Impact of water stress on reproductive development in sweet pepper (Capsicum annuum L.) IV. Inhibition of CEPA-induced ethylene production by silver thiosulphate

H.Z. Jaafar, C.R. Black, J.G. Atherton and J.A. Roberts

Abstract

A glasshouse pot experiment was carried out to further establish that increased water stress-induced endogenous ethylene production has a major role in mediating the induction of flower abscission. The work involved the use of silver thiosulphate (STS) to arrest ethylene-induced abscission. Since ethylenegenerating substance, 2-chloroethylphosphonic acid (CEPA), mimicked the effects of increased water stress-induced flower abscission and increased ethylene evolution preceding abscission, pre-treating flower buds with STS prior to CEPA application should provide protection against CEPA-induced flower abscission.  Administering STS at 1.0 mM one day prior to CEPA application was markedly effective in preventing flower abscission in CEPA treated plants at both concentrations of 50 and 100 mg/litre. The STS treatment also demonstrated a persistent efficacy by retaining all flowers from the 100 mg/litre CEPA treatment even after 40 days of treatment with STS. During the same period, plants sprayed with CEPA and not protected with STS exhibited a marked increase in percentage abscission, which increased with time and with CEPA concentration. Plants treated with 100 mg/litre CEPA and not protected with STS exhibited higher percentage of flower abscission (83% vs 11%) within a shorter period of time (i.e. 3 days after STS treatment). Subsequently complete abscission occurred 2 days later. Plants sprayed with 50 mg/litre CEPA initially exhibited a lower percentage of flower abscission (11%). However, with time the plants ultimately experienced an increased abscission from 50% to 94%, which occurred within 5–7 days after STS application. The results provide strong evidence that ethylene mediate stress-induced abscission of flowers and buds in sweet pepper.

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