Seed priming with copper‐loaded chitosan nanoparticles promotes early growth and enzymatic antioxidant defense of maize (Zea mays L.) seedlings

BACKGROUND The unique features of nanoparticles can improve the effectiveness of seed priming with metallic ions, boosting plant growth and the defense response. The current study aimed to evaluate the effects of nanopriming of maize (Zea mays L.) seeds with chitosan nanoparticles containing copper ions (NPCu) on the growth and photosynthetic activity of non-stressed seedlings, as well as on the germination and antioxidant response of seeds undergoing deterioration caused by high relative humidity and temperature.RESULTS Seed priming with bulk or nanoencapsulated Cu2+ influenced the initial development of greenhouse-grown maize seedlings, mainly by increasing shoot growth and photosynthetic electron transport, compared to the control. Chitosan nanoparticles without Cu (NP) induced minor morphophysiological responses. In the laboratory assay with stressed seeds, NPCu stood out for strongly increasing the activity of antioxidant enzymes. In contrast, priming with NP induced oxidative stress in maize seedlings.CONCLUSION Under normal growing conditions, Cu2+ promoted the initial growth of maize seedlings regardless of the nanoencapsulation. In the stressful condition caused by the deterioration process, NPCu combined the properties of chitosan with the essentiality of Cu2+, promoting the enzymatic antioxidant response. (c) 2021 Society of Chemical Industry (SCI).