Gibberellic acid in combination with pressmud enhances the growth of sunflower and stabilizes chromium(VI)-contaminated soil.

The present study was conducted to assess the impact of gibberellic acid on growth and yield of sunflower in hexavalent chromium [Cr(VI)]-contaminated soil in the presence as well as absence of pressmud. Seeds of sunflower were sown in potted soil amended with pressmud as an organic amendment and contaminated with different levels of Cr(VI) (12, 18, and 24 mg kg(-1)) by using K2Cr2O7 salt. Gibberellic acid (10(-4) M) was applied at time of seedling emergence in the rhizosphere. The results showed that Cr(VI) stress significantly reduced the growth and yield of sunflower. However, application of gibberellic acid and pressmud reversed the toxic effects of Cr(VI) and improved the growth and yield of sunflower. Combined application of gibberellic acid and pressmud further improved growth and yield compared to their separate application in Cr(VI) stress. Moreover, gibberellic acid and pressmud decreased the uptake of Cr and stabilized it in the soil.