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  • Author or Editor: T.K. Broschat x
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Abstract

Principal component analysis, a technique which reduces the dimensionality of multivariate data by removing intercorrelations among variables, has a number of potentially useful applications in horticultural research. It can be used to order multivariate commodity quality data in 1 or 2 orthogonal dimensions called principal components, which express most of the variance of the original data. Scores on these principal components can be used as an index of commodity quality to replace subjective visual quality ratings in conventional statistical analyses. Interpretation of the pattern of variable loadings on these principal components may aid in the elucidation of interactions among variables in the data. Plotting of multivariate data in 2 or 3 dimensional principal component space can be useful for displaying relationships among cultivars or species in taxonomic studies.

Open Access

Abstract

Foliage of 57 species of tropical ornamental plants was harvested and placed under a controlled indoor environment to determine its postharvest life. Foliage was placed in deionized water, pulsed for 4 hr with 2 mm silver thiosulfate, and then transferred to deionized water, pulsed for 4 hr with 800 mg·liter-1 8-hydroxyquinoline citrate (8-HQC) and 20 g·liter-1 sucrose and then transferred to deionized water, or held in 200 mg·liter-1, 8-HQC and 20 g·liter-1 sucrose for the duration of the experiment. Foliage of 40 species lasted longer than 20 days and 28 species lasted 30 days or more in deionized water alone. Pulsing or holding foliage in preservative solutions lengthened postharvest life over that in deionized water for 12 species, but deionized water alone was as good as or better than other solutions for 46 species.

Open Access

Abstract

Ten species of tropical to temperate ornamental tree seedlings. [Bauhinia variegata L., Tabebuia heterophylla (DC.) Britton, T. caraiba (Mart.) Bur., Delonix regia (Bojer) Raf., Bursera simaruba (L.) Sarg., Pongamia pinnata (L.) Pierre, Jacaranda mimosifolia D. Don, Tamarindus indica L., Acer rubrum L., and Quercus virginiana Mill.] were grown outdoors under natural photoperiods or long day (LD) photoperiods during the autumn, winter, and early spring months. Growth response to photoperiod and temperature varied widely among both tropical and temperate species. Jacaranda mimosifolia, B. variegata, and T. indica were classified as quantitative LD plants since growth was enhanced by LD, but not prevented by short days. However, temperature appeared to be an overriding factor in the growth of T. indica. Delonix regia and A. rubrum grew continuously under LD, but ceased all growth when natural daylength (ND) became shorter than 10.8 h. Quercus virginiana, P. pinnata, B. simaruba, and T. heterophylla showed virtually no response to photoperiod, but temperatures below 15°C prevented growth in Q. virginiana. LD increased growth rate in T. caraiba during the autumn months, but low temperature prevented growth in either LD or ND in the winter. ND plants of this species grew more rapidly in the spring than those maintained under LD. This negative influence of LD on growth during the spring months also was noted in other species in this study.

Open Access

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.

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