Salinization
Lab:
Design
your
own
experiment
Due:
October
1)
Objective:
At
the
end
of
this
lab,
you
will
be
able
to
determine
how
salinization
affects
the
germination
of
various
species
of
crop
seeds
and
at
what
salt
level
concentration
will
seeds
no
longer
germinate.
This
will
be
possible
because
the
lab
will
be
conducted
using
a
“strict”
scientific
process…
a
single
manipulate
variable,
controls,
carefully
created
dilutions,
etc.
2)
Introduction
Salt
buildup
is
an
existing
or
potential
hazard
on
almost
all
of
the
42
million
acres
of
irrigated
farmland
in
the
United
States.
Much
of
the
world's
unused
land
is
in
ar?id
and
semiarid
regions
where
irrigation
will
be
necessary.
Water
contains
a
small
amount
of
salt
and
over
time
this
salt
accumulates
in
the
soil.
A
small
amount
of
salt
in
the
soil
will
not
affect
the
germination
and
growth
of
crops.
However,
as
salt
concentrations
increase,
negative
impacts
occur.
Eventually
salt
concentrations
will
affect
the
germination
of
seeds.
Excessive
salinity
is
presently
costing
the
U.S.
billions
of
dollars
in
lost
food
crops.
In
the
vast
farming
area
of
Central
California's
San
Joaquin
Valley,
as
many
as
190,000
acres
have
salinity
levels
that
limit
a
grower's
choice
of
crops.
That
usually
means
cotton
or
sugar
beets,
if
they
can
grow
anything
at
all.
In
Skagit
County
the
problem
of
salt
water
and
crops
is
more
direct.
Much
of
the
farm
land
is
kept
from
flooding
because
of
flood
gates
(they
keep
the
tide
water
from
mixing
back
in
toward
the
land).
However
flood
gates
also
lessen
the
water
that
is
available
for
spawning
salmon…
so
the
problem
is
protecting
salmon
habitat
or
possibly
allowing
too
much
salt
in
the
fields
which
will
hurt
growing/germinating
plants.
Salt
kills
germinating
seedlings
by
removing
the
water
from
their
cells
(plasmolysis,
exomosis).
Several
salts
and
their
ions
are
responsible:
NaCl,
CaCl,
KCl,
MgCl,
MgSO4,
HCO3
‐
CO3
‐‐MgCO3,
NO3‐,
NH4+,
K+.
In
this
investigation
your
team
will
be
investigating
the
effects
of
just
one
salt;
NaCl
will
affect
germinating
seeds
in
a
similar
way,
as
would
other
salts
or
combinations
of
salt.
NaCl
has
a
solubility
of
35.7
grams
per
100ml
of
H20.It
is
known
that
ocean
water
has
a
3.5%
concentration
(3.5
grams
per
100ml
oh
H20).
Freshwater
has
a
concentration
of
0.005%
salt
(0.005
grams
per
100ml
of
H20)
3)
Task:
Complete
the
following
with
your
lab
group.
•
Write
a
problem
in
a
form
of
a
question…
Remember
it
must
be
a
testable
question….
The
question
must
be
related
to
the
problem
of
salinity
and
crops….
Germination.
Make
a
group
decision.
(Example:
How
does
the
concentration
of
salinity
affect
germination
rate?
or…
At
what
level
of
salinity
does
germination
cease
to
occur?
or…
Do
different
strengths
of
salinity
cause
different
rates
of
growth?
(i.e.
size
of
sprout
on
different
days….)
or…..
•
What
variable
will
you
change
in
your
experiment?
(Remember,
you
can
only
change
one
variable….
All
the
other
factors
must
be
done
exactly
the
same.
The
variable
must
address
the
“big
problem”
on
page
one.
•
What
will
you
measure?
(Your
final
graph
must
include
some
kind
of
percentage….)
percentage
of
what?
Decide
as
a
group.
•
Make
a
group
decision
on
a
hypothesis.
What
do
you
think
will
happen?
Be
specific….be
sure
and
include
the
variable
that
you
are
changing
and
what
is
being
measured
in
your
hypothesis.
•
Write
an
experimental
plan
on
a
separate
piece
of
paper.
Provide
as
many
details
as
details…
Be
very
specific.
Exactly
how
many
seeds
will
you
use
for
each
condition,
etc.
o In
your
plan
be
sure
and
include
all
the
conditions
you
will
hold
constant
and
how
you
will
methodically,
carefully
and
incrementally
change
the
variable.
How
will
you
know
at
the
end
of
the
experiment
if
your
data
supports
your
hypothesis?
o In
your
plan,
include
a
control
variable…
•
Possible
Materials:
Seeds
(how
many),
distilled
water,
ruler,
pipette,
graduated
cylinder,
plastic
petri
dishes,
labels,
salt
water
(various
concentrations…..
),
petri
paper
•
Check
the
Plan:
o Does
your
plan
test
only
one
variable?
o Have
you
determined
how
many
seeds
or
plants
you
will
use
in
each
group?
o Have
you
decided
what
you
will
measure?
o Have
you
decided
how
often
you
will
measure?
o Have
you
decided
how
often
you
will
water
your
seeds?
o Have
you
made
a
data
table
that
compares
your
observations/measurements
on
the
the
control
and
experimental
group?
o Have
you
thought
about
what
kind
of
graph
you
will
make?