Water-retention additives' effects on plant water status and some physiological parameters of two olive cultivars under reduced irrigation regimes

In arid and semi-arid zones of world, the majority of annual rainfall or irrigation water is lost due to high evaporation from the soil. The amount of available water in soil can be increased by surface mulching. However, the effect varies with soils, climate and kind of mulch material used. Some physiological and biochemical parameters of two olive cultivars ('Konservolea' and 'Manzanilla') as affected by different water-retention additives (organic, chemical and mineral mulches and hydrogel) and two amounts of irrigation water were studied in pot experiments during 2013. Water stress affects plant water relations and photosynthesis and caused oxidative stress in olive. Our results confirmed that water-retention additives partly mitigated the adverse effects of water stress on olive restoring most of the measured parameters similar to those of control unstressed plants. Mulching treatment enhanced antioxidative defenses and reduced water deficit-induced oxidative damage in olive compared to zero mulching treatment. The results indicated that deoiled olive pomace mulch and pistachio shell mulch-as new mulch materials-proved to be very effective for soil water conservation under arid conditions. It can be concluded that water management through mulch application can strongly influence the cultivar response to water deficit.