Productivity and quality of statice (Limonium sinuatum cv. Soiree Mix) and cockscomb (Celosia argentea cv. Chief Mix) under organic and inorganic fertilization regiments

Very little information is available on organic specialty cut flower production, especially fertilization requirements. In order to better understand organic fertilization requirements of two specialty cut flower crops, Limonium sinuatum and Celosia argentea, we initiated a field and greenhouse experiment to study the effect of compost (organic) and conventional (inorganic) fertilization treatments on the growth and productivity of these crops. Optimum yields in the field, expressed as fresh weight per plot, were achieved at compost applications of 98.8 t ha⁻¹ for both Limonium and Celosia. However, when number of stems, height of the stems, and the environmental impacts of such compost applications are considered we concluded that the optimal organic fertilizer amounts were 12.4 and 24.7 t ha⁻¹, for Limonium and Celosia, respectively. Limonium and Celosia plants in the greenhouse experiment were fertilized with 100, 200, 300, and 400 mg L⁻¹ nitrogen, combined with 0, 5, 10, 20, 40, and 60 mg L⁻¹ phosphorus. The generation of response surfaces for total weight per pot, number of stems per pot, average weight per stem, and average stem length were attempted for each species. The results showed that nitrogen did not significantly contribute to any of the models, except for Celosia average weight and length per stem models. Total weights per pot on the other hand showed both a linear and quadratic relationship over the range of phosphorus applications we tested. Maximum number of stems and total weight per pot were observed between 30 and 46 mg L⁻¹ P in both Limonium and Celosia. Our results suggest that organic fertilizer recommendations, in the form of animal manure composts should be based on phosphorus content of the compost rather than nitrogen content especially for soils high in initial phosphorous content.