Mineral uptake as influenced by growing seasons and developmental stages in spray chrysanthemums grown under a hydroponic system

Characteristics of mineral uptake in spray chrysanthemums grown under a hydroponic system were investigated in relation to growing seasons and developmental stages. The amounts of N, P, K, Ca, and Mg, taken up per plant, differed markedly over the growing seasons and between 'Sei Aloha' and 'Talk'. However, the ratios of P, K, Ca, and Mg to N uptake were similar over both the growing seasons and cultivars. The ratios obtained from the nutrient solution analyses were P/N 13.3 ± 0.4%, K/N 102.6 ± 3.4%, Ca/N 29.6 ± 0.7% and Mg/N 10.0 ± 0.4%. The ratios corresponded to those estimated via plant tissue analyses. Uptake of 4.3-5.2 mg N fertilizer led to an increase of 1g in fresh weight. The rate of N uptake steadily rose after planting until flower buds became visible. The upward trend continued during bud development but decreased rapidly towards harvest. The ratios of P/N and K/N decreased from 16.2% and 134.2% to 8.4% and 69.5%, respectively, from the vegetative growth to the flowering stages. The ratios of Ca/N and Mg/N varied slightly.