Integrated overview of olive reproductive bud dormancy and biennial bearing
Observations of olive bud initiation, growth and dormancy and new experiments with olive shoot explants have broadened our understanding of bud dormancy in potentially reproductive buds, the role of chilling, and biennial bearing. Shoot apex and leaf removal at different times and the effect of temperature on reproductive budburst were tested on shoots and shoot explants sampled from ON (high cropping) and OFF (low cropping) trees. Overall, the results indicate and/or confirm that: 1) there is a long period of dormancy onset in the axillary buds during vegetative shoot growth; 2) floral transition of buds from undefined to reproductive is inhibited by the presence of fruits; 3) dormancy becomes generalized in all axillary buds (winter rest) with autumn low temperatures; 4) leaves play a major role in triggering and maintaining dormancy in axillary buds; 5) chilling accumulation releases potential reproductive buds from dormancy; 6) reproductive bud development is morphologically initiated after winter rest; and 7) similar dormancy-release dynamics occur in potential reproductive buds on explants from shoots sampled from ON and OFF trees and in shoots remaining on those trees. Regarding the significance of low temperatures, we hypothesize that chilling-imposed winter rest impedes the initiation of growth of potentially reproductive buds in winter, promoting synchronized bud burst and standardizing the timing of inflorescence and flower development in buds formed over an extended time the previous year.
Rallo, L., Ramos, A., Rubio-Valdés, G. and Rapoport, H.F. (2018). Integrated overview of olive reproductive bud dormancy and biennial bearing. Acta Hortic. 1199, 97-102
dormancy onset, dormancy release, explants method, floral transition, Olea europaea L., paradormancy, winter rest