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- Author or Editor: John C. Peterson x
Abstract
The floriculture and ornamental nursery crop production industries have implemented significant modifications in cultural technologies within the past 2 decades. This resulted from efforts to enhance crop quality and productivity and to reduce production costs.
Horiba Cardy compact pH, Electrical Conductivity (E.C.), Nitrate (NO3), Sodium (Na), and Potassium (K) meters were used to monitor the nutrient content of solutions extracted from five organic potting media. Solution extracts were collected using the Saturated Extract Method (SEM). Duplicate samples were sent to three analytical labs for comparative purposes. The meters proved to be quick and easy to use and there was good to excellent agreement with lab value for pH, E.C., Na and K. The NO3 meter did not provide good values below 80 ppm. For higher values there was a good relationship to lab values. The standard deviation for meter values was low, as were lab values for all parameter. Results of cell sap measurements as a method for evaluating the nutritional status of plants will be presented.
Abstract
Rooted Pelargonium ×hortorum L.H. Bailey ‘Yours Truly’ and ‘Irene’ geranium cuttings were planted 15 Oct. in raised beds, 11.3 liter plastic pots, 85 liter poly bags, or nutrient film systems within 2 double poly greenhouses. In one greenhouse, high pressure sodium (HPS) lamps supplemented natural light (86 µmol s-1m-2 ± 10 µmol s-1m-2) from 0800 to 2400 hr and in the other greenhouse light was not supplemented. Ambient carbon dioxide levels were enriched with an additional 300–600 ppm of carbon dioxide during daylight hours in the greenhouse without supplemental lighting and during lighted hours in the greenhouse equipped with HPS lights. Cutting number, dry weight, basal stem caliper, and the length of roots produced on harvested cuttings were recorded from 18 Nov. to 3 Jan. There were no differences among cultural systems for any of the parameters measured under natural daylight conditions. When supplementary HPS lighting was utilized, differences in number of cuttings produced and cutting dry weight were apparent, with NFT grown stock plants being the most productive. Growth differences between cultivars were evident for all parameters measured. Treatment of the stock plants was not observed to affect rooting response of cuttings.
Sphagnum peat was blended with CaCO3 or Ca(OH)2 and incubated for 3 weeks at 20C to achieve a pH of ≈ 4.4, 5.4, 6.2, or 7.3. An unlimed control had an initial pH of 3.5. Urea was added to medium treatments at the rate of 125 μg urea-N/cm3. Samples were incubated at 20 ± 1.0C. Medium pH, urea-N,
Abstract
Leaf abscission was promoted in Ficus benjamina L. (weeping fig) by withholding water from plants growing in sand and by the addition of polyethylene glycol 6000 to hydroponically-grown plants. Leaf shedding occurred when plant water potential decreased below about −6 bar in sand and below −3.5 bar in water culture. Shoot and root environmental conditions modified the water status of plants. Leaf shedding can be dramatically reduced by manipulating environmental conditions to maximize water absorption and minimize transpiration.
Abstract
Relationships were examined among water deficits, ABA content of leaf tissue, and leaf abscission in intact Ficus benjamina L. (weeping fig). Water deficits were imposed by withholding water from plants growing in sand and by raising the osmotic potential of water culture solutions through the addition of PEG 6000. Unconjugated ABA was quantitatively analyzed using gas chromatography. A strong inverse linear correlation existed between ABA content of leaves and plant water potential. No relationships between ABA content and leaf abscission were observed. ABA content in leaves collected from plants growing in a greenhouse, having a plant water potential of −0.5 bar, was about 75 fold greater than the ABA content of leaves collected from plants maintained in a controlled environment room, having plant water potentials of −8.0 bar. Results indicate that ABA does not independently regulate leaf abscission in Ficus benjamina.
Abstract
A container growing medium of 2 peat : 1 perlite (v/v) was limed with 0, 0.9, 1.8, 2.7, 3.6, 5.4, 7.2, and 9.0 kg·m–3 dolomite. Media were irrigated with water, providing alkalinity equivalent to 0, 38, and 371 mg·liter–1 CaCO3. Samples were incubated at 25° ± 3°C and pH determined at days 2, 5, 7, 14, 28, 56, and 84. Irrigating with even moderately alkaline water over three months increased pH substantially above levels resulting from dolomite amendments alone.
Abstract
Spagnum peat, perlite, vermiculite, and six media formulated (by volume) from these constituents (2:1, 1:1, 1:2 peat: perlite; 2:1, 1:1, 1:2 peat: vermiculite) were limed with 0, 0.9, 1.8, 2.7. 3.6, 5.4, 7.2, and 9.0 kg∙m−3 dolomite [CaMg(CO3)2]. Media were wet to container capacity with distilled/deionized (d/d) water, incubated at 25° ±3°C, and pH determined at day 0, 2, 5, 7, 14, 28, 56, and 84. Liming reactions in mixes could not be predicted from reactions occurring in sphagnum peat, perlite, and vermiculite constituents alone. Although sphagnum peat made the major contribution to liming reactions, both perlite and vermiculite were found to contribute to liming responses of media in which they were incorporated. The major portion of pH change due to incorporation of pulverized dolomite in peat-based media occurred within 2 days. Change in pH was complete within 14 days.