Challenges Associated with a Successful Management of Regulated Deficit Irrigation in Commercial Fresh-Fruit Production

Regulated deficit irrigation (RDI) is a cultural practice by which the amount of water applied to the crop during specific periods of the growing season is below the maximum water demand. Depending on the crop species, the most recognized benefits of deficit-irrigating fruit orchards are: 1) important water savings [1], 2) increased water productivity and intrinsic water use efficiency [2], 3) improved fruit quality and uniformity of fruit maturity [3] and 4) reduced vegetative growth [4]. Therefore, maximum orchard profitability is reached when water application has induced some level of water stress (Figure 1). Of course, this premise breaks away from the traditional principle that both full irrigation and optimum plant water status are indispensable to maximize profitability. The correct use of RDI implies the use of water stress during periods of the growing season when the sensitivity of reproductive development to drought is moderate or low. It must be carefully handled, because, it is well known that severe water stress may reduce fruit size and compromise yield of the next season (as well as the current season if improperly applied) [5]. This is why RDI has been mostly employed in fruit crops whose economic value is not determined by fresh weight, such as wine grapes [3], almonds [5], and prunes [6], among others. Furthermore, the fact that fresh-fruit growers have been hesitant to use this irrigation technique [7] is a good example of how the adoption of water conservative irrigation strategies, is strongly hindered by farmer’s aversion to risk [8].