Bud Drop of Sweet Pea (Lathyrus odoratus L.) as Affected by Ethylene

Abstract

A spray application of ethrel (ethephon, 2-chloroethylphosphonic acid) at 100 ppm to sweet pea plants induced large numbers of developing flower buds to abscise, whereas that at 25 ppm caused a few buds to abscise. When 0.4 mM silverthiosulfate (STS), an inhibitor of ethylene action, was sprayed immediately following the ethrel application, bud abscission was strongly inhibited.
The rate of ethylene evolution by the buds resulting from the 25 ppm ethrel treatment was low; at 100 ppm, a rapid rate of ethylene evolution was observed 3 to 4 days after the treatment. When 0.8 mM STS was applied concurrently with ethrel or 48 hr later, the subsequent rate of ethylene production was strongly suppressed.
From these results, we consider the induction of autocatalytic ethylene synthesis by ethreltreated sweet pea plants to be responsible for flower bud abscission.