a function of varying periods of anaerobiosis (N(2) atmosphere). Initiation of anaerobic conditions caused an immediate and rapid decline in translocation to about 35 to 45% of the pretreatment rate within 30 to 40 minutes. This inhibition response (first inhibition response) was transient, however, and full recovery to the pretreatment rate occurred during the ensuing 60 to 90 minutes. Following this adaptation response to anaerobic conditions, translocation continued unimpaired for extended periods of time, approaching, and in some cases exceeding, 24 hours. The second inhibition response was permanent and could not be reversed by supplying air during a subsequent 20-hour period.

Ascorbate oxidase isozymes

The ascorbate oxidase of yellow summer squash ( Cucurbita pepo condensa) was separated into five isozymes by polyacrylamide gel electrophoresis. One of the forms accounted for 70 per cent of the recovered total enzymic activity. A reversible association-dissociation occurs in the isozymes as a result of changes in ionic concentration.

Some Environmental Factors Affecting Feeding, Oviposition, and Survival of the Southern Corn Rootworm12

The effect of food, light, humidity, and temperature on feeding, oviposition, and survival of the southern corn rootworm, Diabrotica undecimpunctata howardi Barber, was studied under controlled laboratory conditions. Adult rootworms preferred to feed in the light on lettuce and sliced yellow squash and they preferred to oviposit in the shade or dark on moist cotton in preference to candidate legumes or curcubits. Larvae did not reject any food offered in a forced-feeding (isolation) test, but they preferred sliced yellow squash when given a choice. Humidity has a significant effect on adult survival, oviposition, and egg hatch. A relative humidity above 75% was established as essential. Adult survival, oviposition and longevity were studied at 5 temperatures ranging from 45 to 95°F. Longevity was best at 65°F, and 95°F was detrimental after 3 days’ exposure. Few eggs were deposited at 45°F, large numbers were deposited at all test temperatures above 65°F, and oviposition was optimum at 85°F

Some Effects of Food and Substrate on Oviposition of the Spotted Cucumber Beetle1

Effects of food and substrate on oviposition of the spotted cucumber beetle, Diabrotica undecimpunctata howardi Barber, in laboratory culture were studied. Oviposition in soil placed under various foods was used as a measure of adult feeding preference. Several fresh and processed foods elicited an oviposition response. In replicated tests foods in decreasing order of attractiveness were yellow squash slices, snap bean slices, cucumber slices, broad bean leaves, sweet potato slices, and carrot slices. Various natural and artificial substrates were tested for oviposition preference. Coarse soil particles and soil with cracks were preferred to fine, smooth soil. Artificial substrates in decreasing order of attractiveness were: crushed gray stone (10-20 mesh), crushed gray stone (ungraded), vermiculite (10-20 mesh), yellow sand (10-30 mesh), soil (10-20 mesh), Perlite® (ungraded), vermiculite (ungraded), and Permit (10-20 mesh). Effects of moisture level on a Tift fine sandy loam and a Magnolia clay loam soil were tested. Beetles preferred wet soil of both types for oviposition.