Slow-release fertilization and Trichoderma harzianum-based biostimulant for the nursery production of young olive trees (Olea Europaea L.)

Valorization of local olive cultivars is a key factor for the medium-term development strategy of the Italian olive agroindustry. This involves enhancements in both, cultural practices and nursery techniques. The aim of this research was the evaluation in nursery, on vegetative growth and root development of young olive plants, of two different treatments: substrate enrichment with Osmocote®, a slow-release fertilizer, and Trianum-P a Trichoderma harzianum based biostimulant applied as foliar spray. The trial was carried out on Rotondella and Salella, two autochthonous olive cultivars from the Campania region (southern Italy). Central axis height, number and length of lateral shoots, leaf number and trunk base diameter were monitored during the experiment. Eight months later, all plants were uprooted, and further parameters were measured: total leaf area, trunk cross sectional area (TCSA), fresh and dry weight of the leaves, shoots, trunk, roots, and total dry matter. The canopy/root ratio (C/R) was also determined. Overall, the Osmocote® treatment caused a significant increase in the vegetative growth parameters for both cultivars, with a more evident effect on the development of the canopy organs. The observation reported in the present work can represent a convenient piece of information particularly in relation to stress resilience in nursery production.