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  • Author or Editor: B.K. Harbaugh x
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C.D. Stanley and B.K. Harbaugh

A study was conducted to determine the effect of water table depth on water use and tuber yields for subirrigated caladium (Caladium × hortulanum) production. A field-situated drainage lysimeter system was used to control water table depths at 30, 45 and 60 cm (11.8, 17.7, and 23.6 inches). Water use was estimated by accounting for water added or removed (after rain events) to maintain the desired water table depth treatments. In 1998, tuber weights, the number of Jumbo grade tubers, and the production index (tuber value index) of `White Christmas' were greater when plants were grown with the water table maintained at 30 or 45 cm compared to 60 cm. In 1999, tuber weights, the number of Mammoth grade tubers, and the production index, also were greater when plants were grown at water table depths of 30 or 45 cm compared to 60 cm. The average estimated daily water use was 6.6, 5.1, and 3.3 mm (0.26, 0.20, and 0.13 inch) for plants grown at water table depths of 30, 45, and 60 cm, respectively, indicating an inverse relationship with water table depth. While current water management practices in the caladium industry attempt to maintain a 60-cm water table, results from this study indicate that, for subirrigated caladium tuber production, the water table should be maintained in at 30 to 45 cm for maximum production on an organic soil.

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C.D. Stanley and B.K. Harbaugh

Methodology was developed to estimate water requirements for production of 20 different potted ornamental plant species with practical application for water conservation in commercial operations. Water requirement prediction equations were generated using pan evaporation to estimate evaporative demand along with plant canopy height and width and flower height as input variables. Coefficients of determination (R2) for the prediction equations among plant species ranged from 0.51 to 0.91, with the lower values mostly associated with plant species with an open or less-uniform growth habit. Variation in water use among different cultivars of marigold also was associated with differences in cultivar growth habit. Estimation of the daily water requirements of potted Reiger begonia and Ficus benjamina using their developed prediction equations was compared to actual water use under common growing conditions to demonstrate the implementation of the method for plant species differing in growth habit.

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B.K. Harbaugh and S.S. Woltz

Foliar chlorosis or bleaching, interveinal chlorosis, leaf edge and tip necrosis, a poor root system, and stunted growth of Eustoma grandiflorum (Raf) Shinn seedlings were associated with a medium pH of 5.0 or 5.5 but not when the values ranged from 6.4 to 7.5. The range in medium pH resulting in the best growth of seedings and flowering plants was 6.3 to 6.7. Responses to medium pH were similar, regardless of fertilizer solution pH or cultivar. Eustoma seedling and shoot fresh weights for pH 5.0 and 5.5 were only 23% to 66% of corresponding values for plants grown at pH 6.4. Leaf tissue Zn was extremely high (1050 mg·kg-l dry leaf tissue) at a medium pH of 5.0, but other macro- and micronutrients in leaves were not at abnormal levels.

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J.W. Scott and B.K. Harbaugh

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Brent K. Harbaugh, John W. Scott and David B. Rubino

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Brent K. Harbaugh, John W. Scott and David B. Rubino

Seedlings of commercial lisianthus cultivars form rosettes when grown at 25 to 28°C. Rosetted plants have a basal cluster of leaves, very short internodes typical of biennials, and do not bolt or flower for months without being exposed to 3 to 4 weeks at <15 to 18°C to reverse heat-induced rosetting. Semirosetted plants develop when seedlings are grown at a constant 22 to 25°C or at <22°C night with >28°C day. Semirosetted plants have one or more side shoots which may elongate and flower, but plants flower unpredictably and are of poor quality as cut flowers or potted plants. `Maurine Blue' and Florida Blue' were released from the Univ. of Florida in 1995. To our knowledge, they are the first heat-tolerant lisianthus cultivars. Seedlings and plants can be grown at 28 to 31°C without rosetting. `Maurine Blue' ranged in height from 38 cm (summer) to 67 cm (spring) during 1994 and 1995 production trials in Florida. `Maurine Blue' has potential for use as a tall bedding plant if sold as green transplants, a flowering potted plant if grown with three plants per 15-cm-diameter pot with a growth retardant, or as a bouquet-type cut flower. `Florida Blue' plants (38 cm) grown in an 11.5-cm square pot (0.65-L) with capillary mat irrigation were similar in height to `Blue Lisa' (32 cm) and taller than `Little Belle Blue' (22 cm) and `Mermaid Blue' (24 cm). `Florida Blue' was designated as a semi-dwarf cultivar with an intended use as a bedding plant. Growth retardants would be useful for production in pots <10 to 12 cm in diameter. Complete descriptive information, photographs and pedigrees will be presented.

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J.W. Scott, B.K. Harbaugh and E.A. Baldwin

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Brent K. Harbaugh, B.D. Miranda and G.J. Wilfret