Controlled deficit irrigation as a water-saving strategy for processing tomato

Abstract

In a complex scenario characterized by climate change and increasing population demand, it is necessary to adopt production strategies involving a lower use of water. For this purpose, controlled deficit irrigation, CDI, strategies with an initial full irrigation covering 100 % crop evapotranspiration (ETc) followed by mild (50 %ETc) and moderate (75 %ETc) irrigation restrictions after the fruit set stage were evaluated. The study was performed during two years in two growing areas of processing tomato in Spain, using conventional and high-lycopene cultivars. With moderate levels of CDI an average saving of water of 26.1 % was achieved, but productivity was reduced on average by 10.7 %. It should be considered though, that the effect was dependent on the environment and genotype, and high-yield cultivars seemed to be more sensitive to the negative effects of moderate CDI on productivity. In contrast, mild CDI levels did not affect productivity and still entailed a water saving of 13 %. Moderate CDI levels increased soluble solids content, but this increase was not due to a higher accumulation of taste-related compounds, such as sugars and acids. Indeed, irrigation dose had no significant effect on the levels of fructose, glucose, citric and glutamic acid nor on derived variables related to tomato acceptability and CDI decreased the levels of malic acid. Considering previous results, mild CDI strategies would be preferred to continuous deficit irrigation strategies as the former contribute to reduce the use of water, an increasingly scarce resource, avoiding negative impacts on productivity, a key parameter to promote farmer adoption of CDI strategies.