Light and Temperature Effects - High Tunnels
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This document discusses light and temperature effects on plants grown in high tunnels. It covers several topics: light intensity and photosynthesis; carbon dioxide levels; light color; shading issues; and temperature effects on plant development, stem elongation, photosynthesis, and flowering. For each topic, it provides data on different plant species' responses and optimal conditions. The overall focus is on understanding the light and temperature requirements of various crops to maximize growth and yield in high tunnel environments.
Light and Temperature Effects - High Tunnels
- 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
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- 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. How much light can a plant use for photosynthesis? + CO2 + H2O C2H + O2 © 2009 Regents of the University of Minnesota
- 6. SOUTHERN GROWERS NORTHERN GROWERS © 2009 Regents of the University of Minnesota
- 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. Variation in photosynthetic responses of different species to increasing light intensity © 2009 Regents of the University of Minnesota
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- 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. How much light is getting to your plants? © 2009 Regents of the University of Minnesota
- 14. 750 ft-c January Daily Light Integrals © 2009 Regents of the University of Minnesota
- 15. 3700 ft-c April Daily Light Integrals © 2009 Regents of the University of Minnesota
- 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
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- 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. SOUTHERN GROWERS NORTHERN GROWERS © 2009 Regents of the University of Minnesota
- 20. Increasing DLI versus total flower bud number 10 moles/day © 2009 Regents of the University of Minnesota
- 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. 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
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- 27. How much light can a plant use for photosynthesis? + CO2 + H2O C2H + O2 © 2009 Regents of the University of Minnesota
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- 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. 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
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- 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. 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. Shade Cloth Issues © 2009 Regents of the University of Minnesota
- 39. SOUTHERN GROWERS NORTHERN GROWERS © 2009 Regents of the University of Minnesota
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- 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
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- 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
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- 45. Open roof greenhouses allow for maximum lighting for photosynthesis, little depletion of CO2, and maximum cooling. © 2009 Regents of the University of Minnesota
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- 48. Over-shading is often worst than no shading! © 2009 Regents of the University of Minnesota
- 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. 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. 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. 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
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- 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. Rate of Plant Development © 2009 Regents of the University of Minnesota
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- 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. How does temperature effect stem elongation? © 2009 Regents of the University of Minnesota
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- 70. Sensitivity of stem elongation to temperature varies within a day/night cycle. © 2009 Regents of the University of Minnesota
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- 72. Variation in Daily Temp Sensitivity of Stem Elongation During the Day © 2009 Regents of the University of Minnesota
- 73. Does temperature effect flowering? © 2009 Regents of the University of Minnesota
- 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. -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. Heat stress © 2009 Regents of the University of Minnesota
- 77. 68 ºF 86 ºF © 2009 Regents of the University of Minnesota
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- 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. New Guinea Impatiens ‘Celebration Orange’ © 2009 Regents of the University of Minnesota
- 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. N.G. Impatiens ‘Divine White’ 2 Days After a 1 or 2 hour 95oF Exposure © 2009 Regents of the University of Minnesota
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- 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. 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. Fog Evaporative Cooling © 2009 Regents of the University of Minnesota www.truefog.com
- 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. Other Research Areas © 2009 Regents of the University of Minnesota
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- 92. Potted Plants? Garden Plants? © 2009 Regents of the University of Minnesota
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- 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. Airborne interplant signalling for plant defence © 2009 Regents of the University of Minnesota
- 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. Jasmonates ►Methyl Watercress jasmonate elicits defense responses, just like jasmonic acid. © 2009 Regents of the University of Minnesota
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- 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. Green Roofs © 2009 Regents of the University of Minnesota
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- 106. Liquid culture Seed germination Meristemoid induction in liquid culture In vitro multiplication © 2009 Regents of the University of Minnesota
- 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. 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. 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
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