Professor Marcelis is Head of the Horticulture and Product Physiology Group at Wageningen University, The Netherlands. The Group is widely regarded as one of the world’s leading university centres of expertise on greenhouse cultivation and vertical farming. Professor Marcelis is an internationally-recognised authority on the use of light in greenhouse and other protected systems to optimise crop production.Dr Nazim S. Gruda is Professor of Horticulture at the University of Bonn, Germany. Professor Gruda is internationally-renowned for his research and over 250 publications in areas such as soilless culture, controlled environment cultivation and product quality of horticultural crops. He is Chair of an International Society for Horticultural Science (ISHS) Working Group and has edited Acta Horticulturae for the ISHS. In recognition of his research, Professor Gruda was awarded the 2003 “Dr. Heinrich-Baur-Prize” by the Technical University of Munich, Germany, the 2017 “National Scientific Prize” by the Albanian Academy of Science, and the status of “Distinguished Scientist” by the Chinese Academy of Science in 2020.