EFFECT OF MOWING, RUST INFECTION AND SEED PRODUCTION UPON C-RESERVES AND N-RESERVES AND MORPHOLOGY OF THE PERENNIAL VERATRUM-ALBUM L (LILIALES, MELANTHIACEAE)

In this field study the effect of mowing, rust infection and seed prod uction was determined on nonstructural carbohydrate (C) and Kjeldahl n itrogen (N) reserves in rhizomes, as well as on plant morphology of th e perennial weed Veratrum album L. (Liliales, Melanthiaceae). Rust inf ection and seed production had only a minimal influence on the concent rations of C and of N during either the summer or the following winter . However, mowing one month after early shoot growth led to decreased C (-40%) and increased N (+100%) concentrations of rhizomes sampled du ring the following winter. In a long-term experiment, the decrease in C reserves was shown to coincide with dwarfism of V. album plants. Mow ing for six consecutive years reduced total plant biomass by 50%. Acco rdingly, total N and C reserves per plant rhizome decrease substantial ly. However, seasonal patterns of C and N concentrations were not infl uenced by mowing, except for the differences in winter concentrations that were already observed in the Short-term experiment. Long-time mow ing not only led to dwarfism of V. album plants, but also significantl y decreased generative and vegetative proliferation.