Because of these low concentrations, it has been very difficult to study plant hormones, and only since the late 1970s have scientists been able to start piecing together their effects and relationships to plant physiology.
Debido a estas baixas concentracións, foi moi difícil estudar as hormonas vexetais e só desde finais da década de 1970 se empezou a relacionar debidamente os seus efectos e relacións coa fisioloxía das plantas.