Olive is one of the most important crops in arid and semi-arid areas. Prolonged water stress in these regions may adversely affect olive plant quality and productivity of fruits. To address the mitigation of unfavorable consequences of drought stress, the use of water-retaining mulches can be a beneficial solution. To achieve this purpose, the responses of olive cultivar ‘Zard’ as affected by mulch amendment [olive pomace, animal manure, nylon film, superabsorbent and control (without mulch)] and irrigation level (100 %ET as a normal condition and both 75 %ET and 50 %ET to simulate moderate and severe drought stress, respectively) were assayed. As a result, drought stress significantly retarded growth parameters, but fruit dry matter accumulation indicated the opposite behavior. Chlorophyll a + b, calcium, potassium, relative water content, and fruit yield also represented a declining tendency in severity-dependent behavior and conversely, sodium, antioxidant enzyme activity (catalase and peroxidase), oxidative markers, pulp/pit ratio, osmolytes (proline and total carbohydrates), and phenolic content increased in olive trees exposed to drought stress. Animal manure and especially olive pomace as organic mulches notably exhibited pragmatic influences on morpho-physiological as well as yield traits and improved pomological characteristics, regardless of tree water status. It was concluded that mulches used as water retaining agents, especially olive pomace and animal manure, can be effectively used to promote drought tolerance, growth and yield of olive trees growing in water deficit conditions. In general, using natural mulches is a good way to overcome drought stress.
