Background
Daily light integral (DLI) and photosynthetic photon flux density (PPFD) data is important to greenhouse production because they measure the amount of light that is available to the crop. This data can be used to adjust the growing environment, such as irrigation and carbon dioxide levels, to optimize photosynthesis and crop yield.
DLI is the total amount of light within the photosynthetically active radiation (PAR) spectrum (light wavelengths of 400-700 nm) that impacts a surface in a day. It is measured in moles per meter squared per day (mol/m2/day).
PPFD is the total amount of light within the PAR spectrum that impacts a surface every second. It is measured in micromoles per meter squared per second (µmol/m2/second).
Objectives
The DLI and PPFD Data section of this blog provides greenhouse producers in southwestern Ontario with outdoor light levels on a regular basis year-round. It is meant to serve as a record of the amount of light this location received on a daily basis throughout the year.
Each blog post in this section contains the available data for a one month period.
NOTE: This data is provided for information purposes and does not represent the amount of light at any specific location. It is an approximation and does not represent exact values.
Materials and Methods
The data was collected using a DLI-600 sensor from Apogee Instruments. It measured the extended PAR (ePAR) spectrum (400-760 nm), which includes far red light. The sensor was placed 90 cm off the ground outside of a greenhouse near the Leamington-Kingsville border in Ontario.
DLI data is presented for each day (Table 1), and the ePPFD data is presented in 30-minute intervals (see attached Excel sheet in the last section), when available.
DLI Data
Table 1: DLI data for Leamington-Kingsville for June, 2024.
| Date | DLI (mol/m2/day) |
| 06/06/2024 | 65 |
| 07/06/2024 | 37.4 |
| 08/06/2024 | 61.9 |
| 09/06/2024 | 60 |
| 10/06/2024 | 39.3 |
| 11/06/2024 | 77.5 |
| 13/06/2024 | 67.2 |
| 14/06/2024 | 76.9 |
| 15/06/2024 | 71.2 |
| 16/06/2024 | 62.5 |
| 17/06/2024 | 66.7 |
| 18/06/2024 | 56.8 |
| 20/06/2024 | 65.2 |
| 21/06/2024 | 67.6 |
| 22/06/2024 | 38.4 |
| 23/06/2024 | 64 |
| 24/06/2024 | 44 |
| 25/06/2024 | 46.4 |
| 26/06/2024 | 45.4 |
| 28/06/2024 | 50.7 |
| 29/06/2024 | 64 |
| 30/06/2024 | 73.2 |
| June 2024 DLI average ± standard deviation | 59 ± 12 |