Plant Nutrition

Chapter 37

• Uptake of nutrients happens in roots and leaves.

• Roots, through mycorrhizae and root hairs, absorb water and minerals from soil.

• Essential nutrient required for plant to grow from seed and complete life cycle.

• Macronutrients needed in large numbers; micronutrients are not.

• Texture, pH, composition of soil determines types of plants that grow in area.

• Soil may be acidic or basic because of minerals that absorb in soil.

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• Soil made of topsoil - mixture of rock, living organisms, and humus (residue of partially decayed organic material)

• Can be washed away by water, robbing soil of important nutrients.

• Plants cannot use nitrogen in form of N2.

• Bacteria, nitrogen-fixing bacteria, convert N2 to NH3 (ammonia), via nitrogen fixation.

• Roots also form symbioses with organisms; relationships that are helpful to both species.

• Legume’s roots have swellings called nodules - plant cells that contain nitrogen-fixing bacteria.

• Crop rotation increases amount of nitrogen in soil.

• Farmers do this so nitrogen-rich plants (legumes) can add nitrogen to different soil areas.

• Mycorrhizae - modified roots, made of symbiotic relationships between fungi and roots.

• Fungus increases surface area for water uptake, secretes growth factors that stimulate roots to grow and branch, and produces antibiotics.

• Mycorrhizae - hyphae - help increase surface area; also invade cells by digesting cell wall.

http://www.plantpath.wisc.edu/tddl/tddl/disimg/bp/hyphae.jpg

• Some plants - parasites - will not photosynthesize.

• Tap into other plants that do.• Epiphytes (orchids) - not

parasitic; grow on other plants.• Some plants evolved modified

leaves that trap insects.