Effects of 17 Alpha-Ethinylestradiol, Norethindrone, and Levonorgestrel on Root Growth of Arabidopsis Thaliana

The study investigated the effects of 17 α-ethinylestradiol, norethindrone, and levonorgestrel on the root growth of Arabidopsis thaliana seedlings. Norethindrone at 30 μg·L~(-1) significantly promoted taproot growth and increased lateral root number and length, while 17 α-ethinylestradiol at 3,000 μg·L~(-1) caused taproot bending. Norethindrone was most effective at 300 μg·L~(-1), enhancing taproot length and lateral root development, but at 3,000 μg·L~(-1), it inhibited root-hair growth. Levonorgestrel was highly active, promoting taproot and root-hair growth at 3 μg·L~(-1), and at 300 μg·L~(-1), it increased lateral root number and root hair density. However, at 3,000 μg·L~(-1), it inhibited taproot and lateral root growth.