Inhibition effects of daughter ramets on parent of clonal plant Eichhornia crassipes

The aquatic invasive clonal Eichhornia crassipes was selected to study the effect of nutrients and stolon severing on clonal plants in less heterogenous aquatic environments. Under high nutrient conditions, parent ramets produced more daughter ramets and leaves with higher biomass, and, subsequent to severing daughter ramets, especially those in early stages; parents produced more daughter ramets and leaves with higher biomass. However, leaf number and biomass of individual daughter ramets did not differ from individuals with severed stolons and the control treatment. The biomass and leaves of the daughter ramets were lower than the control and other severing treatments that were carried out at later stages only when the nutrient level was low and the stolons of the daughter ramets were severed at early stages of growth. For this reason, the total number of ramets and leaves were lower in early stage severing treatments than severing treatments at later stages. After severing the connection with the daughter ramets, the root/shoot biomass ratio of the parent ramets increased, indicating that water hyacinths display morphological plasticity after stolon severing by increasing root growth. This study indicates that in aquatic environments where the nutrient distribution is less heterogenous in the same layer of water, daughter ramets of the water hyacinth can inhibit the growth and clonal reproduction of the parent, and this inhibition was strongest at early stages of ramet growth. (C) 2013 Elsevier B.V. All rights reserved.