Gibberellic acid improves growth and reduces heavy metal accumulation: A case study in tomato (Solanum lycopersicum L.) seedlings exposed to acid mine water

This study investigated the effect of gibberellic acid (GA(3)) on the growth of tomato seedlings and heavy metal accumulation within seedlings tissue irrigated with acid mine water (AMW). Three experimental treatments were administered using a completely randomized design with five replicates. The experimental treatments included were gibberellic acid + acid mine water (GA(3) + AMW), acid mine water (AMW), and tap water. Seedlings were irrigated directly in pots with 400 mL of 100% AMW at two-day intervals 21 days after planting. Drenching of the seedlings with GA(3) was done every 24 h for eight consecutive days from 28 days after planting. Results on the physicochemical analysis showed high concentrations of heavy metals (HMs) in AMW compared to tap water and the experimental treatment significantly affected the measured plant growth parameters. Tomato plants irrigated with AMW alone were shorter (4.00 cm) than plants irrigated with tap water (14.00 cm), while plants treated with AMW and GA(3) were much taller (16.50 cm) than the latter (control). Moreover, HM accumulation differed among the three treatments. Seedlings that received AMW with no GA(3) accumulated more HMs (Cd, Cr, Cu, Ni, and Zn) in their roots, stems, and leaves while plants treated with GA(3) had a decrease in the accumulation and distribution of HMs in the different plant tissues (roots, stems, and leaves) relative to AMW alone and the plants irrigated with tap water alone. The study revealed that GA(3) boosted the growth of tomato seedlings irrigated with AMW and also altered HM accumulation with the tissues of the seedlings.