Copper (Cu) is an essential metal for plants. However, its excess in soil can adversely affect plant metabolism. The current study evaluated the effects of gibberellic acid (GA3) foliar applications on the performance of pea plants grown either in Cu-contaminated (Cu+) and non-contaminated (Cu-) soil. GA3 was sprayed (0, 10, 50, and 100 mg·L-1) on 15-days-old plants. The results showed that the increasing concentration of GA3 buffered the phytotoxic effects of Cu and enhanced plant growth, photosynthesis, and leaf chlorophyll content. Foliar-sprayed GA3 up to 100 mg·L-1 alleviated the oxidative stress, as inferred from the lower concentrations of MDA and H2O2 (33.3 µmol·g-1 and 182 µmol·g-1, respectively), and boosted the activity of superoxide dismutase (64.4 U·g-1·FW), peroxidase (122.7 U·g-1·FW), and catalase (226.3 U·g-1·FW). Interestingly, GA3 promoted Cu accumulation in different plant parts when compared to untreated plants, likely due to increased photosynthetic and transpiration rates. Overall, foliar application of GA3 promoted phytoextraction of Cu and alleviated the oxidative stress in pea plants grown in Cu+ soil.
Keywords: Pisum sativum L.; copper and oxidative stresses; foliar application; gibberellic acid.