The technology to drive the output of individual arrays of light-emitting diodes (LEDs) on timescales down to microseconds is enabling plant scientists and growers control over irradiance- and spectrum-induced plant responses. The two light sensing and signaling networks that regulate desired plant responses involve either photoreceptors (PR) and/or photosynthesis (PSN). These networks control morphological, physiological, and developmental processes (e.g., seed development and germination, seedling development, apical meristem formation, differentiation, flowering, etc.) as well as the energy distribution within the plant. Understanding the individual plant responses and the synergy between the PR and PSN networks will assist in the selection and timing of LED light programs for crop regulation and growth. Both networks sense and respond to irradiance and narrow-band spectra between 350 and 750 nm although their modes of action are different. Comparing the PR and PSN networks and their effect on plants shows that the PR network primarily regulates developmental processes in new tissues while the PSN network regulates routine operational processes. The two networks are required for healthy plant growth and are reliant on each other for biological fitness. A balance between these two networks will result in greater plant efficacy and can be achieved by light programs whose irradiance, spectra, duration, and timing can be regulated. Replacing high-intensity discharge (HID) lamps with LEDs is a catalyst for a fundamental change in plant lighting and we are on a steep learning curve to fully realize how to fully control LED technology in plant growth applications.
Light-emitting Diodes and the Modulation of Specialty Crops: Light Sensing and Signaling Networks in Plants