1. Monday 4/23/07 Review transpiration packets Plant nutrition notes Homework: Begin Control system in plant Chapter 39 754-757 Test Friday:Transpiration, Plant nutrition, and Control systems

2. Plant Nutrition Chapter 37

3. 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

4. Essential nutrients Essential nutrients are those plants need for complete life cycle There are 17 essential minerals/nutrients 1. Has identifiable role 2. Cannot be substituted 3. Deficiency leads to incomplete life cycle Hydroponic experiments to determine which nutrients were “essential” Macronutrients needed in greater quantities than micronutrients

5. 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)

6. Table 37.1

7. Nutrient deficiencies Plants can suffer from deficiencies of their essential nutrients and minerals Figure 37.4 Phosphate-deficient Healthy Potassium-deficient Nitrogen-deficient

8. ALL ABOUT SOIL! Topsoil: mix of particles from deteriorating rock and decaying organic material Humus: decaying organisms/organic material Loams: fertile soils with mixes of sand, silt and clay Good soils Drain adequately and retain air pockets Have large surface area for water/minerals Contain decomposers such as fungi and bacteria

9. 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

10. Contour tillage helps slow runoff of water and erosion of soil Figure 37.8

11. Plant Symbiosis Symbiotic nitrogen fixing bacteria Bacteria gains sugar from plant Mycorrhizae Epiphytes Grow on surface of plant in commensalism Parasitic plants Carnivorous plants

12. 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’ flytrap Pitcher plants Sundews Dodder

13. Figure 37.9 Atmosphere N2N2 Soil N2N2 N2N2 Nitrogen-fixing bacteria Organic material (humus) NH 3 (ammonia) NH 4 + (ammonium) H + (From soil) NO 3 – (nitrate) Nitrifying bacteria Denitrifying bacteria Root NH 4 + Soil Atmosphere Nitrate and nitrogenous organic compounds exported in xylem to shoot system Ammonifying bacteria Soil Bacteria Nitrogen-fixing bacteria can convert atmospheric nitrogen (into nitrogenous minerals plants can absorb as nutrients (usually NH3)

14. Protein deficiency Common malnutrition in humans Plants are poor sources of proteins Current research is working on enriching crops with proteins

15. Mycorrhizae aEctomycorrhizae. 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 (fungal sheath) Endodermis Fungal hyphae between cortical cells (colorized SEM) 100  m (a)