A large area of senescence zones was observed in nodules treated
with 750 mg/L of nZnO (Fig. 8b) but only a few infected cells in the
control-nodules exhibited the early stage of senescence (Fig. 8a). The
bacteroids in the early senescence region of controlled nodules appeared
intact but were loosely associated with symbiosome membranes.
Bacteroids, in number of two or three, were enclosed within a
single symbiosome unit (Fig. 11a).