Effects of different green-blue light ratios on growth, stomatal characteristics, and water use efficiency of basil plants (Ocimum basilicum L.) in a plant factory

This study aimed to investigate the effects of different green-blue light ratios (G/B, with the peak wavelengths of 520 and 445 nm, respectively) with the constant total photon flux density and red-light photon flux density (R, 660nm) on the growth, stomatal characteristics, and water utilization efficiency (WUE) of purple leaf basil plants (Ocimum basilicum L.). Seven treatments with different G/B of RB (R:B = 1:1, set as control), RG₁B₇ (R:G:B = 8:1:7), RG₁B₃ (R:G:B = 8:2:6), RG₁B₁ (R:G:B = 8:4:4), RG₃B₁ (R:G:B = 8:6:2), RG₇B₁ (R:G:B = 8:7:1) and RG (R:G = 1:1) were set in this experiment.
Growth parameters, stomatal characteristics, and WUE of purple leaf basil plants were investigated.
The results showed that 1) treatments RG₁B₃ and RG were significantly increased the leaf fresh weight (FW) by 22.6 and 22.9%, respectively, compared with treatment RB, and stem FW was increased by 30.0% under treatment RG. No significant difference in WUE was obtained when compared with treatment RB; 2) Stomatal density of purple leaf basil plants first remained constant with treatment RB, then decreased, and finally increased with increasing G/B. Stomatal area on adaxial of leaf showed a decrease with further increase in G/B, along with g_s (stomatal conductance) and T_r (transpiration rate). We concluded that all the changes in stomatal aperture, density and conductance, even P_n contributed to the WUE under different G/B treatments.
Treatment RG achieved higher yield while maintaining WUE, would be a more suitable light quality combinations for purple leaf basil plants production in plant factories.

X International Symposium on Light in Horticulture

Y. Yang, Y.X. Tong

light spectra, G/B, yield, stomatal traits, WUE

https://doi.org/10.17660/ActaHortic.2025.1423.4