Effects of Light Spectra on Morphology, Gaseous Exchange, and Antioxidant Capacity of Industrial Hemp

Abstract

One of the most important growth factors in cannabis cultivation is light which plays a big role in its successful growth. However, understanding that how light controls the industrial hemp growth and development is poor and needs advanced research. Therefore, a pot study was conducted to investigate the effects of different colors of light, that is, white light (WL), blue light (BL), red light (RL), and 50% red with 50% blue mix light (RBL) on morphology, gaseous exchange and antioxidant capacity of industrial hemp. Compared with WL, BL significantly increase hemp growth in terms of shoot fresh biomass (15.1%), shoot dry biomass (27.0%), number of leaves per plant (13.7%), stem diameter (10.2%), root length (6.8%) and chlorophyll content (7.4%). In addition, BL promoted net photosynthesis, stomatal conductance, and transpiration, while reduces the lipid peroxidation and superoxide dismutase and peroxidase activities. However, RL and RBL significantly reduced the plant biomass, gas exchange parameters with enhanced antioxidant enzymes activities. Thus, blue light is useful for large-scale sustainable production of industrial hemp.

Keywords: antioxidant capacity; gaseous exchange; industrial hemp; light quality; morphophysiological traits.

Figure 1

Effects of differential light quality on SPAD (Soil Plant Analysis Development) value of industrial hemp grown under different color light-emitting diodes. Bars indicated the mean ± SD (n = 3). Different letters on bars indicated significant difference between treatments at p ≤ 0.05. Different abbreviations used in the figure are as follows: WL, white light LED (control); BL, blue light LED, RL, red light LED; RBL, 50% red and 50% blue Light LED.

Figure 2

Effects of differential light quality on net photosynthesis (A), stomatal conductance (B), transpiration rate (C), and intercellular CO₂ concentration (D) in industrial hemp grown under different color light-emitting diodes. Bars indicated the mean ± SD (n = 3). Different letters on bars indicated significant difference between treatments at p ≤ 0.05. Different abbreviations used in the figure are as follows: WL, white light LED (control); BL, blue light LED, RL, red light LED; RBL, 50% red and 50% blue Light LED.

Figure 3

Effects of differential light quality on superoxide dismutase (SOD) activity (A), peroxidase (POD) activity (B), malondialdehyde (MDA) content (C), and proline content (D) in the leaves of industrial hemp grown under different color light-emitting diodes. Bars indicated the mean ± SD (n = 3). Different letters on bars indicated significant difference between treatments at p ≤ 0.05. Different abbreviations used in the figure are as follows: WL, white light LED (control); BL, blue light LED, RL, red light LED; RBL, 50% red and 50% blue Light LED.

Figure 4

Correlation of different studied parameters in industrial hemp. Different abbreviations used in the figure are as follows: SFM, shoot fresh weight; SDM, shoot dry weight; NL, number of leaves per plant; PH, plant height; SD, stem diameter; RL, root length, SPAD, Chlorophyll; Pn, net photosynthesis; Gs, stomatal conductance; Tr, transpiration rate; C _i, intercellular CO₂ concentration; SOD, superoxide dismutase; POD, peroxidase; MDA, malondialdehyde; Pro, proline.

Figure 5

Loading plots of principal component analysis (PCA) on different studied attributes of industrial hemp grown under different color light-emitting diodes. Different abbreviations used in the figure are as follows: SFM, shoot fresh weight; SDM, shoot dry weight; NL, number of leaves per plant; PH, plant height; SD, stem diameter; RL, root length, SPAD, Chlorophyll; Pn, net photosynthesis; Gs, stomatal conductance; Tr, transpiration rate; C _i, intercellular CO₂ concentration; SOD, superoxide dismutase; POD, peroxidase; MDA, malondialdehyde; Pro, proline.