Prevention of floret abscission for Agapanthus praecox requires an adequate supply of carbohydrate to the developing florets

Vase solutions of 2.5 or 5% (w/v) sucrose markedly reduced the abscission of all open florets and buds on cut Agapanthus praecox sterns. Pulsing cut steins with these solutions was not as effective as continuous treatments. Pulse treatments with 10% sucrose for 4-24 h were relatively ineffective at reducing floret and bud abscission but longer pulses of 48 h reduced abscission. The relative ineffectiveness of sucrose pulse treatments appeared to be due to the low water uptake of the steins (1-3 ml/day). Reducing the number of florets and buds on an inflorescence reduced abscission of florets and buds, and increasing stein length from 25 cm to 50 cm decreased bud abscission. This reduction in abscission is possibly due to the increased availability of assimilates for the remaining buds and florets or reduced competition for assimilates. Exogenous ethylene treatments (9 mu l/L for up to 24 h) had no effect on abscission, although STS treatment (4 mM, 4 h) significantly reduced floret abscission when steins were held in vase solutions of sucrose. We conclude that postharvest floret abscission in A. praecox is influenced primarily by the availability of assimilates to the developing florets. (C) 2009 SAAB. Published by Elsevier B.V. All rights reserved.