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Regina P. Bracy and Richard L. Parish

Stands of brassica crops obtained with precision seeders are sometimes inadequate or nonuniform. Although several types of covering devices and presswheels are available from precision seeder manufacturers, the effects of covering devices and presswheels on plant emergence of direct-seeded Brassica crops have not been determined. In Spring and Fall 1996, six crops of mustard [Brassica juncea (L.) Czerniak] and four crops of cabbage (Brassica oleracea L. capitata group) were direct seeded with a precision belt seeder using four covering devices and four rear presswheels. All of the covering devices and presswheels evaluated were adequate for direct seeding mustard and cabbage under the soil moisture conditions and soil type (silt loam or fine sandy loam) found in these experiments. Although poor stands were obtained with all seed covering devices and presswheels when 7.8 inches (199 mm) of rain occurred within 3 days of planting, plant stand of cabbage was greater when the paired arm device was used than with drag-type or no covering devices.

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Charles L. Webber III, Merritt J. Taylor, and James W. Shrefler

design with five treatments and four replications repeated across 2010 and 2011. ‘Enterprise’ yellow squash, a fast growing bush-type squash with a 41-d maturity, was direct-seeded into single rows on raised 36-inch-centered beds on 21 June 2010 and 2011

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Marietta Loehrlein and Dennis T. Ray

Triploid watermelon seed does not germinate in cold, wet soils as well as diploids; germination is slower due to reduced embryo size and thicker seed coat; fissures on the seed coat provide safe harbour for fungal spores; and triploid fruit set is later than most diploid cultivars. Because of these problems producers often transplant rather than direct-seed seedless watermelons. Seed priming has been shown to improve germination in other crops and would be an attractive method allowing for direct seeding of seedless watermelons. Seed from open-pollinated 4n × 2n crosses were primed in solutions of H2O, polyethylene glycol 8000, KNO3, or left untreated. Treatment times were 1, 3, or 6 days, and treated seed were subsequently dried for either 1 or 7 d. Seed were scored for germination in the laboratory and emergence under field conditions. Germination was better using H2O than KNO3 and PEG but not always better than the untreated control. Treatment time of 1 day was superior to 3 or 6 days, but length of drying time was insignificant. In the field trial, treatments did not differ in emergence.

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Winston Dunwell, Dwight Wolfe, William Maksymowicz, and Darrell Slone

Alternative use for float system greenhouse space is being studied in Kentucky. High sugar sweet corn (Zea mays L.) cultivars direct seeded into cool soils germinate poorly. A float transplant production system was used to produce high sugar sweet corn transplants that could be planted into cool soils. 100 seeds of sugar enhanced (se) 'How Sweet It Is' and super sweet (sh2) 'Early Xtra Sweet' sweet corn cultivars wars seeded into trays with a cell size of either 19 or 49 ml/cell. The trays were floated on heated or unheated water in the greenhouse. Percent germination was significantly influencedby cultivar. A greater percent germination was observed for 'How Sweet It Is' compared to 'Early Xtra Sweet' and for seeds sown in the 49 ml/cell trays compared to the 19 ml/cell trays. No significant differences resulted from varying the water temperature. Transplants were planted into cool soils with direct seeded sweet corn on April 21, 1992. The use of transplants resulted in a significantly greater plant stand and a two week earlier harvest than the use of the direct seeding.

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Robert Stubblefield and Robert Wiedenfeld

A field study was conducted in south Texas in the spring 1990 to determine the effects of ground cover, planting method and drip irrigation rates on cantaloupe growth, yield and quality. Transplanting vs. direct seeding enhanced early vine growth with earlier yields, although direct seeding later caught up resulting in comparable final cumulative yields. Black polyethylene mulch also improved earliness but at the loser irrigation rate total yields were reduced due to deflection of rainfall by the mulch. Irrigation at .1, .3, .5, .7 and .9 times pan evaporation had little effect on final cumulative yields with exception to the .1 and .3 rates. Melon sugar content was highest for transplants with direct seeded melons becoming comparable only at mid to final harvest. The combined practices of transplanting and black polyethylene mulch resulted in a 14 day earliness advantage over the treatments that were direct seeded on bare soil although final yields were unaffected. No appreciable increase in soil salinity were found as a result of drip irrigation usage.

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Theresa Bosma, John Dole, and Niels Maness

Marigold flower pigments can be extracted and used as a natural source of food colorants in the poultry and dairy industry. These pigments impart an orange color to egg yolks and a yellowish color to dairy products. We examined four African marigold cultivars for their ability to be commercially grown and harvested mechanically. `E-1236' yielded the highest quantity of lutein (22 kg/ha), a carotenoid pigment, using a spectrophotometer for quantification. `E-1236' and `A-975' were the earliest flowering cultivars, 11 June 1998 for transplants and 9 July 1998 for direct-seeded, at 8 weeks after sowing regardless of field establishment method. `E-1236' produced the greatest number of flowers in a production season, both as transplants (68 flowers/plant) and direct-seeded (57 flowers/plant) at 363,290 plants/ha. Transplants resulted in two more harvests in a single season than direct-seeded plants. Subsequently, more flowers and petal material were produced for pigment extraction than with direct-seeded plants. A one-time application of ammonium nitrate (28.02 kg/ha) at mid-season did not significantly effect flower number, flower weight, or pigment yield. Experiment was repeated in 1999 with four cultivars, two field establishment methods, seven harvest dates, and five nitrogen applications.

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John Caldwell and Maurice Ogutu

Greater plant diversity is associated with reduced insect pest pressure, but field-scale vegetable production systems incorporating plant diversity have been lacking. Cucumber was grown in 1998 and 1999 at the Virginia Tech Kentland experimental farm, by direct seeding or transplanting into rye/vetch mixture rolled to make a no-till mulch alternating with strips of vetch left to flower as a habitat for beneficial insects between cucumber rows, or direct-seeded into black plastic mulch between habitat strips or with bare soil between rows. Rye and hairy vetch were seeded at 56 kg·ha–1 each the preceding fall; only rye was planted in plots without habitats. A rippled coulter, cutting shank, and daisy wheels mounted on a tractor-drawn toolbar enabled a belt-driven seeder to seed cucumbers without pulling the no-till mulch. One hand weeding in cucumber rows at 3 weeks after planting (WAP) provided weed control equivalent to pre-emergence herbicide. At 3 WAP, no-till transplanted cucumbers had higher above-ground plant dry weights than no-till direct seeded cucumbers in both years, but, at 6 WAP, cucumber above-ground plant dry weights were equal (1999) or higher (1998) in direct seeded no-till than in transplanted no-till or black plastic mulch on bare soil. In 1999, Pennsylvania leatherwings, Chauliognathus pennsylvanicus DeG. (Coleoptera: Cantharidae), a cucumber beetle predator, had higher densities and cucumber beetles lower densities in no-till plots than in black plastic mulch plots, and bacterial wilt incidence was reduced in plots with habitat strips and no insecticide application compared to plots without habitat strips and four insecticide applications. Cumulative marketable yields in no-till were 59% higher in 1998 and 23% higher in 1999 compared to yields on black plastic mulch.

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Sylvie Jenni, Pierre Dutilleul, Stephen Yamasaki, and Nicolas Tremblay

In order to investigate their relationships with brown bead, a data set composed of 48 variables characterizing the developmental rate, climate, and nutrients in the soil and in the tissues of heads of broccoli (Brassica oleracea L., Italica group) was collected from 328 plots (41 experimental fields over 3 year× 4 N fertilization level× 2 blocks). The four N treatments were 85-0-0, 85-54-0, 85-54-54, and 85-54-108, the first number indicating the N level (kg·ha-1) applied before planting; the second, N level applied 5 weeks after planting; and the last, N level applied 7 weeks after planting. Broccoli plants were either direct-seeded (26 experimental fields) or transplanted (15 experimental fields). Whether direct-seeded or transplanted, fast-developing broccoli plants showed a lower incidence of brown bead. More particularly, heads of transplanted broccoli plants experiencing warmer temperatures had a lower brown bead incidence and severity. A regular supply of water decreased the incidence and severity of the physiological disorder in both direct-seeded and transplanted broccoli plants. Low levels of Ca and high levels of Mg and K in mature broccoli head tissues were associated with a higher incidence of brown bead. Multiple-regression models were developed to predict the percentage of broccoli heads with brown bead for direct-seeded plants (R 2 = 0.76; n = 104), and for transplanted plants (R 2 = 0.69; n = 44). For direct-seeded broccoli, solar radiation between the button stage (head diameter of 2.5 cm) and maturity (head diameter of 10 cm), as well as soil and tissue Mg content, were among the first variables to enter the regression models. In general, more solar radiation and less precipitation translated into more heads showing brown bead symptoms. For transplanted broccoli plants, the minimum temperature from the button stage to maturity was a key variable in the prediction of the percentage of heads with brown bead and the corresponding index of severity.

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Marshall K. Elson, Ronald D. Morse, Dale D. Wolf, and David H. Vaughan

High summer temperatures may reduce plant stands of direct-seeded fall broccoli (Brassica oleracea var. italica Plenck). The influence of constant and diurnally alternating temperatures in the range of 5 to 42C on germination and emergence of `Packman' broccoli was evaluated. Germination was defined as protrusion of the radicle from the seedcoat, and emergence as 10 mm elongation of the radicle. The range of constant temperatures from 10 to 30C for 14 days was satisfactory for 90% germination and 75% emergence. However, alternating temperatures extended the acceptable emergence range to 5/17 through 20/32C. Since soil temperatures in warm climates often exceed 20/32C during the summer, high-temperature inhibition of seed germination and seedling emergence is a potentially important factor limiting direct-seeded broccoli stands.

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Roland Roberts, David Bender, and Samuel Field

Extension-research teamwork supports Texas High Plains onion grower-shippers in transition from unprofitable labor intensive marketing and culture to profitable mechanical systems that are less stressful to workers. System comparisons include machine harvest vs. lifting and hand clipping; stationary seed grading and bagging vs. mobile field grading and bagging; transplant vs. fall seeding, spring seeding and dry set production. Old marketing systems cost growers $4.30/50-lb. sack, and the innovative system costs $2.59 to $3.00/sack. Old transplant systems average $450 to $500/acre and direct seeding costs $200/acre. Net increase in return to grower management from adoption of new systems range from $1,300 to $1,700. Extension and research conduct economic analysis, cultivar performance trials, seeding technique studies and on-farm demonstrations.