With respect to reeds, plants remained very healthy throughout our study, in spite of the high ammonia-N concentrations in the influent. In the second year, reed productivity was higher as compared to what was obtained the first year and the highest yield was also attained in the bed with the lowest HAR. Statistical analysis of variance shows a significant difference in dry matter production between the two species. Forcattails the maximum productivity was
estimated as 22 kg [d. m.] m2 (22 t ha1) whilst in the case of reeds, the greatest biomass yield obtained was
12 kg [d. m.] m2 (12 t ha1). This fact could be due in part to relative differences in initial rhizome vigour. Reed yields obtained in the present study were very low when compared to values reported for the same plant by otherauthors such as Hofmann (1986) and Ennabili et al. (1998) who reported maximum dry above-ground biomass of 2–3 kg m2
. Nevertheless, a poor establishment of Phragmites (reed) in constructed wetlands as well as a lesser growth of this specie in gravel-bed wetlands treating domestic sewage has been reported (Tanner, 1996).