Table 3.

Effect of foliar application of 30 mM trehalose (Tre) and/or 1 mM salicylic acid (SA) on chlorophyll fluorescence parameters in sweet basil seedlings grown under well-watered (control, CK) and drought stress conditions. Values are the means ± SE (n = 6). Different letters within a column indicate significant differences among means according to Duncan’s multiple-range test at the p < 0.05 level.

Treatments	PSII Efficiency (Fv/Fm)	PSII Quantum Yield (FPSII)	Photochemical Quenching (qp)	Non-Photochemical Quenching (NPQ)
Control (CK)	0.80 ± 0.008 b	0.61 ± 0.02 b	0.87 ± 0.01 a	0.63 ± 0.01 d
CK + Tre	0.86 ± 0.003 a	0.68 ± 0.01 b	0.91 ± 0.009 a	0.44 ± 0.01 e
CK + SA	0.83 ± 0.007 a	0.63 ± 0.007 b	0.90 ± 0.013 a	0.39 ± 0.01 e
CK + Tre + SA	0.91 ± 0.011 a	0.73 ± 0.02 a	0.94 ± 0.016 a	0.35 ± 0.009 f
Drought stress	0.55 ± 0.004 d	0.46 ± 0.007 d	0.60 ± 0.006 d	0.95 ± 0.004 a
Drought stress + Tre	0.67 ± 0.020 c	0.55 ± 0.007 c	0.71 ± 0.010 c	0.73 ± 0.012 c
Drought stress + SA	0.62 ± 0.007 c	0.51 ± 0.008 c	0.67 ± 0.010 c	0.83 ± 0.025 b
Drought stress + Tre + SA	0.90 ± 0.012 a	0.76 ± 0.013 a	0.81 ± 0.005 b	0.68 ± 0.009 d