Shallow roots are better for phosphorus efficiency in soybean: evidence from the field evaluation of an 'applied core collection'

摘要

Phosphorus (P) is one of the major constraints to soybean productivity in South China. Previous studies indicated that shallow roots might be advantageous for P uptake in soybean, but this has not been verified with a diversity of genetic materials for this crop. In the present study, field trials with 500 soybean germplasm materials from an applied core collection were carried out to evaluate root architectural traits and their relationship to phosphorus efficiency. Our results indicated that: 1) Soybean root architecture was closely correlated with P efficiency. The shallower root genotypes generally had higher P efficiency, suggesting that root architecture could be used as an indicator to evaluate soybean P efficiency in the field. 2) Application of P fertilizers significantly changed root distribution along the soil profile. Soybean roots tended to grow more superficially with P addition to the top soil, implying that shallow roots of the P-efficient genotypes might be resulting from a long-term fertilization practice in the topsoil. 3) Soybean genotypes with shallower root architecture appeared to have better rhizobium symbiosis, suggesting that the beneficial effects of root shallowness might be more than just exploring more available P in the top soil.