Optimisation of LED Photoperiod for Resource-Efficient Microgreen Production in a Small-Scale Controlled-Environment Farm

Abstract

This study evaluated LED photoperiod optimisation for broccoli and radish microgreens grown in a small-scale controlled-environment production system at Northern Greens Growtech, Belfast, United Kingdom. Three daily photoperiods (12, 16 and 20 h) were compared using three replicate trays per crop and treatment. Fresh yield, marketable yield, waste, water use and plant height were evaluated, alongside treatment-level lighting electricity consumption. Both crop and photoperiod significantly affected fresh yield, while no significant crop × photoperiod interaction was detected. Fresh yield increased substantially from 12 to 16 h, whereas extension from 16 to 20 h produced no statistically significant additional fresh-yield advantage in either crop. Water-use efficiency was highest at 16 h for both crops, while lighting energy-use efficiency declined with increasing photoperiod. Under the conditions tested, a 16 h daily LED photoperiod provided the strongest balance between microgreen productivity and resource efficiency.