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- Author or Editor: Dean E. Knavel x
Abstract
Direct-seeded bush beans, sweet corn, summer squash, and transplanted tomato and cabbage were grown under varying tillage and cropping systems in 1982 and 1983. Cultural treatments were conventional tillage (CT), no-tillage without cover crop (NT–CC), and no-tillage with a cover crop (NT + CC) of hairy vetch (Vicia villosa) in 1982 and perennial ryegrass (Lolium multiflorum) in 1983. Split applications of N were 56 and 112 kg·ha−1 in CT plots and 0, 56, and 112 kg·ha−1 in NT plots. Plant stand and yields of bush beans and sweet corn were highest in CT plots in both years. Plant stand of squash was less for CT in 1982, but greater for CT than for NT + CC in 1983. Yields of squash were similar, but plant dry weight was greater in CT than in NT + CC. Plant stand of tomato and cabbage for NT + CC was similar to CT in 1982, but cabbage stand was greatest for CT in 1983. Total tomato yields were greater for NT – CC in 1982 and similar to those for CT in 1983, but yields were greatly reduced for NT + CC in 1983. Only in 1982 were cabbage heads of certain treatments marketable and they were greatest for CT. Sidedressing bush bean, sweet corn, cabbage, and summer squash plants with N in NT – CC plots increased yields linearly in 1982. Of the crops grown by NT + CC, only yields of bush beans and cabbage in 1982 and green fruit of tomato in 1982 showed a linear increase by sidedressing with N. Sidedressing with N increased N contents of all crops linearly in 1982, but not in 1983. Weed control was excellent in CT sweet corn and satisfactory in CT and NT – CC plots of the other crops. For the other crops in NT + CC plots, most of the weed and/or cover crop growth was the regrowth of vetch in 1982 and perennial ryegrass in 1983 after weed control chemicals were applied.
Abstract
Killing Sudan grass (Sorghum vulgare var. sudanense) at a 30-cm height with glyphosate and leaving the residue on the soil surface reduced the number of marketable heads, head weight, and total yield of fall transplanted ‘Market Prize’ cabbage (Brassica oleracea L., Capitata Group). The total plant weight and weight of heads where the cover crop was killed at a 15-cm height were equal to those of conventional culture. Killing the grass at different heights also affected the concentration and distribution of N, K, and Ca in leaf petioles, leaf laminae, and the core of the matured plant. There were positive correlations of head weight with N in the petioles of wrapper leaves, laminae of inner leaves, and core and with Ca in the laminae of the oldest leaves, wrapper leaves, inner head leaves, and core. Sidedressing with N increased head weight, marketable yield, and N concentration in all plant parts analyzed. The response to Ca(N03)2 was similar to that of NH4NO3. Chemical names used: N-(phosphonomethyl) glycine (glyphosate).
Abstract
A two-year study of popcorn cultivars grown by no-tillage (NT) and conventional tillage (CT) systems indicated that popcorn can be produced successfully by NT. Plant populations, plant heights, ear lengths, and ear weights were generally greater for NT than for CT. Popping expansion of NT corn, except for ‘Snow Puff’, a white kernel cultivar, was equal to that of CT. The use of either NH4NO3 or Ca(NO3)2 at 56 kg N/ha in 1981 and 84 kg N/ha from NH4NO3 in 1982 produced the highest yields. Increasing N to 140 kg/ha decreased yields of ‘Snow Puff’ in CT. The N levels had no effect on popping quality.
Abstract
Application of 50 or 75 mg/liter chlorflurenol (methyl-2-chloro-9-hydroxy-fluorine) to muskmelon (Cucumis melo L.) 10 to 12 days prior to anthesis eliminated ovule development during later bud growth. The interruption of ovule development increased when chlorflurenol was applied 6-14 days prior to anthesis. Chlorflurenol did not interfere with pollination, pollen germination, or pollen tube growth.
Abstract
Cytokinins were extracted from lettuce leaves (Lactuca sativa L., butterhead type), purified by cation exchange, paper and Sephadex LH-20 column chromatography and bioassayed with tobacco callus. Compounds with chromatographic mobilities corresponding to those of zeatin and zeatin riboside were detected. The inner, developing leaves of the heads contained most of the cytokinin activity.
Abstract
Dwarfness in ‘K70’ a dwarf cultivar of cucumber (Cucumis sativus L.), is due to internodes that are shorter than those of the tall, indeterminate ‘Stono’. Both plant types had the same no. of internodes after 15 weeks growth. Associated with short internodes is a greater no. of smaller cells per unit area of leaf tissue. The darker green appearance of ‘K70’ leaves is due to greater no. of cells, not difference in chlorophyll content.
Internal brown spot (IBS) was found consistently in the `Atlantic' cultivar at Lexington in 1967, 1968 and 1989, and at Owensboro and Quicksand, KY in 1987, Treatments of foliar and soil applied CaSO4 in 1987, soil-applied CaSO4 in 1988, and straw mulching in 1989 did not reduce IBS. Irrigation increased IBS because of larger tubers and increased Ca content of plants as compared with non-irrigated plants. Tubers showing IBS had higher Ca content in affected tissue than in non-affected tissue. Both IBS and Ca content of leaves increased as the plants aged.
Abstract
The environment created by ventilating a greenhouse with mine-air was suitable for the production of high quality spray chrysanthemums (Chrysanthemum morifolium Ramat.) and snapdragons (Antirrhinum majus L.) from mid-February through November without any additional energy requirement. The environment created in the greenhouse from December to February was extremely humid and favored botrytis development and physiological problems which reduced crop quality.