Effect of gibberellic acid and potassium nitrate seed treatments on the emergence and seedling vigor of Amaranth and Cleome gynandra

Abstract

Seed dormancy is the major challenge in the cultivation of Amaranth and Cleome gynandra. Amaranth and C. gynandra are affected by chemical, physical, and physiological dormancy. The current study was conducted at the Marondera University of Agricultural Sciences and Technology (MUAST) farm in 2021 and 2022. The effects of gibberellic acid and potassium nitrate seed treatments on the emergence and seedling vigour of Amaranth and C. gynandra were evaluated. Seeds of Amaranth and C. gynandra were pre-soaked in gibberellic acid (control 0, 100, 200, 300,400, and 500 ppm) and potassium nitrate (control 0%, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5%) solutions for 24 h to have a factorial layout within a randomized complete block design replicated three times. Seeds of Amaranth and C. gynandra treated with gibberellic acid showed a significant difference while potassium nitrate showed no significant difference. The highest emergence percentage and vigor index were recorded in seeds treated with 500 ppm gibberellic acid. The maximum emergence percentages of Amaranth (62.1%) and C. gynandra (60.7%) were obtained in 2022 and 2021. The least emergence percentages of Amaranth (46.4%) and C. gynandra (45.3%) were obtained in control in 2021. The highest vigor index of Amaranth (603) was obtained in 2022, while the highest vigor index of C. gynandra (562) was obtained in 2021. The lowest vigor indices of Amaranth and C. gynandra were 341 and 270, which were recorded in 2021 and 2022. The results showed that gibberellic acid has the potential to reduce seed dormancy.