A series of field and greenhouse experiments was conducted with three cultivars of bell pepper (Capsicum annuum L.) to determine the hormonal basis for flower bud and flower abscission as induced by low light intensity (LLI). Imposition of 80% shade for 6 days increased abscission of reproductive structures by 38% and resulted in an increase in bud ethylene production. Concomitantly, bud reducing sugars and sucrose decreased and these were negatively correlated with ethylene levels and those of its precursor, ACC. Infusion of ACC into the pedicel resulted in flower bud abscission within 48 hr. The results indicate that ethylene is the primary causal agent of pepper flower bud abscission. Production of auxin by the bud plays a role in prevention of abscission. The abscission of disbudded pedicels was prevented by infusion of NAA. Although the three cultivars had similar responses to ACC, they differed in the amount of abscission under stress, bud sugar levels, and the time of onset of ACC and ethylene production. Chemical names used: 1-aminocyclopropane-1-carboxylic acid (ACC); α-napthaleneacetic acid (NAA); (2-chloro-ethyl)phosphonic acid (ethephon).
Received for publication 14 Nov. 1988. Vegetable Crops Paper no. 871. The partial support of this research by Agway, Inc., Petoseed Inc., and Federal Hatch Act funds (Project no. NYC-161425, USDA) is gratefully acknowledged. Seeds of ‘Ace’, ‘Lady Bell’, and ‘Shamrock’ peppers were kindly donated by Takii, Harris-Moran, and Asgrow Seed companies, respectively. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.