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Michael D. Orzolek and Robert A. Scott

“Majestic” cauliflower plants were transplanted into furrows with either a polymer alone or in combination with ammonium nitrate. The polymers were banded in the furrow at planting time at 16.9, 33.7 or 67,4 kg/ha with or without a concurrent application of nitrogen at 44.9 kg/ha. The cauliflower received at least 1.2 cm water from an overhead irrigation system immediately after transplanting. Checks were both watering as plants were set in the field and water with a 12-48-8 starter fertilizer. Highest total yields were recorded when polymers were applied alone in the furrows. The addition of 44.9 kg/ha of the nitrogen generally decreased total marketable yields, head weight and plant weight. Soil samples were taken in the treatment rows after crop harvest. One of the polymer materials reduced soil pH by an average of 0.4 units and decreased the percent saturation of calcium from 90% to 70%.

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A.A. Csizinszky

Green cauliflower (Broccoflower) (Brassica oleracea L. Botrytis Group cv. Alverda) is a relatively new vegetable crop in the United States. Experiments were initiated to investigate the yield potential of `Alverda' green cauliflower in three consecutive plantings (10 Oct. and 24 Nov. 1992 and 12 Jan. 1993) at two in-row spacings (31- and 38-cm) with the factorial combinations of N and K at 98, 196, and 294 kg·ha–1 under subtropical conditions. Crops were grown in an Eau Gallie fine sand with the full-bed polyethylene mulch-seepage (modified furrow) irrigation system. Marketable yields were highest in the January planting with N at 294 kg·ha–1 when 71% of the plants had marketable size (≥0.34 kg) and desirable quality curds. Yields were higher at 38- than at 31-cm spacing. Yields and curd size increased with increasing N rates at all three planting dates (P ≤ 0.01). Potassium rates had no significant effect on yields.

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Julio Muro, Ignacio Irigoyen, and Carmen Lamsfus

Experiments were designed to assess the effects of defoliation and bending back petioles on the head mass of cauliflower (Brassica oleracea L. var. botrytis Alef. subvar. cauliflora, cv. Matra) in the Central Ebro Valley of Spain. Treatments were applied at seven different stages during the growth cycle. Defoliation reduced final head mass, the amount of the reduction increasing with level of defoliation. Bending back the petioles produced a loss in head mass intermediate between that caused by 33% and 66% defoliation. In all four trials, mass loss was highest when defoliation occurred at a head diameter between 20 and 38 mm. Neither defoliation nor bending of the petioles appeared to influence head induction or length of the production cycle. Maximum loss of head mass (85.4% to 64.9%) occurred when cauliflower was totally defoliated at a head diameter of 20—25 mm.

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Carl J. Rosen

Two separate field experiments were conducted to determine the influence of Ca sprays and N fertilizer rate on leaf tipburn incidence in `Snow Crown', `Self Blanche', and `Imperial 10-6' cauliflower. Incidence of leaf tipburn was highest in `Snow Crown' each year and varied with year in `Self Blanche' and `Imperial 10-6'. Delaying planting of `Snow Crown' by 3 weeks decreased tipburn incidence by 20% and decreased the number of tipburned leaves per tipburned plant by 60%. Sprays of CaCl2 or calcium chelate had no effect on cauliflower productivity, nutrition, or tipburn incidence. Increasing N fertilizer rate from 67 kg N/ha to 201 kg N/ha linearly increased yield without significantly affecting tipburn incidence. Concentrations of Ca in tips of nontipburned leaves were two to five times greater than those in tips of tipburned leaves of comparable physiological age. Basal leaf regions had similar Ca concentrations, regardless of tipburn status. Use of resistant cultivars appears to be the best method of reducing tipburn incidence in cauliflower.

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Pat Bowen

Research was conducted to determine whether tillage in the fall rather than spring could be used to prepare fields for transplanting broccoli and cauliflower crops. Because fall-tilled soils are prone to erosion by winter rains, the effects of a fall-planted barley cover crop were also determined. Trifluralin was applied to the spring-tilled plots, according to grower practice. Herbicide treatments applied to fall-tilled plots were early and/or late applications of glyphosate and napropamide following early and late glyphosate applications. Weed emergence was generally increased by the barley cover crop, but the species depended on which herbicides were applied. Napropamide reduced the emergence of some weed species, whether or not a cover crop was grown. Yield of broccoli was reduced by the cover crop, and was highest in fall-tilled plots that received two glyphosate treatments. Yield of cauliflower was highest in spring-tilled plots that were cover-cropped. In fall-tilled plots, cauliflower response to the cover crop and herbicide treatments was inconsistent.

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Nicole Smith and Prem L. Bhalla

Brassica oleracea is an important vegetable crop, which includes fully cross-fertile cultivars such as broccoli, Brussels sprouts, cabbage, cauliflower, collard, kohlrabi, and kale. F1 hybrids are desirable, as plants grown from hybrid seeds benefit from the heterotic effect of crossing genetically distinct pure lines. But, there is no practical and reliable method to create male sterility for hybrid seed production that is suitable for Brassica vegetables. We have been working to induce nuclear male sterility in cauliflower (Brassica oleracea var. botrytis) by antisense inhibition of Bcp1, a unique anther-specific gene of Brassica. The production of nuclear male-sterile lines will enable male lines with superior agronomic traits to be converted to female parents. Thus, vegetative propagation of parent plants for hybrid seed production by tissue culture is desirable. To achieve this objective, we compared various plant tissues, including stem, petiole, leaf, leaf rib, flower stem, pedicel, flower bud, and petal as explants for tissue culture propagation of an Australian cultivar (B-4) of cauliflower, Brassica oleracea var. botrytis. Four different MS based media containing different amounts of BAP, NAA, GA3, and silver nitrate were used. The cultures were incubated at 25°C with a 16-hr photoperiod. Initial response was visible within 10 days, but percentage callus, root, and shoot formation was scored after 3 weeks of culturing. Of all the explants tested, pedicel explants showed maximum shoot initiation and leaf explant did not respond to regeneration under the conditions tested. The results from these on going experiments will be presented and discussed.

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Nanik Setyowati and Dean E. Knavel

Plant growth and yield of broccoli (`Green Comet'), and cauliflower (`Majestic', `Snow Crown') cultivars were evaluated by no-tillage (NT) and conventional tillage (CT) in the fall 1987 with NH4NO3 applied dry or through the trickle line. Total plant dry weight, plant stand, average head weight and number of heads harvested were not affected by tillage system. `Snow Crown' plants had less of the following leaf area, dry weight, plant stand, number of heads harvested, and total head weight, than `Majestic', especially in NT where NH4NO3 applied dry. In the greenhouse, cauliflower cultivars had similar leaf area, leaf dry weight, and mot dry weight at 30, 45, and 60 days after growing in sand culture while broccoli cultivars had similar leaf area, leaf dry weight, and mot dry weight after 35, 50, and 65 days. Generally, nutrient uptake was similar at each sampling date for cultivars within crops. Cultivars had similar leaf water and osmotic potentials when grown for 2 weeks in modified growth chambers at either 23.9 or 29.4 C day, and 18.3 C night. These plants were then root-pruned and grown in sand culture for 3 weeks. Leaf area, mot dry weight, and plant dry weight was greeter for `Majestic' than for `Snow Crown' and `Olympus'.

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Wes Deuel and Sven Svenson

Seedmeal (MSM) and screenings (MS) of meadowfoam (Limnanthes alba H.) were evaluated for their influence on the development of clubroot caused by Plasmodiophora brassicae in potted seedlings. Treatments included MSM at 0%, 5%, 10%, and 20% (by vol.); MSM at 10% (by vol.) plus an 8 oz. application of 3% H2O2 per pot; and MS at 10% (by vol.) pre-sowing incorporation into potting media (Sunshine Mix #1) with a 10% (by vol.) clay-loam soil known to be infested with P. brassicae resting spores. One-hundred percent Sunshine mix #1 was used as a control medium. Following media preparation, seeds of Chinese mustard (Brassica chinensis) and cauliflower (Brassica oleracea var. botrytis `Snowball Y Improved') were sown every 7 days for 4 weeks. Symptoms of P. brassicae infection (clubbing or rotting of roots) occurred in 70% to 90% of all plants grown in pots with media containing infested soil and no MSM or MS, with disease severity ranging from <25% to >50% of root systems clubbed or rotted. Chinese mustard seedlings had more clubbing compared to cauliflower seedlings. All plants grown in media containing MSM or MS showed no clubbing or rotting. Plants grown in 20% MSM or 10% MSM plus a 3% H2O2 had symptoms of phytotoxicity. Plants grown in 10% MSM or 10% MS were taller compared to controls. Although plants grown in MSM and MS showed no clubroot symptoms, asymptotic presence of pathogen has not been excluded.

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C.P. Sharma and Sandhya Singh

When grown in refined sand with one-twentieth normal K supply, cauliflower (Brassica oleracea L. var. botrytis L. cv. Pusi) had lower dry matter and tissue concentration of K than the controls and developed visible symptoms characteristic of K deficiency. In K-deficient plants, the specific leaf weight, diffusive resistance, and proline concentration in leaves were significantly higher and relative water content (RWC), leaf water otential (ψ), stomatal aperture, stomatal density, and transpiration rate were significantly lower than in control plants. When K-deficient plants were supplied additional Na to the extent K was deficient, Na concentration in the plants increased and the plants recovered from the K deficiency effect on free proline concentration, RWC, leaf water potential, stomatal aperture, stomatal density, specific leaf weight, diffusive resistance, and transpiration.

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Claude E. Thomas and E.L. Jourdain

Evaluations for resistance against race 2 of downy mildew, incited by Peronospora parasitica, were conducted on 240 U.S. Plant Introductions (PI) classified as Brassica oleracea var. botrytis (consists of both broccoli and cauliflower types). Plants were inoculated at the two-expanded leaf stage with 5.0 × 103 sporangia per ml. Inoculated plants were incubated in a dark 16C dew chamber for 24 hr and were then placed in a 22C growth chamber with a 12-hr photoperiod. On the 7th day after inoculation, plants were returned to the dew chamber for 30 hr and ratings for downy mildew reaction phenotypes were made at 9 days postinoculation on a 0-9 scale of increasing disease severity. A disease index (DI) was calculated for each entry. Based on the DI, no PI entries were highly resistant. PI entries 181860, 188562, 204765, 204768,204772,204773, 204775,204779,241612, 264656,291567,373906, and 462225 were moderately resistant. (DI of 3.1-5).