Article | 06. 2014 Vol. 32, Issue. 3
Growth and Anthocyanins of Lettuce Grown under Red or Blue Light-emitting Diodes with Distinct Peak Wavelength



Department of Bioindustrial Precision Machinery Engineering, Graduate School, Chonbuk National University1
Department of Bioindustrial Machinery Engineering, College of Agriculture & Life Sciences, Chonbuk National University2
The Institute of Agricultural Science & Technology, Chonbuk National University3




2014.06. 330:339


PDF XML




Growth and anthocyanins of lettuce (Lactuca sativa L., ‘Mid-season’) grown under LED lamps with blue light in the range of 430-470 nm or with red light in the range of 630-670 nm were analyzed in this study. Cool-white fluorescent light was used as the control. Photosynthetic photon flux, photoperiod, air temperature, relative humidity, and CO2 concentration in a closed plant production system were 201 ± 2 μmol・m-2・s-1, 16/8 hours (day/night), 22/18°C, 70%, and 400 μmol・mol-1, respectively. At 21 days after light quality treatment, growth characteristics and anthocyanins content of lettuce as affected by the peak wavelength of blue or red LED were significantly different. Among peak wavelengths treated in this stusy, R1 treatment (peak wavelength 634 nm) and R6 treatment (peak wavelength 659 nm) were effective for increasing leaf width, leaf area, shoot fresh weight, and photosynthetic rate of lettuce. B5 treatment (peak wavelength 450 nm) and B4 treatment (peak wavelength 446 nm) increased the anthocyanins concentration and chlorophyll content in lettuce leaves, respectively. Anthocyanins in lettuce leaves increased linearly with decreasing hue value of leaf color and with increasing SPAD value of lettuce leaves. From these results, it was concluded that the red LED with peak wavelengths of 634 nm and 659 nm and the blue LED with peak wavelengths of 450 nm can be used as potential light spectra for increasing the yield and anthocyanins accumulation of leafy vegetable.



1. An, C.G., Y.H. Hwang, J.U. An, H.S. Yoon, Y.H. Chang, G.M. Shon, and S.J. Hwang. 2011. Effect of LEDs (light emitting diodes) irradiation on growth of paprika (Capsicum annuum ‘Cupra’). J. Bio-Environ. Con. 20:253-257.  

2. Barta, D.J., T.W. Tibbitts, R.J. Bula, and R.C. Morrow. 1992. Evaluation of light emitting diode characteristics for space-based plant irradiation source. Adv. Space Res. 12:141-149.  

3. Botto, J.F., R.A. Sanchez, G.C. Whitelam, and J.J. Casal. 1996. Phytochrome a mediates the promotion of seed germination by very low fluences of light and canopy shade light in arabidopsis. Plant Physiol. 110:439-444.  

4. Brown, C.S., A.C. Schuerger, and J.C. Sager. 1995. Growth and photomorphogenesis of pepper plants under red light-emitting diodes with supplemental blue or far-red lighting. J. Amer. Soc. Hort. Sci. 120:808-813.  

5. Cormier, F., H. Crevier, and C. Do. 1990. Effects of sucrose concentration on the accumulation of anthocyanins ingrape (Vitis vinifera L.) cell suspension. Can. J. Bot. 68:1822-1825.  

6. Eun, J.S., Y.S. Kim, and Y.H. Kim. 2000. Effects of light emitting diodes on growth and morphogenesis of in vitro seedlings in Platycodon gradiflorum. Kor. J. Plant Tissue Culture 27:71-75.  

7. Fuleki, T. and F.J. Francis. 1968. Quantitative methods for anthocyanins. 1. Extration and determination of total anthocyanins in cranberries. J. Food Sci. 33:72-77.  

8. Hirner, A.A., S. Veit, and H.U. Seitz. 2001. Regulation of anthocyanin biosynthesis in UV-A-irradiated cell cultures of carrot and in organs of intact carrot plants. Plant Sci. 161: 315-322.  

9. Johkan, M., K. Shoji, F. Goto, S. Hashida, and T. Yoshihara. 2010. Blue light-emitting diode light irradiation of seedlings improves seedling quality and growth after transplanting in red leaf lettuce. HortScience 45:1809-1814.  

10. Kim, Y.H. 1999. Plant growth and morphogenesis control in transplant production system using light-emitting diodes (LEDs) as artificial light source-Spectral characteristics and light intensity of LEDs. J. Kor. Soc. Agric. Mach. 24:115-122.  

11. Kim, Y.H. and H.S. Park. 2003. Graft-taking characteristics of watermelon grafted seedlings as affected by blue, red and far-red light-emitting diodes. J. Kor. Soc. Agric. Mach. 28:151-156.  

12. Kong, J.M., L.S. Chia, N.K. Goh, T.F. Chia, and R. Brouillard. 2003. Analysis and biological activities of anthocyanins. Phytochemistry 64:923-933.  

13. Konczak-Islam, I., M. Yoshinaga, M. Nakatani, N. Terahara, and O. Yamakawa. 2000. Establishment and characteristics of an anthocyanin-producing cell line from sweetpotato storage root. Plant Cell Rep. 19:472-477.  

14. Lee, J.G., S.S. Oh, S.H. Cha, Y.A. Jang, S.Y. Kim, and Y.C. Um. 2010. Effects of red/blue light ratio and short-term light quality conversion on growth and anthocyanin contents of baby leaf lettuce. J. Bio-Enviro. Con. 19:351-359.   

15. Lee, J.S., H.I. Lee, and Y.H. Kim. 2012. Seedling quality and early yield after transplanting of paprika nursed under light- emitting diodes, fluorescent lamps and natural light. J. Bio- Environ. Con. 21:220-227.  

16. Lee, J.S. and Y.H. Kim. 2012. Measurement system of photosynthetic photon flux distribution and illumination efficiency of LED lamps for plant growth. J. Biosystems Eng. 37:314-318.  

17. Li, Q. and C. Kubota. 2009. Effects of supplemental light quality on growth and phytochemicals of baby leaf lettuce. Environ. Exp. Bot. 67:59-64.  

18. Lin, C. 2002. Blue light receptors and signal transduction. Plant Cell S207-S225.  

19. Mancinelli, A.L., F. Rossi, and A. Motoni. 1991. Cryptochrome, phytochrome, and anthocyanin production. Plant Physiol. 96:1079-1085.  

20. Meyer, J.E., M.F. Pe´pin, and M.A.L. Smith. 2002. Anthocyanin production from Vaccinium pahalae: limitations of the physical microenvironment. J. Biotechnol. 93:45-57.  

21. Ninu, L., M. Ahmad, C. Miarelli, A.R. Cashmore, and G. Giuliano. 1999. Cryptochrome 1 controls tomato development in response to blue light. Plant J. 18:551-556.  

22. Oren-Shamir, M. 2009. Does anthocyanin degradation play a significant role in determining pigment concentration in plants? Plant Sci. 177:310-316.   

23. Park, J.H., J.S. Lee, D.E. Kim, and Y.H. Kim. 2011. Analysis of optimum water cooling conditions and heat exchange of LED lamps for plant growth. J. Biosystems Eng. 36:334-341.  

24. Park, J.H., J.S. Lee, and Y.H. Kim. 2012. Development of a lighting control system for improving light quality of discharge lamps. Proc. Kor. Soc. Agric. Mach. 17(1):351-354.   

25. Son, K.H., J.H. Park, D.I. Kim, and M.M. Oh. 2012. Leaf shape, growth, and phytochemicals in two leaf lettuce cultivars grown under monochromatic light-emitting diodes. Kor. J. Hort. Sci. Technol. 30:664-672.  

26. Smith, C.J. and J.R. Gallon. 2001. Living in the real world: how plants perceive their environment. New Phytol. 151:1-6.  

27. Sponga, F., G.F. Deitzer, and A.L. Mancinelli. 1986. Cryptochrome, phytochrome, and the photoregulation of anthocyanin production under blue light. Plant Physiol. 82:952-955.  

28. Tennessen, D.J., R.J. Bula, and T.D. Sharkey. 1995. Efficiency of photosynthesis in continuous and pulsed light emitting diode irradiation. Photosynth. Res. 44:261-269.  

29. Wang, Y., B. Zhou, M. Sun, Y. Li, and S. Kawabata. 2012. UV-A light induces anthocyanin biosynthesis in a manner distinct from synergistic blue + UV-B light and UV-A/blue light responses in different parts of the hypocotyls in turnip seedlings. Plant Cell Physiol. 53:1470-1480.  

30. Xu, H., Q. Xu, F. Li, Y. Feng, F. Qin, and W. Fang. 2012. Applications of xerophytophysiology in plant production-LED blue light as a stimulus improved the tomato crop. Sci. Hortic. 148:190-196.   

31. Yang, Y., J. Shah, and D.F. Klessig. 1997. Signal perception and transduction in plant defense responses. Genes Dev. 11:1621-1639.  

32. Yorio, N.C., G.D. Goins, H.R. Kagie, R.M. Wheeler, and J.C. Sager. 2001. Improving spinach, radish, and lettuce growth under red light emitting diodes (LEDs) with blue light supplementation. HortScience 36:380-383.  



Article | 06. 2014 Vol. 32, Issue. 3
Growth and Anthocyanins of Lettuce Grown under Red or Blue Light-emitting Diodes with Distinct Peak Wavelength



Department of Bioindustrial Precision Machinery Engineering, Graduate School, Chonbuk National University1
Department of Bioindustrial Machinery Engineering, College of Agriculture & Life Sciences, Chonbuk National University2
The Institute of Agricultural Science & Technology, Chonbuk National University3




2014.06. 330:339


PDF XML




Growth and anthocyanins of lettuce (Lactuca sativa L., ‘Mid-season’) grown under LED lamps with blue light in the range of 430-470 nm or with red light in the range of 630-670 nm were analyzed in this study. Cool-white fluorescent light was used as the control. Photosynthetic photon flux, photoperiod, air temperature, relative humidity, and CO2 concentration in a closed plant production system were 201 ± 2 μmol・m-2・s-1, 16/8 hours (day/night), 22/18°C, 70%, and 400 μmol・mol-1, respectively. At 21 days after light quality treatment, growth characteristics and anthocyanins content of lettuce as affected by the peak wavelength of blue or red LED were significantly different. Among peak wavelengths treated in this stusy, R1 treatment (peak wavelength 634 nm) and R6 treatment (peak wavelength 659 nm) were effective for increasing leaf width, leaf area, shoot fresh weight, and photosynthetic rate of lettuce. B5 treatment (peak wavelength 450 nm) and B4 treatment (peak wavelength 446 nm) increased the anthocyanins concentration and chlorophyll content in lettuce leaves, respectively. Anthocyanins in lettuce leaves increased linearly with decreasing hue value of leaf color and with increasing SPAD value of lettuce leaves. From these results, it was concluded that the red LED with peak wavelengths of 634 nm and 659 nm and the blue LED with peak wavelengths of 450 nm can be used as potential light spectra for increasing the yield and anthocyanins accumulation of leafy vegetable.

Growth and anthocyanins of lettuce (Lactuca sativa L., ‘Mid-season’) grown under LED lamps with blue light in the range of 430-470 nm or with red light in the range of 630-670 nm were analyzed in this study. Cool-white fluorescent light was used as the control. Photosynthetic photon flux, photoperiod, air temperature, relative humidity, and CO2 concentration in a closed plant production system were 201 ± 2 μmol・m-2・s-1, 16/8 hours (day/night), 22/18°C, 70%, and 400 μmol・mol-1, respectively. At 21 days after light quality treatment, growth characteristics and anthocyanins content of lettuce as affected by the peak wavelength of blue or red LED were significantly different. Among peak wavelengths treated in this stusy, R1 treatment (peak wavelength 634 nm) and R6 treatment (peak wavelength 659 nm) were effective for increasing leaf width, leaf area, shoot fresh weight, and photosynthetic rate of lettuce. B5 treatment (peak wavelength 450 nm) and B4 treatment (peak wavelength 446 nm) increased the anthocyanins concentration and chlorophyll content in lettuce leaves, respectively. Anthocyanins in lettuce leaves increased linearly with decreasing hue value of leaf color and with increasing SPAD value of lettuce leaves. From these results, it was concluded that the red LED with peak wavelengths of 634 nm and 659 nm and the blue LED with peak wavelengths of 450 nm can be used as potential light spectra for increasing the yield and anthocyanins accumulation of leafy vegetable.



1. An, C.G., Y.H. Hwang, J.U. An, H.S. Yoon, Y.H. Chang, G.M. Shon, and S.J. Hwang. 2011. Effect of LEDs (light emitting diodes) irradiation on growth of paprika (Capsicum annuum ‘Cupra’). J. Bio-Environ. Con. 20:253-257.  

2. Barta, D.J., T.W. Tibbitts, R.J. Bula, and R.C. Morrow. 1992. Evaluation of light emitting diode characteristics for space-based plant irradiation source. Adv. Space Res. 12:141-149.  

3. Botto, J.F., R.A. Sanchez, G.C. Whitelam, and J.J. Casal. 1996. Phytochrome a mediates the promotion of seed germination by very low fluences of light and canopy shade light in arabidopsis. Plant Physiol. 110:439-444.  

4. Brown, C.S., A.C. Schuerger, and J.C. Sager. 1995. Growth and photomorphogenesis of pepper plants under red light-emitting diodes with supplemental blue or far-red lighting. J. Amer. Soc. Hort. Sci. 120:808-813.  

5. Cormier, F., H. Crevier, and C. Do. 1990. Effects of sucrose concentration on the accumulation of anthocyanins ingrape (Vitis vinifera L.) cell suspension. Can. J. Bot. 68:1822-1825.  

6. Eun, J.S., Y.S. Kim, and Y.H. Kim. 2000. Effects of light emitting diodes on growth and morphogenesis of in vitro seedlings in Platycodon gradiflorum. Kor. J. Plant Tissue Culture 27:71-75.  

7. Fuleki, T. and F.J. Francis. 1968. Quantitative methods for anthocyanins. 1. Extration and determination of total anthocyanins in cranberries. J. Food Sci. 33:72-77.  

8. Hirner, A.A., S. Veit, and H.U. Seitz. 2001. Regulation of anthocyanin biosynthesis in UV-A-irradiated cell cultures of carrot and in organs of intact carrot plants. Plant Sci. 161: 315-322.  

9. Johkan, M., K. Shoji, F. Goto, S. Hashida, and T. Yoshihara. 2010. Blue light-emitting diode light irradiation of seedlings improves seedling quality and growth after transplanting in red leaf lettuce. HortScience 45:1809-1814.  

10. Kim, Y.H. 1999. Plant growth and morphogenesis control in transplant production system using light-emitting diodes (LEDs) as artificial light source-Spectral characteristics and light intensity of LEDs. J. Kor. Soc. Agric. Mach. 24:115-122.  

11. Kim, Y.H. and H.S. Park. 2003. Graft-taking characteristics of watermelon grafted seedlings as affected by blue, red and far-red light-emitting diodes. J. Kor. Soc. Agric. Mach. 28:151-156.  

12. Kong, J.M., L.S. Chia, N.K. Goh, T.F. Chia, and R. Brouillard. 2003. Analysis and biological activities of anthocyanins. Phytochemistry 64:923-933.  

13. Konczak-Islam, I., M. Yoshinaga, M. Nakatani, N. Terahara, and O. Yamakawa. 2000. Establishment and characteristics of an anthocyanin-producing cell line from sweetpotato storage root. Plant Cell Rep. 19:472-477.  

14. Lee, J.G., S.S. Oh, S.H. Cha, Y.A. Jang, S.Y. Kim, and Y.C. Um. 2010. Effects of red/blue light ratio and short-term light quality conversion on growth and anthocyanin contents of baby leaf lettuce. J. Bio-Enviro. Con. 19:351-359.   

15. Lee, J.S., H.I. Lee, and Y.H. Kim. 2012. Seedling quality and early yield after transplanting of paprika nursed under light- emitting diodes, fluorescent lamps and natural light. J. Bio- Environ. Con. 21:220-227.  

16. Lee, J.S. and Y.H. Kim. 2012. Measurement system of photosynthetic photon flux distribution and illumination efficiency of LED lamps for plant growth. J. Biosystems Eng. 37:314-318.  

17. Li, Q. and C. Kubota. 2009. Effects of supplemental light quality on growth and phytochemicals of baby leaf lettuce. Environ. Exp. Bot. 67:59-64.  

18. Lin, C. 2002. Blue light receptors and signal transduction. Plant Cell S207-S225.  

19. Mancinelli, A.L., F. Rossi, and A. Motoni. 1991. Cryptochrome, phytochrome, and anthocyanin production. Plant Physiol. 96:1079-1085.  

20. Meyer, J.E., M.F. Pe´pin, and M.A.L. Smith. 2002. Anthocyanin production from Vaccinium pahalae: limitations of the physical microenvironment. J. Biotechnol. 93:45-57.  

21. Ninu, L., M. Ahmad, C. Miarelli, A.R. Cashmore, and G. Giuliano. 1999. Cryptochrome 1 controls tomato development in response to blue light. Plant J. 18:551-556.  

22. Oren-Shamir, M. 2009. Does anthocyanin degradation play a significant role in determining pigment concentration in plants? Plant Sci. 177:310-316.   

23. Park, J.H., J.S. Lee, D.E. Kim, and Y.H. Kim. 2011. Analysis of optimum water cooling conditions and heat exchange of LED lamps for plant growth. J. Biosystems Eng. 36:334-341.  

24. Park, J.H., J.S. Lee, and Y.H. Kim. 2012. Development of a lighting control system for improving light quality of discharge lamps. Proc. Kor. Soc. Agric. Mach. 17(1):351-354.   

25. Son, K.H., J.H. Park, D.I. Kim, and M.M. Oh. 2012. Leaf shape, growth, and phytochemicals in two leaf lettuce cultivars grown under monochromatic light-emitting diodes. Kor. J. Hort. Sci. Technol. 30:664-672.  

26. Smith, C.J. and J.R. Gallon. 2001. Living in the real world: how plants perceive their environment. New Phytol. 151:1-6.  

27. Sponga, F., G.F. Deitzer, and A.L. Mancinelli. 1986. Cryptochrome, phytochrome, and the photoregulation of anthocyanin production under blue light. Plant Physiol. 82:952-955.  

28. Tennessen, D.J., R.J. Bula, and T.D. Sharkey. 1995. Efficiency of photosynthesis in continuous and pulsed light emitting diode irradiation. Photosynth. Res. 44:261-269.  

29. Wang, Y., B. Zhou, M. Sun, Y. Li, and S. Kawabata. 2012. UV-A light induces anthocyanin biosynthesis in a manner distinct from synergistic blue + UV-B light and UV-A/blue light responses in different parts of the hypocotyls in turnip seedlings. Plant Cell Physiol. 53:1470-1480.  

30. Xu, H., Q. Xu, F. Li, Y. Feng, F. Qin, and W. Fang. 2012. Applications of xerophytophysiology in plant production-LED blue light as a stimulus improved the tomato crop. Sci. Hortic. 148:190-196.   

31. Yang, Y., J. Shah, and D.F. Klessig. 1997. Signal perception and transduction in plant defense responses. Genes Dev. 11:1621-1639.  

32. Yorio, N.C., G.D. Goins, H.R. Kagie, R.M. Wheeler, and J.C. Sager. 2001. Improving spinach, radish, and lettuce growth under red light emitting diodes (LEDs) with blue light supplementation. HortScience 36:380-383.  

1. An, C.G., Y.H. Hwang, J.U. An, H.S. Yoon, Y.H. Chang, G.M. Shon, and S.J. Hwang. 2011. Effect of LEDs (light emitting diodes) irradiation on growth of paprika (Capsicum annuum ‘Cupra’). J. Bio-Environ. Con. 20:253-257.  

2. Barta, D.J., T.W. Tibbitts, R.J. Bula, and R.C. Morrow. 1992. Evaluation of light emitting diode characteristics for space-based plant irradiation source. Adv. Space Res. 12:141-149.  

3. Botto, J.F., R.A. Sanchez, G.C. Whitelam, and J.J. Casal. 1996. Phytochrome a mediates the promotion of seed germination by very low fluences of light and canopy shade light in arabidopsis. Plant Physiol. 110:439-444.  

4. Brown, C.S., A.C. Schuerger, and J.C. Sager. 1995. Growth and photomorphogenesis of pepper plants under red light-emitting diodes with supplemental blue or far-red lighting. J. Amer. Soc. Hort. Sci. 120:808-813.  

5. Cormier, F., H. Crevier, and C. Do. 1990. Effects of sucrose concentration on the accumulation of anthocyanins ingrape (Vitis vinifera L.) cell suspension. Can. J. Bot. 68:1822-1825.  

6. Eun, J.S., Y.S. Kim, and Y.H. Kim. 2000. Effects of light emitting diodes on growth and morphogenesis of in vitro seedlings in Platycodon gradiflorum. Kor. J. Plant Tissue Culture 27:71-75.  

7. Fuleki, T. and F.J. Francis. 1968. Quantitative methods for anthocyanins. 1. Extration and determination of total anthocyanins in cranberries. J. Food Sci. 33:72-77.  

8. Hirner, A.A., S. Veit, and H.U. Seitz. 2001. Regulation of anthocyanin biosynthesis in UV-A-irradiated cell cultures of carrot and in organs of intact carrot plants. Plant Sci. 161: 315-322.  

9. Johkan, M., K. Shoji, F. Goto, S. Hashida, and T. Yoshihara. 2010. Blue light-emitting diode light irradiation of seedlings improves seedling quality and growth after transplanting in red leaf lettuce. HortScience 45:1809-1814.  

10. Kim, Y.H. 1999. Plant growth and morphogenesis control in transplant production system using light-emitting diodes (LEDs) as artificial light source-Spectral characteristics and light intensity of LEDs. J. Kor. Soc. Agric. Mach. 24:115-122.  

11. Kim, Y.H. and H.S. Park. 2003. Graft-taking characteristics of watermelon grafted seedlings as affected by blue, red and far-red light-emitting diodes. J. Kor. Soc. Agric. Mach. 28:151-156.  

12. Kong, J.M., L.S. Chia, N.K. Goh, T.F. Chia, and R. Brouillard. 2003. Analysis and biological activities of anthocyanins. Phytochemistry 64:923-933.  

13. Konczak-Islam, I., M. Yoshinaga, M. Nakatani, N. Terahara, and O. Yamakawa. 2000. Establishment and characteristics of an anthocyanin-producing cell line from sweetpotato storage root. Plant Cell Rep. 19:472-477.  

14. Lee, J.G., S.S. Oh, S.H. Cha, Y.A. Jang, S.Y. Kim, and Y.C. Um. 2010. Effects of red/blue light ratio and short-term light quality conversion on growth and anthocyanin contents of baby leaf lettuce. J. Bio-Enviro. Con. 19:351-359.   

15. Lee, J.S., H.I. Lee, and Y.H. Kim. 2012. Seedling quality and early yield after transplanting of paprika nursed under light- emitting diodes, fluorescent lamps and natural light. J. Bio- Environ. Con. 21:220-227.  

16. Lee, J.S. and Y.H. Kim. 2012. Measurement system of photosynthetic photon flux distribution and illumination efficiency of LED lamps for plant growth. J. Biosystems Eng. 37:314-318.  

17. Li, Q. and C. Kubota. 2009. Effects of supplemental light quality on growth and phytochemicals of baby leaf lettuce. Environ. Exp. Bot. 67:59-64.  

18. Lin, C. 2002. Blue light receptors and signal transduction. Plant Cell S207-S225.  

19. Mancinelli, A.L., F. Rossi, and A. Motoni. 1991. Cryptochrome, phytochrome, and anthocyanin production. Plant Physiol. 96:1079-1085.  

20. Meyer, J.E., M.F. Pe´pin, and M.A.L. Smith. 2002. Anthocyanin production from Vaccinium pahalae: limitations of the physical microenvironment. J. Biotechnol. 93:45-57.  

21. Ninu, L., M. Ahmad, C. Miarelli, A.R. Cashmore, and G. Giuliano. 1999. Cryptochrome 1 controls tomato development in response to blue light. Plant J. 18:551-556.  

22. Oren-Shamir, M. 2009. Does anthocyanin degradation play a significant role in determining pigment concentration in plants? Plant Sci. 177:310-316.   

23. Park, J.H., J.S. Lee, D.E. Kim, and Y.H. Kim. 2011. Analysis of optimum water cooling conditions and heat exchange of LED lamps for plant growth. J. Biosystems Eng. 36:334-341.  

24. Park, J.H., J.S. Lee, and Y.H. Kim. 2012. Development of a lighting control system for improving light quality of discharge lamps. Proc. Kor. Soc. Agric. Mach. 17(1):351-354.   

25. Son, K.H., J.H. Park, D.I. Kim, and M.M. Oh. 2012. Leaf shape, growth, and phytochemicals in two leaf lettuce cultivars grown under monochromatic light-emitting diodes. Kor. J. Hort. Sci. Technol. 30:664-672.  

26. Smith, C.J. and J.R. Gallon. 2001. Living in the real world: how plants perceive their environment. New Phytol. 151:1-6.  

27. Sponga, F., G.F. Deitzer, and A.L. Mancinelli. 1986. Cryptochrome, phytochrome, and the photoregulation of anthocyanin production under blue light. Plant Physiol. 82:952-955.  

28. Tennessen, D.J., R.J. Bula, and T.D. Sharkey. 1995. Efficiency of photosynthesis in continuous and pulsed light emitting diode irradiation. Photosynth. Res. 44:261-269.  

29. Wang, Y., B. Zhou, M. Sun, Y. Li, and S. Kawabata. 2012. UV-A light induces anthocyanin biosynthesis in a manner distinct from synergistic blue + UV-B light and UV-A/blue light responses in different parts of the hypocotyls in turnip seedlings. Plant Cell Physiol. 53:1470-1480.  

30. Xu, H., Q. Xu, F. Li, Y. Feng, F. Qin, and W. Fang. 2012. Applications of xerophytophysiology in plant production-LED blue light as a stimulus improved the tomato crop. Sci. Hortic. 148:190-196.   

31. Yang, Y., J. Shah, and D.F. Klessig. 1997. Signal perception and transduction in plant defense responses. Genes Dev. 11:1621-1639.  

32. Yorio, N.C., G.D. Goins, H.R. Kagie, R.M. Wheeler, and J.C. Sager. 2001. Improving spinach, radish, and lettuce growth under red light emitting diodes (LEDs) with blue light supplementation. HortScience 36:380-383.