Increased Plant Quality, Greenhouse Productivity and Energy Efficiency with Broad-Spectrum LED Systems: A Case Study for Thyme (Thymus vulgaris L.)

Abstract

A light-emitting diode (LED) system covering plant-receptive wavebands from ultraviolet to far-red radiation (360 to 760 nm, “white” light spectrum) was investigated for greenhouse productions of Thymus vulgaris L. Biomass yields and amounts of terpenoids were examined, and the lights’ productivity and electrical efficiency were determined. All results were compared to two conventionally used light fixture types (high-pressure sodium lamps (HPS) and fluorescent lights (FL)) under naturally low irradiation conditions during fall and winter in Berlin, Germany. Under LED, development of Thymus vulgaris L. was highly accelerated resulting in distinct fresh yield increases per square meter by 43% and 82.4% compared to HPS and FL, respectively. Dry yields per square meter also increased by 43.1% and 88.6% under LED compared to the HPS and FL lighting systems. While composition of terpenoids remained unaffected, their quantity per gram of leaf dry matter significantly increased under LED and HPS as compared to FL. Further, the power consumption calculations revealed energy savings of 31.3% and 20.1% for LED and FL, respectively, compared to HPS. In conclusion, the implementation of a broad-spectrum LED system has tremendous potential for increasing quantity and quality of Thymus vulgaris L. during naturally insufficient light conditions while significantly reducing energy consumption.

Investigation of LED Light Qualities for Peppermint (Mentha x Piperita L.) Cultivation Focusing on Plant Quality and Consumer Safety Aspects

“…EO content and yield, expressed on a dry weight basis, were calculated according to the following equations: EO content (%) = (distilled EO (g)/5 g) x 100; EO yield (mg g leaf dry matter −1 (L DM )) = mean of EO yield (mg g L DM −1 ) (n = 8 per spatial replication) x total L DM (g). To determine a possible influence of the temporary aphid infestation on the chemical composition of the monoterpenes, volatiles were extracted according to the procedure described in Tabbert et al, 2021.…”

Application timing and duration of LED and HPS supplements differentially influence yield, nutrient bioaccumulation, and light use efficiency of greenhouse basil across seasons

“…Maximizing efficiency with improved lighting regimes will be vital as global energy demand continues to increase. There is significant potential to utilize continually advancing SL technologies, along with physiology-based application protocols, to develop species-specific lighting regimes for yield and nutrient uptake optimization (Graamans et al, 2018;Jayalath and van Iersel, 2021;Tabbert et al, 2021).…”

GROWTH AND ACCUMULATION OF PHENOLIC COMPOUNDS IN THYME (Thymus vulgaris) BASED ON THE BALANCE OF RED AND BLUE LED LIGHTS

“…The use of low intensities of LED lights (< 50 µmol m -2 s -1 ) is not common in IPPSs, although it is well-known that most plant photoreceptors respond to light intensities below 1 μmol m -2 s -1 (Paradiso and Proleitti, 2022). In this sense, thyme has been reported to resist low light conditions (Murillo-Amador et al 2013;Tabbert et al 2021), therefore investigating the responses of these plants to conditions of low light intensity is a great opportunity. This study applied LED light with wavelengths corresponding to the colors white, red, blue, red-blue 1:3 and red-blue 3:1 at 25 μmol m -2 s -1 on young thyme plants, with the main purpose of evaluating the effect on the growth and accumulation of phenolic compounds and flavonoids.…”