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

Nutritional Needs

Autotrophic does not mean autonomous Plants need…

Sun as an energy source Inorganic compounds as raw materials

Water (H2O)

CO2

minerals

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

Nutrient Deficiency

Lack of essential nutrients Exhibit specific symptoms

Dependent on function of nutrient Dependent on solubility of nutrient

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

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

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

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

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

Global Issues

Fertility

Erosion

Irrigation

Forestry destruction

Fertilizer

“Organic” fertilizers Manure, compost,

fishmeal

“Chemical” fertilizers Commercially

manufactured N-P-K ratio

Irrigation

Most often the limiting factor in plant growth

Issues US rivers reduced

to trickles by diversions of water

Soil becomes salty and infertile

Erosion

Topsoil - lost to water and wind erosion

Precautions Trees as windbreaks Hillside crops Contour pattern

Sustainable Agriculture

Soil Reclamation

Removal and storage of contaminated soils New method: phytoremediation

Biological, nondestructive cheap

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+

Soybean Root Nodule

N fixation by Rhizobium bacteria Symbiotic relationship between nitrogen-

fixing bacteria and legumes Bacteroids inside nodules form

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

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

Carnivorous Plants Photosynthetic, but obtain minerals and nutrients by killing

insects and other small animals Venus’ flytraps, pitcher plants, sundews