Daily Light Integral Plants

Daily light integral dli impacts plant management decisions and will have an impact on water requirements and yield.

Daily light integral plants.

Dli is a cumulative version of par which measures the quantity of light received by plants per area per day mol m 2 d 1. Based on this variability it s not hard to imagine that certain greenhouse crops and even nonnative houseplants are experiencing less than ideal light levels in the. It integrates light intensity in micro mols per square meter per second μmol sq m sec and totals this over a 24 hour period. An area s daily light integral is the number of light particles that are received in one full day.

Measuring daily light integral dli mol m2 day. Daily light integral dli describes the number of photosynthetically active photons individual particles of light in the 400 700 nm range that are delivered to a specific area over a 24 hour period. For example lettuce may only require a minimum dli of 15 while peppers and tomatoes require 22. Light particles particularly those that have a wavelength between 400 and 700 nm provide plants with the energy for photosynthesis.

Many studies have been done evaluating crop performance under different dli levels. Dli daily light integral chart understand your plants ppfd photoperiod requirements how intense light ppfd to expose various species to and for how long. A light emitting ppfd 1000 running 12 hours emits a dli 43 2 moles day computed as 60 sec min 60 min hr 12 hrs day ppfd 1 million. It is important to know that the dli outdoors varies depending on latitude the time of year and the amount of cloud cover.

Light intensity or rather how densely packed light is with photons is measured in micromoles per meter squared per second µmol m2 s. This variable is particularly useful to describe the light environment of plants. Daily light integral dli isn t that friendly of a term. Daily light integral dli is used to understand and evaluate the quantity of light plants are receiving.

The daily light integral dli was developed by scientists to provide a measure of cumulative photosynthetically active radiation par received by plants over the course of the day. For a look at the needs of some different plants check out this document on measuring daily light integral in a greenhouse created by the purdue department. Measuring light for plants the following graph illustrates the year round variability of global horizontal irradiance at apogee instruments in logan utah. From plant to plant there s quite a difference in how much light is required per day.

Dli is an important variable to consider particularly when growing plants in a greenhouse. Daily light integral dli dli ppfd over the course of a light cycle measured as moles of par photons per day example. Growers manipulate the dli all the time sometimes intentionally and sometimes unintentionally. The units are cumbersome and the value is not really easy to measure.