Light-emitting Diode Irradiation and Glycine Differentially Affect Photosynthetic Performance of Black Henbane (hyoscyamus Niger L.)

•The highest Fv/Fo was obtained in R LED light under foliar glycine exposure to 80 mg.l−1.•Glycine-exposed plants under light treatments exhibited higher fluorescence yield at F0, Fm, and Fv compared to normal light conditions.•Plants exposed to control light under foliar glycine treatment at 80 mg. l−1 resulted in higher Vj and Vi than those of different lighting conditions.•Under B LED light conditions, ∆b*, ∆E*, ∆C* and ∆h* were increased in comparison with normal light conditions.•Plants under B LED light upon exposure to glycine treatment at 40 mg. l−1 revealed the highest stomatal conductance.