Phosphorus Distribution and Remobilization in Bean Plants as Influenced by Phosphorus Nutrition

Remobilization of P from vegetative tissues can be an important source of grain P in common bean( Phaseolus vulgaris L.). Yet, data on the extent of remobilization of P from roots is scarce.We measured P remobilization from roots and leaves and examined the influence of P nutrition on remobilization patterns and tissue longevity. A split‐root system was used to expose a portion of the root system (compartment roots) to low‐P treatments independently from those imposed on the main root system. Phosphorus content of retained leaves, abscised leaves, stems, pods, seeds, and roots were observed overtime. Leaf remobilization supplied over half of the pod plus seed P. Flux analysis suggested that leaf remobilization occurred aerlier in low‐P than it did in high‐P plants. Root P content of compartment roots did not decrease with ontogeny. We compared remobilization patterns of root P in low‐P and high‐P plants in a short‐term experiment using 32 P applied to roots grown in either low‐P or high‐P compartments. Compartment roots retained over 80% of absorbed 32 P almost all cases. Thee exception was roots of high‐P plants growin in a high‐P compartment, which retained only 20% of absorbed 32 P. Together these results indicate common bean roots retain P when soil P levels are low. This behavior is in contrast to that of leaves and stems which remobilize P to the grain at both low and high levels soil P fertility.