Sustainable Olive Culture under Climate Change: The Potential of Biostimulants

Climatic extreme events, like droughts, heatwaves, and floods are becoming recurrent and represent a threat to agriculture, lowering plant growth and productivity. The Mediterranean region is a climate-change hotspot, where traditional agricultural systems, like olive groves, are particularly challenged. Both the traditional and intensive systems of olive culture coexist in the Mediterranean. Both systems differ in their demands for water and agrochemicals, but nowadays, the global inputs of agrochemicals and irrigation have increased to achieve high productivity and profitability. Finding sustainable alternatives to maintain high productivity under the ongoing climate change is urgent to meet the EU-Farm to Fork strategy and climate neutrality. Candidate eco-friendly alternatives include biostimulants. These are substances or microorganisms, that activate signaling cascades and metabolic processes, increasing plant yield, quality, and tolerance to stressors. These benefits include a better growth, nutritional status and water availability, leading to a decreased demand for irrigation and agrochemicals. In this review, we aim to present different types of biostimulants (e.g., seaweed, protein hydrolysates, humic substances, microorganisms and nanomaterials), their mode of action and benefits in agriculture. We also explore the current state-of-the-art regarding the use of biostimulants in olive culture, and their potential benefits to increase tolerance to (a)biotic challenges.