EFFECT OF POTASSIUM CONCENTRATION IN NUTRIENT SOLUTION ON GROWTH AND ITS UPTAKE IN POTTED MINIATURE ROSE UNDER RECIRCULATING EBB AND FLOW SYSTEM

In order to decide suitable potassium concentration of nutrient solution for potted miniature rose (Rosa ‘Nakashima 91’) production under recirculating Ebb and Flow system, we investigated the growth and its uptake under three potassium concentrations (20 mg L^-1, 50 mg L^-1 and 80 mg L^-1) through a year, i.e. autumn, spring and summer cultivations. For fresh and dry weight of plants, there were no significant differences among three potassium concentrations. The amount of absorbed potassium in plant in concentration of 50 mg L^-1 had no difference with that of 80 mg L^-1, but there was significant difference between concentration of 20 mg L^-1 and 50 mg L^-1. Potassium content per dry matter of plant in 20 mg L^-1 concentration was significantly lower than those in 50 mg L^-1 and 80 mg L^-1 concentration. The potassium content of soil in 50 mg L^-1 concentration was almost constant, 80 mg L^-1 concentration made accumulating of potassium content in soil, and 20 mg L^-1 concentration made decreasing of potassium content in soil. Therefore, it was concluded that potassium concentration of 20 mg L^-1 was deficient, 80 mg L^-1 was excessive and 50 mg L^-1 was the most suitable for potted rose production under recirculating Ebb and Flow system.