soil, roots and water balance of the plant soil profile – aka soil layers

Download Soil, Roots and Water Balance of the Plant Soil Profile – aka Soil Layers

Post on 25-Dec-2015




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  • Slide 1
  • Slide 2
  • Soil, Roots and Water Balance of the Plant
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  • Soil Profile aka Soil Layers
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  • Soil 101 1. Humus = organics layer on top 2. Topsoil = mix of humus, sand, clay and minerals 3. Subsoil = mix of rocks, inorganic soil with little air or water for plant roots 4. Bedrock = solid rock
  • Slide 6
  • Soil Nutrients 1. Nitrogen 1. Nitrogen critical for leaf, stem development 2. Phosphorus 2. Phosphorus critical for flowering 3. Potassium 3. Potassium proteins and carbohydrates 4. - Roots (stunted if not enough) 4. Calcium 4. Calcium metabolism, growth, cell wall 5. Magnesium 5. Magnesium essential for chlorophyll 6. Trace 6. Trace Elements: Elements: S, Fe, Zn, Mb, B, Cu, Mn, Cl
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  • Modified Roots and Root Associations Prop roots develop from branches (or a vertical stem) to offer support to the plant
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  • Mycorrhizae = fungus root; Root Nodules may form from a symbiotic association with soil bacteria
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  • A root graft is a natural union between the roots of two trees, same or different species
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  • The 4 main functions of roots: 1)Anchorage, 2) absorption, 3) Conduction 4) storage Two main types of root systems are: 1) Taproot (DICOTS) 2) Fibrous root systems (MONOCOTS)
  • Slide 12
  • Nutrient transport in plants 1. Roots absorb water and minerals from the soil 2. Below ground gaseous exchange - roots 3. Xylem - water and minerals 4. Transpiration = water loss through leaves (evaporation) via stomata 5. Photosynthesis cells need a lot of water to do this 6. Phloem - Sugar transport to non-photosynthetic tissues
  • Slide 13
  • Xylem and Water movement Two types of xylem cells Tracheids Tracheids - gymnosperms Vessels Vessels and tracheids - angiosperms Water is moved through xylem by 1. Root pressure 1. Root pressure water is pushed by absorption of more water by roots 2. Transpiration tension 2. Transpiration tension - pulled by evaporation from leaves 3. Cohesionsticky 3. Cohesion water molecules are sticky or attracted to each other, which help pull water up the plant
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  • Primary tissues of a young Dicot Root Ex. Beans or Buttercups
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  • Cross-section through a Monocot root Eg. Corn
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  • Roots have a root cap and root hairs ; they do not usually have nodes, internodes, leaves, or buds
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  • Endodermis- the innermost layer of the cortex; regulates movement of minerals into root xylem (which will eventually be transported up the plant); cells of the endodermis contain the Casparian strip, which blocks movement of water ; this prevents loss of water out of roots back to the soil Waterproof layer between the veins and outside. Cuts off water loss!
  • Slide 18
  • Primary roots possess an epidermis, ground tissues (cortex and pith in certain plants), and vascular tissues Epidermis- protects the root; root hairs aid in water/nutrient absorption (isnt permeable) Cortex - consists of parenchyma cells which store starch
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  • Pericycle - gives rise to lateral roots and lateral meristem Xylem conducts water and dissolved minerals UPWARDS Phloem conducts dissolved sugars up and down the plant
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  • Leaf surfaces are dotted with millions of stomata such as this one. This stomate is lined by two guard cells that control its aperture. Because control requires movement, and movement requires energy, these cells contain numerous mitochondria and chloroplasts (the little green photosynthetic factories that look a bit like brussel sprouts in this shot). Thus they are the only cells in the epidermis that are green. Guard Cells


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