THE RESPONSE TO PHOSPHORUS OF SOME ECOLOGICALLY DISTINCT PLANT SPECIES

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Abstract
Summary: 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.