n Chapter 37 ~ Plant Nutrition

I. Nutrients n A. Essential: required for the plant life cycle u 1. Macro- (large amounts) carbon, oxygen, hydrogen, nitrogen, sulfur, phosphorus, potassium, calcium, magnesium

n 2. Micro- (small amounts; cofactors of enzyme action) chlorine, iron, boron, manganese, zinc, copper, molybdenum, nickel n 3. Deficiency chlorosis (lack of magnesium; chlorophyll production)

4. Fertilizers

II. Soil n A. Determines plant growth & variety (also climate) n B. Composition/horizons: u 1. topsoil (rock particles, living organisms, humus- partially decayed organic material) u 2. loams (equal amounts of sand, silt, and clay)

3. Particle size 3. Particle size SandSiltClay SandSiltClay

3. Water holding capacity SandSiltClay SandSiltClay

III. Nitrogen Fixation n A. Atmosphere, 80% N 2 n B. Some bacteria contain nitrogenase that converts N 2 to: ammonium (NH 4 +) or nitrate (NO 3 -) u 1. This process is energy expensive, requiring 12 ATP/NH 3 thus the soil must be rich in organic matter to provide the fuel for respiration.

n C. Bacteria types: u 1. Ammonifying (through humus decomposition); u 2. nitrogen-fixing (atmospheric N2); u 3. nitrifying (convert NH4+ to NO3-); u 4. denitrifying (convert NO3- to N2) u 5. Nitrogen fixation; crop rotation

IV. Plant symbiosis n A. Bacteria u 1. Rhizobium bacteria (found in root nodules in the legume family) F a. Mutualistic: legume receives fixed N 2 ; bacteria receives carbohydrates & organic materials

B. Fungi n 1. Mycorrhizae (fungi); modified roots u a. Mutualistic: fungus receives sugar; plant receives increased root surface area and increased phosphate uptake

n 2. Two types: u a. ectomycorrhizae – ensheaths/covers the root u a. ectomycorrhizae –(outer) ensheaths/covers the root u b. Endomycorrhizae (inside)-- 90% of plants grows through cell wall but not through cell membrane

V. Plant parasitism & predation n Mistletoe (parasite) n Epiphytes n Carnivorous plants vid venus fly trap fly trap fly trap

Venus Fly Trap

Sundew