Ria T. Leonard

Effect of nitrogen and sulfur applications on pot chrysanthemum production and postharvest performance. II. Plant growth responses

Chrysanthemums are one of the most important flowering plants produced internationally year round. The objectives of this research were to evaluate the effects of reducing nitrogen (N) applications by adding sulfur (S) and to determine if N * S interactions occur during the production and postharvest longevity of pot chrysanthemums. Pot chrysanthemum ‘White Diamond’ was grown in a peat-based medium following a typical production schedule except for fertilization. Plants received N at 50, 100, 150, or 200 mg L−1 in combination with S at 0, 5, 10, 20, or 80 mg L−1. Variables evaluated 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. N * S interactions were significant for significantfor all plant growth response variables. Applications of 50 mg N L−1 resulted inpoor leaf N and S concentration and plants of questionable quality, yet maximal postharvest longevity. Nitrogen applied at 100, 150, or 200 mg L−1 in combination with at least 10 mg L−1 S had acceptable leaf N and S concentrations and produced plants of commercial quality with adequate postharvest longevity. Thus, N applied at 100 mg L−1 was the minimum acceptable fertilizer rate. Thus, N applications can be reduced by half when S is applied during commercial production without compromising postharvest longevity.