Far-red in greenhouse tomato cultivation: from light perception to fruit yield improvement

The adoption of light-emitting diodes (LEDs) for greenhouse supplementary lighting during the winter months plays an important role in reducing the energy consumption of the horticultural sector. This thesis explores how incorporating far-red, a part of the solar spectrum often missing from LED supplementary lighting, can alter plant physiology and boost fruit yield in tomato cultivation. The results show that the increase in fruit yield under far-red supplementation is associated with the daily dose of far-red, rather than the specific timing of its application during the day. Additionally, the location of far-red lighting relative to the plant canopy impacts growth and can be used as a tool to maximise supplementary lighting efficiency. Overall, this research clarifies the biological mechanisms behind far-red-induced yield improvements and provides practical guidelines for growers to implement this technology effectively.