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Root Function

Root Function. 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?. Root Growth.

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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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