ANATOMICAL ADAPTATIONS TO WATERLOGGING IN ROOTS OF WETLAND GRAMINOIDS - LIMITATIONS AND DRAWBACKS

Roots of wetland graminoids possess the following features which help them to survive long-term oxygen deficiency in waterlogged soils: (1) well developed aerenchyma; (2)_a barrier to radial oxygen loss along most of their length. In spite of these adaptations, plants may suffer from oxygen deficiency, e.g. at sites with strongly reducing substrates. In some species, these adaptations do not fully develop under conditions of anaerobiosis combined with excessive nitrogen nutrition. A possible drawback associated with the anatomical adaptations to anaerobiosis is a reduced capacity for nutrient uptake. A solution to this problem may be root dimorphism: "soil" roots, adapted to anaerobic conditions, anchor the plant in the substrate while "aquatic" roots ensure most nutrient uptake. © 1990.