*2.2. Plant Biomass*

Plant fresh and dry biomass were also reduced in response to increasing the B treatment levels. The results obtained exhibited a positive correlation with the root and shoot lengths. Reducing and increasing patterns in plant fresh and dry biomass were observed in the root and shoot lengths. We observed 30% and 32.89% decreases in the root and shoot fresh biomass, respectively. The maximum increase in plant biomass was noted in plants raised from seeds primed with 100 μM of SA, as shown in Table 2. This gain in the plant growth biomarkers was due to the enhanced photosynthetic activity and improved antioxidant status of the plant body (Figure 2).


**Table 2.** Effect of SA (0, 50, 100 and 150 μM) on the plant fresh and dry weight of maize cultivar Gohar-19 under varying B toxicity levels (0, 15 and 30 mg kg<sup>−</sup>1).

Values in the same column with different letters in superscript differ significantly.

#### *2.3. Photosynthetic Pigments*

Elevated B levels significantly reduced the photosynthetic pigment contents of maize seedlings. It was observed that the chl *a* contents were reduced with increasing B treatment levels. The 30 mg kg−<sup>1</sup> B imposed deteriorative effects and reduced the chl *a* contents effectively (Figure 3a). An improvement in the chl *a* concentration was recorded through priming seeds with SA. Seeds primed with 100 μM of SA expressed the maximum chl *a* content, which suggests reduced toxicity effects.

**Figure 3.** Effect of SA on chlorophyll a (**A**), chlorophyll b (**B**), carotenoids (**C**) and anthocyanin (**D**) contents of maize cultivar Gohar-19 under varying B toxicity levels.

The chl *b* contents were also reduced under B toxicity as compared to the control. An increase in the chl *b* contents was observed with respect to the control in the plants emerging from primed seeds. An increase of 30.4% in the chl *b* contents was observed at 100 μM SA treatment, while a non-significant increase was observed at 150 μM SA treatment as compared to the control (Figure 3b). The carotenoid contents were reduced effectively under 30 mg kg−<sup>1</sup> B. The B application at 30 mg Kg−<sup>1</sup> caused reductions of 52.6%, 31.3% and 45% in the chl*a*, chl*b* and carotenoids, respectively. The SA

priming improved the carotenoid contents by reducing the drastic effects of B toxicity. A non-significant change in the carotenoid contents was observed in 50 and 150 μM SA primed seeds, while 100 μM SA significantly enhanced the carotenoid contents as compared to the control (Figures 2 and 3c).

### *2.4. Anthocyanin*

The anthocyanin contents increased with increasing the levels of B toxicity. Significant increases in the anthocyanin contents were observed in plants treated with 15 and 30 mg kg−<sup>1</sup> B. There was a 33.33% increase in anthocyanin contents when 30 mg kg−<sup>1</sup> soil B was applied, as compared to the control. The SA priming reduced the anthocyanin contents overall, but only 100 μM of SA caused a 47.5% reduction in the anthocyanin contents (Figure 2 andFigure 3c).

#### *2.5. Ascorbic Acid*

The toxic effects of B increased the ASA contents of maize seedlings. The B treatment of 30 mg kg−<sup>1</sup> significantly increased the ASA content up to 44% as compared with the control (Figure 4). Priming with SA reduced the B toxic effects. Only 100 and 150 μM of SA effectively mitigated the toxic effects on plants grown in pots containing 15 mg kg−<sup>1</sup> B. However, under a high boron toxicity, only 100 μM of SA significantly reduced the ASA content up to 36% as compared to the control, as shown in Table 3, Figure 2.

**Figure 4.** Effect of SA on the K (**A**,**B**), Ca (**C**,**D**) and nitrate (**E**,**F**) contents in the roots and leaves of maize cultivar Gohar-19 under varying B toxicity levels.


**Table 3.** Effect of SA (0, 50, 100 and 150 μM) on the leaf ascorbic acid, H2O2, proline and glycine betaine contents of maize cultivar Gohar-19 under varying B toxicity levels (0, 15 and 30 mg kg<sup>−</sup>1).
