Changes of Volatiles from Drought Stressed Ashleaf Maple(Acer negundo) in July and August

The volatile organic compounds emitted from three-year-old seedlings of ashleaf maple (Acer negundo L.) under drought stress conditions were examined during July and August of 1999 It was found that in July, ten volatile compounds from ashleaf maple (Acer negundo L.), including butyl alcohol, pentyl alcohol, E-2-hexen-1-al, Z-3-hexen-1-ol, pentanal, pentanoic acid, hexanal, hexanoic acid, acetophenone and longifolene, were affected significantly when the trees were subjected to water stress. The amount of all volatile compounds emitted, except for longifolene, increased when the trees were in drought conditions. When the trees were re-watered the amount of acetophenone increased, but all other volatiles decreased. However, no correlation was found between the ten volatile compounds above and water stress in August. A number of other volatiles from the trees subjected to water stress were found to undergo change greatly, including cyclohexyl isothiocyanate, cinnanitrile, heptanal, longifolene, phenol, naphthalene and benzothiazole. The emission rate of all seven volatile compounds decreased under drought stress, but increased after the ashleaf maples (Acer negundo L.)were re-watered, except for longifolene.