ROOTSThe hidden half of agriculture
Reading for the week
Reading Questions    1) Why have roots been studied so much less than the above-ground                         components ...
Have you ever taken the timeto look closely at crop roots?
What should you look for?                                      extensive white color                         growth into  ...
Bill Darrington (Persia, IA)
Getting dirty with 2 champions of Vertical Farming                                         Francis ChildsRay Rawson       ...
Ken Ferrie inspectingcorn roots on a farm in      central IL.
"One of our primary goals is to get the first three sets of crown roots deep intothe soil… In vertical-tillage, no-till or...
You really won’t know what is happening underground unless you take a look…
All you need is          a shop-vac and            a hose :-> !Its just like going to the dentist!
http://www.agry.purdue.edu/ext/corn/news/timeless/Roots.html
Understanding corn root                                 developmentThe seed roots stopgrowing shortly after   the coleopti...
Have you ever heard of “floppy corn”   or “rootless corn” syndrome?      Where are the nodal roots?
“Floppy corn” or “rootless corn” occurs when surface soil is toodry for healthy elongation of roots from the first node (V...
1926http://www.soilandhealth.org/01aglibrary/010139fieldcroproots/010139toc.html
4 weeks            Corn root development                        documented in the 1920s                                  I...
Wading pool gardens  in my back yard       How is it possible for healthy crops to     grow with such a limited rooting vo...
Watermelon roots that                      grew in a wading poolWading pools do NOT provide an optimal rooting zone but a ...
?
All you need to do to grow healthy corn rootsis use rootworm resistant genetics… right??When rootworm pressure is high, ro...
Rootworm resistant genetics are not a silver bullet !                                     Severe damage by corn           ...
A significant correlation was found between the number of years Cry3Bb1 corn had been grown in a field and  survival of we...
“Most important, though, for effective corn rootwormmanagement is to consider a long-term, integrated approachthat include...
8/17/2012
What do you know about corn rootworm biology ??     Western corn rootworm beetle   Northern corn rootworm beetle         D...
http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList
http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList
http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList
Goose                                             neckinghttp://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=a...
http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList
http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList
http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList
In North and South America, corn rootworms are attacked by  many pathogens, predators and parasitoids, some of which      ...
Studies have shown thatmany of the natural enemiesof CRW are more common inreduced-tillage systems, andin fields with high...
Journal of Economic EntomologyArticle: pp. 330-339 | Abstract | PDF (1.44M)Disruption of Host Location of Western Corn Roo...
When damaged by corn rootworms, the roots ofsome corn plants release a chemical called (E)-β-caryophyllene that recruits a...
The root promoting effects of soil biology are underappreciated
Dramatic effect of steamsterilization and compost on  growth of pepper plants
competition                parasitism Don’t forget that soil biology can both promote and inhibit crop root growth        ...
This unfortunately                   is the norm in                     agriculture Acute  root           VS.disease      ...
Chemical toxicities caninhibit root growth & function                     Aluminum                      toxicity          ...
Understanding aluminum toxicity                         Fe and Mn toxicities also                            occur at lowe...
What damaged these corn roots?         Boron was included          in starter fertilizer
On-line tool for estimating             maximum rates of in-row fertilizer                     Damage is most likely in dr...
N and P promote root branching and proliferationhttp://www.naicc.org/meeting/2011/In%20Reduced%20Tillage%20-Vocasek.pdf
Air pruning promotes root branching
Soil block system for growing transplants       Air pruning promotes root branching
Why do crops on tiled-drained land                tend to be more drought resistant ?Ontario Ministry of Ag and Food
Do crop roots grow toward water?          Roots elongate directed by gravity in aerobic soil!Ontario Ministry of Ag and Food
Soil aeration affects soil temperaturewhich strongly affects rate of root growth     http://www.naicc.org/meeting/2011/In%...
Compaction strongly impacts root growth and function                  Sub-soil water                  and nutrients       ...
What causes sidewall   compaction?     Waiting for drier soilis the most important solution
Tillage systems   affect root   growth and     function           Adapted from Hunt et al. (1986)
Long term no-till                                  (w/ healthy soil biology)             Intensive tillage                ...
Radish roots > 40”after 1.5months            Annual            ryegrass            roots            penetrating 40”
Visual evidence of biodrilling                 (Williams and Weil, 2004)
Another type of biodrill
Weil       Which approach       would you use ?
Why are healthy roots so      important?       Roots perform       many valuable        functions !
In addition to the most obvious functionsphysical support and uptake of water and nutrients                    ROOTS are: ...
What’s                Macro-missing    anatomy of roots if this was a  cornplant?
Micro-anatomy of rootshttp://www.sparknotes.com/biology/plants/plantstructures/section2.rhtml
Physical protection  source of lubrication,   & sensor of gravityWhat is the function of the root cap?
What is the function of root hairs?• Increased surface area for  uptake of water and nutrients• Anchoring of roots allowin...
The cell wall of the endodermis (pink inner strip of cells) is waterproofed by theCasparian strip, which forces water to e...
Apoplast vs. symplastThe movement of fluids from the root hairs to the xylemcan occur through one of two conductive pathwa...
http://www.mie.utoronto.ca/labs/lcdlab/biopic/fig/35.03.jpg
Nutrient uptake can be an active or a passive process outside cell                                                        ...
Outside cellInside cell
K+           H+       -       The pH of a plant’s NO3       rhizosphere changes as             the plant regulates itsH+  ...
Which plant received nitrate (NO3-)?Which plant received ammonium (NH4+)? http://departments.agri.huji.ac.il/plantscience/...
The ins and outs of plant nutrition                                                                  H20                  ...
Plants take up mostly inorganic forms of nutrientswhen inorganic forms of nutrients are readily available  In some natural...
Why does water move   up into   plants?Water moves upward  through plantswhenever there is anegative gradient ofwater pote...
H20A continuous                 Solar energychain of water                              drives the molecules is           ...
Rhizosphere   Roots normallyoccupy < 1% of topsoil       volume The rhizosphere is normally << 10 % of     Zone of root   ...
Navigating the rhizosphere                                                          End of the                           R...
Healthycowpeanodule with a  pinkinterior
Legume  nodules  come inmany shapes and sizes
Lots of complicated biochemistry – very intensively studied!!Legume  love affair                                          ...
Examples of rhizobia innoculant
Subterranean clover*       Inoculation groups for commonly grown legumes                                  White clover   C...
How much N do soybeans fix and how much   of this N is left behind after harvest?                                         ...
Mycorrhizae - internet of the soil
2 main types of mycorrhizal associations                      Ectomycorrhizae                                           AM...
Mycorrhizal Networks: Connecting    plants intra- and interspecifically                                 •Many plants are  ...
Increase nutrient (P) uptake          suppress pathogens Mediate plant competition           Improve soil structure       ...
There are many     mycorrhizal  inoculants on themarket and growing evidence that they can increase cropperformance but it...
Some of the most dramatic responses to  mycorrhizal inoculation occur during         reforestation projects
Have you ever wondered how far out tree roots extend?                         ?
Tree roots often extend >2 times farther than the canopy
Is this tree likely to remain healthy?               ?
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New root presentation
New root presentation
New root presentation
New root presentation
New root presentation
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I shared this presentation with my Soil Fertility class at Western Illinois University in August 2012

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  1. 1. ROOTSThe hidden half of agriculture
  2. 2. Reading for the week
  3. 3. Reading Questions 1) Why have roots been studied so much less than the above-ground components of plants?2) What was the “Green Revolution” and why does Dr. Lynch think ”roots are the key to a second green revolution”?3) How did crop breeders accomplish most of the yield gains achieved during the 20th century and how does Dr. Lynch think they should shift their focus? 4) The article discusses 4 promising strategies for root research under theheadings “Designer roots”, “Stealth scavengers”, “Microbial manipulations” and “A healthy fixation”. For each of the 4 research strategies, describe (in your own words), something that you thought was particularly interesting.5) If you had an opportunity to be involved with innovative root research (e.g., as an intern at a lab or a farmer trying a new technology), briefly describe what you would like to try. Submit your answers to the these questions using WO before the start of class on Friday 8/31.
  4. 4. Have you ever taken the timeto look closely at crop roots?
  5. 5. What should you look for? extensive white color growth into Healthy shoot growth the sub-soilproliferate and high minimal in all yields evidence ofdirections deformities Efficient use of soil resources
  6. 6. Bill Darrington (Persia, IA)
  7. 7. Getting dirty with 2 champions of Vertical Farming Francis ChildsRay Rawson VF = Management system for optimum root extension and function
  8. 8. Ken Ferrie inspectingcorn roots on a farm in central IL.
  9. 9. "One of our primary goals is to get the first three sets of crown roots deep intothe soil… In vertical-tillage, no-till or strip-tillconditions, the first set of crown roots will go down. But, when we do horizontal tillage before planting, except in a few conditions like sand, no matter what we did in the fall, the first two sets of crown roots almost always turn on the dense layer. Hopefully, with fall vertical tillage, the third set will penetrate.“Ken Ferrie – Farm Journal, September 2006
  10. 10. You really won’t know what is happening underground unless you take a look…
  11. 11. All you need is a shop-vac and a hose :-> !Its just like going to the dentist!
  12. 12. http://www.agry.purdue.edu/ext/corn/news/timeless/Roots.html
  13. 13. Understanding corn root developmentThe seed roots stopgrowing shortly after the coleoptile emerges from the soil surface. The nodal root system becomes visible at ~ V1. The nodal root system becomes the dominant system by V6.
  14. 14. Have you ever heard of “floppy corn” or “rootless corn” syndrome? Where are the nodal roots?
  15. 15. “Floppy corn” or “rootless corn” occurs when surface soil is toodry for healthy elongation of roots from the first node (V2 to V4). Young roots emerging from the first node will die if themeristematic tissue desiccates prior to extension into moist soil. The crown of a young corn plant is typically located only 3/4 inch or so below the soil surface and so is particularly vulnerable to dry upper soil conditions.
  16. 16. 1926http://www.soilandhealth.org/01aglibrary/010139fieldcroproots/010139toc.html
  17. 17. 4 weeks Corn root development documented in the 1920s If this was possible 90 8 weeks years ago, just think what is possible today? 16 weeks Crops grown on modern rowspacings generally do not grow such wide root systems 7 feet deep !!
  18. 18. Wading pool gardens in my back yard How is it possible for healthy crops to grow with such a limited rooting volume?
  19. 19. Watermelon roots that grew in a wading poolWading pools do NOT provide an optimal rooting zone but a small root system can support healthy shoot growth with adequate moisture and nutrition.
  20. 20. ?
  21. 21. All you need to do to grow healthy corn rootsis use rootworm resistant genetics… right??When rootworm pressure is high, rootworm resistant genetics normally result in much healthier roots
  22. 22. Rootworm resistant genetics are not a silver bullet ! Severe damage by corn rootworm larvae to roots of a biotech corn rootworm hybrid http://www.ipm.iastate.edu/ipm/icm/2006/11-13/btcorn.html
  23. 23. A significant correlation was found between the number of years Cry3Bb1 corn had been grown in a field and survival of western corn rootworms. Interviews withfarmers indicated Cry3Bb1 corn had been grown for at least three consecutive years in all of the fields containing resistant corn borers. The researchers concluded insufficient planting of refuges and non-recessive inheritance of resistance is likely to have contributed to the development of resistance.They noted a 2009 study done by the Center for Science in the Public Interest indicated only 50% of Bt maize planted in Midwest complied with EPA requirements for refuge size and proximity to Bt fields. http://cornandsoybeandigest.com/blog/bt-resistant-corn-borers-spur-concerns
  24. 24. “Most important, though, for effective corn rootwormmanagement is to consider a long-term, integrated approachthat includes multiple tactics, such as adult suppressionprograms, use of soil insecticides at planting, rotation of Bthybrids that express different Cry proteins, and rotation tononhost crops.Many producers have relied on a single tactic for too manyyears, and unfortunate consequences are beginning to emerge.As harvest gets under way this fall, I suspect that moreproducers in northwestern Illinois will encounter lodged cornthat has been severely damaged by western corn rootworms.As I learn more about this evolving situation, I will keep youinformed”.Mike Gray – U of I Extension Entomologist - 2011
  25. 25. 8/17/2012
  26. 26. What do you know about corn rootworm biology ?? Western corn rootworm beetle Northern corn rootworm beetle Diabrotica virgifera Diabrotica barberi
  27. 27. http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList
  28. 28. http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList
  29. 29. http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList
  30. 30. Goose neckinghttp://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList
  31. 31. http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList
  32. 32. http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList
  33. 33. http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList
  34. 34. In North and South America, corn rootworms are attacked by many pathogens, predators and parasitoids, some of which are specialized natural enemies of corn rootworms. European entomologists are studying natural predators of corn rootworms (collected from soils in N. and S. America) for use incontrolling corn rootworms in Europe (where rootworms are not native)
  35. 35. Studies have shown thatmany of the natural enemiesof CRW are more common inreduced-tillage systems, andin fields with higher levels of organic matter.
  36. 36. Journal of Economic EntomologyArticle: pp. 330-339 | Abstract | PDF (1.44M)Disruption of Host Location of Western Corn Rootworm Larvae withCarbon DioxideE. J. Bernklau, E. A. Fromm, and L. B. BjostadDepartment of Bioagricultural Sciences and Pest Management, ColoradoState University, Fort Collins, CO 80523Elevated concentrations of carbon dioxide (CO2) prevented western cornrootworms from locating the roots of growing corn in behavioral bioassaysconducted in soil tubs. When CO2 was pumped into one end of a soil tub,significantly more larvae were recovered from soil at the treated end thanfrom soil around a growing corn plant at the opposite end of the tub. Incontrols with ambient air pumped into one end of a soil tub, significantlymore larvae were recovered from the soil around the corn plant than fromsoil on the treated side. Larvae were unable to locate the roots of cornseedlings when CO2-generating materials were mixed into the soil.
  37. 37. When damaged by corn rootworms, the roots ofsome corn plants release a chemical called (E)-β-caryophyllene that recruits an entomopathogenic nematode (Heterorhabditis megidis) to feed on corn rootworms. Modern corn breeding has resulted in loss of the (E)-β- caryophyllene signal in many hybrids, reducing their ability to recruit H. megidis. Under field conditions, the infection rate of corn rootworms with H. megidis were found to be 5x higher on a corn variety producing the below-ground signal than on a variety that doesnot. Moreover, spiking the root system of a non-producing variety with synthetic (E)-β-caryophyllene decreased the emergence of corn rootworm adults by > 50%.
  38. 38. The root promoting effects of soil biology are underappreciated
  39. 39. Dramatic effect of steamsterilization and compost on growth of pepper plants
  40. 40. competition parasitism Don’t forget that soil biology can both promote and inhibit crop root growth and functionantibiosis induced resistance
  41. 41. This unfortunately is the norm in agriculture Acute root VS.disease Chronic root malfunction Chemical, physical and biological factors can cause CRM!
  42. 42. Chemical toxicities caninhibit root growth & function Aluminum toxicity Aluminum toxicity Al toxicity is very common in the SE US and in tropical countries like Brazil Brady and Weil
  43. 43. Understanding aluminum toxicity Fe and Mn toxicities also occur at lower pHs Toxic forms of Al are bioavailable at pHs < 5.5 Aluminum toxicity is minimal above a water pH of 5.5 http://www2.ctahr.hawaii.edu/tpss/research_extension/rxsoil/alroot.gif
  44. 44. What damaged these corn roots? Boron was included in starter fertilizer
  45. 45. On-line tool for estimating maximum rates of in-row fertilizer Damage is most likely in dry coarse textured soilshttp://www.sdstate.edu/ps/soil-lab/loader.cfm?csModule=security/getfile&PageID=788496
  46. 46. N and P promote root branching and proliferationhttp://www.naicc.org/meeting/2011/In%20Reduced%20Tillage%20-Vocasek.pdf
  47. 47. Air pruning promotes root branching
  48. 48. Soil block system for growing transplants Air pruning promotes root branching
  49. 49. Why do crops on tiled-drained land tend to be more drought resistant ?Ontario Ministry of Ag and Food
  50. 50. Do crop roots grow toward water? Roots elongate directed by gravity in aerobic soil!Ontario Ministry of Ag and Food
  51. 51. Soil aeration affects soil temperaturewhich strongly affects rate of root growth http://www.naicc.org/meeting/2011/In%20Reduced%20Tillage%20-Vocasek.pdf Soil can get too hot for optimal root growth!
  52. 52. Compaction strongly impacts root growth and function Sub-soil water and nutrients Brady and Weil (2002) Brady and Weil (2002)
  53. 53. What causes sidewall compaction? Waiting for drier soilis the most important solution
  54. 54. Tillage systems affect root growth and function Adapted from Hunt et al. (1986)
  55. 55. Long term no-till (w/ healthy soil biology) Intensive tillage Network Plow pan of cracks and bioporesOntario Ministry of Ag and Food
  56. 56. Radish roots > 40”after 1.5months Annual ryegrass roots penetrating 40”
  57. 57. Visual evidence of biodrilling (Williams and Weil, 2004)
  58. 58. Another type of biodrill
  59. 59. Weil Which approach would you use ?
  60. 60. Why are healthy roots so important? Roots perform many valuable functions !
  61. 61. In addition to the most obvious functionsphysical support and uptake of water and nutrients ROOTS are: Carbon pumps that feed soil organisms and contribute to soil organic matter Energy and nutrient storage organs Chemical factories that change soil pH, poison competitors, filter out toxins, concentrate rare elements, etc. A sensor network that helps regulate plant growth
  62. 62. What’s Macro-missing anatomy of roots if this was a cornplant?
  63. 63. Micro-anatomy of rootshttp://www.sparknotes.com/biology/plants/plantstructures/section2.rhtml
  64. 64. Physical protection source of lubrication, & sensor of gravityWhat is the function of the root cap?
  65. 65. What is the function of root hairs?• Increased surface area for uptake of water and nutrients• Anchoring of roots allowing root extension
  66. 66. The cell wall of the endodermis (pink inner strip of cells) is waterproofed by theCasparian strip, which forces water to enter the symplast before it can enter theroot xylem phloem root hair xylemepidermis endodermis cortex
  67. 67. Apoplast vs. symplastThe movement of fluids from the root hairs to the xylemcan occur through one of two conductive pathways– theapoplast and the symplast.The apoplast route consists of inter-cellular spaceswithin the root cortex along which water and solutes candiffuse.The symplast route consists of channels through cellsalong which water and solutes are actively transported.
  68. 68. http://www.mie.utoronto.ca/labs/lcdlab/biopic/fig/35.03.jpg
  69. 69. Nutrient uptake can be an active or a passive process outside cell inside cell Plants are highly selective for potassium!!
  70. 70. Outside cellInside cell
  71. 71. K+ H+ - The pH of a plant’s NO3 rhizosphere changes as the plant regulates itsH+ internal charge balance.
  72. 72. Which plant received nitrate (NO3-)?Which plant received ammonium (NH4+)? http://departments.agri.huji.ac.il/plantscience/topics_irrigation/uzifert/4thmeet.htm
  73. 73. The ins and outs of plant nutrition H20 Root exudates N, S, P activate soil microbes Transpirational Root growth stream H 20 Diffusion Microorganisms produce most but not all of theenzymes need to digest OM
  74. 74. Plants take up mostly inorganic forms of nutrientswhen inorganic forms of nutrients are readily available In some natural ecosystems (e.g., tundra), organic forms of nutrients are very important
  75. 75. Why does water move up into plants?Water moves upward through plantswhenever there is anegative gradient ofwater potential along the soil-plant- atmosphere continuum
  76. 76. H20A continuous Solar energychain of water drives the molecules is process pulled up through the Plants provide plant the conduit H20 H20 H20
  77. 77. Rhizosphere Roots normallyoccupy < 1% of topsoil volume The rhizosphere is normally << 10 % of Zone of root topsoil volume influence
  78. 78. Navigating the rhizosphere End of the Rhizoplane rhizosphere Endo- Rhizosphere Ecto-RhizosphereMicrobial activity > 90% < 10% of soil volume of soil volume A few millimeters (Lavelle and Spain, 2001)
  79. 79. Healthycowpeanodule with a pinkinterior
  80. 80. Legume nodules come inmany shapes and sizes
  81. 81. Lots of complicated biochemistry – very intensively studied!!Legume love affair Sarrantonio
  82. 82. Examples of rhizobia innoculant
  83. 83. Subterranean clover* Inoculation groups for commonly grown legumes White clover Cowpea Group Alyceclover (Bradyrhizobium japonicum spp.) Cowpea Kudzu Peanut Lespedeza Joint vetch Lupine Group Blue lupine (Rhizobium lupini) White lupine Pea and Vetch Group Bigflower vetch (Rhizobium leguminosarum) Common vetch Hairy vetch Roughpea Winter pea Other** Bird’s-foot trefoil (Rhizobium loti) Cicer milk vetch Crown vetch Sainfoin (Rhizobium)Soybean has its own inoculation group!! Soybean (Rhizobium japonicum) Kura clover Leucaena
  84. 84. How much N do soybeans fix and how much of this N is left behind after harvest? N -N A good soybean crop will fix >150 lbs of N/ac but>200 lbs of N may be removed in the harvested beans.
  85. 85. Mycorrhizae - internet of the soil
  86. 86. 2 main types of mycorrhizal associations Ectomycorrhizae AM endomycorrhizaeArbutoidmycorrhizae Ericoid endomycorrhizae Orchid endomycorrhizae Lavelle and Spain (2001)
  87. 87. Mycorrhizal Networks: Connecting plants intra- and interspecifically •Many plants are connected underground by mycorrhizal hyphal interconnections. •Mycorrhizal (AM) fungi are not host specific.Illustration by Mark Brundrett
  88. 88. Increase nutrient (P) uptake suppress pathogens Mediate plant competition Improve soil structure Glomalin Superglue of the soil ??
  89. 89. There are many mycorrhizal inoculants on themarket and growing evidence that they can increase cropperformance but it isimportant to keep inmind that they are a much less proven technology than legume inoculants
  90. 90. Some of the most dramatic responses to mycorrhizal inoculation occur during reforestation projects
  91. 91. Have you ever wondered how far out tree roots extend? ?
  92. 92. Tree roots often extend >2 times farther than the canopy
  93. 93. Is this tree likely to remain healthy? ?

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