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  • Author or Editor: D.R. Edwards x
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A concern with the greenhouse production of horticultural commodities, particularly those grown in the ground, is the difficulty in managing nutrient runoff. Alstroemeria, a heavy-feeding crop that is nearly always grown in soil, were planted into 26.5-L pots with a medium of LECA. Greenhouse experiments were designed to examine flowering stem production, quality, and nutrient flux under nutrient solution reuse (closed system) and with one of three levels of nutrition (EC of 2.1, 1.6 and 1.1 mS/cm). Plants in the closed treatments were set on troughs sloped towards separate 24-L reservoirs. The control was an open drainage system fed at 2.1 mS/cm. The reservoirs were kept at a constant volume with the addition of water after every irrigation; nutrients were added to restore the EC to demand levels. Stems were harvested twice per week and the nutrient content of the reservoirs were analyzed biweekly by ion chromatography. Data were analyzed as an RCBD with four treatments and blocks. Analysis of data from the preliminary experiment (29 May to 3 Aug. 1998) indicated number of stems and cymes were similar among treatments. Stem length, dry weight, and number of florets were depressed below the control only in lowest fed treatment. Nutrient application was reduced markedly, by up to 1000-fold in the closed vs. the open production system.

Free access

Two studies were conducted to evaluate recycled newspaper mulch for landscape plantings. In the first study, two paper products (pellets and crumble) were tested at three depths. Application of either 25 or 50 mm provided excellent control of prostrate spurge. Of the four annuals grown, ageratum exhibited severe stunting of roots and shoots. In the second study, three annual species were mulched with the two recycled paper products applied at 25 mm each and adjusted with P at 0, 3.75, or 7.5 ppm to bind excess Al. When no P was added, ageratum growth was about half that of the control plants. Addition of P at either rate resulted in similar growth compared to control plants. Marigold and geranium were less affected by recycled paper mulch; however, when P was added growth was always similar to nonmulched control plants.

Free access

The effects of mechanical fruit thinning on pecan [Carya illinoinensis (Wangenh.) K. Koch] yield, nut quality, and profitability were assessed using ‘Sumner’ and ‘Cape Fear’ pecan trees cultivated in a commercial orchard. The moderate to light production year (OFF year) return crop and return crop value of ‘Cape Fear’ and ‘Sumner’ was increased by mechanical thinning in the year of high production (ON year). This enhanced the 2-year total value and 2-year average value of both cultivars. Increased profitability of these cultivars with mechanical fruit thinning results primarily from higher yields and prices in the OFF year of production, which offset any loss in yield and/or crop value generated by fruit thinning in the ON year. Premature germination of ‘Cape Fear’ pecans was reduced from 34% to 4% with mechanical fruit thinning. Mechanical fruit thinning appears to be a highly valuable practice, leading to increased profit potential for ‘Cape Fear’ and ‘Sumner’ pecan.

Free access

Abstract

Three cucumber (Cucumis sativus L.) populations were evaluated to determine the effects of several seed harvesting and handling procedures on seed quality. Fruit maturity at seed harvest, fermentation duration in seed extraction, seed storage time, and germination temperature all significantly influenced germination percentage and rate. About 30% of the observed variation in germination percentage was due to interactions between handling factors rather than to main effects of factors. Although germination in excess of 90% was observed for some combinations of factors with as little as 28 days of fruit maturity (post-pollination), the advantages of greater seed maturity at harvest were evident for rate of germination and tolerance to long fermentation times. Positive responses to short fermentation durations (≤4 days) occasionally were observed, but longer fermentation durations were markedly deleterious under some conditions. Six months of seed storage were effective in improving germination of seed at 15° and 20°C, but had little effect on germination at 25°. The 3 cucumber populations were markedly different in response to some seed handling factors.

Open Access

Excessive moisture is a problem in evaluating recycled paper products as mulch to replace other common mulch materials and in landscape and container uses. To isolate the water associated with soil and/or media, two recycled paper products, pellets or crumble, were used as mulches in trade gallon containers in a greenhouse. Pine bark, pellets, and crumble needed to obtain standard mulch depth were enclosed in plastic mesh. These mulches were placed in containers that contained 1 kg of a 7 pine bark : 1 sand media. All containers were saturated with tap water for 24 hours. Mulches were placed on each container and allowed to drain for 1 hour. Weights of media, mulch, and media and mulch were obtained every 24 hours for a total of 312 hours. Water content of the media was not influenced by any of the mulch treatments. Water content of the paper products was increased by a factor of two. Pine bark mulch water content was zero 96 hours after an initial dry down cycle began, while the water content of pellet and crumble were 100 and 90 cm of water. Total water content of the media plus the mulch was increased by 30% to 35% when compared to pine bark mulch alone. However, the increase was associated with the water content of the waste paper mulch.

Free access

`Riesling' grapevines (Vitis vinifera L.) were subjected for 4 years (1987-90) to three shoot densities (16, 26, and 36 shoots/m of row) combined with three crop-thinning levels (1, 1.5, and 2 clusters/shoot) in a factorialized treatment arrangement. Weight of cane prunings per vine (vine size) decreased linearly with increasing shoot density and clusters per shoot. Cane periderm formation (in terms of percent canes per vine with >10 ripened internodes) was inhibited by increased shoot density, while vine winter injury (primarily bud and cordon) increased slightly in a linear fashion with increasing clusters per shoot. Canopy density and leaf area data suggested that fruit clusters were most exposed to sunlight at a shoot density of 26 shoots/m of row due to reduced lateral shoot growth and a trend toward slightly smaller leaves. Yield, clusters per vine, and crop load (yield per kilogram of cane prunings) increased with increasing shoot density and clusters per shoot, while other yield components (cluster weight, berries per cluster, and berry weight) decreased. Soluble solids and pH of berries and juices decreased with increasing shoot density and clusters per shoot, but titratable acidity was not substantially affected. Free volatile terpenes increased in berries and juices in 1989 with increasing shoot density, as did potentially volatile terpenes in 1990. Shoot densities of 16 to 26 shoots/m of row are recommended for low to moderately vigorous `Riesling' vines to achieve economically acceptable yields and high winegrape quality simultaneously.

Free access

Abstract

Application of limestone to a Cahaba sandy loam increased exchangeable soil Ca and decreased extractable soil Al and Mn. Leaf tissue composition of ‘Calhoun Gray’ and ‘Dixielee’ watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] was significantly influenced by soil pH. Increased levels of limestone significantly increased tissue Ca and reduced tissue Al and Mn concentrations. High soil acidity was closely associated with high tissue Mn in both cultivars. Tissue Al levels were not as sharply reduced by increasing soil pH as were tissue Mn levels. Tissue Al influences on yield were not significant in either cultivar at any soil pH. In nonlimed plots, ‘Calhoun Gray’ tissue Mn was highly correlated with depressed crop yield, while ‘Dixielee’ produced no marketable fruit at soil pH 5.0. Foliar Mn toxicity symptoms were observed on the 2 cultivars at soil pH 5.0. Maximum watermelon yield was obtained at soil pH 6.0 on plots that received 112 kg N/ha.

Open Access

Abstract

‘Redglobe’ peaches (Prunus persica (L.) Batsch) were grown under drip irrigation and no irrigation, with and without fumigation with 1,2–dibromo–3–chloropropane (DBCP). The irrigation treatments were 1) nonirrigated, 2) irrigated until harvest, 3) irrigated from harvest to dormancy, 4) irrigated all season. Fumigation increased trunk cross-sectional area by 18 cm2, and when postharvest water was applied the increase was 25 cm2 at the end of 1978. Irrigation increased marketable yields of fresh peaches from 3.6 to 7.4 MT/ha (62-150 bu/acre) in 1977. In 1978, fumigation did not increase yields unless preharvest water was applied; then, yields were increased from 12.1 to 17.2 MT/ha (232-357 bu/acre). Fumigation apparently increased water use as indicated by the increased rate of controlled water application. Fumigation reduced populations of Macroposthonia xenoplax (Raski) DeGrisse and Loof, from a range of 30-400 to a range of 1-30 nematodes/150 cm3 of soil.

Open Access

Abstract

‘Redglobe’ peaches [Prunus persica (L.) Batsch] were grown under drip irrigation. Applications of NH4NO3 through the irrigation system were compared with broadcast applications. Soil pH, where NH4NO3 was applied through the irrigation system, decreased in the top 30 cm from 6.2 to 3.7 pH in the zone wetted by emitters that had been in place for 2 years, and from 6.2 to 4.5 pH in the zone where emitters had been in place for 6 months. Aluminum concentration in wetted zones increased from 0.01 to 1.45 meq/100 g of soil after 2 years and from 0.02 to 0.73 meq/100 g of soil after 6 months of NH4NO3 application through drip irrigation. Soil Ca and Mg concentrations were reduced in both wetted zones, but the greatest decrease occurred in the 2-year emitter site. The addition of NH4NO3 in the irrigation water substantially reduced root growth in the vicinity of the emitters, irrigation water application, and fruit yield, because of the high A1 concentration in the wetted zone.

Open Access