applied to only half of a split root system while amino acid concentrations
were analyzed in soil solution around the other isolated
root half (Fig. 1). Although it must be recognized that the concentration
of amino acids in the soil solution of this compartment reflects
a balance between their release from alive (exudation) and
dead cells and root uptake, applying the cytokinin-producing
B. subtilis IB-22 to one compartment enhanced rhizodeposition of
amino acids in the untreated compartment (relative to control
plants), even though root mass within this compartment remained
unchanged (Table 1). Amino acid exudation is not always directly
related to root mass, since defoliation of Festuca rubra plants
increased root exudation even though root growth was inhibited
(Paterson et al., 2005).