Auxin and cytokinin are two plant hormones that work together to boost root and branch development. The apical shoots produce auxin, which is then delivered to the roots via an intracellular pathway to boost root development. Meanwhile, the roots produce cytokinin, which travels back up to the shoots via the same intracellular pathway, where it promotes branch development and leaf growth. That means, if you cut off the apical shoots, the roots will produce more cytokinin, which will make the Plant Bushier.