THE RESPONSE TO PHOSPHORUS OF SOME ECOLOGICALLY DISTINCT PLANT SPECIES

Abstract

Seedlings of four ecologically distinct species were grown in solution cultures containing a range of phosphorus concentrations. Evidence for relationships between their relative growth rates and phosphorus absorption was then considered. Descliampsia flexuosa and Scabiosa columbaria , the two species from edaphically extreme habitats, had slow relative growth rates, but differed in their response to phosphorus. Deschampsia flexuosa grew continuously in concentrations as low as 10 −7 M and respontled only slightly to concentrations as high as 10 −3 M. Scabiosa columbaria whose response was poor at 10 −7 m responded more markedly to 10 −3 M at which concentration there was a significant increase of phosphorus in the roots. Rumex acetosa and Urtica dioica , the two ruderal species, had high relative growth rates and differed in their response to phosphorus; Rumex acetoso survived over the whole range; Urtica dioica thrived only at 10 −5 M or above. These results, particularly the increase of phosphorus in roots of Scabiosa columbaria , were considered to be of ecological importance.