There are other inherent difficulties in working with seeds.
Events essential for the release from dormancy and the
completion of germination may occur only within a relatively
few cells associated with the embryonic root axis. Thus, the
presence in experimental material of nonresponding cells in
the axis or the presence of other seed parts, such as cotyledons
and endosperm, that do not behave similarly can mask
or dilute the changes sought. In seeds with coat-enhanced
dormancy, the use of isolated embryos or axes is unsatisfactory
because they are no longer dormant! Some interesting
observations have been made using isolated dormant
embryos, but again, these are composed of severa1 tissue
types; moreover, the cellular bases for the imposition and
breaking of their dormancy may be different from those for
seeds with coat-enhanced dormancy.