B. Jeong, Chiwon W. Lee
An experiment was conducted to determine the best NH4+:NO3- ratios for the growth of 11 bedding plant species in a greenhouse with daily average air temperatures 14–22C and CO2 enrichment at 600–1,000 ppm. Seedlings were grown in cellpacks (5.5 cm x 6.0 cm x 5.5 cm) containing the Colorado State Univ. soil mix (1 soil:3 sphagnum peat:2 pearlite, v/v, steamed) with nutrient solutions (pH 6.50) containing 0, 25, 50, 75 and 100% NH4+ in combination, respectively, with 100, 75, 50, 25 and 0% NO3-. In all solutions, nitrogen and total ion concentration were fixed at 16 and 50 meq·l-1, respectively.

Most species grew best with mixtures of NH4+ and NO3-: begonia, coleus, impatiens, marigold, petunia, salvia and zinnia at 50:50 (%), and snapdragon at 25:75 (%). However, ageratum grew best with 100% NH4+, celosia with 100% NO3-, and lobelia with either 100% NH4+ or 100% NO4-, NH4+ toxicity symptoms were observed only in marigold and salvia grown with 100% NH4+. Number of plants flowered in begonia, lobelia, petunia and salvia was not significantly different among treatments.

Jeong, B. and Lee, Chiwon W. (1992). AMMONIUM AND NITRATE NUTRITION OF 11 BEDDING PLANT SPECIES. Acta Hortic. 319, 505-510
DOI: 10.17660/ActaHortic.1992.319.79

Acta Horticulturae