Plant Nutrition Flashcards
Source of plant nutrients
Dissolved nutrients in plant soil
Macronutrients
Main 3: C (CO2), O (CO2), H (H2O)
Rest: N (NO3- or NH4+; organic material), K (K+; rock minerals), Ca (Ca+2; rock minerals), Mg (Mg+2; rock minerals), P (H2PO4- or HPO4-2; organic material), S (SO4-2; organic material)
Micronutrients
Act as enzyme activators or cofactors
Come from minerals in soil
Cl, Fe, Mn, B, Zn, Cu, Ni, Mo
How to determine which nutrients are essential for plant growth
Control solution: solution containing all minerals
Experimental solution: solution without a certain mineral
See effects of lack of mineral on plant growth
Chlorosis
Lack of chlorophyll in a plant
Phosphate deficient: can see anthocyanin (purple color)
Potassium or nitrogen deficient: can see carotenoids (yellow-orange color)
Mobile nutrient
Can move in plant
Nitrogen deficient: can see in old leaves (nitrogen travels to new leaves)
Immobile nutrient
Cannot move in plant
Iron deficient: can see in young leaves (iron is confined to old leaves)
Epiphyte
Slow growing plant
Grows on other plants and symbiotically gains nutrients from them
Photosynthetic parasite
Taps into xylem of other plants
Limited nitrogen: high transpiration
Example: mistletoe
Carnivorous plants
Acidic soils with low nitrogen: make up for lack of nutrients by consuming other organisms (usually insects)
Example: pitcher plant
Components of soil
Water (25%) Rock (45%) Organic material (5%) Air (25%) Pore space: water and air
Tropical forest soil
Red in color (high iron content)
Deep (lots of weathering)
Organic material content low (lots of decomposition)
Prairie soil
Dark color
Not as deep
Lots of organic material: good for growing crops
Soil forming factors
"TROPC" Time (younger soil-richer) Relief (topography) Organisms Parent material (rock material that underlies soil) Climate- temperature and rainfall
Cation exchange complex
Soil particles are negatively charged on the outside
Cations are attracted to the outside
Plant secretes H+ that displaces other cations, so they can be absorbed by the plant
Nitrogen fixation
Done by rhizobium (bacteria)
N2 + many ATP molecules -> NH3
Nitrogenase (enzyme secreted by rhizobium) catalyzes reaction
Leghemoglobin (iron-containing protein) regulates oxygen supply in reaction
Nitrogen cycle
Reactions mediated by bacteria N2 or organic material -> NH3 NH3 + H+ (from soil) -> NH4+ NH4+ -> NO3- (absorbed by plant) Leftover NO3- -> N2
Formation of nodules
Chemical signals from root attract bacteria, which cause infection thread
Bacteroids form from infection thread in root
Growth of bacteroids continues and a root nodule forms
Nodule develops vascular tissue
Mycorrhizae
Mutualistic relationship of fungus and plant
Increased surface area: increased absorption
Generally facultative
Can stimulate growth
Endomycorrhizae
Penetrate cell wall, but not plasma membrane
Corn, wheat
Ectomycorrhizae
Penetrate roots, but in between cell walls
Pine, oak, maple (truffels, morels)
Mantle
Fungal sheath formed by micorrhizae
