Interspecific competition in Arabidopsis thaliana: root hairs are important for competitive effect, but not for competitive response
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Background and aims
The role of root hairs in intraspecific competition for Phosporus (P) is well examined, but their importance during interaction with other plant species is unknown, as is the differential meaning for competitive effect and response. This study aims to fill this gap of knowledge.
Competitive abilities of Arabidopsis thaliana wildtype and mutants with aberrant root hair phynotypes (root hair deficient, rhd2-1 or excessive root hair density, prc1-1) were examined in a pot-experiment with P-deficient sand. Competitive effects on a phytometer (Hieracium pilosella) or on A. thaliana itself were assessed as well as competitive responses to species mixtures.
In intraspecific interaction, the competitive effect of wildtype was superior to that of rhd2-1 or prc1-1. This was much less pronounced in interspecific interaction. Competitive response was entirely uniform between Arabidopsis root phenotypes.
The notion that root hairs are important for competition for P should be differentiated. With A. thaliana root hairs less important in inter- than in intraspecific interaction and with root hairs entirely unimportant for competitive response, functional mechanisms of competition for P appear quite complex. Such differential importance of root traits in different facets of competition might well be more common than previously thought.
KeywordsArabidopsis thaliana Competitive effect Competitive response Interspecific interaction Root hair deficiency Species mixture
Photon flux density
Specific root area
Total dry weight
Zone of influence
The authors would like to thank their colleagues at the Institute of Botany in Regensburg for support and helpful contributions to the project, especially Ingeborg Lauer for assistance with plant harvest and root photography. We are grateful to Iris Finkemeier (LMU Munich) and two anonymous reviewers for helpful comments on an earlier draft.
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