Download plants

Chapter 37
Plant Nutrition
PowerPoint TextEdit Art Slides for
Biology, Seventh Edition
Neil Campbell and Jane Reece
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 37.1 Root and shoot systems of a pea seedling
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 37.2 The uptake of nutrients by a plant:
a review
CO2, the source
of carbon for
Photosynthesis,
diffuses into
leaves from the
air through
stomata.
H2O
CO2
O2
Through
stomata, leaves
expel H2O and
O2.
O2
Minerals
Roots absorb
H2O and
minerals from
the soil.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
CO2
H2O
Roots take in
O2 and expel
CO2. The plant
uses O2 for cellular
respiration but is
a net O2 producer.
Figure 37.3 Hydroponic Culture
APPLICATION In hydroponic culture, plants are grown in mineral solutions without soil. One use of
hydroponic culture is to identify essential elements in plants.
TECHNIQUE Plant roots are bathed in aerated solutions of known mineral composition. Aerating the
water provides the roots with oxygen for cellular respiration. A particular mineral, such as potassium, can
be omitted to test whether it is essential.
Control: Solution
containing all minerals
Experimental: Solution
without potassium
RESULTS
If the omitted mineral is essential, mineral deficiency symptoms occur, such as stunted
growth and discolored leaves. Deficiencies of different elements may have different symptoms, which
can aid in diagnosing mineral deficiencies in soil.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Table 37.1 Essential Elements in Plants
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 37.4 The most common mineral
deficiencies, as seen in maize leaves
Healthy
Phosphate-deficient
Potassium-deficient
Nitrogen-deficient
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 37.5 Soil horizons
The A horizon is the topsoil, a mixture of
broken-down rock of various textures, living
organisms, and decaying organic matter.
A
B
The B horizon contains much less organic
matter than the A horizon and is less
weathered.
C
The C horizon, composed mainly of partially
broken-down rock, serves as the “parent”
material for the upper layers of soil.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 37.6 The availability of soil water and minerals
Soil particle surrounded by
film of water
Root hair
K+
–
Water
available to
plant
Soil particle
–
Cu2+
–
–
–
K+
–
–
Mg2+
–
+
– K
Ca2+
H+
H2O + CO2
H2CO3
HCO3– + H+
Root hair
Air space
(a) Soil water. A plant cannot extract all the water in the
soil because some of it is tightly held by hydrophilic soil
particles. Water bound less tightly to soil particles can
be absorbed by the root.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
(b) Cation exchange in soil. Hydrogen ions (H+) help
make nutrients available by displacing positively
charged minerals (cations such as Ca2+) that were
bound tightly to the surface of negatively charged soil
particles. Plants contribute H+ by secreting it from root
hairs and also by cellular respiration, which releases
CO2 into the soil solution, where it reacts with H2O to
form carbonic acid (H2CO3). Dissociation of this acid
adds H+ to the soil solution.
Figure 37.7 Deficiency warnings from “smart”
plants
No phosphorus
deficiency
Beginning
phosphorus
deficiency
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Well-developed
phosphorus
deficiency
Figure 37.8 Contour tillage
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 37.9 The role of soil bacteria in the nitrogen
nutrition of plants (layer 1)
Atmosphere
N2
Atmosphere
Soil
N2
Nitrogen-fixing
bacteria
H+
(from soil)
Soil
NH3
(ammonia)
NH4 +
(ammonia)
Ammonifying
bacteria
Organic
material (humus)
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 37.9 The role of soil bacteria in the nitrogen
nutrition of plants (layer 2)
Atmosphere
N2
N2
Atmosphere
Soil
N2
Nitrogen-fixing
bacteria
Denitrifying
bacteria
H+
(from soil)
Soil
NH3
(ammonia)
NH4 +
(ammonia)
Ammonifying
bacteria
Organic
material (humus)
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Nitrifying
bacteria
NO3 –
(nitrate)
Figure 37.9 The role of soil bacteria in the nitrogen
nutrition of plants (layer 3)
Atmosphere
N2
N2
Atmosphere
Soil
N2
Nitrogen-fixing
bacteria
Denitrifying
bacteria
H+
(from soil)
Soil
Nitrate and
nitrogenous
organic
compounds
exported in
xylem to
shoot system
NH4 +
NH3
(ammonia)
NH4 +
(ammonia)
Nitrifying
bacteria
NO3 –
(nitrate)
Ammonifying
bacteria
Organic
material (humus)
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Root
Figure 37.10 Root nodules on legumes
5 m
Bacteroids
within
vesicle
Nodules
Roots
(a) Pea plant root. The
bumps on this pea plant
root are nodules
containing Rhizobium
bacteria. The bacteria fix
nitrogen and obtain
photosynthetic products
supplied by the plant.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
(b) Bacteroids in a soybean
root nodule. In this TEM,
a cell from a root nodule
of soybean is filled with
bacteroids in vesicles.
The cells on the left are
uninfected.
Figure 37.11 Development of a soybean root nodule
1 Roots emit chemical
signals that attract
Rhizobium bacteria.
The bacteria then emit
signals that stimulate
root hairs to elongate
and to form an
infection thread by an
invagination of the
plasma membrane.
Infection
thread
Infected
root hair
Rhizobium
bacteria
Dividing cells
in root cortex
Bacteroid
Dividing cells in
pericycle
1
2
2 The bacteria penetrate
the cortex within the
infection thread. Cells of
the cortex and pericycle
begin dividing, and
vesicles containing the
bacteria bud into cortical
cells from the branching
infection thread. This
process results in the
formation of bacteroids.
Developing
root nodule
3
3 Growth continues in the
affected regions of the
cortex and pericycle,
and these two masses
of dividing cells fuse,
forming the nodule.
4
4 The nodule develops
vascular tissue that
supplies nutrients to the
nodule and carries
nitrogenous compounds
into the vascular
cylinder for distribution
throughout the plant.
Bacteroid
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Bacteroid
Nodule
vascular
tissue
Figure 37.12 Mycorrhizae
1 Ectomycorrhizae. The mantle
of the fungal mycelium
ensheathes the root. Fungal
hyphae extend from the mantle
into the soil, absorbing water
and minerals, especially
phosphate. Hyphae also
extend into the extracellular
spaces of the root cortex,
providing extensive surface
area for nutrient exchange
between the fungus and its
host plant.
2 Endomycorrhizae. No mantle
forms around the root, but
microscopic fungal hyphae
extend into the root. Within the
root cortex, the fungus makes
extensive contact with the plant
through branching of hyphae
that form arbuscules, providing
an enormous surface area for
nutrient swapping. The hyphae
penetrate the cell walls, but not
the plasma membranes, of
cells within the cortex.
Epidermis
Cortex
Mantle
(fungal
sheath)
100 m
Endodermis
Fungal
hyphae
between
cortical
cells
Mantle
(fungal sheath)
Epidermis
Cortex
Cortical cells
(colorized SEM)
10 m
Endodermis
Fungal
hyphae
Vesicle
Casparian
strip
Root
hair
Arbuscules
(LM, stained specimen)
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 37.13 Unusual Nutritional Adaptations in Plants
EPIPHYTES
Staghorn fern, an epiphyte
PARASITIC PLANTS
Host’s phloem
Dodder
Haustoria
Mistletoe, a photosynthetic parasite Dodder, a nonphotosynthetic
parasite
Indian pipe, a nonphotosynthetic parasite
CARNIVOROUS PLANTS
Venus’ flytrap
Pitcher plants
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Sundews
37.13 Sun Dew Trap Prey
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings