Light and
     Temperature
    Effects in High
        Tunnels
•   Light Intensity and Photosynthesis
•   Carbon dioxide (...
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
Light and
     Temperature
    Effects in High
        Tunnels
•   Light Intensity and Photosynthesis
•   Carbon dioxide (...
How much light can a plant use
    for photosynthesis?


      + CO2 + H2O                              C2H + O2




     ...
SOUTHERN GROWERS

                        NORTHERN GROWERS




© 2009 Regents of the University of Minnesota
Response to increasing
    light intensity
     (irradiance).
          Units are in umol m-2 s-1

Multiply umol m-2 s-1 b...
Variation in photosynthetic responses of
different species to increasing light intensity




              © 2009 Regents ...
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
What we learned
• Species differed in how much light saturates
  photosynthesis.
• Species studied showed photosynthetic s...
How much light is getting
    to your plants?



        © 2009 Regents of the University of Minnesota
750 ft-c




    January Daily Light Integrals
© 2009 Regents of the University of Minnesota
3700 ft-c




             April Daily Light Integrals
© 2009 Regents of the University of Minnesota
In general, light penetration into a
 greenhouse varies from about 30-85%.
 60% light transmission is very common.
   Sing...
© 2009 Regents of the University of Minnesota
3700 ft-c x 0.45 = 1,665 ft candles
                         (333 umol m-2 s-1)




             April Daily Light Integra...
SOUTHERN GROWERS

                        NORTHERN GROWERS




© 2009 Regents of the University of Minnesota
Increasing DLI versus total flower bud number




          10 moles/day




             © 2009 Regents of the University...
Light and
     Temperature
    Effects in High
        Tunnels
•   Light Intensity and Photosynthesis
•   Carbon dioxide (...
Response to increasing
 carbon dioxide (CO2).
          Units are in umol m-2 s-1

Multiply umol m-2 s-1 by 5 to get footc...
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
How much light can a plant use
    for photosynthesis?


      + CO2 + H2O                              C2H + O2




     ...
© 2009 Regents of the University of Minnesota
What we learned . . .
• Species differed in how much CO2 they could
  utilize under our conditions (300 umol m-2 s-1).
• P...
Light and
     Temperature
    Effects in High
        Tunnels
•   Light Intensity and Photosynthesis
•   Carbon dioxide (...
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
What we know . . .
• Any leaf filtering increases leaf size, increases
  stem elongation, and decreases flower
  number.
•...
Light and
     Temperature
    Effects in High
        Tunnels
•   Light Intensity and Photosynthesis
•   Carbon dioxide (...
Shade Cloth Issues




   © 2009 Regents of the University of Minnesota
SOUTHERN GROWERS

                        NORTHERN GROWERS




© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
Why do we use shade cloth?
• Limit heating in the greenhouse!
• In general, we have been finding that any shading
  that r...
© 2009 Regents of the University of Minnesota
We routinely over-shade in
 greenhouses and high tunnels!

 The best shading materials are
materials that we can change th...
© 2009 Regents of the University of Minnesota
Open roof greenhouses allow for
maximum lighting for photosynthesis, little
 depletion of CO2, and maximum cooling.




  ...
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
Over-shading is often worst than
         no shading!




          © 2009 Regents of the University of Minnesota
Take Home Messages
• Get a light meter!
• Don’t over-crowd!
• Find out how much CO2 is in your high tunnels! High
  light ...
Take Home Messages
• Consider retractable roof high tunnels to
  maximize light/CO2/temperature for optimal
  plant growth...
Light and
     Temperature
    Effects in High
        Tunnels
•   Light Intensity and Photosynthesis
•   Carbon dioxide (...
Response to increasing
    temperature.
      Units are in degrees Celsius

Multiply times 1.8 plus 32 to get units in
   ...
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
What did we learn?
• Species differed in how temperature affected
  photosynthesis.
• The optimal temperature for photosyn...
Rate of Plant Development




        © 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
Optimum leaf unfolding rate of
  many plants occurs around 76-
84oF. When temperatures exceed
84oF, leaf unfolding slows a...
How does temperature effect stem
          elongation?




          © 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
Sensitivity of stem elongation to
temperature varies within a day/night
                 cycle.




            © 2009 Reg...
© 2009 Regents of the University of Minnesota
Variation in Daily Temp Sensitivity of Stem Elongation
                     During the Day




                 © 2009 Reg...
Does temperature effect
      flowering?




      © 2009 Regents of the University of Minnesota
Arabidopsis after 8 d Temperature Exposures




         20 C           24 C                28 C               32 C       ...
-These data suggest that the
                             window for inhibition of
                          flowering may...
Heat stress




© 2009 Regents of the University of Minnesota
68 ºF                                               86 ºF




    © 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
In general, your leaf temperature is
     5-7oF warmer than the air
    temperature on sunny days.




            © 2009 ...
New Guinea Impatiens ‘Celebration Orange’




            © 2009 Regents of the University of Minnesota
Does the length of the high
temperature exposure make a
difference in how long or much
 photosynthesis is depressed?




 ...
N.G. Impatiens ‘Divine White’
  2 Days After a 1 or 2 hour 95oF Exposure




           © 2009 Regents of the University o...
© 2009 Regents of the University of Minnesota
Cooling leaves in the middle of
   the day on sunny days can
increase photosynthesis! Why?
     By cooling leaves. . . . ....
Overhead
  irrigation
 increases
photosynthe
  sis in the
  middle of
   the day.
This occurs
presumably
through leaf
   c...
Fog Evaporative Cooling




   © 2009 Regents of the University of Minnesota
                                             ...
Take Home Messages
• Buy an infrared thermometer ($75).
• When you let your night temperatures drop and
  allow day temper...
Other Research Areas




    © 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
Potted Plants?




Garden Plants?
         © 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
0 ppm                           600 ppm
Marigold

  Fast-drying

(86 F/ 45% RH)
  Afternoon




  Slow-drying
(59 F/ 85% R...
Airborne interplant signalling for plant
               defence




            © 2009 Regents of the University of Minnes...
Other Airborne Signals?
   volatile profile from
    undamaged Alnus




    volatile profile from
   beetle-infested Alnu...
Jasmonates
►Methyl
                                                       Watercress
 jasmonate elicits
 defense
 response...
© 2009 Regents of the University of Minnesota
K. glaucescens




K. manginii




K. uniflora


                 9    10         11         12          13           14  ...
Green Roofs




      © 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
© 2009 Regents of the University of Minnesota
Liquid culture
         Seed germination




Meristemoid induction in liquid culture                         In vitro mult...
Bailey Endowed
Chair for Nursery
 Crops Research


Todd and Barbara
Bachman Chair for
  Marketing of
Horticulture Crops


...
Additional Special Thanks

• Participants in the FRA and
  the Young Plant Center

• USDA-ARS, SAF, Lin
  Schmale, and you...
Industry Acknowledgements
► MNLA Foundation
► American Floral Endowment
► Gloeckner Foundation
► Altman Plants, Inc.
► Oro...
© 2009 Regents of the University of Minnesota
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Light and Temperature Effects - High Tunnels

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Presented by University of Minnesota professor John Erwin at the 2009 Minnesota Statewide High Tunnel Conference in Alexandria, MN on Dec. 2-3, 2009.

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Light and Temperature Effects - High Tunnels

  1. 1. Light and Temperature Effects in High Tunnels • Light Intensity and Photosynthesis • Carbon dioxide (CO2) • Light color • Shading issues • Temperature effects on: – Development, stem elongation, photosynthesis and flowering. © 2009 Regents of the University of Minnesota
  2. 2. © 2009 Regents of the University of Minnesota
  3. 3. © 2009 Regents of the University of Minnesota
  4. 4. Light and Temperature Effects in High Tunnels • Light Intensity and Photosynthesis • Carbon dioxide (CO2) • Light color • Shading issues • Temperature effects on: – Development, stem elongation, photosynthesis and flowering. © 2009 Regents of the University of Minnesota
  5. 5. How much light can a plant use for photosynthesis? + CO2 + H2O C2H + O2 © 2009 Regents of the University of Minnesota
  6. 6. SOUTHERN GROWERS NORTHERN GROWERS © 2009 Regents of the University of Minnesota
  7. 7. Response to increasing light intensity (irradiance). Units are in umol m-2 s-1 Multiply umol m-2 s-1 by 5 to get footcandles. © 2009 Regents of the University of Minnesota
  8. 8. Variation in photosynthetic responses of different species to increasing light intensity © 2009 Regents of the University of Minnesota
  9. 9. © 2009 Regents of the University of Minnesota
  10. 10. © 2009 Regents of the University of Minnesota
  11. 11. © 2009 Regents of the University of Minnesota
  12. 12. What we learned • Species differed in how much light saturates photosynthesis. • Species studied showed photosynthetic saturation between 200 and 600 umol m-2 s-1 (1,000-3,000 footcandles). • When crops are spaced close, lighting levels should be based on light intensity at lower leaf levels. • By all accounts, tomato and pepper are high light requiring plants, i.e. saturate at 600 umol m-2 s-1 (3000 footcandles). © 2009 Regents of the University of Minnesota
  13. 13. How much light is getting to your plants? © 2009 Regents of the University of Minnesota
  14. 14. 750 ft-c January Daily Light Integrals © 2009 Regents of the University of Minnesota
  15. 15. 3700 ft-c April Daily Light Integrals © 2009 Regents of the University of Minnesota
  16. 16. In general, light penetration into a greenhouse varies from about 30-85%. 60% light transmission is very common. Single glass is the highest (85-90%), followed by Exalite and single poly (65- 75%), following by double poly (45-60%). This is without condensation! © 2009 Regents of the University of Minnesota
  17. 17. © 2009 Regents of the University of Minnesota
  18. 18. 3700 ft-c x 0.45 = 1,665 ft candles (333 umol m-2 s-1) April Daily Light Integrals © 2009 Regents of the University of Minnesota
  19. 19. SOUTHERN GROWERS NORTHERN GROWERS © 2009 Regents of the University of Minnesota
  20. 20. Increasing DLI versus total flower bud number 10 moles/day © 2009 Regents of the University of Minnesota
  21. 21. Light and Temperature Effects in High Tunnels • Light Intensity and Photosynthesis • Carbon dioxide (CO2) • Light color • Shading issues • Temperature effects on: – Development, stem elongation, photosynthesis and flowering. © 2009 Regents of the University of Minnesota
  22. 22. Response to increasing carbon dioxide (CO2). Units are in umol m-2 s-1 Multiply umol m-2 s-1 by 5 to get footcandles. © 2009 Regents of the University of Minnesota
  23. 23. © 2009 Regents of the University of Minnesota
  24. 24. © 2009 Regents of the University of Minnesota
  25. 25. © 2009 Regents of the University of Minnesota
  26. 26. © 2009 Regents of the University of Minnesota
  27. 27. How much light can a plant use for photosynthesis? + CO2 + H2O C2H + O2 © 2009 Regents of the University of Minnesota
  28. 28. © 2009 Regents of the University of Minnesota
  29. 29. What we learned . . . • Species differed in how much CO2 they could utilize under our conditions (300 umol m-2 s-1). • Photosynthesis of some species is saturated at lower CO2 levels (600 ppm; Rieger Begonia, Poinsettia), while photosynthesis on other species saturated at higher CO2 levels (<1000 ppm; cyclamen, impatiens, tomato, pepper). • High tunnel crops are likely CO2 starved! High light with limited CO2 is useless! © 2009 Regents of the University of Minnesota
  30. 30. Light and Temperature Effects in High Tunnels • Light Intensity and Photosynthesis • Carbon dioxide (CO2) • Light color • Shading issues • Temperature effects on: – Development, stem elongation, photosynthesis and flowering. © 2009 Regents of the University of Minnesota
  31. 31. © 2009 Regents of the University of Minnesota
  32. 32. © 2009 Regents of the University of Minnesota
  33. 33. © 2009 Regents of the University of Minnesota
  34. 34. © 2009 Regents of the University of Minnesota
  35. 35. © 2009 Regents of the University of Minnesota
  36. 36. What we know . . . • Any leaf filtering increases leaf size, increases stem elongation, and decreases flower number. • It is desirable to have short plants, that are well spaced to maximize leaf area per plant and limit shading. • Spacing plants too close reduces yield, increases labor/management costs. © 2009 Regents of the University of Minnesota
  37. 37. Light and Temperature Effects in High Tunnels • Light Intensity and Photosynthesis • Carbon dioxide (CO2) • Light color • Shading issues • Temperature effects on: – Development, stem elongation, photosynthesis and flowering. © 2009 Regents of the University of Minnesota
  38. 38. Shade Cloth Issues © 2009 Regents of the University of Minnesota
  39. 39. SOUTHERN GROWERS NORTHERN GROWERS © 2009 Regents of the University of Minnesota
  40. 40. © 2009 Regents of the University of Minnesota
  41. 41. Why do we use shade cloth? • Limit heating in the greenhouse! • In general, we have been finding that any shading that reduces light levels below 3000 footcandles (600 umol m-2 s-1) is detrimental to yield! • Shading selection should be based on light level at plant level! • Shading selection/management will change if covering materials age and light transmission is reduced over time. © 2009 Regents of the University of Minnesota
  42. 42. © 2009 Regents of the University of Minnesota
  43. 43. We routinely over-shade in greenhouses and high tunnels! The best shading materials are materials that we can change the % shading over time such as: 1) spray on shading 2) having different levels of light screening. © 2009 Regents of the University of Minnesota
  44. 44. © 2009 Regents of the University of Minnesota
  45. 45. Open roof greenhouses allow for maximum lighting for photosynthesis, little depletion of CO2, and maximum cooling. © 2009 Regents of the University of Minnesota
  46. 46. © 2009 Regents of the University of Minnesota
  47. 47. © 2009 Regents of the University of Minnesota
  48. 48. Over-shading is often worst than no shading! © 2009 Regents of the University of Minnesota
  49. 49. Take Home Messages • Get a light meter! • Don’t over-crowd! • Find out how much CO2 is in your high tunnels! High light with little CO2 is useless! • Consider shading screens with high light transmission if needed that are pulled only on certain days and at certain times of the day! Also consider spray shading compounds. • Realize that poly transmission decreases over time and that your shading management should change as well! © 2009 Regents of the University of Minnesota
  50. 50. Take Home Messages • Consider retractable roof high tunnels to maximize light/CO2/temperature for optimal plant growth. © 2009 Regents of the University of Minnesota
  51. 51. Light and Temperature Effects in High Tunnels • Light Intensity and Photosynthesis • Carbon dioxide (CO2) • Light color • Shading issues • Temperature effects on: – Development, stem elongation, photosynthesis and flowering. © 2009 Regents of the University of Minnesota
  52. 52. Response to increasing temperature. Units are in degrees Celsius Multiply times 1.8 plus 32 to get units in Fahrenheit. © 2009 Regents of the University of Minnesota
  53. 53. © 2009 Regents of the University of Minnesota
  54. 54. © 2009 Regents of the University of Minnesota
  55. 55. © 2009 Regents of the University of Minnesota
  56. 56. © 2009 Regents of the University of Minnesota
  57. 57. © 2009 Regents of the University of Minnesota
  58. 58. What did we learn? • Species differed in how temperature affected photosynthesis. • The optimal temperature for photosynthesis varied from low temperature optima crops (59oF; Rieger begonia) to medium temperature optima (68oF; New Guinea impatiens) to high temperature optima (76oF; gerbera, tomato, pepper) under our experimental conditions. © 2009 Regents of the University of Minnesota
  59. 59. Rate of Plant Development © 2009 Regents of the University of Minnesota
  60. 60. © 2009 Regents of the University of Minnesota
  61. 61. © 2009 Regents of the University of Minnesota
  62. 62. © 2009 Regents of the University of Minnesota
  63. 63. © 2009 Regents of the University of Minnesota
  64. 64. Optimum leaf unfolding rate of many plants occurs around 76- 84oF. When temperatures exceed 84oF, leaf unfolding slows and yield will be reduced! © 2009 Regents of the University of Minnesota
  65. 65. How does temperature effect stem elongation? © 2009 Regents of the University of Minnesota
  66. 66. © 2009 Regents of the University of Minnesota
  67. 67. © 2009 Regents of the University of Minnesota
  68. 68. © 2009 Regents of the University of Minnesota
  69. 69. © 2009 Regents of the University of Minnesota
  70. 70. Sensitivity of stem elongation to temperature varies within a day/night cycle. © 2009 Regents of the University of Minnesota
  71. 71. © 2009 Regents of the University of Minnesota
  72. 72. Variation in Daily Temp Sensitivity of Stem Elongation During the Day © 2009 Regents of the University of Minnesota
  73. 73. Does temperature effect flowering? © 2009 Regents of the University of Minnesota
  74. 74. Arabidopsis after 8 d Temperature Exposures 20 C 24 C 28 C 32 C 36 C 40 C Warner, R. Studies on high temperature effects on flower development. PhD Thesis, Department of Horticultural Science, University of Minnesota, St. Paul, MN USA. © 2009 Regents of the University of Minnesota
  75. 75. -These data suggest that the window for inhibition of flowering may be smaller than we thought. -These data also suggest that there is a cumulative effect and how temperatures were provided was irrelevant. Rather, it was an accumulation of degree-hours that was important (>32C). Warner, R., and J.E. Erwin. 2005. Naturally-occurring variation in high temperature induced floral bud abortion across Arabidopsis thaliana accessions. Plant, Cell and Environ, 28:1255-1266. © 2009 Regents of the University of Minnesota
  76. 76. Heat stress © 2009 Regents of the University of Minnesota
  77. 77. 68 ºF 86 ºF © 2009 Regents of the University of Minnesota
  78. 78. © 2009 Regents of the University of Minnesota
  79. 79. In general, your leaf temperature is 5-7oF warmer than the air temperature on sunny days. © 2009 Regents of the University of Minnesota
  80. 80. New Guinea Impatiens ‘Celebration Orange’ © 2009 Regents of the University of Minnesota
  81. 81. Does the length of the high temperature exposure make a difference in how long or much photosynthesis is depressed? © 2009 Regents of the University of Minnesota
  82. 82. N.G. Impatiens ‘Divine White’ 2 Days After a 1 or 2 hour 95oF Exposure © 2009 Regents of the University of Minnesota
  83. 83. © 2009 Regents of the University of Minnesota
  84. 84. Cooling leaves in the middle of the day on sunny days can increase photosynthesis! Why? By cooling leaves. . . . . © 2009 Regents of the University of Minnesota
  85. 85. Overhead irrigation increases photosynthe sis in the middle of the day. This occurs presumably through leaf cooling. © 2009 Regents of the University of Minnesota
  86. 86. Fog Evaporative Cooling © 2009 Regents of the University of Minnesota www.truefog.com
  87. 87. Take Home Messages • Buy an infrared thermometer ($75). • When you let your night temperatures drop and allow day temperatures to get hot, you INCREASE stem elongation. • Consider dropping temperatures during the first 2-3 hours to no lower than 55oF for tomatoes/peppers and 45-50oF for spinach and other leafy crops. • Manage high tunnel environments to achieve as close to 76-80oF LEAF temperatures on bright days as possible! © 2009 Regents of the University of Minnesota
  88. 88. Other Research Areas © 2009 Regents of the University of Minnesota
  89. 89. © 2009 Regents of the University of Minnesota
  90. 90. © 2009 Regents of the University of Minnesota
  91. 91. © 2009 Regents of the University of Minnesota
  92. 92. Potted Plants? Garden Plants? © 2009 Regents of the University of Minnesota
  93. 93. © 2009 Regents of the University of Minnesota
  94. 94. 0 ppm 600 ppm Marigold Fast-drying (86 F/ 45% RH) Afternoon Slow-drying (59 F/ 85% RH) Morning © 2009 Regents of the University of Minnesota
  95. 95. Airborne interplant signalling for plant defence © 2009 Regents of the University of Minnesota
  96. 96. Other Airborne Signals? volatile profile from undamaged Alnus volatile profile from beetle-infested Alnus From Tscharntke et al. 2001. Biochem. Syst. Ecol. 1025–1047. © 2009 Regents of the University of Minnesota
  97. 97. Jasmonates ►Methyl Watercress jasmonate elicits defense responses, just like jasmonic acid. © 2009 Regents of the University of Minnesota
  98. 98. © 2009 Regents of the University of Minnesota
  99. 99. K. glaucescens K. manginii K. uniflora 9 10 11 12 13 14 15 hrs Photoperiod (hrs) © 2009 Regents of the University of Minnesota
  100. 100. Green Roofs © 2009 Regents of the University of Minnesota
  101. 101. © 2009 Regents of the University of Minnesota
  102. 102. © 2009 Regents of the University of Minnesota
  103. 103. © 2009 Regents of the University of Minnesota
  104. 104. © 2009 Regents of the University of Minnesota
  105. 105. © 2009 Regents of the University of Minnesota
  106. 106. Liquid culture Seed germination Meristemoid induction in liquid culture In vitro multiplication © 2009 Regents of the University of Minnesota
  107. 107. Bailey Endowed Chair for Nursery Crops Research Todd and Barbara Bachman Chair for Marketing of Horticulture Crops © 2009 Regents of the University of Minnesota
  108. 108. Additional Special Thanks • Participants in the FRA and the Young Plant Center • USDA-ARS, SAF, Lin Schmale, and you for your support through the National Floriculture and Nursery Research Initiative © 2009 Regents of the University of Minnesota
  109. 109. Industry Acknowledgements ► MNLA Foundation ► American Floral Endowment ► Gloeckner Foundation ► Altman Plants, Inc. ► Oro Farms/Florida Specialty Plants ► Nurseryman’s Exchange ► Wagner’s Greenhouse ► Pleasant View Gardens ► Smith Greenhouses ► Sakata, Syngenta, Goldsmith, Ball Horticultural © 2009 Regents of the University of Minnesota
  110. 110. © 2009 Regents of the University of Minnesota
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