Farimah Omidi - Irrigation Science and Engineering PhD. Tehran, Iran
Mehdi Homaee - Chair of Agrohydrology Research Group, Engineering Faculty, Tarbiat Modares University, Tehran, Iran

Nowadays, the growing population and its ever increasing need for food are the main challenges in agricultural sector worldwide. Regarding to produce more food, the climate change can be regarded as one of the most important obstacles. As a result of drought duration and lack of precipitation, water scarcity is the most important challenge for farmers to produce optimal yield. Water deficit not only reduces the crop yield, but affects the quality of soil as well. In order to decrease the negative effects of water scarcity and salinity, farmers turn into applying chemical fertilizers. As a result of drought, salinity and nutrient imbalances, crops undergo abiotic stresses which have been studied altogether in this research. Four different irrigation treatments, three salinity treatments ant three nitrogen treatments were designed in order to quantify the effect of simultaneous effect of these stresses on green pepper (Capsicum Annum). The results indicated that simultaneous effect of all three stresses can be concluded in a linear equation. Following that, a nonlinear, crop production function-based method was incorporated to calculate the irrigation water price. Our results further indicated that irrigation water price in regions with sever climate situations is sensitive to pricing method, crop tolerance to the stress and crop price. As for crop management, an analytical framework has been implemented in order to optimize irrigation water quantity; while using deficit irrigation as a water saving method. The results confirmed that using more expensive, drought sensitive and salinity sensitive crops can affect deficit irrigation application by narrowing the range of deficit levels of irrigation. Since a narrow range of deficit levels implies greater risks, the decision maker should consider the results of optimization in cropping pattern. It can be concluded that in addition to marketing opportunities along with crop price, the effect of climate change is of vital importance which can path the way for decision makers to technically and economically schedule the optimal program for the farms.

Climate change, drought, deficit irrigation, soil salinity, nitrogen, crop production functions