Abstract:

To screen suitable parents for Dendrobium hybrid breeding and clarify the interspecific cross-compatibility as well as parental role bias, 20 Dendrobium germplasm resources preserved by the Fuzhou Institute of Agricultural Sciences were used as materials, and 93 interspecific cross combinations were designed. A total of 335 pollination experiments were completed using standardized artificial pollination technology. The number of cross combinations, number of fruit-setting combinations, total number of pollinated flowers, and total number of fruit-setting fruits were counted; the combination fruit-setting rate and pollination fruit-setting rate were calculated. The hybrid fruit-setting ability and parental role bias of each variety were comprehensively evaluated based on the above two indicators. The results showed that: (1) there were significant differences in hybrid fruit-setting ability among different germplasms. Among the 93 combinations, 41 cross combinations achieved successful fruit-setting, producing 97 hybrid fruits. Specifically, Dendrobium Oriental Magic‘Carmen’and Dendrobium ‘CT Fairy Kiss’ performed optimally when they were used as female parents (combination fruit-setting rate: 50.00%-54.55%, pollination fruit-setting rate: 53.57%-55.56%), and Dendrobium ‘Red Star’, Dendrobium ‘Little Blueberry’, and Dendrobium ‘Sunny Red’ showed significant advantages when they were used as male parents (combination fruit-setting rate: 66.67%-75.00%, pollination fruit-setting rate: 52.00%-54.55%). (2) The parental role bias was obvious. Seven varieties exhibited a single parental role bias: Dendrobium ‘Rainbow Dance Akane’, Dendrobium Oriental Magic‘Carmen’, and Dendrobium ‘Sweet’ were only suitable for female parents (pollination fruit-setting rate ≤26.92% when used as male parents); Dendrobium ‘Red Star’, Dendrobium ‘Splash Ink Pink Fantasy’, Dendrobium ‘Little Blueberry’, and Dendrobium ‘Sunny Red’were only suitable for male parents (pollination fruit-setting rate ≤7.14% when used as female parents). Among the 25 reciprocal cross combinations, 11 combinations could set fruit bidirectionally, 8 combinations could only set fruit unidirectionally, and 6 combinations failed to set fruit in both reciprocal crosses. (3) The core evaluation indicators were clear. The combination fruit-setting rate and pollination fruit-setting rate could synergistically characterize the hybrid fruit-setting ability, and their combination enabled more accurate screening of suitable parents. This study confirms that there are significant differences in interspecific cross-compatibility among ornamental Dendrobium species. The screened excellent parents and the revealed parental role bias provide a scientific basis for parent selection in Dendrobium hybrid breeding, which can effectively improve breeding efficiency.

Key words: Dendrobium, fruit-setting ability, hybridization, evaluation, fruit set rate, one-way fruit set, parental bias