Magnesium oxide nanoparticles (MgO NPs) have great potential to enhance the crop productivity and sustainability of agriculture. Still, a thorough understanding is lacking about its essentiality or toxicity and precise dose for the safe cultivation of oilseed crops. Thus, we assessed the dual effects of MgO NPs (control, 5, 10, 20, 40, 80, and 200 mg/L) on the seed germination, growth performance, photosynthesis, total soluble protein, total carbohydrates, oxidative stress markers (hydrogen peroxide as H₂O₂ and superoxide anion as O₂^•‒), lipid peroxidation as MDA, and antioxidant defence machinery (SOD, CAT, APX, and GR activities, and GSH levels) of seven different oilseeds (Brassica napus L.) cultivars (ZY 758, ZD 649, ZD 635, ZD 619, GY 605, ZD 622, and ZD 630). Our findings revealed that low doses of MgO NPs (mainly at 10 mg/L) markedly boosted the seed germination, plant growth (shoot and root lengths) (15‒22%), and biomass (fresh and dry) (11‒19%) by improving the levels of photosynthetic pigments (14‒27%), net photosynthetic rate, stomatal conductance, photosynthetic efficiency (Fv/Fm), total soluble protein and total carbohydrates (16‒36%), antioxidant defence, and reducing the oxidative stress in B. napus tissues. Among all B. napus cultivars, these beneficial effects of MgO NPs were pronounced in ZD 635. ile, elevated levels of MgO NPs (particularly at 200 mg/L) induced oxidative stress, impaired antioxidant scavenging potential, photosynthetic inhibition, protein oxidation, and carbohydrate degradation and lead to inhibit the plant growth attributes. These inhibitory effects were more pronounced in ZD 622. Collectively, low-dose MgO NPs reinforced the Mg contents, protected the plant growth, photosynthesis, total soluble carbohydrates, enzyme activities, and minimized the oxidative stress. While, the excessive MgO NP levels impaired the above-reported traits. Overall, ZD 622 was highly susceptible to MgO NP toxicity and ZD 635 was found most tolerant to MgO NP toxicity.

氧化镁纳米粒子（MgO NPs）在提高作物生产力和农业可持续性方面具有巨大潜力。尽管如此，人们对其重要性或毒性以及油籽作物安全种植的精确剂量仍缺乏透彻的了解。因此，我们评估了 MgO NP（对照、5、10、20、40、80 和 200 mg/L）对种子发芽、生长性能、光合作用、总可溶性蛋白、总碳水化合物、氧化应激标记物的双重影响（七种_不同油籽^（ _{Brassica napus} L. ）品种（ZY 758、ZD 649、ZD 635、ZD 619、GY 605、ZD 622 和 ZD 630）。我们的研究结果表明，低剂量的 MgO NPs（主要为 10 mg/L）显着促进了种子发芽、植物生长（芽和根长度）（15-22%）和生物量（新鲜和干）（11-19%） ）通过提高光合色素水平（14-27%）、净光合速率、气孔导度、光合效率（ Fv / Fm ）、总可溶性蛋白质和总碳水化合物（16-36%）、抗氧化防御以及减少氧化甘蓝型油菜组织中的应激。在所有甘蓝型油菜品种中，MgO NP 的这些有益作用在 ZD 635 中最为明显。碳水化合物降解并导致抑制植物生长属性。这些抑制作用在 ZD 622 中更为明显。 总的来说，低剂量的 MgO NPs 增强了镁含量，保护了植物生长、光合作用、总可溶性碳水化合物、酶活性，并最大限度地减少了氧化应激。然而，过量的 MgO NP 水平会损害上述特性。总体而言，ZD 622 对 MgO NP 毒性高度敏感，而 ZD 635 对 MgO NP 毒性最耐受。