Effect of Deficit irrigation on the Productivity of Processing Potato

The area under potatoes in Lebanon has extended to over 15.000 ha to form 17% of irrigated arable land. More farmers rely on processing varieties for prices and marketing reasons. Studies focused so far on irrigation and fertilization of table potatoes. The current recommendations indicate excess N fertilizer input exceeding 600 kg N/ha in the form of compound fertilizers. Potato is irrigated with macro sprinklers with a water input reaching 850 mm/season. Water mismanagement and shortage eventually influence the yield quantity and quality of processing potatoes. Therefore, deficit irrigation is an important water saving tool regarding the increasing pressure on limited water resources in the dry areas. Information on potato response to water stress imposed at different crop stages is available. The aim of this paper is to study the impact of continuous deficit irrigation imposed from the stage of maximum plant development-flowering stage until physiological maturity on the performance of processing potato (Santana) and water and fertilizer use efficiency. Fertilizer placement and irrigation were done through fertigation using drip system. A neutron probe was used to assess water consumption from the soil. The 15N methodology was used to follow the N recovery as affected by water deficit