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Plant Nutrition
Powerpoint adopted from: http://209.85.173.132/search?q=cache:MhSZ0kbKXowJ:teachers.sduhsd.net/lolson/AP%2520Biology/Powerpoint%2520files/35Ch37PlantNutrition2005a.pdf+ap+biology+plant+nutrition&hl=en&ct=clnk&cd=2&gl=us&lr=lang_en&client=safari
http://www.holmdel.k12.nj.us/faculty/cconover-pannone/Plants/Plant%20Nutrition.pdf
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Nutritional Needs
Autotrophic does not mean autonomous Plants need…
Sun as an energy source Inorganic compounds as raw materials
Water (H2O)
CO2
minerals
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Essential Elements
Macronutrients (needed in relatively large amounts) Carbon (C) Oxygen (O) Hydrogen (H) Nitrogen (N) Phosphorous (P) Sulfur (S) Potassium (K) Calcium (Ca) Magnesium (Mg)
Micronutrients (needed in very small amounts) Chlorine Iron Manganese Boron Zinc Copper Nickel Molybdenum
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Nutrient Deficiency
Lack of essential nutrients Exhibit specific symptoms
Dependent on function of nutrient Dependent on solubility of nutrient
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Water and mineral uptake
Water uptake Plants cannot extract
all water from soil, only free water
osmosis
Cation uptake Cation uptake is aided
by H+ secreation by root cells (proton pump)
Active transport
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The Role of Soils
Plants are dependent on soil quality Texture/structure
Relative amounts of various sizes
of soil particles Composition
Organic and inorganic
chemical component Fertility
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Importance of organic matter
Topsoil Most important to plant growth Rich in organic matter
Humus Decomposing organic material
Breakdown of dead organisms, feces, fallen leaves & other organic refuse by bacteria and fungi
Improves soil texture Reservoir of minerals
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Importance of organic matter, cont.
Topsoil, cont. Organisms
1 teaspoon of topsoil has 5 billion
bacteria living with fungi, algae,
protists, insects, earthworms,
and nematodes
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Soil health as a global issue
Lack of soil conservation Growing wheat Raising cattle Land exposed to wind
erosion Drought
Soil conservation and sustainable agriculture Maintaining healthy
environment Production of food
supply Economically viable
farming industry
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Global Issues
Fertility
Erosion
Irrigation
Forestry destruction
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Fertilizer
“Organic” fertilizers Manure, compost,
fishmeal
“Chemical” fertilizers Commercially
manufactured N-P-K ratio
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Irrigation
Most often the limiting factor in plant growth
Issues US rivers reduced
to trickles by diversions of water
Soil becomes salty and infertile
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Erosion
Topsoil - lost to water and wind erosion
Precautions Trees as windbreaks Hillside crops Contour pattern
Sustainable Agriculture
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Soil Reclamation
Removal and storage of contaminated soils New method: phytoremediation
Biological, nondestructive cheap
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Nitrogen Fixation
Atmosphere
Soil
N2
(gas)
N2
(gas)
Nitrogen-Fixing Bacteria
NH3 (ammonia)
Organic material (humus)
Ammonifying Bacteria
NH4+ (ammonium)
H+ (from soil)
Root
Nitrifying bacteria
Denitrifying bacteria
NO3- (nitrate) NH4+
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Soybean Root Nodule
N fixation by Rhizobium bacteria Symbiotic relationship between nitrogen-
fixing bacteria and legumes Bacteroids inside nodules form
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Mycorrhizae and Plant Nutrition
Symbiotic relationship Mycorrhizal fungus gets sugars from the plant
In return, mycorrhizal fungus provides better absorption of water and minerals for the plant
Ectomycorrhizae versus Endomycorrhizae
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Unusual Adaptations
Epiphytes Grows on branches and
trunks of trees Staghorn ferns, orchids
Parasitic Plants Absorbs sugars and
minerals from living hosts Mistletoe, dodder, and Indian pipes
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Carnivorous Plants Photosynthetic, but obtain minerals and nutrients by killing
insects and other small animals Venus’ flytraps, pitcher plants, sundews