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  • Author or Editor: Rebecca G. Bichsel x
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Three experiments were conducted to determine how nitrogen (N), phosphorus (P), and potassium (K) rate and nutrient termination date would affect the growth of Dendrobium nobile Red Emperor `Prince'. For each experiment, 150 one-year-old liner plugs, each with a single psuedobulb, were potted on 4 Feb. 2005. Each of the factorial experiments had five rates of the nutrient and three termination dates. The rates for N and K were 0, 50, 100, 200, and 400 mg·L-1. P rates were 0, 25, 50, 100, and 200 mg·L-1. Termination dates for all experiments were 1 Sept., 1 Oct., and 1 Nov. 2005. Ten months after planting when plants had ceased growing, data were collected for plant height, node number, number of leaves remaining, chlorophyll readings for the lower, middle, and upper leaves, and pseudobulb width and thickness. With one exception, interactions between fertilizer rate and termination date were nonsignificant for the variables measured. For all nutrients, terminating fertilization on 1 Oct. or 1 Nov. resulted in decreased pseudobulb thickness compared to 1 Sept. Prolonged fertilization with N resulted in slightly thinner pseudobulbs. Pseudobulbs grew taller as N rate increased, reaching its peak at 100 and 200 mg·L-1, and declined as N further increased to 400 mg·L-1. Plants had increasing chlorophyll readings in the middle leaves with increasing N rate. All P rates resulted in taller plants with equally more nodes compared to 0 mg·L-1. As K rate increased from 0 to 100 mg·L-1, height and node number increased, but there were no further increases in height at high rates. Number and percentage of leaves remaining increased as N and K rates increased.

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Experiments were conducted to determine how nitrogen (N), phosphorus (P), and potassium (K) rate and fertilizer termination time affect the growth and flowering of a Dendrobium nobile Lindl. hybrid, Dendrobium cv Red Emperor ‘Prince’. Nitrogen, P, and K were tested in separate experiments as a factorial combination of five rates and three termination dates (1 Sept., 1 Oct., and 1 Nov. 2005). Nitrogen and K rates were 0, 50, 100, 200, and 400 mg·L−1. Phosphorus rates were 0, 25, 50, 100, and 200 mg·L−1. Levels of the nutrients not being tested were held constant. For all nutrients, ending fertilization on 1 Sept. resulted in greater or similar pseudobulb thickness compared with ending fertilization on 1 Oct. or 1 Nov. Pseudobulbs grew taller as the N rate increased, peaking at 100 and 200 mg·L−1. There were interactions between the N rate and fertilizer termination time on all reproductive characteristics. For all fertilizer termination times, flower number increased once N was applied. When ended on 1 Nov., 200 and 400 mg·L−1 N caused a delay to reach anthesis. All P rates resulted in taller plants with equally more nodes when compared with 0 mg·L−1. As the K rate increased from 0 to 100 mg·L−1, plant height increased, with no further increase at higher rates. The number of leaves remaining increased as N and K rates increased up to 200 mg·L−1. Total flower number and flowering node number increased as the K rate increased to 100 mg·L−1 (terminated on 1 Sept.) or 50 mg·L−1 (terminated on 1 Oct. or 1 Nov.). In the fourth experiment, only N was ended at four termination times, whereas all other nutrients continued to be supplied until flowering. Control plants received all fertilizer elements until flowering. The duration of N application did not affect vegetative or flowering characteristics. No aerial shoots were observed as a result of prolonged application of N at all rates. In summary, 100 mg·L−1 N, 25 mg·L−1 P, and 100 mg·L−1 K are recommended for optimal vegetative growth and reproductive development of Dendrobium cv Red Emperor ‘Prince’.

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