Chapter 37: Plant Nutrition. Where does mass come from? Mineral nutrients-- essential elements minimal contribution to mass Water – 80-85% of herbaceous.

Chapter 37: Plant Chapter 37: Plant NutritionNutrition

Where does mass come from?Where does mass come from? Mineral nutrientsMineral nutrients-- essential elements-- essential elements

minimal contribution to massminimal contribution to mass Water – 80-85% of herbaceous plants Water – 80-85% of herbaceous plants

over 90% lost via transpirationover 90% lost via transpiration Retained HRetained H22O = solvent, maintain O = solvent, maintain

turgidityturgidity Assimilated COAssimilated CO2 2 makes up most of organic makes up most of organic

molecules mass.molecules mass.

How do plants get How do plants get nutrients?nutrients?

Dry WeightDry Weight 95% organic (carbs, CHO, 95% organic (carbs, CHO,

cellulose).cellulose). 5% inorganics5% inorganics

nitrogen, sulfur, and phosphorusnitrogen, sulfur, and phosphorusFound in many organicsFound in many organics

Plant NutrientsPlant Nutrients Essential nutrientsEssential nutrients-- required for a -- required for a

plant to grow from a seed and plant to grow from a seed and complete the life cycle.complete the life cycle.

Plants require 9 macronutrients and Plants require 9 macronutrients and 8 microsnutrients8 microsnutrientsHydroponic cultures identify Hydroponic cultures identify

essential nutrientsessential nutrients

HydroponicsHydroponics

MacronutrientsMacronutrients Needed in large quantities Needed in large quantities 9 macronutrients 9 macronutrients

carbon, oxygen, hydrogen, carbon, oxygen, hydrogen, nitrogen, sulfur, and phosphorus nitrogen, sulfur, and phosphorus (found in organics)(found in organics)

potassium, calcium, and potassium, calcium, and magnesium (ions)magnesium (ions)

MicronutrientsMicronutrients Needed in very small amounts Needed in very small amounts 8 micronutrients 8 micronutrients

iron, chlorine, copper, zinc, iron, chlorine, copper, zinc, magnanese, molybdenum, boron, magnanese, molybdenum, boron, and nickel.and nickel.

Cofactors of enzymatic reactions.Cofactors of enzymatic reactions. Lacking micronutrients can Lacking micronutrients can

kill/sicken a plant.kill/sicken a plant.

Mineral Deficiencies (ex: Mineral Deficiencies (ex: Chlorosis)Chlorosis) Since Mg and Fe are involved in the production Since Mg and Fe are involved in the production

of chlorophyll, their deficiencies are marked by of chlorophyll, their deficiencies are marked by yellow leaves (chlorosis)yellow leaves (chlorosis)

Mineral DeficienciesMineral Deficiencies Mobile NutrientsMobile Nutrients

symptoms of the deficiency will appear symptoms of the deficiency will appear first in older organs first in older organs

Ex: chlorosis affects older leaves firstEx: chlorosis affects older leaves first Immobile Nutrients Immobile Nutrients

affect young parts of the plant firstaffect young parts of the plant first Older tissue = adequate supplies for Older tissue = adequate supplies for

shortagesshortages

SoilSoil The type of soil (composition/texture) The type of soil (composition/texture)

determines the plants that can survive determines the plants that can survive Originates from weathered rock Originates from weathered rock

(minerals)(minerals) Topsoil (product of weathering)Topsoil (product of weathering) Rich in decaying organic material Rich in decaying organic material

(humus), bacteria and rock(humus), bacteria and rock Horizons Horizons Horizontal layers of soil Horizontal layers of soil

SoilSoil

Soil TextureSoil Texture Depends on the size of its particles Depends on the size of its particles

(coarse sand to microscopic clay)(coarse sand to microscopic clay) LoamsLoams

Most fertile soils (equal silt/sand/clay)Most fertile soils (equal silt/sand/clay) fine particles = large surface area for fine particles = large surface area for

retaining minerals and waterretaining minerals and water course particles = air spaces that supply course particles = air spaces that supply

oxygen to the root (respiration)oxygen to the root (respiration)

Waterlogged Soil Waterlogged Soil Too much Too much HH22OO

Water in air spaces can suffocate a Water in air spaces can suffocate a plantplant

Unfavorable molds can grow and Unfavorable molds can grow and attack plant.attack plant.

Mangroves have long, hollow, tube Mangroves have long, hollow, tube roots that allow them to survive in roots that allow them to survive in marshland.marshland.

Topsoil OrganismsTopsoil Organisms 1 teaspoon = approx. 5 billion bacteria.1 teaspoon = approx. 5 billion bacteria. Organisms’ alter the physical and Organisms’ alter the physical and

chemical properties of the soil.chemical properties of the soil. Earthworms aerate soil (burrowing) add Earthworms aerate soil (burrowing) add

mucus holds fine particles together.mucus holds fine particles together. Bacteria (ie: nitrogen fixation)Bacteria (ie: nitrogen fixation) Plants extract nutrients, affect soil pH, Plants extract nutrients, affect soil pH,

and reinforce the soiland reinforce the soil

HumusHumus Decomposing organic materialDecomposing organic material Formed by the action of bacteria Formed by the action of bacteria

and fungi on dead organisms, feces, and fungi on dead organisms, feces, leaves, etc.leaves, etc.Crumbly soil -- retains water, Crumbly soil -- retains water,

porous enough for aeration of porous enough for aeration of rootsroots

Rich in minerals from decomp.Rich in minerals from decomp.

How does Soil Hold Water?How does Soil Hold Water?

•Electrostatic attraction between soil particles and water molecules.

•Plants extract the more loosely bound water molecules

•Surface of soil is charged (hydrophilic)

How does Soil Hold MineralsHow does Soil Hold Minerals

Positively charged minerals (KPositively charged minerals (K++, Ca, Ca2+2+, , MgMg2+2+ are not leached out by rain are not leached out by rain because they adhere to negative because they adhere to negative surface of clay (remember origins!)surface of clay (remember origins!)

Negatively charged mineral ions Negatively charged mineral ions (NO(NO33

--, H, H22POPO44--, SO, SO44

2-2-) leach out more ) leach out more

easily.easily.

Cation ExchangeCation Exchange (+) mineral ions are made available to (+) mineral ions are made available to

the plant when Hthe plant when H++ ions in the soil ions in the soil displace the mineral ions from the displace the mineral ions from the clay particles.clay particles.cation exchangecation exchange

roots secrete Hroots secrete H++ and compounds and compounds that form acids in the soil solutionthat form acids in the soil solution

How does Soil Hold Water?How does Soil Hold Water?

Soil MismanagementSoil Mismanagement The Dust Bowl The Dust Bowl

(1930’s)(1930’s) Farmers removed Farmers removed

grasses that held grasses that held soil in place during soil in place during droughtsdroughts

Topsoil was blown Topsoil was blown away and soil away and soil uselessuseless

FertilizersFertilizers Agriculture requires a lot of mineralsAgriculture requires a lot of minerals Fertilizers replace the minerals in Fertilizers replace the minerals in

the soilthe soil ““10-12-8” Fertilizer = 10% nitrogen, 10-12-8” Fertilizer = 10% nitrogen,

12% phosphorus and 8% potassium12% phosphorus and 8% potassium Used to increase crop yieldUsed to increase crop yield Organic Fertilizers (ie: manure)Organic Fertilizers (ie: manure) Too much = pollution of Too much = pollution of

groundwatergroundwater

Water Availability and Water Availability and IrrigationIrrigation Top limiting factor for plant growthTop limiting factor for plant growth Irrigation = bring water to dry Irrigation = bring water to dry

areas (ie desert)areas (ie desert) Irrigated water that evaporates Irrigated water that evaporates

leaves salt behind.leaves salt behind.Lowers soil HLowers soil H22O potentialO potential

plasmolysisplasmolysis

Wind and ErosionWind and Erosion

Wind destroys topsoil of many Wind destroys topsoil of many crops.crops.

Planting trees or other crops Planting trees or other crops (alfalfa) in rows between (alfalfa) in rows between fields.fields.Acts as a windbreak for soilActs as a windbreak for soil

Wind and ErosionWind and Erosion

Sustainable AgricultureSustainable Agriculture

The goal is to eventually The goal is to eventually develop farming techniques develop farming techniques that are maximally that are maximally conservation minded, conservation minded, environmentally friendly, and environmentally friendly, and profitable.profitable.

Human InfluenceHuman Influence Humans have made many areas Humans have made many areas

uninhabitable for both flora and faunauninhabitable for both flora and fauna contamination and/or overdevelopment.contamination and/or overdevelopment.

Phytoremediation – Phytoremediation – Use of plants that Use of plants that utilize toxic contaminants to clean up our utilize toxic contaminants to clean up our messmess Ex: alpine pennycress (Ex: alpine pennycress (Thlaspi Thlaspi

caerulescenscaerulescens) accumulates zinc in its ) accumulates zinc in its shootsshoots

Nitrogen FixationNitrogen Fixation Atmosphere = 80% nitrogen, yet Atmosphere = 80% nitrogen, yet

plants suffer from deficienciesplants suffer from deficiencies Plants cant use NPlants cant use N22 (g) directly (g) directly

Must be taken as NHMust be taken as NH44++ or NO or NO33

--

Decomp. of humus by microbes Decomp. of humus by microbes releases usable nitrogen into the releases usable nitrogen into the soilsoil

Denitrifying BacteriaDenitrifying Bacteria

Convert NOConvert NO33-- (usable) into N (usable) into N22

(not usable) which diffuses (not usable) which diffuses into atmosphereinto atmosphere

Denitrifying bacteria remove Denitrifying bacteria remove usable nitrogen from the soilusable nitrogen from the soil

Nitrogen-Fixing BacteriaNitrogen-Fixing Bacteria Nitrogen FixationNitrogen Fixation

Soil microbes convert NSoil microbes convert N22 (not usable) (not usable)

into NHinto NH33 (will be usable) (will be usable)

Nitrogen fixation restocks the soil Nitrogen fixation restocks the soil with usable forms of nitrogen with usable forms of nitrogen (specifically ammonia)(specifically ammonia)

Nitrogenase complex of enzymes Nitrogenase complex of enzymes catalyze rxnscatalyze rxns

Nitrogen Cycle in the SoilNitrogen Cycle in the Soil

Nitrogen FixationNitrogen Fixation Once bacteria release NHOnce bacteria release NH33, it picks up , it picks up

extra Hextra H++ to become NH to become NH44++ which plants which plants

can assimilate directlycan assimilate directly Much NHMuch NH44

++ oxidized to NO oxidized to NO33- - (also (also

absorbed) absorbed) Once absorbed, plants incorporate Once absorbed, plants incorporate

nitrogen into amino acids and nitrogen into amino acids and organicsorganics

SymbiosisSymbiosis When a species participates in a When a species participates in a

direct relationship with an direct relationship with an individual of another species.individual of another species.

Often involve microorganisms.Often involve microorganisms. Can be good, bad, or neutral for Can be good, bad, or neutral for

one or both of the organisms.one or both of the organisms.

Nitrogen-Fixing Root Nitrogen-Fixing Root NodulesNodules

RhizobiumRhizobium bacteria exist in specialized bacteria exist in specialized projections in roots of legumesprojections in roots of legumes

The bacteria fix nitrogen into usable The bacteria fix nitrogen into usable forms. forms.

The plant supplies nutrients to the The plant supplies nutrients to the nodule through xylem and phloem.nodule through xylem and phloem.

Relationship is good for both.Relationship is good for both. Plant gets nitrogen, the bacteria Plant gets nitrogen, the bacteria

obtains nutrients.obtains nutrients.

Root NodulesRoot Nodules

Root NodulesRoot Nodules

MycorrhizaeMycorrhizae Symbiosis b/t fungi and root of nearly Symbiosis b/t fungi and root of nearly all plantsall plants..

Early evolutionary adaptation??Early evolutionary adaptation?? Fungi gets a good (protected) environment with Fungi gets a good (protected) environment with

nutrients from plantnutrients from plant Plant Benefits:Plant Benefits:

FungusFungus surface area and absorbs surface area and absorbs minerals in the soil and supplies them to the minerals in the soil and supplies them to the plant.plant.

Fungi secretes growth factors that stimulate Fungi secretes growth factors that stimulate root growth.root growth.

Fungi produce antibioticsFungi produce antibiotics

Plant ModificationsPlant Modifications Parasites – Plants Parasites – Plants

that steal nutrients that steal nutrients from other plants (ie: from other plants (ie: tap into vascular tap into vascular tubes)tubes)

Carnivores – Plants Carnivores – Plants that eat meat (ex: that eat meat (ex: venus fly trap)venus fly trap)