450e8c1c_Plant_Hormone_Theory__Effects
[Name] Ethylene (ETH) [Speculated Role] Deficiency of oxygen (and too much carbon dioxide?) [Effects] 
Inhibits root growth. Stimulates root hair growth maybe increasing the roots ability to directly absorb oxygen from gaps in the soil granules. Induces aerenchyma during flooding which are hollow tubes from the shoot to the rot through which oxygen can be obtained and maybe carbon dioxide expelled. Induces adventitious roots during flooding, maybe also to facilitate gas exchange because adventitious roots are exposed to the air. Stimulates shoot growth and the broadening of leaves all in an attempt to increase the intake of oxygen and the diffusion out of the plant at night of carbon dioxide? Stimulates the use of oxygen stores and the inhibition of processes that produce carbon dioxide? Causes the abscission of leaves. . . .This one is hard to explain. Maybe it causes the abscission of leaves that don't absorb oxygen or release carbon dioxide at night anymore. Induce cell senescence acting in concert with GA, strigolactones and ABA?
Plant Hormone Theory
Effects