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Root Function

Learn about root growth, turnover, mycorrhizae, nodules, and more in plants. Explore the role of roots in nutrient uptake and support for plant health. Discover fascinating insights into root systems' importance in plant development.

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Root Function

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  1. Root Function

  2. Root Growth • Can grow as much as 1 cm/day • Controlled by • Temperature • 0.36 mm/day at 5C • 3.4 mm/day at 20C • Water, Nutrients • More nutrients => fewer roots • On infertile sites, more photosynthate goes to the roots – WHY?

  3. Root Growth • Total root production can be 50-70% of Net Primary Productivity (NPP) • Fine root growth, respiration & loss • Seasonal Root Turnover • Begins at snowmelt • Declines at budburst • Restricted by water stress • Root death is a MAJOR part of nutrient and carbon cycling!

  4. SeasonalRootTurnover LUKAC, M., CALFAPIETRA, C. & GODBOLD, D.L. (2003)Production, turnover and mycorrhizal colonization of root systems of three Populus species grown under elevated CO2 (POPFACE).Global Change Biology9 (6), 838-848.doi: 10.1046/j.1365-2486.2003.00582.x

  5. Growth: Root vs. Shoot

  6. Root : Shoot Ratios

  7. Root Hairs

  8. Root Hairs • 1 cell wide, last hours to weeks • Continually form just behind root tip • Increase surface area for absorption of water and mineral nutrients • Attachment for soil-borne microbes • Increase adhesion between roots & surroundings • Sensitive to desiccation • Most are produced in the spring (95%) and are seasonal

  9. Root Water Uptake(primary function)

  10. How do plants get water and nutrients?

  11. Rhizosphere • Absorbing root – soil interface • About 1 mm in width, it surrounds the • Epidermis of the living root hairs • Boundary cells of mycorrhizae • Hyphae growing out from some mycorrhizae • This is where all the action takes place • Water absorption • Nutrient absorption

  12. Mycorrhizae(Myco = fungus; rhiza = root) • Formed by invasion of fungus (5000 species); 90% of all plants in nature • Symbiotic relationship with tree

  13. Mycorrhizae

  14. The Effect of Mycorrhizaeon Redwood Seedlings

  15. Nitrogen Fixation in Trees • Symbiotic relationship between the tree and bacteria • Bacteria gets steady food supply • Tree gets steady nitrogen source • Important in N-limited systems and impoverished sandy soils • Occurs often in black locust and alder • Black locust / Rhizobium can produce 60-100 kg N / ha / yr (53-89 lb N/acre/yr)

  16. Root Nodules • Modified roots • Continue to grow and divide • Nodules contain a certain class of bacteria (actinomycetes) • Symbiotic relationship • Nitrogen for the plant • Food supply for the bacteria

  17. Root Grafting

  18. The Living Stump From The Living Stump Discovery Project website http://pfranc.com/projects/LSD/

  19. The Living Stump The Natural Bridge, Upper Rogue River, Southern Oregon

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