A bio-based strategy for sustainable olive performance under water deficit conditions

Abstract

Olea europaea L., olive tree, has a very important role in the economy of the Mediterranean region, where 93 % of the world's olive oil is produced. This species is well adapted to the environmental conditions of this area, but the increase in the frequency of extreme climatic events, due to climate change, is affecting the yield and quality of olive products. The use of eco-friendly solutions, like plant-beneficial microorganisms, can be a sustainable agronomic tool to improve plant tolerance to stress and boost agricultural production. We aim to unravel the effects of the pre-treatment of olive plants with the bacterium Pseudomonas reactans Ph3R3 on drought tolerance. Young potted olive plants were treated with a solution of P. reactans (soil inoculation) or with distilled water, and then exposed to two watering conditions (well-watered or water deficit). Plant water status, photosynthesis, pigments, carbohydrates, oxidative stress biomarkers, and total antioxidant capacity were evaluated 61 and 191 days after the beginning of the watering treatments. The pre-treatment with P. reactans improved leaf dry biomass production, and soil C and N availability. Moreover, under drought conditions, P. reactans increased leaf water availability, N levels, and the intercellular CO2, leading to improved net CO2 assimilation rate and carbohydrates production. Also, P. reactans activated stress protective strategies (total antioxidant capacity) that helped to control oxidative stress. These data demonstrated that the benefits triggered by P. reactans pre-treatment promoted olive performance and tolerance to drought and could be a promising strategy to improve olive culture sustainability.