Root proliferation in response to P stress and space: implications for the study of root acclimation to low P supply and P acquisition efficiency

Aims The experiment was conducted to understand how root morphological traits contributed to the contrasting P-acquisition efficiencies of two Trifolium subterraneum cultivars. Methods Phosphorus acquisition, root length proliferation and root acclimation to P deficiency were investigated by varying the P supply (20–300 mg P kg −1 ) and planting density (1–12 plants pot −1 ) of clover micro-swards. Results The shoot yield of both cultivars increased in response to increased P supply and increased planting density. Higher planting densities increased shoot yield by reducing the time to leaf canopy closure. In P-deficient soil, the ‘less P-efficient’ cultivar acquired less P and yielded relatively poorly compared with the ‘more P-efficient’ cultivar when planting density was low (