Exogenously supplied sucrose improves the postharvest quality of Grevillea ‘Sylvia’ inflorescences

Abstract

Summary. Short vase life (e.g. 3–7 days) is a problem with inflorescences of Grevillea used as cut flowers and may be associated with depletion of respirable substrates. A series of 4 experiments addressing this hypothesis were conducted with Grevillea hybrid ‘Sylvia’ inflorescences. In experiment 1, the effect of leaf retention on inflorescence stems and a range of sucrose concentrations (0–6% w/v) in vase solutions was investigated. In experiment 2, the relationship between inflorescence maturity (4 stages) and sucrose supply was studied. In experiment 3, the effect of sucrose concentration as a short period pulse and pulsing duration was determined. In experiment 4, simulated handling and transport was undertaken to gauge the practical usefulness of sucrose pulsing to the cut flower industry. These vase life experiments were conducted in a constant temperature room (22 ± 2°C) at 50–80% relative humidity. All vase solutions contained 10 mg chlorine/L to suppress microbial growth.

Three percent sucrose (w/v) was found in experiment 1 to be the best vase solution. This treatment gave a mean vase life of 10.1 ± 0.2 days, which was 44% longer than the control (no sucrose) treatment. Inflorescences picked at the ‘early looping’ stage and provided with 3% (w/v) sucrose had the best overall vase life (12.0 ± 0 days) and visual appeal in experiment 2. Sucrose pulsing (10% w/v) for 6–24 h extended vase life by at least 1 day. The presence of leaves shortened the vase life of both sucrose-pulsed and non-pulsed inflorescences by about 1 day in experiment 3. Storage for 5 days at 5°C as handling/transport simulation in experiment 4 did not shorten the vase life of Grevillea ‘Sylvia’ inflorescences. Sucrose pulsing (10% w/v) before simulated handling/transport did not result in a significant increase in the vase life of Grevillea ‘Sylvia’ inflorescences, and is therefore not recommended. To achieve the best floral display, Grevillea ‘Sylvia’ inflorescences should be picked at the ‘early looping’ stage of maturity and then placed in a vase solution containing 3% (w/v) sucrose.