Phenotypic plasticity of two submersed plants in response to flooding

A pond experiment was designed to investigate the adaptive response of two submersed plants to two patterns of flooding (suddenly vs stepwise flooding). Under conditions of constant water depth (i.e., sudden flooding), Myriophyllum spicatum allocated less biomass to roots and stems and more to leaves, and generally plant height increased with depth of water. Potamogeton maackianus allocated more biomass to stems but less to roots and leaves, while shoot length increased and then decreased with depth. When water level flooded at different rates (2cm/d, 4cm/d, 6cm/d, 10cm/d), with the increase of the flooding rate, biomass allocation of M spicatum showed the same tendency as in the constant depth treatment, but the proportion of biomass allocation to roots and stems was larger while it was smaller to leaves. Furthermore, plant height increased with increase of flooding rate; plant height of P maackianus increased and then decreased, but no significant difference was found in total biomass and biomass allocation between flooding rates.