Influence of phosphorus fertilization on coleus growth

B.E. Whipker, M.S. Ballance, P. Veazie, K. Hicks, W.G. Owen
Two coleus (Coleus scutellarioides) cultivars (FlameThrower™ ‘Salsa Verde’ and Main Street ‘Wall Street’) were grown at six phosphorus (P) concentrations (2.5, 5, 10, 15, 20, or 40 mg L‑1) to determine the effect on plant growth. Plants were grown for 8 weeks and measured for leaf tissue nutrient concentration, plant height, plant diameter, and shoot dry mass, along with calculating the growth index (GI), an integrated measurement of plant height and diameter. The two cultivars varied in vigor, therefore to compare responses between both cultivars, the data was analyzed on a percentage difference basis from their mean for each cultivar to determine overall trends. Phosphorus concentrations <5 mg L‑1 resulted in less plant growth (height, diameter, dry weight, and growth index) when compared with >10 mg L‑1. When the data was analyzed with a quadratic plateau model, a P concentration of 14.3 mg L‑1 (X0) maximized GI. Based on the target fertilization rate of 14.3 mg L‑1 P, foliar P concentrations were 1.0% P in ‘Salsa Verde’ and 1.09% P in ‘Wall Street’ when fertilized with 15 mg L‑1 P. Higher concentrations should be avoided due to the increased fertilizer cost and the impact on the environment.
Whipker, B.E., Ballance, M.S., Veazie, P., Hicks, K. and Owen, W.G. (2024). Influence of phosphorus fertilization on coleus growth. Acta Hortic. 1389, 247-254
DOI: 10.17660/ActaHortic.2024.1389.28
nutrition, fertilizers, floriculture, sustainability

Acta Horticulturae