Feb 27 2017: Horticulture is an emerging application area for LED lighting, where energy efficiency and spectral control of LED sources can deliver significant benefits for the growers. However, this domain requires metrics and test procedures that are quite different from other application areas.
American Society of Agricultural and Biological Engineering (ASABE) is working on LED-based horticultural lighting standards.
ASABE has passed a bylaw to form a committee to coordinate the activities of ASABE related to LEDs and other electromagnetic radiation source applications for plant growth. The is also is developing guidelines, recommendations, and standards in the horticulture areas.
The ASABE ES-311 Committee is also developing a standard document that will meet industry needs. It is developing a standard to define the metrics used for horticultural lighting. Till date, most lighting standards are based on human sensitivity to light, which is usually biased positively to green and yellow light and negatively to blue and red light.
Plants utilize light for photosynthesis and adjust their developmental processes like seed germination, stem elongation, etc, according to light signals received through different photoreceptors.
Today, many LED lighting products for horticultural applications provide continuous spectra, which are developed particularly for plants. Human-biased lighting standards have low in efficiency, but from a plant perspective, their efficiency is high. Hence, the existing lighting standards for LEDs are not appropriate for horticulture applications.
ASABE committee has completed the drafted standard—‘Quantities and Units of Electromagnetic Radiation for Plants (Photosynthetic Organisms).’ This document deals with the definitions and descriptions of metrics used for radiation measurements for plant (photosynthetic organism) growth, development, and production. The draft is now in the finalisation stage.
The new standard provides information on the metrics used in horticultural applications including terminologies, quantities, and units. The new standard encompasses the Photosynthetically Active Radiation or PAR band from 400-700 nm, the ultraviolet radiation band from 280-400 nm, and the far-red radiation band from 700-800 nm.
The new standard used quantities for plant biological applications in two groups—radiation measurements (physics based) and photon measurements (chemistry based).
A testing or measurement document—Recommended Methods of Measurements and Testing for LED Radiation Products for Plant Growth and Development is also being developed. The LED industry lacks a standardized method of measurements for LED lighting products for plants growth.
ASABE ES-311 committee believes that reliable and consistent test and measurement methods are must for horticulture applications. The new standard will give information to plant growers about the light or radiation provided within the plant growth spectrum.
Measurements for horticultural lighting and testing equipment are also not standardized, and this leads to a wide range of inconsistencies. Plant growers want reliable measurements that quantify the amount of radiation on the plant surface or photons at the plant levels.
The committee is also developing a performance standard. Plants require an electromagnetic radiant environment that differs in from the needs of people or animals. For example, the effect of electromagnetic radiation; the efficiency of radiation in generating horticultural lighting products.
The new standard will address these issues with a performance measurement standard for the electromagnetic radiation system. This standard will provide guidelines for appropriate performance measures and design characteristics for the electromagnetic radiation system used for plants.