I wish you success in your work. Did dark roots have soft rot?

hope this link is useful

link.springer.com/content/pdf/10.1007%2F978-3-642-39019-7.pdf

regards

Dear @Şahimerdan Türkölmez

Thank you to you'r answer, those are like normal hairy root. But after changing the color, they are soft and destroy gradually.

Dear Nima

Thanks.

Bacterial factors can cause such problems