5-1 Plant and Soil Nutrition Flashcards
How do plants get O2?
through photosynthesis and get the nutrients from roots, shoots, and leaves
How do plants get CO2?
through the leaves in the stomata
How do plants get Minerals?
they come from the soil through the water in roots
How do plants get H2O?
Xylem and Phloem allow for water
What are organic nutrients the product of?
Carbon and Hydrogen
Elements and compounds for proper plant nutrition: Essential
- 17 overall
- three: C, H, O which makes up 96% of the plant tissues (dry mass)
Elements and compounds for proper plant nutrition: Mineral
- 14 are from soil via root
- found as ions in the soil
- broken down to micro and macro nutrients
Elements and compounds for proper plant nutrition: micronutrients
- needed for the trace amounts
- used in enzymes cofactors, photosthetic pigments, plant hormones, and H2O balance
- EX: Cl Fe Mn Zn Cu Ni Mo
Elements and compounds for proper plant nutrition: Macronutrients
- Needed in trace amounts
- N P and K are limiting nutrients and will limit the plants growth
Macronutrients: Nitrogen
- a limiting macronutrient
- average 1% to 5% of dry mass
- ATP, nucleic acids, chlorophyll, hormones, coenzymes
- acquired from soil either from NH4+ or NO3-
Macronutrient: Phosphorus
- limiting
- average 0.2% dry mass
- ATP, nucleic acids, phospholipids, coenzymes
- acquired from soil either from H2PO4- or HPO2^2-
Macronutrient: Potassium
- limiting
- average 1% dry mass
- used for osmotic adjustment, organic molecule synthesis, an enzyme cofactor
- Available to plants as K+
Macronutrient: Calcium
- average 0.5% dry mass
- regulatory function, cell wall & membrane structure singaling, cofactor
- available to plants as Ca2+
Macronutrient: Magnesium
- average 0.2% dry mass
- important in chlorophyll
- an activator for many enzymes
- available to plants as Mg2+
Macronutrient: Sulfur
- average 0.1% dry mass
- protein construction, coenzymes, elector transport chains
- available as SO4^2-
What are the NPK numbers on a fertilizer bag?
- bags lists the percent by weight of nutrient
- Nitrogen - Phosphorus - Potassium
- EX: 10% of fertilizer is N So 100 grams of fertilizers will have 1p 0 grams of N
Mobile vs Immobile elements within plants
Mobile: older leaves show signs of deficiency (N P K Mg)
Immobile: new leaves show deficiency because nutrients are tied up in older leaves (Fe Ca)
What tissues do deficiencies manifest in?
Stunted growth, chlorosis, necrosis, wilting/off colors
The 5 factors that influence soil formation:
Number of size of horizons vary over space and time
- Parent materials
- Climate
- Topography
- Biological factors
- Time
Factors w/Soil formation: Parent materials
- particle size
- mineral composition
- pH
Factors w/Soil formation: Climate
- Temperature: warmer speeds up decomposition
- Precipitation: Moves materials through the soul; moist, nut not saturated materials decompose faster
- Glaciers (in some places): pushed & ground up soil
Factors w/Soil formation: Topography
- where you are on the landscape determines the quality of the soil
- processes = erosion and depostion
Factors w/Soil formation: Biological factors
- Crops/Annual plants = shallow routes, shallow OM later
- Perennial grasses = deeper routes, deep OM layer
- Forest tend to have organic matter below ground
Elements of soil texture: Time
- Materials weather
- OM accumulates
- Horizons develop
How does sandy texture influence the availability of O2 and water?
- low water availability = water drains through
- high O2 availability = many spaces
How does silty texture influence the availability of O2 and water?
- Moderate water availability = water clings to clay
- Moderate O2 availability
How does clay texture influence the availability of O2 and water?
- high water availability = water clings to clay
- low O2 availability = few spaces
What is organic matter?
and how does it alter soil moisture and nutrient availability?
- Organic matter helps create more pores
- 5% of soil is OM
- results from the decomposition of living organisms
- includes organic carbon (but also other nutrients)
- ‘humus’
- complex molecules that contain organic carbon + other nutrients
- needs to be decomposed to release nutrients for use in organisms (plants need inorganic nutrients)
How does OM alter soil moisture and nutrient availability?
- water clings to OM = soil stand moist longer
- high nutrient availability = source of nutrients, high cation exchange capacity, anions remain in solution (water does not drain)
- OM helps create spaces = leads to higher oxygen availability
- OM does not pack tight - allows for root penetration
What is cation exchange?
when protons (H+) or other soluble cations bind to the negative charged soil particles and cause bound cations to be released
How does cation exchange relate to soil texture and pH?
- released cation are available for uptake by roots
- released cations are vulnerable to leaching
How do cations and anions behavior change in soils with different cation exchange capacity?
Cations (+) =
- dissolve in water
- not as available to plants
- attracted to the a negative charge of OM and clay particles
Anions (-) =
- in soil solution (interact w/H-bonds)
- readily available for plant absorption
- easily leached from soil
Compare and contrast the three ways nutrients move toward roots (diffusion, mass flow, and root interception)
Diffusion: most important process moving nutrients to roots, movement from area of high concentration to low, roots depletede areas of nutrients (diffusion shell), more nutrients diffuse in
Mass Flow: movement by soil flowing water, water will move through soil driven by plant uptake & nutrients along, saturated flow (movement of water by gravity)
Root interception: minor mode of plant nutrition, plant roots will intercept nutrients as the root grows through soil
What is the process of nutrient uptake?
- nutrient uptake moves with passive transport
- more inside than outside = STRONG concentration gradient
- nutrients must move AGAINST concentration gradient to get in the cell
- Proton pump (cations) = root cells establish a concentration gradient of protons, pump H+ out of cell (use ATP), increase the membrane potential, cells get negative charge and cations passively enter through channel proteins
- Contransporter (anions) = move against concentration gradient, two ions at once (H+ plus anion), NO3- and H+
How do root hairs increase the surface area for absorption?
root hair have high surface area and max absorption from the soil
What are the different routes to the xylem?
- Simplistic (via plasmodesmata)
- Transmembrane (via Aquaporin protiens)
- Apoplastic (between cells)
What are the mechanisms used in plants to avoid uptake?
- Passive exclusion = molecules cannot pass through Casparian strip
- active methods
(metallothioneins, phyochelatins and antiporters) = binds to metals and prevent them from acting like a Posion
What are mycorrhized fungi?
They are plant symbionts because:
- they increase surface area for nutrient absorption
- use exoenzymes to access nutrients
- exchange these for carbon fixed in photosynthesis
What structures and processes are associated with rhizobia infection and nodule development?
(nod factors, molybdenum, nitrogenase, leghemoglobin)
Compare and contrast plants with high and low nutrient use efficiencies.
High: tend to be late successional; nutrient environments dominated by species that are wasteful w/nutrients
Low: tend to be weedy and early succession, Low nutrient environments dominated by species that conserve nutrients
Alternate nutrient strategies of plants parasitic?
- getting carbon and nutrients from host
- not green = not photosynthesizing
-stealing sugar and nutrients
Alternate nutrient strategies of plants epiphytic?
- not parasitic
- just growing on the other plant (not in soil)
- absorb water and nutrients from rainwater, dust, etc.
Alternate nutrient strategies of plant carnivorous?
- photosynthesize (carbon from air, energy from sun)
- trap insects for NUTRIENTS
- costly
- live in soils that are poor in nutrients
- other plants cannot live there so they can compete, could not compete in other soils
