LED (Lighting Emitting Diode) lighting is light-emitting diode lighting, which is a semiconductor solid-state light-emitting device. It uses solid semiconductor chips as luminescent materials, and emits excess energy through carrier recombination in the semiconductor to cause photon emission, directly emitting red, yellow, blue, and green light. On this basis, using the principle of three primary colors and adding phosphors, it can emit red, yellow, blue, green, cyan, orange, purple, white and other colors of light.

Traditional light sources such as incandescent lamps, fluorescent lamps, high-pressure sodium lamps, and high-pressure mercury lamps are used in agriculture and biology. They have the disadvantages of low biological light efficiency, high energy consumption and high operating costs. Taking artificial light plant factories as an example, the energy consumption cost of light sources accounts for about 40% to 60% of the system operating costs. Compared with traditional lighting, LED light sources can form spectral absorption peaks that are basically consistent with plant photosynthesis and its morphological construction. They have the advantages of high efficiency, low energy consumption, no mercury pollution, precise wavelength, and intelligent controllable system. The system saves more than 50% energy and has broad application prospects in many fields such as greenhouse lighting, plant tissue culture, plant factories, and genetic breeding.

This article reviews the progress of standards for LED lighting for plant growth and discusses the framework of the standard system for LED lighting for plant growth. The National Semiconductor Lighting Engineering Research and Industry Alliance (CSA) began standardization work on LED lighting for plant growth in 2012, and released the first group standard T/CSA021-2013 "Performance requirements for LED flat panel lights for plant growth" in 2013; afterwards, it promoted the formulation of national standards GB/T32655 "Terms and definitions of LED lighting for plant growth" and group standards T/CSA 032-2016 "General technical specifications for LED lamps for plant lighting".

Group standard T/CSA 021-2013 "Performance requirements for LED flat panel lights for plant growth"

There are many forms of LED lighting products for plant growth, such as flat panel lights, double-ended lights, flexible light strips, etc., and they will gradually change with the development of technology. Around 2013, LED flat panel lights were mainly used in tissue culture seedlings. This standard specifies the terms and definitions, classification and naming, technical requirements, test methods, inspection rules, marking, packaging, transportation and storage of LED flat panel lights for plant growth. The content of the standard shows the basic measurement indicators of LED light sources for plant growth, which are quite different from the parameters of light used for living lighting.

This standard defines the main radiation wavelength of LED flat panel lights for plant growth, which refers to the red-orange radiation band with a radiation wavelength range of 600-700nm and the blue-violet radiation band with a radiation wavelength range of 400-500nm. Based on this, the blue-violet radiation illuminance and red-orange radiation illuminance are defined, and then the red-blue radiation illuminance ratio is defined; based on physical quantities, the standard defines the total radiation flux (unit: W) and total radiation illuminance (unit: W/m2) to support the production, testing, acceptance and other work in the field of plant growth LED lighting. The standard defines photosynthetic photon flux density [unit: μmol/(m2·s)], which refers to the number of photons within a certain wavelength range emitted by the lamp received by the plant per unit area per unit time when the plant performs photosynthesis. However, because the number of photons received by the plant during photosynthesis is difficult to measure, its technical requirements are not reflected in the standard.

The standard proposes the basic safety requirements of GB7000 that LED flat panel lights for plant growth should meet, and the control device meets the requirements of GB19510.14, GB/T 24825, and electromagnetic compatibility performance requirements; in terms of electrical characteristics, it stipulates power and power factor requirements; in terms of radiation performance, it stipulates initial radiation flux/radiation efficiency, radiation intensity distribution, radiation illuminance and red-blue radiation illuminance ratio, and uniformity of radiation illuminance; it also makes requirements in terms of radiation spectrum characteristics and life characteristics.

Group Standard T/CSA 032-2016 "General Technical Specifications for LED Lamps for Plant Lighting"

This standard focuses on the general technical performance and evaluation indicators of LED lamps. Since there are many types of lamps used in the plant lighting industry, with different specifications and models, and uneven performance and quality, it is urgent to establish relatively unified standards for the identification and evaluation of performance indicators. Since this industry is an emerging industry, relevant standards should be introduced as soon as possible to guide the development of industrial technology and product positioning. However, because the evaluation of some technical performance is not mature enough, the requirements of some parameters (such as photon flux efficiency, the degree of consistency between the spectral distribution of the light source and the plant spectrum, etc.) need to be further improved.

According to the requirements of the application environment, this standard supplements the terms such as C3 plants, C4 plants, and CAM plants classified according to the photosynthetic cycle mode of plants. LED lamps for plant lighting are classified according to the purpose of lamps, plant photosynthesis mode, and control mode. The safety performance, structural appearance, electrical performance (power, power factor), optical performance, reliability, electromagnetic compatibility, etc. of LED lamps for plant growth are standardized, the photon flux efficiency of lamps is graded, and the detection method is given according to the technical requirements.

In the structural appearance requirements, requirements are put forward for the surface corrosion resistance (reaching WF2) and anti-ultraviolet aging of the lamps; in the optical performance requirements, photon flux, photon flux efficiency [the measured value should not be less than 0.7μmol/(s·W)], spectral distribution, light distribution curve and other parameter requirements are stipulated; the reliability part mainly makes requirements for photon flux maintenance rate and environmental adaptability; in the energy efficiency classification of lamps, first of all, corresponding to the key points of photon flux efficiency of high-pressure sodium lamps [1.9μmol/(s·W)] and fluorescent lamps [1.3μmol/(s·W)], the photon flux efficiency of LED light sources is divided into three categories: Category I [ηP ≥ 1.9μmol/(s·W)], Category II [1.3μmol/(s·W) ≤ηP <1.9μmol/(s·W)] and Category III [(0.7μmol/(s·W) ≤ηP《1.3μmol/(s·W)］. Secondly, according to the degree of coincidence of the spectral distribution of the light source, the light source can be divided into 3 categories or 3 levels according to different latitudes. The division of energy efficiency levels takes into account two factors: the photon flux efficiency of the light source and the degree of coincidence of the spectral distribution. Combining the above two factors, the energy efficiency is divided into 3 grades and 3 categories, totaling 9 levels.

National Standard GB/T 32655-2016 "Terms and Definitions of LED Lighting for Plant Growth"

The terminology defined in this standard is generally divided into 2 parts: one part is about plant growth, mainly from the terms currently used in production, teaching and scientific research in my country. This part of the content is formulated for the first time at home and abroad; the other part is about the terms related to LED products and testing, citing some terms in IEC 60050 and GB/T 24826-2016 (IDT IEC62504) standards to ensure the coordination of the standard system.