Effects of root constriction on vegetative growth and yield efficiency in young trees of a low- and a high-vigor olive cultivar

Key messageRoot constriction (RC) by wire mesh reduced yield and growth in young olive trees of high- and low-vigor cultivars. Yield efficiency, although different between cultivars, was unaffected by RC.There is strong interest in intensifying olive cultivation. This requires small plants with high and constant production. In this study, the effects of root constriction (used as a dwarfing technique) on growth and yield efficiency of young olive trees were evaluated. Two cultivars with different vigor 'Arbequina' (low vigor) and 'Frantoio' (high vigor) planted in a super-high-density (SHD) olive grove were compared. At transplanting (2006), the tree roots were placed in a galvanized wire mesh container and buried with it. Tree growth, biomass of pruning material and productivity were then compared with a control treatment without wire mesh. By the end of the trial (2016), 'Frantoio' had much larger trunk cross-sectional area (TCSA) than 'Arbequina', and for both cultivars, the plants with the wire mesh had lower TCSA than the control: 47% and 36% less in 'Arbequina' and 'Frantoio', respectively. Pruning biomass was almost none in 'Arbequina' and much higher in 'Frantoio' and for both cultivars, higher in the control. Cumulative yield was similar between cultivars, but about half in the wire mesh treatments. Yield efficiency was higher in Arbequina, but similar between treatments, within cultivars. Total tree growth (i.e., TCSA increment over the experiment) across all treatment combinations (2 cultivars x 2 treatments) was inversely related to yield efficiency. The results show that root constriction allows reducing tree growth without changing yield efficiency. This could potentially allow maintaining a fruiting canopy for longer in SHD systems, thus improving the suitability of traditional vigorous cultivars to this new system.