Experiment was conducted to determine the effects of different organic mediums and potassium rates on the growth, yield and quality of cut flower and nutrient uptakes of calla lily (Zantedeschia Spreng). Two kinds of organic mediums (mushroom compost and peatmoss) and four rates of potassium fertilizer (0, 150, 300 and 450 K₂O kg/ha) were used in this experiment. The results indicated that there were no significant difference on the yield of cut flower between the treatments of 150, 300 and 450 K₂O kg/ha, but the best yield of cut flower (3.50 No./plant) was found on the treatment of 300 K₂O kg/ha on mushroom compost medium. For peatmoss medium, the best yield of cut flower (3.50 No./plant) also found on the application of 300 K₂O kg/ha, but there were no significant difference on the yield of cut flower between the treatments of 300 and 450 K₂O kg/ha. The maximum N, P, K, Ca and Mg uptakes of the shoot and root of calla lily showed on the application of 150 and 300 K₂O kg/ha with growing on mushroom compost medium. For the N, P, K, Ca and Mg uptakes of the tuber of calla lily, the maximum values found on the application of 300 and 450 K₂O kg/ha. The maximum N, P, K, Ca and Mg uptakes of the shoot, root and tuber of calla lily showed on the application of 300 and 450 K₂O kg/ha with growing on peatmoss medium. In respect of the yield of cut flower and the nutrient uptakes of calla lily, the optimum amount of 150 and 300 K₂O kg/ha were recommended for the cultivation of calla lily at blooming stage with growing on mushroom compost and peatmoss medium, respectively.

Key words: Calla Lily (Zantedeschia spp. ), organic medium , potassium fertilizer, cut-flower, nutrient uptake .