*3.4. Concentration, Uptake, and Translocation of Vanadium*

This study depicted that V treatment significantly raised the V concentration in both shoots and roots, and maximum concentrations were recorded in 75 mg L−<sup>1</sup> treated plants; 32.03 mg kg−<sup>1</sup> DW in the shoots of sweet potato and 52.68 mg kg−<sup>1</sup> DW in the roots of sweet potato (Table 3). Similarly, the accumulation of V was found to be higher in the roots than in the shoots. Moreover, V uptake by shoots and roots of sweet potato significantly augmented as the level of V increased. In the same way, the translocation of V from root to shoot was also raised significantly by the increment of V concentration (Table 3).

**Figure 2.** The influence of various V treatments on root morphological traits; (**A**) root length, (**B**) root volume, (**C**) surface area, (**D**) average diameter, (**E**) projected area, (**F**) number of root tips per plant, (**G**) number of root forks per plant, (**H**) number of root crossings per plant, and (**I**) root length per volume. Duncan's test specifies a significant difference (*p* < 0.05) between the means of the five treatments indicated by different letters.

**Figure 3.** The influence of various V treatments on leaf gas exchange elements; (**A**) transpiration rate, (**B**) photosynthetic rate, (**C**) stomatal conductance, and (**D**) intercellular CO2. Duncan's test indicates a significant difference (*p* < 0.05) between the means of the five treatments indicated by different alphabets.



Duncan's test indicates a significant difference (*p* < 0.05) between the means of the five treatments indicated by different alphabets.

### *3.5. Photosynthetic Pigments*

The chlorophyll (Chl) was significantly influenced by the application of V stress. Compared to the control, adding 10 mg L−<sup>1</sup> V did not significantly raise the concentration of chlorophyll and carotenoid (Car) (Figure 4). On the other hand, higher treatment of V (25, 50, and 75 mg L<sup>−</sup>1) showed a significant negative impact on the photosynthetic pigments, and utmost reduction was detected at 75 mg L<sup>−</sup>1. Compared to the control, 77% reduction in the content of total chl, 65.9% in chl a, 70.5% in chl b, and 50.3% in Car were detected (Figure 4).

**Figure 4.** Influence of various V treatments on the photosynthetic pigments in the leaves of sweet potato. (**A**) Total chlorophyll content (T. Chl), (**B**) chlorophyll a (chl a), (**C**) chlorophyll b (chl b), and (**D**) carotenoid (Car) content. Duncan's test indicates a significant difference (*p* < 0.05) between the means of the five treatments indicated by different alphabets.
