Foliar spray of silver thiosulphate (STS) reduced abscission of flower buds, flowers and fruitlets in pepper plants, grown for four days under heat-stress conditions. Likewise, STS inhibited the abscission of flowers from explants (fixed on agar medium) under conditions of heat stress. Concomitantly, STS increased ethylene production by the flower explants. Ethephon, applied to STS-treated flowers was less effective in inducing flower abscission than when given to flowers which had not been treated with STS. The fruits which developed from the STS-treated plants were deformed. Similar fruit deformities were observed in ethephon, 2,3,5,-triiodo-benzoic acid (TIBA) and naphthalene acetic acid (NAA) treated plants; Ethephon, STS and TIBA inhibited the basipetal transport of [H-3]-NAA in flower-bud peduncles. We suggest that STS reduced flower abscission by blocking ethylene action, and causes deformation of the developing ovary and fruit by inhibiting the export of auxin from the flower buds.
