Breeding Cut Roses for Better Keeping Quality: First Steps

Water stress is one of the most common postharvest quality problems, resulting in shorter vase life of cut flowers. Since vase life is a key factor for the consumers’ satisfaction, breeding for better control of water loss is an important goal. In this study, we evaluated the stomatal responses to leaflet desiccation in a subset of a segregating tetraploid cut rose population (60 genotypes) grown at high relative air humidity (RH = 85%). Additionally, the vase life was determined in six contrasting genotypes in their stomatal responsiveness. The population screening revealed extreme differences among genotypes, i.e., the relative water content (RWC) after 4 h of leaflet desiccation ranged between 7 and 62% (20 and 51% the RWCs for the two parents). Genotypes with low stomatal responsiveness to desiccation had an average vase life of 8 days, and in two out of three genotypes the flower did not open. These effects are related to high postharvest water loss rates. On the other hand, genotypes with high stomatal responsiveness lasted longer (10-21 days), their flower reached the maximum opening stage, and they showed a lower postharvest water loss. It is concluded that there is a large variation in the stomatal hydrosensitivity, which increases the possibilities for breeding for cultivars with longer vase life (better control of water loss). The selection of genotypes with high stomatal responsiveness, after cultivation at high RH, considerably increases the degree of certainty that the cut flower will last a minimum length of time, and will have an unhampered flower opening.