Effect of root pruning on vegetative-reproductive balance of young olive trees

Root pruning represents a potential tool to control tree vegetative growth and early fruit production in high-density olive orchards. Pruning intervention should be specifically calibrated according to species, age and planting density in order to produce persisting results on tree growth without compromising plant health and yield. A 13-months experiment was conducted on a 2-year-old high-density olive orchard testing the effect of root pruning on plant vegetative and reproductive performances, root and shoot growth and plant physiology. A preliminary root topographic study indicated that over the 70% of the total root system was located in the upper 0.3 m layer on a clay soil and in presence of fertigation. The root pruning was performed at 0.3 m distance from the trunk and at 0.3 m depth. The root pruning was effective in reducing shoot growth, increasing production and persistently reducing root density in the soil. Leaf gas exchange rate recovered within 11 days after root pruning thus ascribing the effects on plant growth to a transfer on metabolites allocation pattern rather than to a reduction of plant activity.