*3.4. IRGA Parameters and Chlorophyll Contents*

IRGA parameters such as transpiration rate, stomatal conductance and photosynthetic rate gradually reduced under increased Cr concentrations alone. The transpiration rate was greater at 25 mg·kg−<sup>1</sup> of Cr stress and decreased with increasing Cr stress levels at concentrations from 50 to 100 mg·kg<sup>−</sup>1. Without microbial inoculation, transpiration rate decreased by 12%, 21% and 32% under 25, 50 and 100 mg·kg−<sup>1</sup> Cr stress, respectively, as compared to control (Figure 3A). Similarly, stomatal conductance and photosynthetic rate in uninoculated plants also reduced with increasing Cr concentrations. Stomal conductance decreased by 9%, 25%, 45% and photosynthetic rate decreased by 12%, 25% and 46% under 25, 50 and 100 mg·kg−<sup>1</sup> Cr stress, respectively, as shown in Figure 3B,C. These results explain the effective role of bacterial inoculation in improving gas exchange attributes in Cr-stressed wheat plants by comparing uninoculated plants. Similarly, chlorophyll a contents decreased by 9.40%, 26.21% and 40.08% in inoculated plants and by 10.66%, 28.02% and 41.87% in uninoculated plants under 25, 50 and 100 mg·kg−<sup>1</sup> Cr stress, respectively, as shown in Figure 3D. On the other hand, as compared to untreated control, chlorophyll b was reduced by 15.36%, 27.27% and 40.80% in uninoculated wheat plants and by 14.44%, 27.24% and 40.63% in inoculated wheat plants under 25, 50 and 100 mg·kg−<sup>1</sup> Cr stress, respectively, as shown in Figure 3E. A gradual decrease in carotenoid contents was also observed in inoculated and uninoculated plants with increasing level of Cr stress, where inoculated plants showed 6%, 19% and 27% reduction in carotenoid contents while uninoculated plants showed 9%, 19% and 28% reduction under 25, 50 and 100 mg·kg−<sup>1</sup> Cr stress, respectively (Figure 3F)

**Figure 3.** Influence of the different Cr levels (0, 25, 50, 100 mg·kg<sup>−</sup>1), with and without peat-moss-based microbial inoculation, on transpiration rate (**A**), stomatal conductance (**B**), photosynthetic rate (**C**), chlorophyll a (**D**), chlorophyll b (**E**) and carotenoids (**F**) of wheat plants. Bars indicate the mean values and standard deviation of three replicates. Different bar letters show significant changes among various treatments at *p* < 0.05.
