Root Traits for Phosphorus Acquisition in Brazilian Common Bean.

Common bean (Phaseolus vulgaris L.) is considered a major source of protein and minerals in the diets of many developing countries. However, the yield of this crop is often limited due to deficiency of phosphorus in soils. Identify cultivars with high efficiency of P uptake is an alternative of management for soils with low P available. We aimed to evaluate the P use efficiency (PUE) of Brazilian bean cultivars and assess differences in root architecture which have an impact on phosphorus acquisition by determining angle, basal root number, basal root whorl number, adventitious roots number, total length and mean diameter. A set of 19 bean cultivars was evaluated for performance under low phosphorus availability in the greenhouse and in the field. In the first were evaluated 19 bean cultivars utilizing isotopic dilution technique with 32P to determine L-value in order to evaluate P uptake; in the second were evaluated 10 cultivars regarding root traits using the WinRhizo software. There was a genetic variation among the bean cultivars in regards dry shoot mass (DMS), accumulation of P, the specific activity of the 32P and PUE. Our results suggested the possibility of selecting bean cultivars in relation to the PUE in low plant-available P by specific activity of the 32P in controlled environment. In field root traits varied significantly among bean cultivars, the results indicate that basal root number and basal root whorl number are associated with increased of PUE. New crop cultivars incorporating these traits may be used for improved yield in low phosphorus soils and offers the potential for breeding more stress-tolerant cultivars of this crops.