Effect of supplementary irrigation and planting date on the physical and economic water productivity of wheat and barley plants under Urmia dryland conditions

The ​​ Urmia Lake catchment is one of the most susceptible agricultural areas that has been affected by water stress and environmental problems which caused by the drying of Lake Urmia in recent decades. Using simulation models in exploring management options can be a reliable and appropriate tools for catchment areas. In this research, the effect of two management options that leads to controlling and increasing the productivity of water resources in the Lake Urmia basin and the Urmia region is investigated by the AquaCrop model. These options included: (1) complete supplementary irrigation (I) at the right time due to the plant growth period and its optimum depth; and (2) the planting date. The effect of these management options on the physical Water Productivity (TWP), the Economic Water Productivity of supplementary irrigation (EWP) and dry yield (DY) of wheat and barley plants under dryland condition was investigated. Simulation was performed using climatic information about 1393-94. The results showed that supplementary irrigation of wheat and barley was 200 and 140 days after planting date, respectively. The highest amount of TWP of wheat and barley was in supplementary irrigation treatments of and , respectively. (0.61 and 0.44 Kg. m-3 for wheat and barley respectively). According to EWP values, the highest economic productivity of water was obtained in treatment for wheat and barley (4580 and 1052 Rials.m-3 for wheat and barley, respectively). The optimum planting date for maximum amounts of TWP, EWP, and DY was obtained for in the first decade of October and the first decade of November for wheat and barley, respectively.