The relationship between growth of a rose plant and its nutrient and water uptake in hydroponic culture.

摘要

To develop a new method of fertigation in cut flower production of roses, the relationships between plant growth and nutrient and water uptake, and the ratio of cut flower growth to total plant growth on a FW basis, were investigated. Two-year-old rose plants, cultivars Sonia and Carl Red, grafted on Rosa multiflora, were grown hydroponically for about a year. The overall plant growth was determined by weighing separately the cut flowers, prunings, defoliated leaves, roots, trunks and old leaves. The growth rate decreased immediately after harvesting of the cut flowers and pruning. On a long term basis, however, the growth rate was slower in summer than during the other seasons. Growth of Sonia plants was faster than that of Carl Red plants. Afterflower production had become stable, the ratio of cut flowers to plant growth on a FW basis was always about 40% in both cultivars. The amounts of nutrients absorbed per 100 g plant FW in both cultivars were about 0.70 g N, 0.10 g P, 0.40 g K, 0.17 g Ca, and 0.04 g Mg. The amounts of nutrients absorbed per 100 g cut flowers were 2.5 times greater than those on a per plant FW basis. Sonia plants absorbed 2-3 litres of water in winter, 4-5 litres in spring and autumn, and 8-9 litres in summer per 100 g FW. Carl Red plants absorbed more water than Sonia plants. The concentrations of nutrients absorbed by the plants (nutrient absorption/water absorption) were lower in summer than in winter, and in Carl Red were approximately 80% of those of Sonia. The amount of N absorbed by Sonia was about 230 ppm in winter, 145 ppm in spring and autumn, and 110 ppm in summer. The values for P, K, Ca and Mg uptake by plants were, on average, 14, 60, 24 and 6 percent of that for N, respectively.