| Abstract: | Root architectural responses to phosphorus (p) availability may be an important trait for P acquisition efficiency. In the present study, The authors examined the effects of P availability on root architectural responses of different common bean genotypes. Five common bean (Phaseolus vulgaris L.) genotypes representing different origins and ecotypic races were compared both in a specially designed paper pouch system and a stratified P buffer sand culture system with computer image analysis. The results showed that root architecture was regulated by P availability. P deficiency led to form a shallower root system, as indicated by increased relative distribution of basal root length in the upper layers and decreased the growth angle of basal roots. There was significant genetic variation in root architecture in response to P deficiency both in the paper pouch system and the stratified sand culture system. Under low P conditions some genotypes were more gravitropically sensitive to low P availability, resulting in producing a shallower root system and enhanced root exploration into the surface soil, where soil available P is more concentrated. G19833 and DOR364, which were most contrasting in P efficiency, were also very different in root architectural response to P availability. The results from this study suggest that P availability regulates root architecture and P deficiency leads to shallower root architecture in beans. The genetic potential of root architecture provides the possibility of selecting this trait for improving P acquisition efficiency in common bean. |
