Abstract

TOUREIRO, C. M.; SERRALHEIRO, R. P.  and  OLIVEIRA, M. R.. Deficit irrigation as a criterion for irrigation water management with sunflower and maize crops. Rev. de Ciências Agrárias [online]. 2007, vol.30, n.1, pp.33-47. ISSN 0871-018X.

Some results are presented from a project aiming the water use optimisation from an environmental point of view. This means that the decision criterion in irrigation management is “deficit irrigation”, rather than maximum ETc as the irrigation water amount. Some experiments with “deficit irrigation” of a sunflower crop (in 2004 irrigation season) and maize (in 2005) were carried out in the Irrigation District of Divor (Alentejo, South Portugal). Crop growth and production parameters were evaluated relative to three experimental irrigation regimes: 1) irrigation opportunity and amount with soil available water equalling “optimum yield level”, this corresponding to a non restrictive water use by the crop, according to current procedure, irrigation amount corresponding to maximum ETc; 2) and 3) levels 1 and 2 of deficit irrigation, considering irrigation opportunity with soil available water respectively 10% and 30% under the “optimum yield level” and irrigation amounts 10% and 30% less than ETc between irrigation events. During the flowering periods normal irrigation for full ETc was practiced in all experiment plots. Crop yield data and the economic analysis show that a remarkable potential exists for saving water with “deficit irrigation”.

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