Apogee Instruments DLI-400: PAR, Daily Light Integral, and Photoperiod Meter (Sunlight Only, 400-700 nm)

The Apogee Instruments DLI-400 is an affordable, user-friendly device for spot-checking photosynthetically active radiation (PAR) levels and measuring daily light integral (DLI) and photoperiod under sunlight and certain broadband light sources. DLI represents the total PAR or extended PAR (ePAR) incident on a plane over 24 hours, while photoperiod is the total time PAR or ePAR is incident on a plane in a day. PAR, DLI, and photoperiod significantly impact plant growth and development, making them crucial measurements in greenhouses and growth chambers. The DLI-400 offers accurate readings under sunlight and specific broadband light sources, with an industry-leading accuracy drift rate of less than 2% per year. This rugged, water-resistant meter features two screen modes: stored data (displaying DLI, photoperiod, and collection date) and live view data (showing a running PPFD average). It can be used for single or continuous measurements, with data viewable onscreen or downloadable via USB-C for analysis. Built to withstand harsh environments, the DLI-400 includes a carrying case, batteries, a quickstart guide, a screwdriver, a soil spike, and a USB-C cable. Manufactured in the USA, Apogee Instruments backs the DLI-400 with a four-year warranty and US-based customer support.