This phenomenon refers to the tendency of olive trees to alternate years of high fruitfulness with years of low or no production. The molecular mechanisms influencing this alternation have been revealed by sequencing transcripts in leaves and shoots during the years of loading and unloading.
Obviously, the growth of the shoots in the year before fruiting has a significant influence on the rotation of production. Three phases make up fruiting: induction, initiation and differentiation. Each phase is essential for successful production, with the time of flowering being crucial, as it coincides with the completion of the hardening of the kernel of the olive fruit.
Vigorous vegetative growth of one-year-old shoots during spring, followed by a summer pruning strategy, appears to play a key role in enhancing flower bud induction and shoot differentiation. A high fruit load may negatively affect the elongation of mixed one-year-old shoots, leading to a reduction in the production of new reproductive buds for the following year. However, it is worth noting if fruit removal during a year of heavy fruiting is effective in inducing flowering only if done one to a few months before the start of the induction period. It is therefore obvious that the phenomenon of mis-harvesting becomes more pronounced in plants that are harvested late or not harvested at all.
After induction, the initiation phase does not show morphological changes in the shoot, but is highly dependent on the hours of chilling (< 12.5 °C) in order to enter the dormancy phase. The last phase, differentiation, starts with the formation of the inflorescence in the bud and is the only phase that brings about visible morphological changes. Soil nutrient status and water availability are also factors that influence the development of new shoots, and the optimal period for these processes is often not clear.
Therefore, the growth pattern of the vegetative part of the mixed shoots of one year (year n) and the flowering of the following year (n + 1) under agronomic management conditions was studied.
The results of the study revealed that the number of inflorescences on mixed one-year-old shoots in the following year is influenced by the level of vegetative growth. In particular, early shoots showed more inflorescences per bud. Nodes developed in June and July yielded the most inflorescences per bud, in contrast to those developed in spring or late summer.
Overall, therefore, to effectively manage interception and ensure consistent production each year, early harvesting of olives, ideally before December, and proper management of vegetative growth during spring and early summer are required, the study finds.
By Ελαίας Καρπός