**2.1. Sustained deficit irrigation**

Sustained deficit irrigation is an irrigation strategy based on the distribution of a reduced water volume, controlled by a water stress indicator or as a percentage of the full water requirements for a crop throughout the whole irrigation season, so that the water deficit is intended to be uniform over the whole crop cycle to avoid the occurrence of severe water stress at any particular moment that might have unfortunate results [29]. At the end of the 1970s, field experiments on irrigation below the ETc demand, but at very frequent intervals, have shown very promising results [30].
