Scientific Study

Conventional planting and management systems for almond (Prunus dulcis (Mill.) D. A. Webb) orchards involve trees trained from an early age to produce multiple large scaffold branches, which in mature orchards form closed light inefficient canopies. Treatments included a single round of selective limb removal pruning applied at the start of the research to remove the large scaffold branches that cause shading between trees. Treatments were applied to two groups of 5-year-old ‘Nonpareil’ trees on ‘Nemaguard’ rootstock planted at 6 × 3 m spacing (556 trees/ha) in the Riverland region of South Australia. Each year, reflective ground covers were installed beneath one group of pruned trees to reflect light back into the lower canopy zones. A third group of control trees were left unpruned without reflective ground covers. Yield, kernel quality and light transmission within canopy zones were monitored for 3 subsequent years. Results demonstrated that in control trees, less than 10% of incoming sunlight was transmitted to lower canopy zones. This was insufficient to ensure cropping in these zones. Although pruning selected limbs and using reflective ground covers increased the amount of light and thus yields in the lower canopy zones, this was not sufficient to increase total tree yield nor improve kernel quality. Furthermore, the fruit in these lower zones were not ready for harvest until 2–3 weeks after the main crop. https://doi.org/10.1016/j.scienta.2021.110508