Phenology and productivity of Pistia stratiotes L. on the Volta Lake, Ghana.
Growth of P. stratiotes at the southern-most tip of the man-made Volta Lake in Ghana was measured over 1 year. Biomass and relative growth rate remained fairly constant from September to December (during flowering period) but fell drastically from December to February and leaves became yellow. In March and April the relative growth rate reached a maximum and the abundant vegetative reproduction of young rosettes resulted in high plant density and a low percentage of yellow leaves; from May to August biomass and relative growth rate declined slowly. These observations are discussed in relation to lake-water composition and the possible seasonal variation in nutrient supply. It is concluded that the seasonal fluctuations in growth of P. stratiotes are probably related to the nutrient content of the water and not to the incidence of virus disease as suggested in WA 20, 285. From summary.