Abstract
Different light qualities affect plant growth and physiological responses, including stomatal openings. However, most researchers have focused on stomatal responses to red and blue light only, and the direct measurement of evapotranspiration has not been examined. Therefore, we quantified the evapotranspiration of sweet basil under various red (R), green (G), and blue (B) combinations using light-emitting diodes (LEDs) and investigated its stomatal responses. Seedlings were subjected to five different spectral treatments for two weeks at a photosynthetic photon flux density of 200 µmol m−2 s−1. The ratios of the RGB light intensities were as follows: R 100% (R100), R:G = 75:25 (R75G25), R:B = 75:25 (R75B25), R:G:B = 60:20:20 (R60G20B20), and R:G:B = 31:42:27 (R31G42B27). During the experiment, the evapotranspiration of the plants was measured using load cells. Although there were no significant differences in growth parameters among the treatments, the photosynthetic rate and stomatal conductance were higher in plants grown under blue LEDs (R75B25, R60G20B20, and R31G42B27) than in the R100 treatment. The amount of water used was different among the treatments (663.5, 726.5, 728.7, 778.0, and 782.1 mL for the R100, R75G25, R60G20B20, R75B25, and R31G42B27 treatments, respectively). The stomatal density was correlated with the blue light intensity (p = 0.0024) and with the combined intensity of green and blue light (p = 0.0029); therefore, green light was considered to promote the stomatal development of plants together with blue light. Overall, different light qualities affected the water use of plants by regulating stomatal conductance, including changes in stomatal density.
Highlights
Indoor farming has emerged as a new form of agriculture for the future [1]; considerable effort has been made to understand plant physiology to enhance the productivity of plant production by correctly controlling their growth environment
Sweet basil grown under different light spectra for 2 weeks showed no significant differences in canopy leaf temperature, chlorophyll content, and general growth parameters, including shoot fresh/dry weight, root fresh/dry weight, and leaf area (Table 1)
Previous studies indicated a significant influence of light quality on plant growth [21,23], our results showed that 2 weeks of light quality treatments did not significantly alter the additional growth of sweet basil grown under the same PPFD
Summary
Indoor farming has emerged as a new form of agriculture for the future [1]; considerable effort has been made to understand plant physiology to enhance the productivity of plant production by correctly controlling their growth environment. Artificial light sources have been developed to replace sunlight to grow plants in controlled environmental production systems, and many studies have been conducted to promote the efficiency of the artificial light source and effectively use it for plant production [2,3]. The study of light quality has been accelerated by the development of light-emitting diode (LED) technology, which is one of the most predominant artificial light sources for plant production [6]. LEDs can provide a specific light spectrum; they are appropriate for studying the effect of light quality on plant behaviors for observing the response of plants to a target wavelength without the interference of other wavelength ranges, and various combinations of light wavelengths can be applied [7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
