Agricultural Water Management 100 (2011) 1–8 Contents lists available at SciVerse ScienceDirect Agricultural Water Management j ourna l ho me page: www.elsevier.com/locate/agwat Validation and testing of the AquaCrop model under full and deficit irrigated wheat production in Iran B. Andarzian a,∗ , M. Bannayan b , P. Steduto c , H. Mazraeh a , M.E. Barati d , M.A. Barati e , A. Rahnama a a Agricultural and Natural Resources Research Institute of Khuzestan, P.O. Box 61335-3341, Ahvaz, Iran b Ferdowsi University of Mashhad, Faculty of Agriculture, P.O. Box 91775-1163, Mashhad, Iran c Water Resources, Development and Management Service, Land and Water Division, FAO, Room B-721, Via delle Terme di Caracalla 00100, Rome, Italy d Tehran University, Tehran, Iran e Islamic Azad University of Tehran, Iran a r t i c l e i n f o Article history: Received 29 May 2010 Accepted 26 August 2011 Available online 17 September 2011 Keywords: AquaCrop model Crop modeling Water use efficiency Wheat irrigation a b s t r a c t Accurate crop development models are important tools in evaluating the effects of water deficits on crop yield or productivity and predicting yields to optimize irrigation under limited available water for enhanced sustainability and profitable production. Food and Agricultural Organization (FAO) of United Nations addresses this need by providing a yield response to water simulation model (AquaCrop) with limited sophistication. The objectives of this study were to evaluate the AquaCrop model for its ability to simulate wheat (Triticum aestivum L.) performance under full and deficit water conditions in a hot dry environment in south of Iran, to study the effect of different scenarios of irrigation (crop growth stages and depth of water applied) on wheat yield. The AquaCrop model was evaluated with experimental data collected during the three field experiments conducted in Ahvaz. The AquaCrop model was able to accurately simulate soil water content of root zone, crop biomass and grain yield, with normalized root mean square error (RMSE) less than 10%. The analysis of irrigation scenarios showed that the highest grain yield could be obtained by applying four irrigations (200 mm) at sowing, tillering, stem elongation and flowering or grain filing stages for wet years, four irrigations (200 mm) at sowing, stem elongation and flowering stages for normal years and six irrigations (300 mm) at sowing, emergence, tillering, stem elongation, flowering and grain filing stages for dry years. The least amount of irrigation water to provide enough water to response to evaporative demand of environment and to obtain high WUE for wet, normal and dry years were 100, 200 and 250 mm, respectively. © 2011 Elsevier B.V. All rights reserved. 1. Introduction On a global scale irrigated agriculture uses about 72% of available fresh water resources (Geerts and Raes, 2009). The rapid increase of the world population and the corresponding demand for extra water by sectors such as industries and municipal forces the agri- cultural sector to use its irrigation water more efficiently on the one hand and to produce more food on the other hand. Defin- ing optimum strategies in planning and management of available water resources in the agricultural sector is becoming a national and global priority (Smith, 2000). Various studies have shown that one of the promising irrigation strategies might be deficit irrigation (Farre and Faci, 2009; Kipkorir, 2002; Pereira et al., 2002; Debaek and Aboudrare, 2004; Fereres and Soriano, 2007; Ali and Talukder, 2008; Behera and Panda, 2009; Blum, 2009; Geerts and Raes, 2009), ∗ Corresponding author. Tel.: +98 916 311 9819; fax: +98 611 336 2305. E-mail address: bahramandarzian@yahoo.com (B. Andarzian). whereby less water than required is applied during the growing period. Although this inevitably results in crop water stress and yield depression, high yield can still be obtained by supplying the required amount of irrigation water during sensitive crop growth stages, and by restricting the water stress to tolerant growth stages (Blum, 2009; Geerts and Raes, 2009). Examining the yield response to different water applications in field and/or controlled experi- ments is laborious and expensive. Considering such limitations, modeling can be a useful tool to study and develop promising deficit irrigation strategies (Zairi et al., 2000; Kipkorir et al., 2001; Lobell and Ortiz-Monasterio, 2006; Benli et al., 2007; Heng et al., 2007; Lorite et al., 2007; Pereira et al., 2009; Blum, 2009; Geerts and Raes, 2009). Models allow a com- bined assessment of different factors affecting yield in order to derive optimal irrigation quantities for different scenarios (Pereira et al., 2002; Liu et al., 2007). Furthermore, They can allow differen- tiating evapotranspiration between transpiration and evaporation and splitting up crop production in different sub-models (e.g. Raes et al., 2006, 2009a; Geerts et al., 2009; Steduto et al., 2009), which 0378-3774/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.agwat.2011.08.023