*3.6. Priming Effect of SPM on Antioxidative Enzyme Activities under Cr Stress*

Under Cr alone treatments, an upsurge in the activities of antioxidant (SOD, CAT, POD, and APX) activities were noticed inside the shoots and roots of both cultivars, but this increment was more conspicuous in shoots compared to roots. The outcomes demonstrated, compared to control plants, the Cr toxicity significantly surged the enzymatic activities i.e., SOD (58.1/47.9, 62.9/54.7%), APX (58.9/52.2, 65.9/63.1%), POD (70.4/58.5, 82.1/67.3%), and CAT (56.2/48.4, 64.9/53.2%) in shoots/roots of both cultivars CY927, and YLY689, respectively (Figure 4a–h). Interestingly, seed primed with SPM further enhanced the enzymatic activities such as SOD (29.1/16.2%, 38.7/19.5%), APX (35.7/26.6, 41.1/34.3%), and POD activity by 23.9/22.4, 28.6/25.9%, and CAT activity by 39.5/24.7%, 44.4/32.9% inside shoots/roots of both cultivars CY927, and YLY689, correspondingly (Figure 4a–h). Our outcomes revealed that seeds primed with SPM developed a higher possibility of scavenging the reactive oxygen species and increased plant tolerance capability with greater effect in YLY689 than CY927.
