Effect of nitrogen and sulfur applications on pot chrysanthemum productionand postharvest performance. I. Leaf nitrogen and sulfur concentrations

Chrysanthemums are one of the most important flowering plants produced inte rnationally year round. The objectives of this research were to evaluate th e effects of reducing nitrogen (N) applications by adding sulfur (S) and to determine if N * S interactions occur during the production and postharves t longevity of pot chrysanthemums. Pot chrysanthemum 'White Diamond' was gr own in a peat-based medium following a typical production schedule except f or fertilization. Plants received N at 50, 100, 150, or 200 mg L-1 in combi nation with S at 0, 5, 10, 20, or 80 mg L-1. Variablesevaluated were leaf N and S concentrations, plant height, leaf area, days to bud set, and first flower color and inflorescence anthesis as well as size and longevity under simulated interior conditions. In this article, leaf N and S concentration s are the variables discussed. Tn general, N * S interactions were signific ant for leaf S, but not leaf N concentration. Applications of 50 mg N L-1 r esulted in poor leaf N and S concentration and plants of questionable quali ty. Nitrogen applied at 100, 150, or 200 mg L-1 in combination with at leas t 10 mg S L-1 had acceptable leaf N concentrations and produced plants of c ommercial quality. Thus, N applications can be reduced by half when S is ap plied during commercial production.