An Analysis of Competition Between Plants of Trifolium repens L. Populations Collected from Contrasting Soils

Abstract

Plants of Trifolium repens from natural populations found on calcareous soils are more tolerant of calcareous soils than those from acid soils, whilst plants of populations from acid soil are more tolerant of acid soil (Snaydon 1962). Similar differences between populations in response to acid and calcareous soils occur within several other plant species (Ramakrishnan 1965; Hutchinson 1967). The differences between plants of T. repens populations, in growth on calcareous and acid soils, are increased both by inter-population competition (Snaydon 1962) and by inter-specific competition (Snaydon & Bradshaw 1962b, and unpublished). The object of this study was to investigate the nature of the competition that occurred between plants of T. repens populations, collected from both calcareous and acid soils, when grown on each of those soil types. The independent effects of shoot competition and root competition were investigated using a technique modified from that of Donald (1958). The nature of root competition was further investigated by chemical analysis of the plant material. Plants collected from calcareous soils differ morphologically from those collected from acid soils (Snaydon, unpublished); these differences might affect shoot competition between the plant types (Black 1961). The populations also differ in response to phosphate (Snaydon & Bradshaw 1962a) and to Ca, Mg and K (Snaydon & Bradshaw 1969); these differences might influence root competition between them on the two soil types.