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  • Author or Editor: S.D. Nelson x
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Abstract

The effect of donor plant photoperiod on subsequent in vitro adventitious bud production of Begonia × hiemalis (Fotsch) cv. Schwabenland Pink was monitored by sampling petiole explants from plants maintained in either short- (8 hr, SD) or long-day (16 hr, LD) photoperiods. Adventitious bud production on SD and LD explants was similar for the first 28 days of treatment. A subsequent loss of regenerative capacity occurred in SD explants and was associated with the changing physiological status of the donor plant. Maintaining donor plants in LD increased bud production and extended the time during which the donor plants could be used effectively in commercial micropropagation programs.

Open Access

Where coarse-textured materials, such as gravel, underlie the root-zone layer of sports turf soil profiles, water retention in the root-zone layer is increased. The objective of this research was to determine the water retention characteristics in sand and sand: peat mixtures placed over coarse-textured layers and to determine how sand particle size and type of peat in the mixtures influenced water distribution after drainage. Soil profiles consisted of 30 cm of sand or sand: peat mixtures over 5 cm of predominantly coarse and very coarse sand, which in turn was over 10 cm of gravel. Excess water was added to the profile and allowed to drain for 24 or 48 h, following which water content and air-filled porosity (AFP) in the mixtures were evaluated. Regardless of the root-zone mixture, the coarse-textured sublayers resulted in a wet zone in the lower portion of the root-zone mixture. An unamended, predominantly medium and coarse sand, when used in the 30- cm root-zone layer, maintained ≈10% AFP in the lower 6 cm after drainage. Sand: peat mixtures using this sand generally maintained 3% to 8% AFP in the lower 12 cm of the root-zone layer. An unamended, predominantly fine and medium sand root-zone layer had ≈6% AFP in the lower 9 cm and sand: peat mixtures using this sand had <5% AFP in the lower 12 to 18 cm of the root-zone layer, with significant portions remaining at or near saturation after 24 or 48 h of drainage.

Free access

One of the proposed alternative chemicals for methyl bromide is 1,3-D. The most common forms of 1,3-D products are cis- or trans-isomers of 1,3-D with the fungicidal agent, chloropicrin, containing such mixtures as 65% 1,3-D and 35% chloropicrin (C-35). Soil fumigants are commonly applied under a polyethylene film in Florida raised bed vegetable production. Much of the research regarding cropping system effects of alternative fumigants to methyl bromide has focused primarily on plant growth parameters, with little regard to the atmospheric fate of these chemicals. The objective of this research was to determine both the atmospheric emission of 1,3-D under different plastic film treatments and to evaluate effects of application rates of 1,3-D and C-35 on plant pests, growth, and yield of Sunex 9602 summer squash (Cucurbita pepo L.). Results showed that use of a high barrier polyethylene film (or virtually impermeable film - VIF) greatly reduced fumigant emission compared to ground cover with conventional polyethylene films or uncovered soil. Summer squash seedling survival was a severe problem in several of the 1,3-D alone treatments where no fungicidal agent was added, whereas C-35 resulted in excellent disease control at both full and one-half of the recommended application rates for this chemical. Both 1,3-D and C-35 provided good plant stands and higher yields when applied at their recommended application rates. However, all squash yields were lower than typical squash production levels due to late planting and early winter frost kill. Chemical names used: 1,3-dichloropropene (1,3-D); trichloronitropropene (chloropicrin).

Free access

Methyl bromide (MeBr) is an important and effective soil fumigant commonly used to control weeds and soilborne pests. Because MeBr has been implicated as a contributor to the depletion of stratospheric ozone, it is scheduled for phaseout by 2005. This study examined nonchemical and chemical practices as alternatives to MeBr. Off-season flooding followed by a series of soil preplant chemical treatments [MeBr with 33% Pic; 1,3-D mixed with 17% (C-17) and 35% (C-35) Pic combined with Peb; and metam-Na combined with 1,3-D and Peb were evaluated on spring tomato (Lycopersicon esculentum Mill.) and eggplant (Solanum melongena) production in northern Florida. Pest control and tomato and eggplant yields were not significantly different between the flooded and non-flooded control plots. The most effective alternatives to MeBr were 1,3-D and Pic mixtures (C-17 and C-35) combined with Peb. Tomato and eggplant yields for these chemicals were statistically equivalent to that of MeBr. Tomato, but not eggplant, yield and nematode control were poor with metam-Na combined with 1,3-D and Peb in comparison to the other fumigant combinations. Chemical names used: 1,3-dichloropropene (1,3-D); trichloronitromethane [chloropicrin (Pic)]; S-propyl butyl(ethyl)thiocarbamate [pebulate (Peb)]; sodium N-methyldithiocarbamate (metam-sodium (metam-Na)].

Free access

Annual-hill strawberry (Fragaria ×ananassa Duch.) production with black plastic mulch and drip irrigation is gaining popularity in North Carolina. Two experiments (E1 and E2) were conducted on a Wagram loamy sand (Arenic Kandiudult) in 1992 and on a Norfolk sandy loam (Typic Kandiudult) in 1993 to investigate the effects of fall-applied N and spring-applied N and K on `Chandler' strawberry yield and fruit quality. E1 treatments included factorial combinations of banded fall-applied N (0, 34, and 67 kg·ha-1) and drip spring-applied N (0, 0.19, 0.37, 0.56, and 0.75 kg·ha-1·d-1 and 0, 0.37, 0.75, and 1.12 kg·ha-1·d-1 in 1992 and 1993, respectively). E2 treatments included combinations of drip spring-applied N (0.56, 1.12, 1.68, and 2.24 kg·ha-1·d-1) and K (0.46, 1.39, and 2.32 kg·ha-1·d-1 and 0, 0.75, 1.49, and 2.24 kg·ha-1·d-1 in 1992 and 1993, respectively). There were no significant interactions among main effects for any of the measured variables. Market yield maximized with total N at ≈120 kg·ha-1 with one-half banded in the fall and the remainder drip-applied in the spring. Fruit firmness decreased with increasing N rate. Fruit pH and concentrations of total acids and soluble solids were not affected by N treatments, but soluble solids increased as the harvest season progressed. Plant crown number was not affected by N treatment but crown yield increased with N rate similar to market yield. There was no response to drip-applied K for any variable in either year. Based on soil test, fall-applied K (broadcast-soil incorporated) met the K requirements both years.

Free access

Plant establishment and lateral growth of glyphosate-resistant creeping bentgrass [Agrostis stolonifera (synonym A. palustris)] were assessed to determine if the insertion of the construct conferring herbicide tolerance affected establishment rate or aggressiveness characteristics in unmowed situations. Field studies were carried out in Michigan, Illinois, Ohio, and Oregon in 2000 and 2001 to examine the relative lateral growth of several transformed lines of creeping bentgrass, non-transformed controls, and cultivar standards. Vegetative plugs of creeping bentgrass were transplanted into replicated bare-soil plots and irrigated as needed to prevent moisture stress for an initial 6-week period. Measurements of maximum and minimum stolon spread, percent cover, and stand density for each entry were made in the field at all locations during 2000 and 2001. Few statistical differences (P = 0.05) in establishment and lateral growth were observed between individual lines of transgenic creeping bentgrass, non-transformed control lines, and standard cultivars and over a 15- to 18-month period. Overall, lateral growth and establishment rate of transgenic lines were similar to their non-transformed parent and the standard cultivars tested. Transgenic creeping bentgrass lines should have no greater potential for lateral growth than conventional creeping bentgrass cultivars currently in use.

Full access

The results of six experiments conducted over 3 years were analyzed to develop a relationship between nutrient uptake rate and growth rate in hydroponically grown Dendranthema ×grandiflorum (Ramat.) Kitamura, cv. Fiesta. Plants subjected to two levels of CO, and three levels of irradiance in four greenhouses were periodically analyzed for growth and the internal concentration of 11 mineral elements. The resulting data were used to determine relative accumulation rate and relative growth rate, which were included in linear regression analyses to determine the dependence of uptake on growth. The regression equations were significant, with a slight trend toward nonlinearity in some elements. This nonlinearity seems to be related to the aging of the plant and suggests a process in the plant capable of controlling uptake rate, perhaps as a result of changes in the rate of formation of different types of tissues.

Free access

Abstract

The depletion of N applied to a moderately N-deficient Kentucky bluegrass (Poa pratensis L.) turf was measured using a soil sampling procedure. Nitrogen as either Ca(NO3)2 or (NH4)2SO4 was applied in solution at 5 g N/m2 and washed into the thatch and soil with an additional 0.3 cm of water. Both N forms were located primarily in the thatch and upper 1 cm of soil. The NO 3 was present in the soil solution, while the NH 4 + was mainly exchangeable (86%). The concentrations of NO 3 and NH 4 + in the soil solution were 452 and 56 μg N/ml, respectively, in the upper 1 cm of soil. Depletion of both NO 3 and NH 4 + from the turf was very rapid, with 70% to 80% of the applied N disappearing during the first 24 hr. Essentially all of the applied N was depleted by 48 hr. Results using (l5NH4)2SO4 indicate that ≈75% of the NH 4 + depletion is attributable to absorption by the turf. Similar results were obtained following fertilization of perennial ryegrass (Lolium perenne L.), tall fescue (Festuca arundinaceae Schreb.), and creeping bentgrass (Agrostis palustris Huds.).

Open Access

Abstract

Succinic acid-2,2-dimethylhydrazide (daminozide) applied to ‘Raven’ blackberries at 4000 ppm and to ‘Raven’ and ‘Brazos’ at 2000 ppm between full bloom and first color development and at 2000 ppm in a multiple application applied at full bloom, 2 weeks, and 3 weeks after full bloom resulted in reduced berry size and yield with no beneficial effects on fruit quality. (2-Chloroethyl) phosphonic acid (ethephon) applied to the same cultivare at 1000 ppm 4 days prior to the first harvest increased the amount of fruit mechanically harvested on the first harvest. Ethephon treatment improved color but resulted in mechanically harvested fruit having lower soluble solids and acidity.

Open Access

Abstract

The development of a mechanical harvester for erect blackberries is traced from its inception to commercialization. The harvesting and production system tested in this study required productive, erect cultivars that are mechanically pruned to form continuous hedgerows. An acceptable processed product is obtained from the system.

Open Access