Search

• Terrestrial plants experience multiple stresses when they are submerged, caused both by oxygen deficiency due to reduced gas diffusion in water, and by shade due to high turbidity of the floodwater. It has been suggested that responses to submergence arede factoresponses to low light intensity.• We investigated the extent to which submergence and shade induce similar acclimation responses by comparing two terrestrialRumexspecies that differ in their responses to flooding.• Our study confirms that there are strong similarities between acclimation responses to shade and submergence. Petiole length, specific leaf area (SLA), chlorophyll parameters and underwater light-compensation points changed at least qualitatively in the same direction. Maximum underwater photosynthesis rate, however, did discriminate between the functionality of the responses, as the acclimation to submergence appeared to be more effective than acclimation to shade at saturating light.• We conclude that acclimation to submergence involves more than an increase in SLA to achieve the significant reduction of diffusion resistance for gas exchange between leaves and the water column.New Phytologist(2005)doi: 10.1111/j.1469-8137.2005.01404.x© New Phytologist(2005) [ABSTRACT FROM AUTHOR]

Resistance to complete submergence was tested in three Rumex species that occur in the Dutch river forelands. The species differ in both habitat and life history characteristics. The annual or biennial R.maritimus and the biennial or short lived perennial R. palustris grow on frequently flooded mud flats of low elevation, while the perennial R. thyrsiflorus can he found on dykes and river dunes that are seIdom flooded. The flooding characteristics of the habitats of the three species were determined. These data were used to design experiments to determine the survival and biomass development of the three species during submergence and and the influence of plant size and light level on these parameters. It was shown in all three species that plants submerged during daytime were much more resistant to flooding than those submerged at night. This is most probably due to the generation of oxygen or carbohydrates by underwater photosynthesis. Mature plants of the three species showed higher survival after submergence than juvenile plants, which might by caused by higher carbohydrate levels in the taproots of mature plants. In addition, the three species clearly differed in survival and biomass development during submergence. Rumex thyrsiflorus, the species least subjected to flooding, is least tolerant to complete submergence. Rumex maritimus, which can avoid the floods In having a short life cycle, is less tolerant to submergence than R. palustris which has to survive the floods as a vegetative plant. It was noted that some plants that survived the flooding period itself, still died in the following period of drained conditions, possibly due to post-anoxic injury. [ABSTRACT FROM AUTHOR]