In this work it has been found that ethylene production increased only slightly under conditions of a moderate or severe water stress. However, the rehydration of the plants at full turgor after desiccation caused a high emission of ethylene. The desiccation would not irreversibly inactivate the enzymes of the ethylene pathway, since rehydration made the synthesis recommence almost immediately. Water deficit also increased the free radical levels and the antioxidant scavengers, such as superoxide dismutase. Free radicals promote the conversion of 1-amino-cyclopropane-1-carboxylic acid to ethylene, then it is logical to think that both chemical species are involved in the phenomenon of the acceleration of the grain maturity before the plant collapses.