Elemental deficiencies of N, P, K, Ca, Mg, S, Fe, Mn, Cu, Zn, or B were induced in plants of Pentas lanceolata `Butterfly Red'. Rooted stem cuttings were planted in 4.87-L plastic containers and fertilized with a complete modified Hoagland's solution or this solution minus the element that was to be investigated. Plants were harvested to measure dry weights when initial foliar symptoms were expressed and later under advanced deficiency symptoms. Deficiency symptoms for all treatments were observed within 7 weeks. The most dramatic expression of foliar symptoms occurred with N (medium green young leaves with interveinal chlorosis on base and tip), S (spindle-like young and recently mature leaves), Cu (purple-brown roots and young leaves with downward pointed leaf tips), and B (multiple youngest leaves arising from shoot tip). At the initial stage, all nutrient-deficient plants had similar dry weights, when compared to the control. Dry weights of plants treated with solutions not containing P were significantly lower when compared to the control under an advanced deficiency. In order to help prevent the development of deficiencies, minimal critical tissue levels have to be determined for adaptation by the greenhouse industry for nutritional monitoring.
James L. Gibson, Jude Groninger, Sharon Wombles, and Kathryn Campbell
Brent K. Harbaugh
Interveinal chlorosis of lower (oldest) leaves followed by development of interveinal necrotic spots, marginal necrosis, downward cupping of leaves, and leaf abscission were symptoms of a disorder commonly observed during production of potted pentas. The disorder was determined to be an Fe toxicity problem associated with accumulation of extremely high levels of foliar Fe (649 to 1124 ppm). Cultivars varied in their response to soil-applied Fe-DTPA chelate solutions: `Starburst', `Mauve' and `Ruby Red' were very susceptible, `Pink Profusion' was intermediate, and `White', `Lavender Delight', and `Pink Rose' were resistant. Potted plant production in a root medium with an initial pH of 6.7 ± 0.1 and a end pH of 6.4 ± 0.2 reduced the accumulation of foliar Fe to levels ranging from 59 to 196 ppm and prevented development of significant visual symptoms for all Cultivars.
Timothy K. Broschat and Kimberly A. Klock-Moore
Areca palms [Dypsis lutescens (H. Wendl.) Beentje & J. Dransf.], spathiphyllums (Spathiphyllum Schott. `Figaro'), ixoras (Ixora L. `Nora Grant'), tomatoes (Lycopersicon esculentum Mill. `Floramerica'), marigolds (Tagetes erecta L. `Inca Gold'), bell peppers (Capsicum annuum L. `Better Bell'), and pentas [Pentas lanceolata (Forssk.) Deflers. `Cranberry'] were grown in a pine bark-based potting substrate and were fertilized weekly with 0, 8, 16, 32, or 64 mg (1.0 oz = 28,350 mg) of P per pot. Shoot, and to a much lesser extent, root dry weight, increased for all species as weekly P fertilization rate was increased from 0 to 8 mg/pot. As P fertilization was increased from 8 to 64 mg/pot, neither roots nor shoots of most species showed any additional growth in response to increased P. Root to shoot ratio decreased sharply as P fertilization rate was increased from 0 to 8 mg/pot, but remained relatively constant in response to further increases in P fertilization rate.
Michelle A. Grabowski and Dean K. Malvick
Plasmopara obducens , the causal organism of Impatiens Downy Mildew. Pentas lanceolata Graffiti Bright Red ® was not included in the field trial as a result of a crop failure at the nursery. Statistical analysis. Using Hartley’s Fmax test, it was
S.M. Scheiber, Richard C. Beeson Jr, and Sudeep Vyapari
sandy soils to decrease irrigation requirements. Materials and Methods Pentas lanceolata Schum. ‘New Look Red’ were obtained from a commercial nursery in 0.72-L containers and transplanted on 3 Sept. 2003 into 12 drainage lysimeters made from
Alan W. Meerow
Growth of Pentas lanecolata (Forssk.) Deflers `Starburst Pink' and Ixora coccinea L. `Maui' was compared in container media using sphagnum peat, sedge peat, or coir dust as their peat components. Growth index and top and root dry weights of both crops were significantly better in coir-based medium than sedge peat-based medium. Pentas grew equally well in coir- and sphagnum peat-based medium. Growth index and top dry weight of Ixora were significantly lower in the coir-based than the sphagnum peat-based medium, although root dry weights were equal. This difference was not apparent and may have been caused by N drawdown in the coir-based mix. The sedge peat-based medium had the highest air porosity and the lowest water-holding capacity of the three media at the initiation of the trials, but at the termination of the study, it showed a reversal of these characteristics. The coir-based medium showed the least change in these attributes over time. Coir dust seems to be an acceptable substitute for sphagnum or sedge peat in soilless container media, although nutritional regimes may need to be adjusted on a crop-by-crop basis.
Millie S. Williams, Terri W. Starman, and James E. Faust
The photoperiodic responses were determined for the following species: Bacopa speciosa `Snowflake', Bidens ferulifolium, Brachycome multifida `Crystal Falls', Helichrysum bracteatum'Golden Beauty', Lysimachia procumbens (Golden Globes), Pentas lanceolata `Starburst', Scaevola aemula `New Blue Wonder', Streptocarpella hybrid `Concord Blue', and Streptosolen jamesonii (Orange Browallia). Each plant species was grown at 8-, 10-, 12-, 14-, and 16-hour photoperiods. Photoperiods were provided by delivering 8 hours sunlight, then pulling black cloth and providing daylength extension with incandescent bulbs. Bacopa speciosa `Snowflake', Bidens ferulifolium, Brachycome multifida `Crystal Falls', Helichrysum bracteatum `Golden Beauty', Scaevola aemula `New Blue Wonder', and Streptocarpella hybrid `Blue Concord' were day neutral, i.e., no difference in days to visible bud or days to anthesis in response to photoperiod were observed. Pentas lanceolata `Starburst' and Lysimachia procumbens (Golden Globes) were quantitative long day plants, i.e., days to anthesis decreased as daylength increased. No difference in days to visible bud, number of lateral shoots, number of nodes, or internode length were observed for Pentas lanceolata `Starburst'; however, days to anthesis for 14- and 16-hour photoperiods occurred 9 days earlier than 8-hour photoperiods. Days to visible bud for Lysimachia procumbens (Golden Globes) occurred 7 days earlier and days to anthesis was 9 days earlier under 14- and 16-hour photoperiods than 8-hour photoperiods. By week 8, only one flower per plant developed in the 8-hour photoperiod while 11 flowers per plant developed in the 14-hour photoperiod. Streptosolen jamesonii (Orange Browallia) was a qualitative short day plant. There was no difference in the days to anthesis between 8- and 10-hour daylength, each averaging 36 days from start of photoperiod treatment. Plants under 12- to 16-hour photoperiods did not flower.
Terri Woods Starman and James E. Faust
The objective was to provide options for hanging basket production schedules by varying the number of plants per pot (one to four) and the number of manual pinches per basket (zero to two). Several species were evaluated in Spring 1995 and heat tolerance was assessed throughout the summer. Plugs (82 plugs per flat) were transplanted into 25-cm hanging baskets in a 22/18°C (venting/night temperature set points) glasshouse. Bacopa speciosa `Snowflake', Brachycome iberidifolia `Crystal Falls', Helichrysum bracteatum `Golden Beauty', Scaevola aemula `New Blue Wonder', and Streptocarpella hybrid `Concord Blue' produced quality baskets with three or more plugs per basket and no pinch. Pentas lanceolata `Starburst' and Lysimachia procumbens (Golden Globes) produced quality baskets with fewer than three plants per basket if plants received at least one pinch, however length of growing time was increased. Pentas lanceolata `Starburst', Scaevola aemula `New Blue Wonder', and Streptocarpella hybrid `Concord Blue' proved to be heat tolerant, blooming throughout the summer. Bacopa speciosa `Snowflake', Brachycome iberidifolia `Crystal Falls', and Lysimachia procumbens (Golden Globes) were not heat tolerant, i.e., ceased developing flowers in June and resumed flowering in September. Bidens ferulifolium did not produce an acceptable quality hanging basket under any experimental treatments.
T.K. Broschat, D.R. Sandrock, M.L. Elliott, and E.F. Gilman
In a series of three experiments, st. augustinegrass (Stenotaphrum secundatum ‘Floratam’), areca palm (Dypsis lutescens), canna (Canna × generalis ‘Richard Wallace’), pentas (Pentas lanceolata), allamanda (Allamanda cathartica ‘Hendersoni’), and nandina (Nandina domestica) were grown on highly leached sand soils in two locations in Florida. They were fertilized with typical turfgrass fertilizers having high nitrogen (N)-to-potassium (K) ratios and no magnesium (Mg), or several types of landscape palm fertilizers having low N:K ratios and 100% of their N, K, and Mg in controlled release form. St. augustinegrass, pentas, nandina, and allamanda visual quality were similar for all fertilizer types tested. However, cannas and areca palms had higher visual qualities when fertilized with an 8N–0.9P–10.0K–4Mg palm fertilizer than with higher N:K ratio turf fertilizers. High N:K turf fertilizers resulted in K deficiency severity equivalent to that of unfertilized controls and Mg deficiency that was more severe than unfertilized areca palms.
Sudeep Vyapari*, S.M. Scheiber, and Richard C. Beeson Jr.
During Fall 2003, a study was conducted to determine the effect of soil amendments on growth and response of Pentas lanceolata `New Look Red' in the landscape. Pentas were grown in 250L drainage lysimeters in an open-sided clear polyethylene covered shelter filled with local top soil (Apopka fine sand). The treatments used were non-amended top soil (control) and soil amended with either compost (5% by volume) or clay (5% by volume) in the top 15 cm. Best Management Practices were followed. Irrigation frequency and rate were regulated using a tensiometer-controlled automatic irrigation system. When plant available water in each soil type had declined to 70% or less, the plants were irrigated back to field capacity. Data were recorded on initial and final growth indices, shoot dry weight, and root dry weight. Final growth indices between control and soil amended with compost were not different; however, growth in the clay-based soil was significantly less than the compost-based soil type. The mean shoot dry weight (77.2 g) produced from plants in compost amended soil type was significantly higher than either control (57.45 g) or clay amended (54.92 g) soil types. No significant differences were found for either initial growth indices or root dry weight among the three treatments.