OLIVE ROOT GROWTH WITH DIFFERENT ORGANIC MATTERS

The addition of organic residues from plant and/or animal origin in organic and biodynamic farming represents the basic practice to enhance overall soil fertility, thereby greatly influencing root development. The objective of our experimental work was to investigate the response of plant roots, in terms of growth and distribution, to the presence of different kinds of organic matter. Self-rooted plants of Olea europaea L. (‘Tortiglione’) were grown for 90 days in Plexiglas bench rhizotrons of 30 x 80 x 2 cm. The four treatments were: i) control (basic peat-vermiculite-sand substrate); ii) olive husks (O) (control + 10% in volume of dry olive husks); iii) hay (H) (control + 10% in volume of dry mixed grass hay); iv) olive husks and hay (OH) [control + husks (2%) and dry mixed grass hay (10%)]. After one year, the H treatment showed the highest root growth, number of roots and root dry weight, whereas the O treatment showed reduced root development, equivalent to the control, which produced the lowest root response. The OH treatment showed an intermediate degree of root growth between H and control. Mean root length and relative root growth rate were not influenced by the treatments. It can be argued that the controversial effect of olive husk (likely source of nutrients and cause of toxicity) resulted neutral to olive plant growth because of root plasticity. The hay amendment played a mitigatory role, likely reducing the phytotoxicity caused by the olive husks.