Morphogenetic Changes Induced by a Low Red: Far-Red Ratio and their Growth Consequences in Water Hyacinth (Eichhornia crassipes)

Plants of water hyacinth (Eichhornia crassipes) were grown under two red/far-red ratios (Z) to investigate the effects on morphology and growth of the light quality component of canopy shade. Experiments were conducted in diffuse sunlight in the presence or absence of far-red radiation. Under low Z conditions, fewer new ramets were produced and their stolons were shorter. The number of leaves per ramet was unchanged, but petiole length and blade area were increased. This change in biomass partitioning resulted in a lower investment in the main resource-acquiring organs (leaf blades and roots). The lower allocation of biomass to the leaf blades was compensated for by a higher net assimilation rate, such that relative growth rate remained unchanged.