Search Results
You are looking at 11 - 20 of 24 items for
- Author or Editor: Dyremple Marsh x
Abstract
Studies were undertaken to determine the critical Zn levels for cowpea [Vigna unguiculata (L.) Walp] grown in low N medium and inoculated with Rhizobium. Cowpea ‘California Blackeye No. 5’ was grown for 40 days in a sand culture using Zn application rates of 0, 0.06, 0.5, 1.0, 1.5, 2.0, 2.5, 2.8, 3.0, 3.1, 3.4, 3.7, 4.0, and 4.5 ppm Zn as ZnSO4. N2 fixation was estimated by acetylene reduction. Critical Zn deficiency levels were determined as 12.5, 20, 30, and 50 ppm for upper leaf petioles, upper leaf blades, lower leaf petioles and lower leaf blades, respectively, Critical Zn toxicity levels for these tissues was determined as 145, 273, 300, and 440 ppm, respectively. It was concluded that upper, recently matured, leaf petiole tissue should be used to assess plant Zn status. The percentage of reduction of N2 fixation was greater than the percentage of reduction in dry-matter accumulation under Zn-deficient conditions. N2 fixation increased linearly with increased Zn content of nodules and roots. At Zn levels above 150 ppm for both tissues, however, N2 fixation declined significantly. Applied Zn did not affect the growth and development of the root system and had little effect on reproductive development.
Sweetpotato (Ipomoea batatas) cultivars, Carver, Potojam, Jewel and Centennial were evaluated for slip production, using topsoil, sawdust, sand and a general-purpose peat-based commercial growing media as bed covers. Temperature measured 2 inches (5.1 cm) below the surface of the hot bed varied with covers and date measured. Sand maintained the highest bed temperature, 77 °F (25.0 °C) at 0800 hr and 79 °F (26.1 °C) at 1400 hr, throughout the growing season. Peat-covered roots produced the maximum number of slips/plot (111), while roots covered with topsoil and sawdust produced comparable yields, 55 and 45 slips/plot, respectively. Slip production varied according to harvest date, with the third harvest producing the most slips/plot (83 and 153, in year 1 and year 2, respectively), which, was likely related to increased temperatures. Cultivar significantly influenced number of slips, length of slips, and number of roots per slip. `Potojam' was the most prolific slip producer for both early and mid season production under all bed covers.
A greenhouse experiment was conducted to examine the relationship between tissue B concentration and dry matter accumulation in broccoli. `Pirate ' was grown in fine silica sand and supplied nutrient solutions containing 0.2, 0.8, 1.4, 2.0, 2.6, 3.2, 3.8, and 4.4 mg·liter-1 B. Plants were sampled for the 5th, 10th, and 15th fully expanded mature leaf, and plant material was collected' for dry matter measurement and boron analysis at each growth stage. The lowest specific leaf weights for the 5th, 10th, and 15th leaves were obtained with the 4.4 mg·liter-1 treatment. At maturity, leaf, petiole stalk, and shoot dry weights were lowest at 4.4 mg·liter-1 B. Treatments supplying less than 3.2 mg· liter-1 B, resulted in a notable decrease in tissue B concentrations from the 5th to the 15th leaf. There was a linear increase' in B concentration in all leaf tissue samples as B treatment increased. At maturity, optimum B concentrations of 531.5, 73.7, 29.8, and 64.6 mg·g-1 were found for the lamina, petiole, stalk, and head, respectively. These concentrations occurred in plants receiving treatment levels of 2.0-3.8 mg·liter-1 B.
The enzyme-linked immunosorbent assay was used to determine the competitive ability of three Rhizobium strains introduced into Antiguan soil. Strain-specific antisera were prepared against each strain. Field experiments were conducted in Antigua using Rhizobium strains USDA 3384, USDA 3473, and USDA 3474 as a peat-base inoculant and pigeon pea as the test crop. Nodules from the respective treatments were removed and prepared for ELISA studies. There was cross reactivity between the antisera, but it was greatly reduced or eliminated by repeat adsorption with the cells of the cross-reacting strains. Nodule occupancy by plants treated with Rhizobium 3384, 3473, and 3384 was 70%, 90%, and 100%, respectively. Nodules from 3384 and 3474 treated plants contained cells with no antigenic homology to the three antisera. We concluded that these nodules were developed from indigenous Rhizobium strains found in Antiguan soils.
Abstract
Greenhouse and field studies were conducted to determine the influence of container type and cell size on cabbage [Brassica oleracea (L.) Capitata Group] transplant growth and subsequent yield. Cabbage seedlings were grown in the greenhouse in two types of containers, Sutton polystyrene and Speedling styrofoam “Todd Trays”. Four sizes of each tray were tested, ranging from 8.0 to 80.5 cm3 for polystyrene and 7.5 to 80 cm3 for styrofoam. In general, stem diameter, plant height, and leaf area of seedlings increased with increase in container size, but container type had no influence. In the field, head width and length were similar for all treatments. Plants grown from the large cell sizes had higher head weight than those from small cell sizes.
Chemically fixed nitrogen is a costly import for Caribbean Basin Countries. Increased cost of fertilizer only serves to reduce crop yields in these areas. This greenhouse research was undertaken to evaluate the N2 fixing capabilities and yield potential of several Phaseolus vulgaris lines developed for use in Caribbean Basin countries. Ten common bean lines from breeding programs at the Universities of Puerto Rico and Wisconsin and two efficient Rhizobium phaseoli strains were used for the study. Plants treated with Rhizobium UMR 1899 and UMR 1632 had significantly higher stem and leaf dry weight than the control plants. Bean lines WBR 22-34, WBR 22-50, WBR 22-55, PR9056-98B and the cultivar Coxstone showed increased dry matter accumulation over that of the control plants. Plants treated with the Rhizobium strain UMR 1899 had the highest stem and leaf dry matter accumulation. Nodulation was significantly higher when plants were treated with UMR 1632. The lines WBR 22-34 and PR 9056-98B produced more nodules than the other lines used. Pod yield as measured by number of immature pods was highest for PR 9056-98B when inoculated with Rhizobium UMR 1899.
The use of cowpea as a forage for Central Missouri has been limited. High mid summer temperatures and frequent drought suggest that an alternative forage for livestock may be advantageous during the hot summer months. The ability of cowpea to withstand drought, high temperature and maintain high foliage protein, justifies research of the forage potential of this crop. Forage yield potential of two cowpea cultivars was evaluated in field experiments in 1968 and 1989, For both years a split plot experimental design was utilized with cowpea cultivar the main plot and harvest date the subplot Dry matter yields for both cultivars were similar at the early harvest dates. However, both fresh and dry shoot yields of Vita 3 (V3) were significantly higher than that of California Blackeye #5 (CB #5) at the later harvest stages. CB #5 plants produced a significantly higher stem dry weight while V3 produced higher leaf dry matter. Foliage regrowth after clipping was substantial for both cowpea cultivars. However, V3 produced 30% higher growth than CB #5. In vitro dry matter digestibility (IVDDM) varied with sample date (plant age) and plant parts sampled. IVDDM was 77% for leaves and 60% for stems of CB#5, and 80% for leaves and 65% for stems of V3.
The germination percentage of eastern gamagrass under normal field conditions ranges from 5 to 10%. These rates are considered low and methods to improve stand establishment in this species are necessary, Studies were initiated to determine if cupule removal and seed hydration were effective in improving the germination percentage of eastern gamagrass. Seeds from which the cupules were removed were incubated for 30 days at 5° C in 100% ethylene glycol (EG). Control were seeds incubated in distilled water. At 12, 18, 24 and 30 days after the start of incubation, seeds from each group were removed and subjected to rapid warming at 25 - 27° C. Cupule removal significantly increased seed germination by as much as 55% over the control. Seeds with cupule removed and incubated in EG had a 65% germination rate,
The USDA, Louisiana State University, and Lincoln University have released a new southernpea cultivar named WhipperSnapper. The new cultivar is the product of a plant breeding effort to incorporate genes conditioning superior yield and seed characteristics of Asian vegetable cowpeas into American snap-type southernpeas. The new cultivar was developed for use by home gardeners and market gardeners as a dual-purpose cultivar that can be used to produce both fresh-shell peas and immature, fresh pods or snaps. Typical ready-to-harvest WhipperSnapper snaps are green colored, 6.4 mm in diameter, 7.6 mm in height, and 24 cm long; the pods are slightly curved at the attachment end. Typical mature-green pods suitable for fresh-shell harvest exhibit an attractive yellow color, are 25 cm long, and contain 14 peas. Fresh peas are cream-colored, kidney-shaped, and weigh 24.5 g/100 peas. Dry pods exhibit a light straw color, and the dry peas have a smooth seed coat. The quality of WhipperSnapper seed is excellent. In replicated field trials, WhipperSnapper produced significantly greater yields of both snaps and peas than the snap-type cultivar Bettersnap. WhipperSnapper has potential for use as a mechanically-harvested source of snaps for use by food processors in mixed packs of peas and snaps. Protection for WhipperSnapper is being sought under the Plant Variety Protection Act.