WATER PRODUCTION FUNCTION AND MATHEMATICAL OPTIMIZATION OF REGULATED DEFICIT DRIP IRRIGATED PEACH

Egypt is one of the countries facing great challenges due to its limited water resources associated with expanding population. Therefore, new approaches for irrigation management are required to reduce water consumption and improve water use efficiency. Regulated deficit irrigation (RDI) is the strategy of reducing irrigation rates during a specific period of growth and development, with the objective of conserving water and managing plant growth while maintaining or improving yield and fruit quality. A two years old Peach trees in sandy soil under drip irrigation system were subjected to a range of irrigation deficits from pit hardening to harvest during the 2011 and 2012 seasons to evaluate the effects of deficit irrigation on peach yield. Four irrigation treatments were evaluated according to irrigation water requirements: 120% of full irrigation (I120), 100% full irrigation (I100), 80% full irrigation (I80), 60% full irrigation (I60).A cost-benefit analysis was performed for two and three years old peach plantation [prunuspersica]to determine profitability under regulated deficit irrigation (RDI). The opportunity cost of water is higher than the delivery cost of water. One major point of this analysis is the dramatic differences between the delivery cost of water and its opportunity cost which is almost 10 times more than the delivery cost. It is clear that such a cost ought to be considered as the value of water. Regression equations were developed to predict crop yield resulting from water deficit. The study recommended the model to predict crop yield and water saving. As long as the main goal is to maximize the profit as well as saving water, it could be said that the optimal profitable yield is not necessarily the maximum one, but could be less. Deficit irrigation technique is recommended in arid regions such as Egypt where water resources are limited.