DORMANCY AND ALTERNATE BEARING IN OLIVE
Three aspects of the reproductive biology of the olive are presented: a) the biennial cycle; b) the influence of cropping in the sequential reproductive and vegetative processes and c) the influence of temperature on bud dormancy. The timing of the sequential reproductive and vegetative processes is critical to understand the biennial bearing habit of the olive. A calendar of these processes for Córdoba (38N, 5W), taken into account the new concept of the role of chilling in this species, is presented and discussed. A quantitative study to relate cropping to different indexes of the sequential reproductive and vegetative processes indicates that although the inhibition of floral induction by seeded developing fruits is the major factor in the biennial bearing habit, the succesive reproductive and vegetative processes try to compensate for the unbalance brought about by differential floral induction. The influence of temperature during the period of endodormancy on the subsequent growth of axillary buds at favorable growing temperatures showed that: a) there was a period of endodormancy in which natural chilling was equal or more efficient than constant temperatures to release floral buds from dormancy; b) average 13,8° C was the most efficient constant temperature to release floral buds from endodormancy; c) there was a period of release of endodormancy in which the effect of constant temperature in the range 5–15° C linearly increased the subsequent growth of axillary buds in the greenhouse; d) greenhouse (9–22° C) or growth chamber (21–23 ° C) temperatures retarded the growth of the axillary buds during this period compared to the above constant temperatures, and e) the growth of axillary buds at the period of ecodormancy was impeded in the range 5–10° C whereas it was increased with temperatures above 10° C. These results support previous data concerning the role of winter chilling in releasing olive floral buds from dormancy.
Rallo, L., Torreño, P., Vargas, A. and Alvarado, J. (1994). DORMANCY AND ALTERNATE BEARING IN OLIVE. Acta Hortic. 356, 127-136