COMPARISON OF BIOMASS AND METAL UPTAKE BETWEEN 2 POPULATIONS OF PHRAGMITES-AUSTRALIS GROWN IN FLOODED AND DRY CONDITIONS

The biomass and metal concentrations of two populations of Phragmites australis were studied by growth in a glasshouse in three ameliorated substrata [Mai Po (MP) sediment, fly ash (FA) and lead/zinc mine taili ngs (TL)] under hooded and dry conditions for 90 d. Plants were raised From seeds from 'clean' (Mai Po, Hong Kong) and metal-contaminated (P lombieres, Belgium) sites. Seedling growth was best in fly ash, root d ry weights being higher in flooded than dry conditions, and growth poo rest in tailings, in which shoot and root dry weights were higher unde r dry conditions for both populations. However, in the MP substratum c onditions did not significantly affect shoot and root dry weights of e ither population. In the fly ash and tailings, more metals were genera lly taken up in both roots and shoots in flooded than dry conditions, but there was little difference in the MP substratum. Metal uptake was mostly similar in both populations in seedlings grown in the same sub stratum, there being no clear evidence of ecotypic differentiation. (C ) 1998 Annals of Botany Company.