Which plant hormone hastens early rooting in cuttings during vegetative propagation?

Formation of auxin is checked by

Dr. $F$. Went removed the coleoptile tips and placed them in agar for one hour. The agar block then caused curvature in decapitated coleoptiles. What does this experiment demonstrate?

$IAA$ and $IBA$ synthesis requires:

Plants which are deficient in zinc will show reduction in the biosynthesis of

Which of the following hormones is synthetic?