Mapping of Average DLI Obtained over 17 Years in Different Regions of Côte d’Ivoire: A Sustainable Agricultural Decision-Making Tool

Plants require a certain amount of photosynthetic active radiation (PAR) every day to grow efficiently. The total amount of daily photosynthetic light or the daily light integral (DLI), comes from global solar radiation and may sometimes be insufficient or in excess to grow specific plants in certain regions. Indeed, DLI, a performance factor directly linked to the photosynthetic activity of crops, has an effect on the development, growth, quality and yield of these crops. It is, therefore, of great importance for producers to know the average DLI in their regions to strategically design their agricultural risk management and mitigation plans. However, this major factor of crop performance is very little or almost not integrated into farm management in West Africa. In this context, the objective of this study is to present a mapping of DLI averages over 17 years in the main regions of Côte d’Ivoire. First, we determined the PAR/Global Radiation ratio, and then the DLI was calculated from the global solar radiation data obtained over the period from 2004 to 2020. The results revealed that the DLI varies between 28.73 ± 0.62 mol∙m−2∙d−1 and 52.47 ± 0.53 mol∙m−2∙d−1 across the country depending on the region. The lowest DLIs are recorded in the months of June, July, August, and September; and the peaks are observed during the months of March, April, and May. Through these results, one can easily select the appropriate region and the adequate growing period for growing plants with known daily photosynthetic active radiation requirements. Decisions to integrate compensation techniques such as supplemental artificial lighting to increase photosynthetic active radiation for certain areas or throughout certain periods can be made. These results may also explain the low yields obtained for certain crops, and furthermore trigger a positive change in the habits of farmers for a successful adaptation to climate change.