Assessing the effect of cork oak fertigation on crown and root structure using electro-magnetic tracking system

Cork oak (Quercus suber L.) mortality events have spurred scientific research into new afforestation techniques, particularly the use of fertigation to accelerate tree growth and hasten the onset of the productive phase when cork stripping becomes feasible. This study examines the effects of fertigation on the development of root and aerial systems, with the objective of determining if fertigation can eventually be discontinued without compromising tree vitality. Six seven-year-old trees growing under natural conditions were selected for analysis, grouped into three pairs, each with similar crown sizes but subjected to different watering regimes – fertigation and rainfed. These trees were analyzed using the Fastrak Polhemus method, focusing on seven parameters: volume, area, length, root diameter, root-to-shoot ratio, shape area, and circularity. Analyses were conducted both graphically and using partial correlation statistics. The findings indicate that tree size accounted for the most significant differences in these parameters. Conversely, fertigation was associated with an increase in trunk volume, while rainfed conditions led to larger root diameters, likely as an adaptation to drought. The most pronounced differences were observed in smaller trees, where both groups exhibited unbalanced but opposing root-to-shoot ratios: rainfed trees invested more in root development, while fertigation trees prioritized aerial growth. The impact of irrigation on the development of below-ground and above-ground biomass in arid regions is crucial in the context of ongoing climate change, which will further intensify drought during the growing seasons.