Improving the quality of various Grevillea cultivars grown in Israel by postharvest treatments

Grevillea (Grevillea spp.) is a relatively new cut flower crop of the Proteaceae family that is rapidly gaining increased importance to the Israeli growers. The commercial industry of Grevillea in Israel (70 ha) is based on various sub-tropical species and cultivars originated in Australia, with G. 'Spiderman' being the main cultivar (70% of the Grevillea export), due to its relatively long vase life. Vase life of Grevillea cut flowers is limited particularly due to rapid senescence and associated wilting, abscission, and colour fading of the inflorescences. Previous reports on treatments with sugars, growth regulators, ethylene inhibitors, and substances that may delay stem end blockage showed limited efficacy in extending Grevillea vase life. In this study further postharvest physiological characteristics of cultivars are reported, including ethylene production and respiration rates at different flower developmental stages and during vase life, sensitivity to ethylene, effects of inhibitors of thylene biosynthesis (aminoethoxyvinylglycine - AVG) and activity (silver thiosulfate - STS or 1-methylecyclopropene - 1-MCP), effects of pulsing with different preservatives and sucrose, effect of provision of sucrose in the vase solution, and effects of cytokinins (benzyladenine - BA and thidiazuron - TDZ) applied by pulsing or dipping. Our results show that the various Grevillea cultivars varied in their ethylene production and respiration patterns, sensitivity to ethylene, and responses to preservatives and ethylene inhibitors. However, all the examined Grevillea cultivars positively reacted to provision of sucrose in the vase solution and to dipping the inflorescences in cytokinin, with TDZ being more effective than BA. A combined treatment of dipping the inflorescences in TDZ, STS and Rovral enabled sea shipment of G. 'Spiderman' cut flowers with extended vase life.