Effects of different levels of gibberellic acid and potassium nitrate solutions on the emergence and seedling vigor of amaranth and Cleome gynandra

The effects of gibberellic acid and potassium nitrate on seed emergence and seedling growth of amaranth and Cleome gynandra were investigated in the greenhouse at Marondera University of Agricultural Sciences and Technology. The study was laid out in a factorial layout within a completely randomized design replicated three times. Potassium nitrate (dry seeds, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, and 1%) and gibberellic acid (dry seeds, 100, 200, 300, 400, 500, 600, 700, 800, 900, and 1000 parts per million) were used, respectively. A total of 100 seeds of both crops were planted in each plastic pocket. Seed emergence percentage and vigor index of amaranth and C. gynandra were evaluated. The effects were more pronounced in seeds treated with gibberellic acid than in potassium nitrate. Seed emergence and vigor index of amaranth and C. gynandra seeds treated with gibberellic acid showed a significant difference at p < 0.01, while potassium nitrate showed no significant difference at p > 0.05. The maximum seed emergence percentage of amaranth and C. gynandra was 67.1% and 64.8%, which was obtained in 2022 and 2021, while the lowest was 35.5% and 37.5%, which was obtained in 2021. The highest vigor index I of amaranth and C. gynandrawas 590.3 and 586.2, which was observed in 2022 and 2021, while the lowest vigor index I was 45.2 and 170, which was obtained in 2021 and 2022. The results obtained indicated that the application of gibberellic acid on seeds of amaranth and C. gynandra can alleviate seed dormancy.