Monday 4/23/07

Review transpiration packetsPlant nutrition notes

Homework:Begin Control system in plantChapter 39754-757Test Friday: Transpiration, Plant nutrition, and Control systems

Plant NutritionChapter 37

Mineral Nutrients

Essential chemical elements plants need comes from soil, water & air

More than 50 inorganic substances found in many plants

Minerals are inorganic substances containing 2 or more elements

Essential nutrients

Essential nutrients are those plants need for complete life cycleThere are 17 essential minerals/nutrients

1. Has identifiable role2. Cannot be substituted3. Deficiency leads to incomplete life cycle

Hydroponic experiments to determine which nutrients were “essential”Macronutrients needed in greater quantities than micronutrients

Nutrients

Macro: C, O, H, N, S, P, K, Ca, Mg

Micro: Cl, Fe, B,Mn, Z, Cu, N, Mo

Deficiency: chlorosis (lack of Mg; chlorophyll production)

Table 37.1

Nutrient deficiencies

Plants can suffer from deficiencies of their essential nutrients and minerals

Figure 37.4

Phosphate-deficient

Healthy

Potassium-deficient

Nitrogen-deficient

ALL ABOUT SOIL!Topsoil: mix of particles from deteriorating rock and decaying organic materialHumus: decaying organisms/organic materialLoams: fertile soils with mixes of sand, silt and clayGood soils

Drain adequately and retain air pocketsHave large surface area for water/mineralsContain decomposers such as fungi and bacteria

Agriculture and Soil

Agriculture can cause a strain on healthy soil

Depletes mineral context of soil

Encourages erosion of soil

Chemical fertilizers are not slow release, cause excess nutrients to flood soil

Runoff from over fertilized land pollutes lakes/streams and groundwater

Contour tillage helps slow runoff of water and erosion of soil

Figure 37.8

Plant Symbiosis

Symbiotic nitrogen fixing bacteriaBacteria gains sugar from plant

Mycorrhizae

EpiphytesGrow on surface of plant in commensalism

Parasitic plants

Carnivorous plants

Plant Symbiosis

Staghorn fern, an epiphyte

EPIPHYTES

PARASITIC PLANTS

CARNIVOROUS PLANTS

Mistletoe, a photosynthetic parasite Dodder, a nonphotosynthetic parasite

Host’s phloem

Haustoria

Indian pipe, a nonphotosynthetic parasite

Venus’ flytrapPitcher plants Sundews

Dodder

Figure 37.9

Atmosphere

N2

Soil

N2 N2

Nitrogen-fixingbacteria

Organicmaterial (humus)

NH3

(ammonia)NH4

+

(ammonium)

H+

(From soil)

NO3–

(nitrate)Nitrifyingbacteria

Denitrifyingbacteria

Root

NH4+

SoilAtmosphere Nitrate and

nitrogenousorganic

compoundsexported in

xylem toshoot system

Ammonifyingbacteria

Soil Bacteria

Nitrogen-fixing bacteria can convert atmospheric nitrogen (into nitrogenous minerals plants can absorb as nutrients (usually NH3)

Protein deficiency

Common malnutrition in humans

Plants are poor sources of proteins

Current research is working on enriching crops with proteins

Mycorrhizaea Ectomycorrhizae. The mantle

of the fungal mycelium ensheathes the root. Fungal hyphae extend from the mantle into the soil, absorbing water and minerals, especially phosphate. Hyphae also extend into the extracellular spaces of the root cortex, providing extensive surface area for nutrient exchange between the fungus and its host plant.

Mantle(fungal sheath)

Epidermis Cortex Mantle(fungalsheath)

Endodermis

Fungalhyphaebetweencorticalcells

(colorized SEM)

100 m(a)