Optimalisation of the greenhouse cultivation of basil, mint and chives by varying the light conditions

Basil (Ocimum basilicum L.) is an important aromatic herb cultivated worldwide. As a vegetative crop it offers a short cultivation cycle creating high commercial value. For Belgium, basil is mostly grown in greenhouses. Although plants are cultivated in a highly controlled, technological cultivation system, several challenges remain. The aim of this research project was to optimize light use in the commercial cultivation of basil, both in greenhouses and vertical farming.

Actual light conditions in a commercial greenhouse and crop growth of basil over an entire year were recorded. Significant changes in light intensity, photoperiod and light quality present were observed. Applying optimal light intensity and composition is an important element to optimize energy consumption for indoor farming. The minimal light quantity needed for realizing optimal basil growth was determined. Artificial light sources available for the cultivation of leafy vegetables were evaluated. They were scored insufficient for commercial indoor plant cultivation due to plant quality problems. Using a multispectral research LED lamp (containing 16 different LEDs) different combinations of blue and red light were evaluated for basil growth. Furthermore different combinations of green, far-red and infrared light within a white light spectrum were studied. Both green and far-red light were identified as determinative to induce the shade avoidance response, alter plant morphology and increase biomass production in basil.

Basil has been proven to be an excellent crop to grow in a multilayer system. Also for other crops like mint, dill and cilantro promising results were obtained using artificial light. Yet, further horizontal and vertical scaling offers serious technical and scientific challenges, but a new transition in food production is coming up.