Effect of LED on growth and quality of sweet and purple basil, parsley and coriander

Vertical farms and plant factories with artificial lighting (PFALs) make it possible to improve the use efficiency of inputs like surface, water, and nutrients and to grow crops without or reduced use of pesticides. Herbs have a high potential to be grown in PFALs. Energy and lighting costs are still high, but light-emitting diodes (LEDs) allow to develop species-specific spectra which optimize yield and qualitative traits. In the present research, the effect of four red and blue light (R:B 0.5, 1, 2, 4) combinations on the growth and nutritional quality of sweet and purple basil (Ocimum basilicum), parsley (Petroselinum crispum), and coriander (Coriandrum sativum) was studied. The R:B ratio of 4 enhanced the plant height of sweet basil, parsley, and coriander. In contrast, the growth of purple basil didn't differ between the light treatments, but a lower R:B ratio resulted in significantly more anthocyanins. Increasing the red light fraction also enhanced the chlorophyll and total phenolics content in coriander. In parsley, an R:B ratio of 2 was more optimal for the chlorophyll content, but negatively impacted the total phenolics content. The phytochemicals in sweet basil were not influenced by the different R:B ratios.