Effect of Calcium Levels in Culture Solution on Growth and Cut Flower Quality of Chrysanthemum

The relationship between calcium (Ca) uptake and growth of chrysanthemum, cv. Shuhounochikara, grown hydroponically for the cut flower market was investigated. 1. In experiment 1, plants grown with 20, 40 and 80 ppm Ca, grew vegetatively at a similar rate for 22 days, but their Ca uptake increased proportionately to the Ca concentration in the culture solution. 2. In experiment 2, which began on 4 August and ended on 5 November, involved 5 plots; one plot was readjusted weekly to 40 ppm Ca; the other 4 plots were supplied with 50, 100, 200 and 400 mg Ca per plant (two-stem training system) at the beginning of the experiment. The photoperiod was interrupted at midnight (night break by use of fluorescent lamps) from 6 Aug. to 20 Sept. to inhibit flowering. Plants supplied with 400 mg Ca produced good quality cut flowers, whereas those supplied with 200 mg had small inflorescences and the upper leaves exhibited Ca deficiency symptoms. In plants, supplied with 50 and 100 mg Ca, the shoot tips and young leaves exhibited severe Ca deficiency symptoms, these plots were discontinued at 12 and 14 weeks after planting, respectively. Plants grown at a constant 40 ppm level of Ca had excessively large leaves and thick stems. From our results, we recommend that 400 mg Ca per plant (or 200 mg per cut flower shoot) in the hydroponic system is ideal for producing good quality chrysanthemum flowers.