Effect of Amber (595 nm) Light Supplemented with Narrow Blue (430 nm) Light on Tomato Biomass

Abstract

Full-spectrum light-emitting diodes (LEDs) mainly comprising 460-nm + 595-nm light are becoming a mainstay in the horticulture industry, and recent studies indicate that plant productivity under white LEDs is higher than combined blue and red LED lighting. Different light properties (wavelength and bandwidth) in full-spectrum light, particularly for the blue and amber light regions, have only partly been explored. This research aimed to characterize the effects of amber + blue light wavelengths and bandwidths on tomato (Solanum lycopersicum cv. Beefsteak) growth, morphology, and production efficiency. Tomato seedlings were subjected to four different light treatments for 60 days: narrow amber light (595 nm), narrow blue + narrow amber light (430 nm + 595 nm) with a 1:10 ratio, white LED (455 nm + 595 nm), and a high-pressure sodium (HPS) lamp (control). The highest mean fresh mass yield occurred with the narrow blue + narrow amber light (479 g), followed by white LED at 20% less, HPS at 34% less, and narrow amber at 40% less. Dry mass and plant height were similar among light treatments. Supplementing narrow amber light with 430-nm blue light led to a 20% increase in chlorophyll content. Findings indicate that narrow amber light is more efficient in biomass accumulation than broad amber light and that precise selection of different blue and amber wavelengths can greatly impact the growth and development of tomato seedlings. This energy-efficient narrow-wavelength combination shows improvement over white LED lighting for maximizing tomato growth.

Keywords: LEDs; Solanum lycopersicum; biomass; chlorophyll; greenhouse; photosynthesis.

Figure 1

Effect of the different experimental light treatments on tomato plant growth (n = 6): (a) chlorophyll content (SPAD values), (b) height (cm), (c) stem diameter (mm), and (d) number of internodes. Bars with different letters represent significant differences using Tukey’s post hoc test. LED: light emitting diode; HPS: high-pressure sodium.

Figure 2

Chlorophyll content per leaf area (µmol m⁻²) measured for tomato plants under the different light treatments. Bars with different letters represent significant differences using Tukey’s post hoc test. LED: light-emitting diode; HPS: high-pressure sodium.

Figure 3

Relative spectra of the four experimental light treatments: narrow amber light, narrow blue + narrow amber light, white LED light, and high-pressure sodium (HPS) light (control).