THE ROLE OF GIBBERELLIC-ACID IN THE SENESCENCE OF CARNATION FLOWERS

Gibberellic acid when applied to the stems of cut carnations at a concentration of 10(-4) M delayed their senescence. This hormone delayed the onset and reduced the climacteric peak of ethylene production. GA3 also affected the respiratory climacteric. Pretreatment with 10(-4) M GA3 for 48 h reduced the sensitivity of carnation flowers to both ethrel and 2,4-D. Normal inrolling of the petals associated with senescence was replaced by petal shrivelling when flowers were treated with GA3. Petal inrolling was restored when 2,4-D or ethrel were applied to the GA3-pretreated flowers. A possible natural role for gibberellins in carnation flower senescence is discussed.