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Tadashi Higaki, Joanne S. Imamura and Robert E. Paull

The optimum fertilizer levels of N, P, and K for flower production of field-grown Anthurium andraeanum Andre in Hawaii were determined. Applications were at 0, 224, and 448 kg·ha-1·year-1 with all combinations of each nutrient level. Optimum flower production was achieved at 312N-448P-375K kg·ha-l·year-1. Increased N and K application resulted in a linear increase in flower size. Flower stem length also increased with increasing N, P, and K rates. Maximum flower yield occurred when leaf-tissue levels were 1.87% N, 0.17% P, and 2.07% K. Flower stem length and flower size were at their maximum with leaf N at 1.59% and 1.67% and K at 2.20% and 1.86%, respectively. No relationship was observed between leaf percent P, flower size, or stem length. A range of leaf-tissue levels associated with optimum anthurium flower production was determined for Ca, Mg, B, Mn, Fe, Zn, Cu, and Mo).

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D.G. Mortley, P A. Loretan, A.A Trotman, P. P David, L.C Garner and G. W. Carver

The effects of altering, nutrient solution N:K ratio on growth of `TI-155' sweetpotato [Ipomoea batatas (L.) Lam] was evaluated in a greenhouse, as part of NASA's Closed Ecological Life Support Systems (CELSS) program for long duration space missions. Vine cuttings of `TI-155', were grown using nutrient film technique (NFT) in a modified half Hoagland's solution in channels (0.15×0.15×1.2 m). Plants were grown for 42 days in a culture solution in which N was doubled (6 mM) in order to accelerate foliage growth after which treatment N:K ratios of 1:2.4, (control) 1:4.8, and 1:7.2 were initiated. A randomized complete block design with 4 replications was used. The number of storage roots/plant increased linearly as K was increased in the solution. Storage root fresh and dry weights, growth rate (g m-2 d-1), fibrous root dry weight, foliage fresh and dry weights, and edible biomass index (root mass/total plant mass), though not significant all increased as K was increased in the nutrient solution. Nutrient solution analyses showed that K uptake was greatest in plants at the highest K level, while nitrate uptake was steady over the duration of crop growth regardless of treatments.

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George Hochmuth, Jeff Brecht and Mark Bassett

Carrot production in Florida has been centered in two major organic-soil vegetable production areas. These areas are the Everglades Agricultural Area near Belle Glade, in southern Florida, and the Zellwood vegetable area in central Florida. The state of Florida is currently in the process of purchasing most of the organic soils used for vegetable production near Zellwood, leading to a movement of vegetable production to the surrounding sandy soil or to other vegetable production regions in the state. The move to sandy soils has lead to questions by growers about fertilization of vegetables such as carrot. We conducted a series of fertilization experiments with `Nantes' and `Imperator' carrot to evaluate yields and carrot quality responses to N and K. Carrot yield was maximized with 170 kg·ha–1 N, confirming current extension recommendations for carrot on sandy soils in Florida. The soil used for the K study tested medium (50 mg·kg–1) in K (Mehlich-1 extracted). Carrot yield responded positively to K up to 50 kg·ha–1 K, near the amount predicted for soils testing N medium in K.

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David Studstill, Michela Farneselli, Eric Simonne and Bob Hochmuth

Petiole sap testing using ion-specific electrodes is a simple method that can be used to guide in-season applications of N and K to vegetable crops. This method requires petiole sampling and sap extraction using a sap press. Because some vegetables are grown with foliar applications of N and/or K and because some crops have large petioles, petioles may need to be washed and/or cut before being pressed. Because limited information is available on the effect of washing/cutting on sap testing results, muskmelon, bell pepper and tomato petioles were used to test if washing/cutting reduced NO3-N and K concentrations and changed the subsequent interpretation of plant nutritional status. Washing for 30, 60, or 120 seconds in distilled water and cutting petioles before or after washing significantly reduced sap concentrations (p = 0.01 and p = 0.04 for NO3-N and K, respectively) in 7 of 12 tests when compared to the control method (petioles cut and not washed). The average concentration reductions between the control and the lowest value among all the washing/cutting treatments were 30% for NO3-N and 19% for K. These losses due to washing/cutting are likely to change the diagnosis of nutritional status from “sufficient” to “less than sufficient” and therefore may suggest the need for unnecessary fertilizer applications.

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Thomas J. Burr, Cheryl L. Reid, Barbara H. Katz, Maria Elisabetta Tagliati, Carlo Bazzi and Deborah I. Breth

Agrobacterium radiobacter (Beijerinc and van Delden) Conn strain K-84 failed to control raspberry (Rubus idaeus L.) crown gall caused by A. tumefaciens (E.F. Smith and Townsend) Conn. Agrobacterium tumefaciens strains isolated from galls on plants that had been treated with K-84 were not sensitive to agrocin 84 in vitro. These strains were isolated from `Titan' and `Hilton' raspberry in New York state and from `Himbo Queen' and `Schönemann' raspberry in Italy. Almost all strains were identified as A. tumefaciens biovar 2. Raspberry crown gall was not controlled by K-84 in three field experiments in New York state. In two of the experiments, plants were produced by micropropagation and were known to be pathogen-free. The other plant source was shown to be contaminated with the pathogen before treatment with K-84. Crown gall was not controlled either on raspberry in a greenhouse experiment or on Kalanchoe diagremintiana (Hamet. and Perrier) plants that were coinoculated with K-84 and strains of A. tumefaciens isolated from galls on raspberry.

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John A. Biernbaum, William Argo and Janet Pumford

Unlike vegetable and fruit crops, where petiole analysis has been used for many years, root media analysis is the primary method of checking fertility status of container-grown flowering greenhouse crops. With the emphasis on lower constant water-soluble fertilizer rates to prevent nutrient runoff, petiole analysis may be a better indicator of N and K status. During Fall 1993, samples were collected from 10 flowering pot plant species subirrigated with either 50, 100, or 200 mg·liter–1 N and K concentrations. During Spring 1995, samples were collected from major bedding plant species and Easter lilies. Sap was extracted using a hydraulic press and nitrate and potassium were measured with the Cardy flat electrode ion meters. Sampling methods and protocols will be presented with results of sampling technique experiments. Floriculture plant nutrition researchers were contacted to identify other research in progress, potential applications, and possible concerns with using this technique. Further research needed will be identified.

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J. A. Wolpert and M. M. Anderson

Petioles were gathered at three times during the season: bloom, veraison, and harvest, in two trials `Chardonnay' (Ch) and `Cabernet Sauvignon' (CS). In each trial, scions were grafted onto 14 rootstocks. Petioles were analyzed for NO3-nitrogen, %N, and %K. Averaged over rootstocks, CH petiole NO3 levels were highest at harvest and lower at both bloom and veraison. A similar trend was seen in `Cabernet Sauvignon', although, on average, NO3 levels were higher on all sampling dates. In Ch, the rootstocks `Ramsey', `St George', and `110R' were among the highest in NO3, while Harmony and 1616C were among the lowest. In CS, O39-16 was among the highest in NO3, while 44-53M was among the lowest. In both cultivars and among all rootstocks, petiole NO3 was positively correlated with petiole %N in Ch, petiole K declined throughout the year, while in CS most rootstocks were relatively stable. In Ch, the rootstocks `Harmony', `1616C', and `44-53M' had high levels of K, while in CS `44-53M' was among the highest.

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Jinsheng Huang* and Sieglinde Snapp

Potassium (K) and boron (B) nutrition play an important role in control of tomato quality. To evaluate the interactive effects of K and B on yield and fruit quality in fresh market tomatoes, two-year field experiments were conducted in 2002 and 2003 in Southwest Michigan, using the industry standard cultivar `Mountain Spring' and recommended practices for irrigated, staked fresh market production. Six treatments evaluated three fertilizer regimes applied during fruit development (1N:1K, 1N:2K and 1N:3K) and two weekly B foliar sprays (none and 300 mg·L-1 B) at fruit set stage. Increasing K concentration in the fertilizer increased K content in both leaf and fruit tissue, but reduced calcium content in leaf tissue. 1N:3K fertilizer treatment increased tomato shoulder check incidence. The overall total percent shoulder check defect was 32.7%, 33.5% and 38.2% for 1N:1K, 1N:2K and 1N:3K fertilizers, respectively. Weekly B foliar spray increased both tomato marketable yield and fruit quality. Less shoulder check incidence was obtained with a foliar B spray. Boron foliar spray also increased K content in fruit tissue for 1N:1K and 1N:2K treatments. The 1N:2K plus B foliar spray is recommended for improving tomato yield and quality.

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Kimberly A. Williams and Paul V. Nelson

Soilless substrates have little capacity to sorb PO4. One way to reduce PO4 leaching during production is to increase the substrate retention of PO4. Adsorption isotherms were created at 25 C for alumina (aluminum oxide); the 2:1 calcined clays arcillite (montmorillonite plus illite) and attapulgite.; and a medium of 70 peat: 30 perlite using solutions of KH2PO4 at rates of P ranging from 0 to 20000 μg·ml-1. Material sorbed at the rate resulting in maximum P adsorption was then desorbed 22 times. Sorbing concentrations necessary to establish an equilibrium P concentration of 10 μg·ml-1 in the substrate solution were estimated from these curves. Materials were-charged with P at these estimated rates and evaluated in a greenhouse study in which each material was tested at 10 and 30% by volume of a 70 peat: 30 perlite substrate used to produce Dendranthema × grandiflorum `Sunny Mandalay'. Phosphate, K, and pH were determined on unaltered soil solutions biweekly throughout the cropping cycle and foliar analyses were determined on tissue collected at mid- and end-crop. Isotherm and greenhouse data indicated that alumina, arcillite, and attapulgite effectively retained and slowly released K as well as PO4 over time. Alumina was most effective at retaining P, sorbing 16800 μg/cc compared to 3100 and 7800 μg P sorbed/cc for arcillite and attapulgite, respectively, when sorbed at P concentrations resulting in an equilibrium concentration of approximately 10 μg P/ml.

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M.L. Witt, W.M. Fountain, R.L. Geneve and D.L. Olszowy

America the Beautiful and Urban and Community Forestry grant programs, part of the expanded Forestry Title of the 1990 Farm Bill, authorized funding to encourage citizen involvement in creating and supporting long-term and sustained urban and community forestry programs. U.K. Woody Ornamental scientists and the KY Division of Forestry Urban Forestry Coordinator planned and implemented the following educational programs to this end: 1) comprehensive training manual on Managing Trees in the Urban Environment, including a guide for the care and protection of trees, grant application, and managing of volunteers; 2) three publications on small, medium-sized, and large trees for urban spaces; 3) interactive hypertext version of tree selector publications; 4) statewide workshops on Trees in Communities; 5) annual statewide Urban Forestry Short Course; 5) Plant Health Care and Hazard Trees workshops for arborists. The comprehensive program brings city planners, government personnel, public work's personnel, arborists, builders and developers, horticulturists and landscape architects, tree board members, homeowners' associations, Master Gardeners, and other community volunteers together to support quality programming for preservation and enhancement of valuable natural resource of trees.