"Inflorescences treated with brassinolide alone had no effect on ethylene production. However, when brassinolide was used in combination with IAA there was a dramatic increase in ethylene production above the induction promoted by IAA alone. " 104 Why this makes sense - IAA causes increases in respiration as it is an indicator of oxygen surplus. Once ethylene is produced, it starts pushing out nutrients. Adding BR is like adding fuel to the fire and leads to a climacteric export of all nutrients including oxygen thus leading to an even greater evolution of ethylene.