Excessive bicarbonate concentrations and high irrigation water pH affect the growth and appearance of nursery plants in southern Florida. A greenhouse experiment consisting of five nitrogen (N) rates of urea or nitric acid was conducted to evaluate the influence of N sources and rates in irrigation water on bicarbonate concentrations, medium pH, and growth and appearance of anthurium (Anthurium andraeanum Lind.) plants. Pot medium pH, dry weight, plant appearance and N uptake by plants were significantly affected by N rates in irrigation water amended with either liquid urea or nitric acid, but the differences between the two N sources were not significant. The optimum growth and the best appearance of anthurium were achieved when N was added to irrigation well water as either urea or nitric acid at a rate of 20 mg·L-1 (ppm) and an electrical conductivity in a range of 0.36 to 0.42 dS·m-1 Nitrogen rates at 80 and 120 mg·L-1 induced adverse plant growth because of the greater salinity of the solutions and the lower pH of the medium.
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