Figure
3
.
N03
-
uptake
by
tap,
basal
and
lateral
roots
of
21
day
old
seedlings
.
(50,45,
6
-
8
cm
respectively)
(Values
are
means,
error
bars
represent
SE
.
n=5
in
tap
root;
n=5
in
basal
roots;
n=6
in
lateral
roots)
(From
Toulemonde,
1992)
It
can
be
seen
from
these
graphs
that
the
different
types
of
root
have
different
spatial
patterns
of
uptake
(along
the
length
of
the
root)
as
well
as
differential
temporal
patterns
.
With
potassium
uptake,
the
spatial
pattern
on
the
tap
root
changes
from
day
7
to
day
14,
with
both
being
different
than
the
basal
root
pattern
.
The
absolute
rate
of
potassium
uptake
for
the
tap
root
actually
increases
from
day
7
to
day
14
.
Similar
responses
are
observed
with
nitrate
uptake,
except
the
pattern
and
rate
of
nitrate
uptake
for
the
tap
root
remains
constant
from
day
7
to
day
14
(data
not
shown)
.
It
appears
that
once
the
lateral
rootshave
begun
to
take
up
nitrate,
both
tap
and
basal
roots
reduce
their
rates
to
a
lower
rate
which
is
commonwith
the
distal
parts
of
the
lateral
roots
.
This
data
suggests
that
different
types
of
root
differ
in
their
functional
characteristics
as
well
as
their
developmental
patterns
.
The
demonstration
that
they
are
genetically
distinct
in
terms
of
initiation
(Zobel,
1975),
combined
with
this
demonstration
of
differential
gene
activity
related
to
function
suggests
a
need
to
evaluate
root
system
function
based
on
the
separate
root
types
existing
in
that
root
system
.
Literature
Cited:
Toulemonde,
T
.
G
.
1992
.
Masters
Thesis,
Department
of
Soil,
Crop
and
Atmospheric
Sciences,
Cornell
University
.
May,
1992
.
pp119
.
Zobel,
R
.
W
.
1975
In:
The
development
and
function
of
roots
.
Academic
Press,
London
..
p
.
261
-
275
.
Zobel,
R
.
W
.
,
L
.
V
.
Kochian
and
T
.
G
.
Toulemonde
.
1992
.
In:
Proceedings
PPI
Conference
on
Roots
of
Plant
Nutrition,
Champaign
IL
July,
1992
p
.
30
-
40
.
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