Contents lists available at ScienceDirect Agricultural Water Management journal homepage: www.elsevier.com/locate/agwat Physiological improvements of young olive tree (Olea europaea L. cv. Chetoui) under short term irrigation with treated wastewater Ameni Ben Hassena a, ⁎ , Mohamed Zouari b , Lina Trabelsi b , Wahid Khabou a , Nacim Zouari c,d, ⁎⁎ a Laboratory of Amelioration and Protection of Olive Genetic Resources, Olive Tree Institute of Sfax, University of Sfax, Sfax, Tunisia b Laboratory of Improvement of Olive Productivity and Fruit Trees, Olive Tree Institute of Sfax, University of Sfax, Sfax, Tunisia c Laboratory of Enzyme Engineering and Microbiology, Engineering National School of Sfax, University of Sfax, Sfax, Tunisia d High Institute of Applied Biology of Medenine, University of Gabes, Medenine, Tunisia ARTICLE INFO Keywords: Olea europaea Treated wastewater Nutrient uptake Photosynthesis Growth ABSTRACT The treated wastewater (TWW) reuse in crop irrigation is becoming a frequent practice in areas with limited water resources. This alternative water may be considered as nutrients source that can fill the water deficit. However, TWW contains high salts concentration and may negatively affect plant performances. The ability of short term irrigation with TWW in order to improve young olive (Olea europaea L. cv. Chetoui) performance was studied. One-year-old olive plants were subjected, for four months, to different concentrations (33, 50 and 100%) of TWW. As compared to the control olive plants, results showed that irrigation with TWW induced an enrichment of plant tissues with macro- and micronutrients. This enhancement significantly (p≤0.05) improved the photosynthesis activity, soluble sugars and thus plant growth. The irrigation with undiluted TWW was more efficient than diluted TWW in ameliorating the physiological performance of young olive plants. Therefore, TWW seems to be an interesting bio-fertilizer of young olive plant when applied for a short period. 1. Introduction In the recent years, the irrigated areas expansion has caused a de- crease in the availability of fresh water as irrigation is fundamental for the development of agriculture (García-Ruiz et al., 2011). Generally, agriculture is the major consumer of water as it accounts for around 70% of all global water use (Winpenny et al., 2010). Alternative sources of water like treated wastewater (TWW) could be a useful option to satisfy different agricultural needs (Uzen et al., 2016). Recently, TWW reuse in agriculture is gradually becoming a frequent practice in areas with limited sources of water (Petousi et al., 2015). The potential benefits in using TWW for irrigation purposes include (i) reducing fresh water demand (ii) recycling nutrients and (iii) minimizing the discharge of pollutants into the waterways (Hanjraa et al., 2012). According to Martínez et al. (2013), TWW is a rich source of nutrients (nitrogen (N), phosphorus (P), potassium (K) and micro- nutrients), which reduce the need for chemical fertilizers resulting in net cost savings to farmers. Kiziloglu et al. (2008) showed that waste- water irrigation increases the availability of nitrogen, phosphorus and potassium as well as micro-elements to plants, which lead to increase the yields of cauliflower and red cabbage. Many studies related to TWW application in agriculture were developed for several crops including eggplant, tomato (Cirelli et al., 2012), lemon (Pedrero et al., 2012), chickpea (Tak et al., 2013) and cotton (Uzen et al., 2016). These authors showed the benefits of TWW irrigation in increasing the biomass and the production, in improving the plant mineral status and in reducing the fertilizers application rates. Indeed, Tekaya et al. (2016) reported that TWW irrigation improved the growth and increased the photosynthetic capacity of olive tree (Olea europaea L.). However, some disadvantages like salinization of soil, sensitive plants damage and contamination by coliforms such as Es- cherichia coli that represent a public health, are still a concern (Cirelli et al., 2012; Bedbabis et al., 2015). Interestingly, it was suggested that good agricultural practices executed with planning and management may reduce these undesirable consequences (WHO, 2006). In Tunisia, oleiculture is considered as one of the main economical and agricultural sectors. This species known for its tolerance to drought (Wang et al., 2018) and salinity (Chehab et al., 2018) constituted the most important crop. Recently, in water-scarce countries such as Tu- nisia, TWW was used as an additional water resource for plant irriga- tion. According to Hentati et al. (2014), in the Mediterranean Basin, Tunisia is considered as a country suffering of a high level of water scarcity. To a large extent, TWW may be considered as an important source of nutrients for olive crop production, which can reduce the https://doi.org/10.1016/j.agwat.2018.05.024 Received 25 January 2018; Received in revised form 29 May 2018; Accepted 31 May 2018 ⁎ Corresponding author. ⁎⁎ Corresponding author at: High Institute of Applied Biology of Medenine, University of Gabes, Medenine, Tunisia. E-mail addresses: benhassena.ameni@yahoo.fr (A. Ben Hassena), znacim2002@yahoo.fr (N. Zouari). Agricultural Water Management 207 (2018) 53–58 0378-3774/ © 2018 Elsevier B.V. All rights reserved. T