LED lighting cuts costs for greenhouse tomato growers

Supplemental light-emitting diode (LED) lighting treatment can help greenhouse tomato growers reduce energy cost without affecting fruit quality attributes, new research suggests.

The findings suggest that energy-saving LEDs could be a feasible alternative to high-pressure sodium lamps (HPS) in greenhouse operations.

"There is great interest in (LEDs) potential to influence the phytochemical and flavour profile of various high-value crops," said the researchers from Purdue University in Indiana, US.

"However, little fruit quality-attribute work with LEDs has been done on a long-duration, full grow-out of tomatoes," the researchers said.

The scientists conducted three separate studies to investigate the effect of supplemental light quantity and quality on greenhouse-grown tomatoes.

Plants were grown either with natural solar radiation only (the control), natural solar radiation plus supplemental lighting from high-pressure sodium lamps, or natural solar radiation plus supplemental light from intracanopy (IC) LED towers.

The scientists analysed plant responses by collecting chromacity, Brix, titratable acidity, electrical conductivity, and pH (acidity) measurements.

"Contrary to our hypothesis, fruit quality was largely unaffected by direct, IC supplemental lighting," the authors said.

The study also included sensory panels in which tasters ranked tomatoes for colour, acidity, and sweetness using an objective scale.

The tasters were also asked to rank tomato colour, aroma, texture, sweetness, acidity, aftertaste, and overall approval using a five-point hedonic (preference) scale.

"This study demonstrated that greenhouse tomato fruit quality was unaffected by both the type of supplemental lighting as well as supplemental lighting per se," the scientists said.

The findings appeared in the journal HortScience.