IRRIGATION SCHEDULING FOR GARLIC BY USING THE OPTIMIZED REGULATED DEFICIT IRRIGATION

Aspects as water availability and increasing energy costs condition the viability of irrigation activities in many areas of the world. This paper aims to determine the most suitable irrigation strategy for improving the profitability of purple garlic in the Protected Geographical Indication "Ajo Morado de Las Pedroneras" (PGIAMP) (Spain) depending on the availability of water resources through Optimized Regulated Deficit Irrigation (ORDI) and Typical Meteorological Year (TMY) methodologies. The ORDI methodology was used to determine the irrigation strategy for each growth stage that produces the highest yield (estimated by using the model proposed by FAO-33) in the PGIAMP for three (0.9, 0.8, and 0.7) certain overall deficit target (accumulated daily ETa divided by the accumulated daily ETm for the whole crop cycle) using an optimization software and the TMYs generated from the climatic data of 18 weather stations. For the climatic conditions of three studied years (2000 to 2002), and inserting in the optimiser the restriction of reaching ETa/ETm >= 0.8 during the Kc (I) for guarantying nascence and establishment, the ORDI methodology can lead to an increase in water productivity compared with the irrigation strategy where the stress levels remain constant during the whole growth cycle (CDI). ORDI may slightly increase garlic yield in the IGPAMP by 3 to 9% compared with the CDI strategy, which is significantly increasing due to the high profitability of this crop in the area. The combination of ORDI with TMY may increase the water use efficiency at farm and/or basin scale.