Ethylene is a potent plant hormone.
Ethylene levels in closed plant growth chambers at NASA-KSC routinely increase to 0.05 to 0.1 ppm. Reduced seed set and even complete sterility have been associated with elevated ethylene levels, but no controlled studies have been done to clearly implicate ethylene in the poor seed set. We examined ethylene levels from 1 to 20 ppm on Super-Dwarf wheat in replicate growth chambers and compared the effects to control chambers without ethylene. Plants grew well at even 20 ppm ethylene but plant height decreased as ethylene increased. There was no effect on the rate of development as indicated by the time of heading.