Stock Plant Nutrition Influences the Adventitious Rooting of ‘Rotundifolia’ Holly Stem Cuttings

Abstract Containerized stock plants of Ilex crenata Thunb. ‘Rotundifolia’ were liquid-fertilized at least three times per week with nitrogen (N) at five rates (25, 50, 100,200, and 300 mg N/l) and in two forms (100% NH4NO3 or 50% NH4NO3 + 50% urea) in a factorial treatment design. Phosphorus and potassium were included in a constant ratio with N (100 N:15 P:50 K). Leaf and stem percent N levels were suboptimal at the lowest fertilizer rate and excessive at the highest fertilizer rate. Percent rooting of stem cuttings decreased linearly with fertilizer rate. With increasing fertilizer rates, total nonstructural carbohydrate (TNC) levels increased in leaves and remained constant in stems. Stem cutting percent moisture increased and was highly correlated with fertilizer rate. The form of N applied made no statistical difference in these trends. The decrease in percent rooting with increasing fertilizer rates was attributed to increases in shoot growth activity and decreased tissue maturation.