Light Requirement for AgNO3 Inhibition of Ethrel-Induced Leaf Abscission from Cuttings of Vigna radiata

To obtain information regarding the antiethylene properties and binding site of Ag(+), studies were initiated to define conditions under which Ag(+) does or does not inhibit ethylene action. AgNO(3), applied as a leaf spray, inhibited 2-chloroethylphosphonic acid (Ethrel)-induced leaf abscission from green cuttings of Vigna radiata in white light but lost considerable activity in the dark. In the absence of Ethrel, AgNO(3) stimulated abscission in the dark. When cuttings were dark-aged for 24 hours prior to treatment with AgNO(3) and aged for an additional 24 hours in the dark after treatment, good inhibition of subsequent Ethrel-induced abscission was restored by returning the cuttings to light. However, when dark aging was preceded by far-red irradiation, considerably less inhibition of Ethrel-induced abscission was restored in the light. AgNO(3) was completely inactive on cuttings aged in the dark and treated with Ethrel in the dark. Light is required for the antiethylene activity of AgNO(3) with regard to leaf abscission of Vigna.