Root hairs confer a competitive advantage under low phosphorus availability

• Published in: Plant and soil 2001-10, Vol.236 (2), p.243-250
• Main Authors: Bates, Terence R., Lynch, Jonathan P.
• Format: Article
• Language: English
• Subjects: Absorption. Translocation of ions and substances. Permeability; Acquisitions & mergers; Adaptation to environment and cultivation conditions; Agronomy. Soil science and plant productions; Biological and medical sciences; Biomass; Classical genetics, quantitative genetics, hybrids; Ecological competition; Economic plant physiology; Fecundity; Flowers & plants; Fundamental and applied biological sciences. Psychology; Genetics and breeding of economic plants; Genetics of eukaryotes. Biological and molecular evolution; Genotypes; Monoculture; Nutrient availability; Nutrition. Photosynthesis. Respiration. Metabolism; Phosphorus; Plant competition; Plant physiology and development; Plant roots; Plants; Pteridophyta, spermatophyta; Root hairs; Seeds; Soil solution; Varietal selection. Specialized plant breeding, plant breeding aims; Vegetals; Water and solutes. Absorption, translocation and permeability
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1023/A:1012791706800

Root hairs are presumably important in the acquisition of immobile soil resources such as phosphorus. The density and length of root hairs vary substantially within and between species, and are highly regulated by soil phosphorus availability, which suggests that at high nutrient availability, root hairs may have a neutral or negative impact on fitness. We used a root-hairless mutant of the small herbaceous dicot Arabidopsis thaliana to assess the effect of root hairs on plant competition under contrasting phosphorus regimes. Wildtype plants were grown with hairless plants in a replacement series design at high (60 µm phosphate in soil solution) and low (1 µm phosphate in soil solution) phosphorus availability. At high phosphorus availability, wildtype and mutant plants were equal in growth, phosphorus acquisition, fecundity and relative crowding coefficient (RCC). At low phosphorus availability, hairless plants accumulated less biomass and phosphorus, and produced less seed when planted with wildtype plants. Wildtype plants were unaffected by the presence of hairless plants in mixed genotype plantings. Wildtype plants had RCC values greater than one while hairless plants had RCC values less than one. We conclude that root hairs increase the competitiveness of plants under low phosphorus availability but do not reduce growth or competitiveness under high phosphorus availability.