Phosphorus deficiency is a primary limitation to bean (Phaseolus vulgaris L.) production in the tropics. Bean genotypes differ in their P efficiency, defined as growth and yield in low P sail. Traits conferring P efficiency may be useful only in specific soil types, or may represent more general adaptations to low P availability. This information is essential in selecting and breeding more P efficient bean germplasm. Our objective was to determine if P efficiency in bean is limited to specific soil types. Sixteen contrasting genotypes were grown in pots of Andosol, Ultisol, and Oxisol soil at three levels of applied P in the tropics. At 35 d after planting, shoot growth, root growth, P accumulation, and symbiotic status were evaluated. Genotypes differed significantly in P efficiency. The relative ranking of genotypes for shoot biomass, root biomass, root length, or P accumulation under all P levels was not affected by soil type and was not related to the degree of rhizobial or mycorrhizal infection. Large-seeded Andean genotypes were superior to small-seeded Mesoamerican genotypes, especially under low P. Small-seeded Mesoamerican genotypes were more responsive to added P. We conclude that (i) large genetic variation for P efficiency exists in tropical bean germplasm, (ii) this variation reflects a general adaptation to low P availability rather than an interaction with specific soil types or soil microbes, (iii) large-seeded germplasm appears to have superior P efficiency under low P availability, and (iv) Mesoamerican genotypes are more responsive to added P.
