Distribution of Nutrients in Cut-flower Roses and the Quantities of Biomass and Nutrients Removed during Harvest

Pollution of the environment, especially groundwater, may be reduced by proper fertilizer management, based in part on crop removal. The weights and concentrations of nutrients in tissue components of cut-flower roses ( Rosa hybrida L.) were determined to assist in developing a fertilizer management system that sustains a high level of production but also is environmentally friendly. Harvested flower stalks of the cv. Royalty were cut to 45-cm length, and sectioned into 15-cm units, from which blossom, leaf, and stem components were separated, weighed, and analyzed for nutrients. The flower represented 28.5%, leaves 46.0%, and stem 25.5% of the total weight of the stalk. Upper leaves had the highest levels (g·kg -1 ) of N (29.3), Ca (21.8), and Mg (3.0), and (mg·kg -1 ) Fe (74) and Mn (71). The flower was highest in K (18.4 g·kg -1 ), P (3.0 g·kg -1 ), Zn (29 mg·kg -1 ), and B (23 mg·kg -1 ). Annual removal of nutrients by 45-cm flower stalks totaled: 256.2, 187.5, 116.3, 30.0, 26.0, and 21.1 kg·ha -1 of N, K, Ca, P, Mg, and S, respectively. Micronutrients removed per annum totaled 700, 470, 260, 200, and 190 g·ha -1 of Fe, Mn, Zn, Cu, and B, respectively. Assuming 50% recovery of applied N and 80% of K, a total annual application of N at 512 kg·ha -1 and K at 234 kg·ha -1 may replace the amounts removed. However, actual rates of N and K, as well as other nutrients applied, should be adjusted based on soil and tissue analysis results. Removal of nutrients will be greater if stalks harvested are >45 cm in length, which may necessitate additional nutrient application, depending on soil conditions.