Transcript Monday 4/23/07

Monday 4/23/07
Review transpiration packets
Plant nutrition notes
Homework:
Begin Control system in plant
Chapter 39
754-757
Test Friday: Transpiration, Plant nutrition,
and Control systems
Plant Nutrition
Chapter 37
Mineral Nutrients
Essential chemical elements plants
need comes from soil, water & air
More than 50 inorganic substances
found in many plants
Minerals are inorganic substances
containing 2 or more elements
Essential nutrients
Essential nutrients are those plants need for
complete life cycle
There are 17 essential minerals/nutrients
1. Has identifiable role
2. Cannot be substituted
3. Deficiency leads to incomplete life cycle
Hydroponic experiments to determine which
nutrients were “essential”
Macronutrients needed in greater quantities
than micronutrients
Nutrients
Macro: C, O, H, N, S, P, K, Ca, Mg
Micro: Cl, Fe, B,Mn, Z, Cu, N, Mo
Deficiency: chlorosis
(lack of Mg; chlorophyll production)
e 37.1
Nutrient deficiencies
Plants can suffer from deficiencies of
their essential nutrients and minerals
Healthy
Phosphate-deficient
Potassium-deficient
Nitrogen-deficient
Figure 37.4
ALL ABOUT SOIL!
Topsoil: mix of particles from
deteriorating rock and
decaying organic material
Humus: decaying
organisms/organic material
Loams: fertile soils with
mixes of sand, silt and clay
Good soils
Drain adequately and retain air
pockets
Have large surface area for
water/minerals
Contain decomposers such as
fungi and bacteria
Agriculture and Soil
Agriculture can cause a
strain on healthy soil
Depletes mineral context of
soil
Encourages erosion of soil
Chemical fertilizers are not
slow release, cause excess
nutrients to flood soil
Runoff from over fertilized
land pollutes lakes/streams
and groundwater
Contour tillage helps slow runoff
of water and erosion of soil
Figure 37.8
Plant Symbiosis
Symbiotic nitrogen fixing bacteria
Bacteria gains sugar from plant
Mycorrhizae
Epiphytes
Grow on surface of plant in commensalism
Parasitic plants
Carnivorous plants
Plant Symbiosis
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
Sundews
Soil Bacteria
Nitrogen-fixing bacteria can convert
atmospheric nitrogen (into nitrogenous
minerals plants can absorb as nutrients
(usually NH3)
Atmosphere
N2
N2
Soil
Nitrogen-fixing
bacteria
NH3
(ammonia)
Denitrifying
bacteria
H+
(From soil)
Nitrate and
nitrogenous
organic
compounds
exported in
xylem to
shoot system
+
NH4
–
+
NH4
(ammonium)
Ammonifying
bacteria
Organic
material (humus)
Figure 37.9
N2
Atmosphere
Soil
Nitrifying
bacteria
NO3
(nitrate)
Root
Protein deficiency
Common malnutrition in humans
Plants are poor sources of proteins
Current research is working on
enriching crops with proteins
Mycorrhizae
Epidermis
(a)
a 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.
Cortex
Mantle
(fungal
sheath)
100 m
Endodermis
Mantle
(fungal sheath)
Fungal
hyphae
between
cortical
cells
(colorized SEM)