Deficit Irrigation as a Strategy in Irrigating Citrus Tree Plantings Under Water Scarcity Conditions

Abstract

AbstractCitrus is a major fruit crop produced (on 120,000 ha) and exported from Morocco, consuming 10,000 m3 of irrigation water per ha annually. Currently, irrigation water is becoming very scarce, and drip irrigation is the water supply system used in plantings because of its high water use efficiency and productivity. Recent research indicates that additional water saving and higher efficiency can be obtained via adoption of deficit irrigation strategies such as sustained deficit irrigation (SDI), regulated deficit irrigation (RDI), and partial root zone drying (PRD). These irrigation strategies were applied on citrus clementine (Citrus reticulata) plantings for two years at different tree phonological stages. Four cultivars were included: ‘Sidi Aissa’ and ‘Orogrande’ in 2017 and ‘Bruno’, and ‘Esbal’ in 2018. Results indicate that water saving was in the range of 6 to 31% compared to control fully irrigated plantings depending on the strategy. However, deficit irrigation reduced fruit size, yield, and vegetative growth but enhanced fruit quality with PRD treatments having more significant effect than SDI or RDI. The negative effect of water deficit stress was more pronounced on total yield than on fruit size, particularly in high vapor pressure deficit (VPD) years and for PRD strategy. Under years of mild VPD, this negative effect was significant but equal for fruit size and yield. Water productivity decreased with water amounts applied. However, since clementine fruit is destined to fresh market which demands fruit of large size, it can be safe to recommend use of RDI and avoid PRD under semi-arid conditions.KeywordsClementine mandarinDeficit irrigationPartial root zone dryingYieldFruit qualityWater savingWater productivity