Grains
of
five
genotypes
of
wheat
(four
Polish
and
one
Finnish),
differing
in
their
tolerance
to
drought
stress
were
chosen
for
this
investigation.
Electron
paramagnetic
resonance
spectroscopy
allowed
obser-
vation
of
transition
metal
ions
(Mn,
Fe,
Cu)
and
different
types
of
stable
radicals,
including
semiquinone
centers,
present
in
seed
coats,
as
well
as
several
types
of
carbohydrate
radicals
found
mainly
in
the
inner
parts
of
grains.
The
content
of
paramagnetic
metal
centers
was
higher
in
sensitive
genotypes
(Radunia,
Raweta)
than
in
tolerant
ones
(Parabola,
Nawra),
whereas
the
Finnish
genotype
(Manu)
exhibited
inter-
mediate
amounts.
Similarly,
the
concentrations
of
both
types
of
radicals,
carbohydrates
and
semiquinone
were
significantly
higher
in
the
grains
originating
from
more
sensitive
wheat
genotypes.
The
nature
of
carbohydrate
radicals
and
their
concentrations
were
confronted
with
the
kinds
and
amounts
of
sugars
found
by
the
biochemical
analyses
and
microscopy
observations.
It
is
suggested
that
some
long
lived
radicals
(semiquinone
and
starch
radicals)
occurring
in
grains
could
be
indicators
of
stress
resistance
of
wheat
plants.