Can LEDs Provide the Light Plants Need?


Can LEDs Provide the Light Plants Need?

The answer is yes, they can!  LEDs can provide the light plants need in a way that is more targeted and efficient than other lighting sources.  In this entry, I describe how LEDs are useful for plant growth and development, including how they could be utilized in the future.

Earlier this year I gave a presentation at the 2016 Greenhouse Crop Production & Engineering Design Short Course at the University of Arizona Controlled Environment Agriculture Center (CEAC). In the presentation I discussed the definition of light, how it is utilized by plants in terms of spectra, and the benefits of LEDs for horticulture lighting.

I wanted to show the audience the overall view of how LEDs are utilized in horticulture but at the same time explain the science behind light utilization by plants.  For example, it is widely known that land plants utilize a broad spectrum of light, despite what their photosynthetic pigments absorb.  To explain why, I first pointed out why photosynthesis takes place in the chloroplast.  Then, I showed data that compares the photosynthetic response of isolated chloroplasts vs. whole leaf tissue, suggesting that increases in biomass and canopy are a major attribute leading to the broadening of photosynthetic wavelength utilization.

Later in the talk, I discussed photoreceptors and the current state of understanding when it comes to interacting light and environmental parameters.  By giving the audience the big picture as well as the science behind why plants respond to different light, I removed some of the mystery growers have when they are trying to decide if LEDs can work for them.

The talk is divided into three parts.  This is the second section and covers the following topics:

(I) Photosynthesis-A History

  • The start of oxygenic photosynthesis
  • Land plants
  • Chloroplast (site of photosynthesis)

(II) Light

  • Electromagnetic radiation
  • Photons
  • Visible light

 (III) Humans vs. plants vs. pigments

  • Human sensitivity to visible light
  • Plant photosynthetic utilization of visible light
  • Plant pigment absorption of visible light
  • Importance of using photon quanta vs. lumens

(IV) Photosynthesis absorption

  • Total leaf tissue vs. chloroplast
  • Microalgae vs. land plant

(V) Photosynthetic efficiency and industrial lighting

  • Photon vs. energy-weighted photosynthetic yield
  • Metal halide, HPS, and fluorescent spectrums
  • Beneficial attributes of using LEDs

(VI) Photoreceptors, cross-light, and cross-parameter signaling

  • Human sensitivity to visible light
  • Plant photosynthetic utilization of visible light
  • Examples for controlling plant development with light wavelength

As always, I hope you find this presentation informative.  Please leave us your comments and feel free to contact us (illumitex.com/contact) with questions about your application of LEDs in controlled environment agriculture.  Stay tuned for more educational videos from myself and other experts here at Illumitex.