Agriculture & Food, Volume 8, 2020

Abstract: Two-year-old, self-rooted olive plants (Olea europaea L. cv. Koroneiki) were tested. The potted plants were grown in two types of soil: acidic (AC) and alkaline (AL) and they were fertilized with a liquid organic product containing fulvic and humic acids, following four different schedules: * Treatments AC1 & AL1: No application of organic product; * Treatments AC2 & AL2: Application of organic product (1.66 ml/kg soil) at the petal fall stage; * Treatments AC3 & AL3: Application of organic product (1.66 ml/kg soil) at the petal fall and 20 days after the petal fall stage; * Treatments AC4 & AL4: Application of organic product (1.66 ml/kg soil) at the petals fall, 20 and 40 days after the petal fall stage. In all the above treatments 0.42 g N/kg soil were applied as granular fertilizer (type 21-0-0; ammonium sulfate for acidic soil and 26-0-0; calcareous nitric ammonium for alkaline soil), at the beginning of the experiment. The results showed that AL4 treatments significantly amplified the vegetative vigor of olive plants (new shoot length), whereas the organic treatments in the acidic soil led to adverse results. Moreover, the experimental data showed that AL3 treatment resulted in a significant increase in the leaf concentration of chlorophyll a, b and carotenoids. Significant increase in leaf dry weight was also observed in AC4, AC3 and AL3 treatments, at the end of the experiment.