Research on Capitol Hill

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College of Agriculture and Applied Sciences


Plants, Soils, and Climate Department

Faculty Mentor

Bruce Bugbee


Increasing blue light from LEDs reduces leaf length in kale

Boston Swan and Bruce Bugbee Crop Physiology Laboratory Utah State University

Despite years of research, the effect of light quantity (intensity) and quality (color) on plants remains poorly understood. Light emitting diodes (LEDs) now facilitate this research because of their narrow band wavelength. Blue light (400-500 nm) has been known to reduce leaf expansion and petiole elongation in some crops (Cope and Bugbee, 2013; Cope et al, 2014; Snowden et al, 2016).

Kale is one of seven vegetables in the species Brassica oleracea and was chosen as a representative for the species because of its nutrient value.

The system included 16 chambers; eight chambers at low Photosynthetic photon flux density, (PPFD; 200 µmol m-2 s-1) and eight at high PPFD (500 µmol m-2 s-1). The spectral distributions for each chamber are included below.

Whole plant fresh and dry mass decreased slightly with increasing blue light, but the effect was not statistically significant. We also found that leaf length decreased significantly with increasing blue light. Our data indicate that studies should focus on selecting wavelengths of light that enhance cell enlargement and the development of leaf area and radiation capture.


Cope, Kevin R., and Bruce Bugbee.(2013) Spectral Effects of Three Types of White Light-emitting Diodes on Plant Growth and Development: Absolute versus Relative Amounts of Blue Light. HortScience 48.4: 504-09.

Cope, Kevin R., M. Chase Snowden, and Bruce Bugbee. (2014) Photobiological Interactions of Blue Light and Photosynthetic Photon Flux: Effects of Monochromatic and Broad-Spectrum Light Sources. Photochemistry and Photobiology 90 : 574-84.

M. Chase Snowden, Kevin R. Cope, and Bruce Bugbee. (2016) Sensitivity of seven diverse species to blue and green light: interactions with photon flux. In press for the journal PLOS ONE

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