Plant nutrition Chapter 37

Plant nutrition Roots: Absorb water & minerals from soil. Leaves: CO2 diffuses from surrounding air through stomata.

Nutrients

Nutrients CO2 fixation in photosynthesis H2O solvent, cell turgid, volume for cell elongation Several inorganic nutrients Organic substances majority of plant weight (sugars, cellulose) O2 cellular respiration

Soil Soil horizons: Distinct soil layers Top soil most important Loams: Most fertile top soil Supports most growth

Fig. 37-2 A horizon B horizon Figure 37.2 Soil horizons C horizon

Soil Topsoil: Particles derived from rock (minerals) Living organisms Humus: Decaying matter Bacteria, algae, fungi, insects, worms

Topsoil Inorganic: Cations (K, Ca, Mg) Cation exchange: Exchange with H ions Absorbed through root hairs Anions (nitrate, sulfate, phosphate)

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Soil pH Water

Cultivation Depletes nutrients Crop rotation Fertilizers

Fig. 37-5 Figure 37.5 Contour tillage

Phytoremediation Process of removing contamination Soil & water by plants TCE (trichloroethylene) organic solvent TNT (trinitrotoluene) Heavy metals (Pb, Cd)

Nutrients Essential: Required nutrients Macronutrients C, O, H, N, P, S Components of organic substances Ca, Mg, K Micronutrients Cofactors in enzymatic reactions

Nutritional deficiency Symptoms of mineral deficiency Magnesium deficiency (chlorophyll) Causes yellowing of the leaves, or chlorosis Iron deficiency Cofactor in chlorophyll synthesis also causes chlorosis

Nutritional deficiency

Healthy Phosphate-deficient Potassium-deficient Nitrogen-deficient Fig. 37-7 Healthy Phosphate-deficient Potassium-deficient Figure 37.7 The most common mineral deficiencies, as seen in maize leaves Nitrogen-deficient

Nutritional deficiency

Food Fortification Genetically modified plants Absorb nutrients-human consumption Breakfast cereals additional nutrients in the grains Golden rice (vitamin A fortified)

Nitrogen Nitrogen makes proteins & nucleic acids Atmospheric nitrogen is N2 Bacteria can “fix” nitrogen Plants can absorb it Bacteria live near roots or found in plant tissue

Nitrogen Rhizophere: Soil layer bound to roots Rhizobacteria: Bacteria in the rhizophere

Nitrogen

Mycorrhizae Roots & fungi mutualistic relationship Help absorb nutrients Ectomycorrhizae Fungi produces mantle Arbuscular mycorrhizae Penetrate root cells

Nutritional adaptations Epiphyte: Grows on another plant Absorbs water and minerals from rain Parasitic: Absorb nutrients from plant host Carnivores: Obtain nitrogen and minerals from insects

Nutritional adaptations

Nutritional adaptations