Snapp, S.S.; Lynch, J.P.


Crop Science, Volume 36, Issue 4, p.929-935 (1996)

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Remobilization of P from vegetative tissues can be an important source of seed P in common bean ( Phaseolus vulgaris ). However, data on the extent of remobilization of P from roots is scarce. P remobilization from roots and leaves, and the influence of P nutrition on remobilization patterns and tissue longevity, were examined. 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 over time. Leaf remobilization supplied over half of the pod plus seed P. Flux analysis suggested that leaf remobilization occurred earlier in low-P than it did in high-P plants. Root P content of compartment roots did not decrease with ontogeny. Remobilization patterns of root P were compared 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 in almost all cases. The exception were roots of high-P plants grown in a high-P compartment, which retained only 20% of absorbed 32 P. Together these results indicate that common bean roots retain P when soil P levels are low. This behaviour is in contrast to that of leaves and stems which remobilize P to the seeds at both low and high levels of soil P fertility.