tosynthetically Active Radiation (PAR) refers to the spectral range of solar radiation that is crucial for photosynthesis in plants. This light energy is absorbed by pigments such as chlorophyll, initiating the process of converting carbon dioxide and water into glucose and oxygen. MAX / MIN / AVG Data. This spectrum includes wavelengths of light that are utilized by plants for photosynthesis, typically ranging from 400 to 700 nanometers PAR meters can also be valuable tools. They allow gardeners and farmers to assess the amount of sunlight available in different areas of their outdoor growing spaces. PAR meters are commonly used by horticulturists, botanists, and indoor gardeners to ensure that plants receive the appropriate amount of light for optimal growth. It can be widely used for on-site monitoring of light radiation in plant lamp manufacturers, soilless cultivation of plants, greenhouses, and other plant growth processes.