EMISSION OF WATER-STRESS ETHYLENE IN WHEAT (TRITICUM-AESTIVUM L) EARS- EFFECTS OF REWATERING

In this work it has been found that ethylene production increased only slightly under conditions of a moderate or severe water stress. Howev er, the rehydration of the plants at full turgor after desiccation cau sed a high emission of ethylene. The desiccation would not irreversibl y inactivate the enzymes of the ethylene pathway, since rehydration ma de the synthesis recommence almost immediately. Water deficit also inc reased 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 thi nk that both chemical species are involved in the phenomenon of the ac celeration of the grain maturity before the plant collapses.