Growth and foliar nutrient concentration response of Clerodendrum thomsoniae to increasing fertilization

Abstract: The growth response, root substrate environment, and foliar nutrient concentrations of clerodendrum were evaluated in a range of fertilizer concentrations. A green-leaf selection of clerodendrum was grown for 129 days using a complete fertilizer containing micronutrients at concentrations of 50, 100, 200, 300 and 400 mg L^-1 N. Shoot length and dry weight; root substrate electrical conductivity (EC); and foliar N, P, K, Cu, and Mn levels increased with increasing fertilizer concentration, while root substrate pH and foliar Mg and S decreased. The response of foliar Ca, Fe, Zn, and B concentrations to fertilizer concentration was not significant. Although clerodendrum grown with 100 to 400 mg L^-1 N had similar foliar N, P, and K concentrations by mean separation, foliage was lighter green at <100 mg L^-1 N; thus 200 mg L^-1 N is recommended because it provided adequate fertility without excessive shoot growth.