Appropriate management of phosphorus (P) in soil will lead to higher yields and sustainability for sugarcane
production. Our study evaluated the importance of differences in root structure and function, and the differential
composition of the bacterial community in four sugarcane cultivars, in relation to the efficiency for P uptake
and also to assess changes in soil P with distance from the rhizoplane. Experiments were performed in pot trials
using a sandy clay loam Ferralsol. In the first experiment, the effect of P application (78.4 mg P kg-1 soil astriple
superphosphate) on sugarcane cultivars RB92-579; RB85-5156; RB86-7515 and RB96-6928 was investigated.
Secondly, we evaluated P rates of 0; 9.8; 19.6; 39.2 and 78.4 mg kg-1 soil using cultivar RB96-6928 which was
shown to be one of the more growth responsive cultivars. The cultivar RB96-6928 exhibited the highest root
dry matter and root surface area, while the bacterial communities found in the rhizosphere of these plants were
not different from other cultivars, as determined by PCR-DGGE. From the P dose-dependent experiment for
this cultivar, optimal plant performance occurred at a P supply up to 38.5 mg P kg-1 soil. Collectively, our results
indicate that P efficiency in sugarcane was predominantly associated with the generation of high root biomass
and surface area.