In-vivo and in-vitro experiments were carried out to evaluate the effect of biostimulants on olive growth. In the in-vivo experiment, two biostimulants based on peptides/amino acids were used on young potted olive trees. The control trees received the same amount of nitrogen as contained in the biostimulant. The stem diameter, tree height and biomass (at the end of the experiment) and photosynthetic activity of the leaves were determined. There was no significant difference between the trees treated with the biostimulants and the control ones. Further studies would be useful to test other concentrations and application times. In the in-vitro experiment a biostimulant based on protein hydrolysates was applied by soaking the explants in a solution containing different concentrations: 1.5, 3.0 and 6.0 g/L.
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The effects of treatments were evaluated by determining the number, length and weight of proliferated shoots and their multiplication rate. The most effective concentration of the biostimulant was 3.0 g/L, which also gave better results than the control. The control solution had received the same amount of nitrogen as the biostimulant, demonstrating that the effects were due to the biostimulant and not to the nitrogen.
