ROUSSEAUX Maria Cecilia
congresos y reuniones científicas
Effect of time of pruning on new shoot development in olive trees.
Simposio; VIIth International Symposium on Olive Growing; 2012
New growth generated in response to pruning plays a key role in the interactions that determine the balance between vegetative and reproductive growth in olive. In order to understand the factors that influence post-pruning vegetative growth, we evaluated the response to two different timings of the pruning operation on shoot demography. Pruning treatments were applied at the end of winter (August 2009, R40A) or in late spring (December 2009, R40D) to five year old Arbequina trees growing in La Rioja with warm winter and high levels of fertigation. Approximately 0.75 m of canopy was removed on both E and W sides of the tree, imitating disk mechanical pruning. This removed 40% of the original canopy volume. Pruned trees were compared to non-pruned trees (R0). The number of new 1st and 2nd order shoots, and first and second watersprouts was quantified on 12 headed branches per tree (n=6). The total number of branches removed per tree at each pruning was around 350 (p <0.05). Around 90% of removed branches were 1 and 2 years old, and the other 10% were 3 or 4 years old. The number of new 1st order shoots was ca. 1.7 shoots per branch in all treatments (R40A, R40D, R0). However, R40A and R40D shoots were twice as long compared to R0 that were only 5 cm long. On the other hand, the number of 2nd order shoots per 1st order shoot was 2.1, 1.1 and 0.2 for R40A, R40D, and R0 respectively, with no difference in length between treatments. Lastly, R40A had twice as many watersprouts (0.7 vs 0.36) of a longer length (50 vs 25 cm) than R40D and R0. Moreover, those R40A watersprouts had 3 times more 2nd order shoots (15 vs 4.5) of longer length (9 vs 4.5 cm) than the R40D and R0 ones. We conclude that delaying pruning from winter to end of spring generated a less vigorous response that was mainly explain by a reduced number of watersprouts of smaller size, similar to those of the the unpruned trees.