Fig. 4

Responses of physiological traits and thermal infrared indices to drought. (A) Drought effects on plant physiology during the TF experiment. The B104 genotype and four physiological traits, i.e. stomatal conductance (g_s, mol H₂O m⁻² s⁻¹), effective quantum yield of photosystem II (ϕPS₂), transpiration rate (E, mmol H₂O m⁻² s⁻¹) and leaf water potential (ψ, MPa), were selected for this analysis. (B) Responses of thermal infrared (TIR) indices to drought. B104 maize plants (n_WD: 19, n_WW: 19) were imaged daily and TIR indices were calculated using the formulas described in Table 1. Well-watered (WW) and water-deficit (WD) maize plants were monitored from V4 until the silking stage. The average trends of the WW and WD treatments are indicated by blue solid and red dashed lines, respectively. The 95% confidence interval of the average is represented by gray shading (A) and the standard deviation by blue and red shading for the WW and WD treatments, respectively (B). Individual measurements of the plants are visualized by blue dots (WW) and red circles (WD). The black vertical line indicates the start of the WD treatment. The days on which significant treatment differences were observed are marked with a light gray vertical shading behind the average trend and dots (P < 0.05)