Variation in ethylene-induced postharvest flower abscission responses among Chamelaucium Desf. (Myrtaceae) genotypes

Postharvest flower abscission is an ethylene-mediated process that can reduce the marketability of cut Chamelaucium Desf. (Myrtaceae) flowers. The sensitivity of 51 Chamelaucium cut flower genotypes to ethylene was evaluated. Sensitivity varied among genotypes both between and within different species and crosses. C. uncinatum × C. micranthum cv. ‘Sweet Georgia’ and C. uncinatum cvv. ‘Early Nir’, ‘Paddy’s Late’, ‘Purple Pride’, ‘CWA Pink’ and ‘Early Hard’ flowers were highly sensitive to ethylene. These genotypes shed 10 % of their flowers in response to a 12 h treatment with < 0.01 μl l ethylene at 20 °C. In contrast, C. megalopetalum ‘Winter White’ and ‘Iceberg’ flowers were insensitive to ethylene even at 100 μl l for 12 h at 20 °C. Sensitivity to ethylene varied between harvests during the flowering season and for the same genotypes harvested from different farms. Sensitivity of C. uncinatum cv. ‘Purple Pride’ flowers to treatment with 1 μl l ethylene also decreased towards the end of vase life in association with slight dehydration. Variation in ethylene-induced abscission responses highlights the need to screen flowers from multiple harvests and varying growing conditions when assessing ethylene sensitivity. Screening genotypes for ethylene sensitivity should facilitate selection of Chamelaucium species with greater durability for export handling.