Search Results

You are looking at 1 - 10 of 22 items for

  • Author or Editor: B.W. Roberts x
Clear All Modify Search

Easter liliy (Lilium longiflorum Thunb. `Nellie White') bulbs were stored in moist peatmoss for up to 85 days at – 1.0 or 4.5C. Bulbs were periodically removed from storage and analyzed to determine levels of soluble carbohydrates and starch. Storage at – 1.0C induced large accumulations of sucrose, mannose, fructose, and oligosaccharide in both mother and daughter scales. Starch concentration declined substantially during this period. Storage at 4.5C resulted in less dramatic alterations in bulb carbohydrates, although trends toward increased soluble carbohydrates and reduced starch levels were seen. The accumulation of mannose suggests that glucomannan, a secondary storage carbohydrate, was also degraded during – 1.0C storage.

Free access

Raised beds approximately 20 cm tall by 76 cm wide were formed on 1.8 m centers in the spring of 1988 and 1989. Beds were either left bare or seeded with rye (Secale cereale) or hairy vetch (Vicia villosa) at 84 or 45 kg ha-1 respectively. All plots were sprayed with glyphosate in August of each year. In 1988, a 30 cm strip was tilled in the center of each bed. In 1989, there was no tillage or mowing.

The design was a randomized complete block with four levels of nitrogen (45, 90, 134, and 179 kg ha-1) at each soil cover. Broccoli seedlings were transplanted in double rows on 30 cm spacings into the plots each year in late August.

Height of the raised beds was maintained with both rye and vetch. Broccoli yields were highest in the bare soil treatments In 1988, the lowest yield was with vetch, and in 1989 the lowest yield was with rye. There was a positive linear yield response to nitrogen. The number of heads harvested did not differ significantly between soil covers

Free access

Bell pepper (Capsicum annuum L.) was grown in 1989, 1990, and 1991. Cultural modifications were used in an effort to alleviate heat stress, improve fruit set, reduce sunscald, and improve yield quantity and quality. Treatments included bare soil, plastic mulch (both black and white), straw mulch, living rye (Secale cereale) mulch, and row covers (white and black) suspended above the foliage. Soil temperature at 2.5, 10, and 20 cm, soil moisture at 20 cm, and yield parameters were recorded. In general, plots containing white rowcovers produced good yields each year, straw mulched plots produced good yields two out of three years, plots with black plastic mulch gave poor yields two out of three years, and plots with living rye gave consistently poor yields. Yield inconsistency from year to year was correlated with, and can be explained by, soil temperatures. Sunscald was reduced by rowcovers.

Free access
Authors: and

Soil conditions may not be adequate for uniform yields when perennial pasture is converted to vegetable production. This occurred with `Pip' bell pepper (Capsicum annuum var. annuum L.) planted in a 0.17-acre field 3 years after conversion from perennial pasture. Depths of the A-horizon and pH levels, as well as concentrations of N, P, and K were variable throughout the field when sampled after the last harvest. Marketable yields from plots established in the field ranged from 4.1 to 14.5 tons/acre. The A-horizon depth, soil pH, and residual N, P, and K levels were correlated with yield at specific A-horizon depths and pH levels. An intensive soil-testing regime likely will be required so that nutrient levels can be maintained to support bell pepper production on soil converted from perennial pasture.

Free access

Phosphorus was either banded, broadcast, or incorporated into raised beds at 33, 66, 99, or 132 kg·ha-1. Sweet corn was planted in two rows 30 cm apart on the beds. Substantial differences in plant growth were observed between the two rows on each bed. Yield response to P treatments was masked by this variability. Plant tissue samples were collected at mid-season and at harvest time, and were analyzed for P, K, Ca, Mg, Zn, and Fe. Strong positive correlations were found between corn yield and plant Fe content, and strong negative correlations were found between corn yield and plant Zn content. Phosphorus content of tissue was positively correlated with plant Fe and negatively correlated with plant Zn content. Differences in plant height measured at mid-season could not be explained by nutrient concentrations in the tissue at that time. Corn ear yield was best explained by Fe concentration of the shuck (positive correlation), and by zinc concentration of the foliage (negative correlation) at harvest time. The range in ear weight was greater with the banded P treatments than with broadcast or incorporated P.

Free access

Drip irrigation systems are used extensively by commercial vegetable producers. Such systems permit precise water placement and efficient water utilization. Emitters in drip irrigation lines can easily become clogged if water supplies contain solid particles. Most farm water is not suitable for drip irrigation unless filters are used to remove solid particles from the water. Small scale or part time vegetable producers often find the cost of conventional filter systems to be a substantial financial investment.

A filter which is small, lightweight, and portable was designed, built, and tested. The system is constructed from standard hardware and plumbing materials that can be purchased for less than $50. Construction time is four hours or less. The filter system works well for small scale operations that require low flow rates of water.

Specifications for construction, including a materials parts list and construction details will be presented.

Free access
Authors: and

Solid particles in water such as sand, silt, clay, or organic debris can clog drip irrigation systems. Filters that remove these particles from the water are necessary, but expensive, for small-scale or part-time farmers. A falter that is functionally similar to commercial units can be built from a steel barrel and common plumbing supplies for about $100. Components and instructions to build such a falter are presented here.

Full access

Abstract

The effects of reduced irradiance on dry weight partitioning in Easter lilies was examined by forcing vernalized bulbs of Lilium longiflorum Thumb. ‘Nellie White’ during two growing seasons. Forcing commenced in a glasshouse under standard growing conditions; immediately following flower bud initiation (FBI), plants were transferred to a range of irradiance reduction treatments (0%, 20%, 50%, or 85% reduction) in the greenhouse or to complete darkness in a growth chamber. Greenhouse irradiance reduction treatments resulted in alterations in whole-plant source-sink relationships. Total plant dry weight and overall plant quality were reduced in shaded plants. The depletion rate of mother bulb dry matter was not affected by reduced irradiance, whereas daughter bulb reserve loss was increased by irradiance reduction treatments. There was no daughter bulb reserve remobilization in plants grown in complete darkness after FBI. Flower bud and open flower dry weights were progressively reduced as irradiance was reduced. With an 85% irradiance reduction, plants forced from 17.5-cm bulbs had 63% bud abortion, whereas, with 20.0-cm bulbs, only 12% of the buds aborted. Plants grown in complete darkness after FBI became etiolated, and flowers failed to open. These results demonstrate differences in the ability of various morphological regions of the bulb to respond to reductions in greenhouse irradiance. Since the daughter bulb response to reduced irradiance was relatively slow, additional remobilization of dry matter from the daughter bulb is probably of minimal benefit during short periods of reduced irradiance in commercial greenhouses.

Open Access

Abstract

Changes in carbohydrate types and quantities in the bulbs, stems, leaves, and buds of Easter lilies (Lilium longiflorum Thunb. ‘Nellie White’) forced under ambient or reduced irradiance conditions were investigated. Analysis by high-performance liquid chromatography (HPLC) revealed that sucrose is the dominant soluble carbohydrate in bulb tissues, with glucose, fructose, and mannose present at significantly lower concentrations. During growth of the flowering shoot, mother bulb reserves are preferentially used regardless of greenhouse irradiance. Beginning 40 days after planting, there was a steady decrease in mother bulb starch concentration until anthesis, 70 days later. Increased bulb sucrose, glucose, mannose, and fructose concentrations were correlated with the induction of starch breakdown and carbohydrate export. Under natural greenhouse irradiance conditions, daughter bulb carbohydrate reserves were not used, as starch and soluble carbohydrate concentrations remained constant. Irradiance reductions of 50% to 85% significantly reduced total carbohydrate concentration in leaves and floral buds and induced export from the daughter bulb, as evidenced by elevated levels of daughter bulb soluble carbohydrates and reductions in starch concentration. Dark-grown plants exhibited similar daughter bulb carbohydrate metabolism patterns as plants grown in full sun: starch was not hydrolyzed and soluble carbohydrates did not increase in concentration. Collectively, these results suggest 1) bulb export metabolism is characterized by elevated soluble carbohydrate concentrations, 2) there is a minimum irradiance requirement for carbohydrate export processes from the daughter bulb, and 3) reductions in greenhouse irradiance result in reduced carbohydrate levels in Easter lily leaves and flower buds.

Open Access

The pawpaw (Asimina triloba) is the largest fruit native to the U.S. and has potential as a new fruit crop. Few methods are available to clonally propagate pawpaw, with grafting or budding onto a seedling rootstock being the only currently feasible method. Developing new options for clonal propagation of pawpaw could help advance this growing industry. Layering has been used to clonally propagate other difficult to root tree species. The objective of this study was to examine trench layering as a method to clonally propagate pawpaw. A randomized factorial experiment was implemented to examine the roles of plant juvenility and auxin concentration on rooting in a greenhouse trench layering system. Seedlings were defoliated, tipped, and transplanted into trench layering beds at 3, 6, and 12 weeks after emergence. Shoots were etiolated, then girdled and treated with three levels of IBA (0, 5000, and 10,000 ppm). The main effects of age and IBA concentration significantly affected the percentage of shoots producing roots. Juvenility enhanced rooting, with 15% of the shoots of the 3-week-old pawpaw seedlings producing roots, compared to only about 5% of the 12-week-old seedlings rooting. Auxin application to shoots also promoted rooting, with 16% of IBA-treated shoots producing roots, compared to the untreated control, with only 2% of shoots producing roots. There was no significant difference in rooting percentage between the two concentrations of IBA. The treatment combination most successful at promoting root initiation was 10,000 ppm IBA applied to shoots of 3-week-old seedlings, with 31% of shoots rooting.

Free access