Abstract
When white lupin plants face P-deficiency, they develop 'cluster roots7, which has an exudative ability of organic acids and acid phosphatase. However, responses of cluster roots to lack of other nutrients remain still unclear. This study aims to estimate function of cluster roots of white lupin grown under P- or N-deficient conditions. White lupin plants were grown in soils fertilized with (Control; C) or without P (-P) or N (-N).
Phosphatase activity was highest in -P senescent cluster roots, and was similar level between -N and Control, suggesting that increase of phosphatase activity in cluster roots is specific in P-deficiency. It was shown that peptidase activity in the rhizosphere soil was increased during low available-N with a few nodules, indicating that organic-N were utilized prior to the activation of N-supply from nodules. The peptidase activity in the rhizosphere soil was similar level between cluster and non-cluster roots.
