Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Chapter 37 Plant Nutrition

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Overview: A Nutritional Network Every organism continually exchanges energy and materials with its environment For a typical plant, water and minerals come from the soil, while carbon dioxide comes from the air

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 37.1: Plants require certain chemical elements to complete their life cycle Plants derive most of their organic mass from the CO 2 of air, but they also depend on soil nutrients such as water and minerals Minerals H2OH2O H2OH2O O2O2 O2O2 CO 2

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Macronutrients and Micronutrients A chemical element is considered essential if it is required for a plant to complete its life cycle Researchers use hydroponic culture to determine which chemicals elements are essential Control: Solution containing all minerals Experimental: Solution without potassium

Nine of the essential elements are called macronutrients because plants require them in relatively large amounts The remaining are called micronutrients because plants need them in very small amounts

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Symptoms of Mineral Deficiency Symptoms of mineral deficiency depend on the nutrient’s function and mobility within the plant The most common deficiencies are those of nitrogen, potassium, and phosphorus

Healthy Phosphate-deficient Potassium-deficient Nitrogen-deficient

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Texture and Composition of Soils Topsoil is a mixture of particles of rock, living organisms, and humus (the remains of partially decayed organic material) A B C

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings After a heavy rainfall, water drains from the larger spaces of soil, but smaller spaces retain water because of its attraction to clay and other particles Animation: How Plants Obtain Minerals from Soil Animation: How Plants Obtain Minerals from Soil Soil particle surrounded by film of water Root hair Water available to plant Root hair Air space Cation exchange in soil Soil water Soil particle

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 37.4: Plant nutritional adaptations often involve relationships with other organisms Two types of relationships plants have with other organisms are mutualistic: – Symbiotic nitrogen fixation, involving roots and bacteria – Mycorrhizae, involving roots and fungi

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Role of Bacteria in Symbiotic Nitrogen Fixation Symbiotic relationships with nitrogen-fixing bacteria provide some plant species with a built-in source of fixed nitrogen For agriculture, the key symbioses between plants and nitrogen-fixing bacteria occur in the legume family (peas, beans, and other similar plants)

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Bacteroids within vesicle Nodules Roots Pea plant root. Bacteroids in a soybean root nodule. 5 µm Along a legume’s roots are swellings called nodules, composed of plant cells “infected” by nitrogen-fixing Rhizobium bacteria

LE Infected root hair Infection thread Rhizobium bacteria Bacteroid Dividing cells in root cortex Bacteroid Developing root nodule Dividing cells in pericycle Nodule vascular tissue Bacteroid

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Symbiotic Nitrogen Fixation and Agriculture Crop rotation takes advantage of the agricultural benefits of symbiotic nitrogen fixation A non-legume such as maize is planted one year, and the next year a legume is planted to restore the concentration of nitrogen in the soil

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Mycorrhizae and Plant Nutrition Mycorrhizae are mutualistic associations of fungi and roots The fungus benefits from a steady supply of sugar from the host plant The host plant benefits because the fungus increases the surface area for water uptake and mineral absorption

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Two Main Types of Mycorrhizae In ectomycorrhizae, the mycelium of the fungus forms a dense sheath over the surface of the root Epidermis Mantle (fungal sheath) Fungal hyphae between cortical cells Endodermis Mantle (fungal sheath) Cortex Ectomycorrhizae. 100 µm (colorized SEM)

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings In endomycorrhizae, microscopic fungal hyphae extend into the root Epidermis Fungal hyphae Cortex Endomycorrhizae. Root hair Endodermis Vesicle Casparian strip Arbuscules Cortical cells 10 µm (LM, stained specimen)

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Epiphytes, Parasitic Plants, and Carnivorous Plants Some plants have nutritional adaptations that use other organisms in nonmutualistic ways Video: Sun Dew Trapping Prey Video: Sun Dew Trapping Prey

LE 37-13a Staghorn fern, and epiphyte. This tropical fern (genus Platycerium) grows on large rocks, cliffs, and trees. It has two types of fronds: branched fronds resembling antlers and circular fronds that form a collar around the base of the fern.

LE 37-13b Mistletoe, a photosynthetic parasite. Dodder, a nonphotosynthetic parasite. Indian pipe, a nonphotosynthetic parasite. Dodder Host’s phloem Haustoria

LE 37-13c Venus’ flytrap. Pitcher plants.Sundews.