Tuber yield and irrigation water productivity in early potatoes as affected by irrigation regime.

Excessive amounts of irrigation water are often utilized for early potato cultivated in the Mediterranean basin. Given that water is an expensive and limited resource in semi-arid areas, it is crucial to provide a better irrigation management and/or irrigation technologies that facilitate its efficient and effective use, in turn leading to savings in water. With the aim of achieving appropriate irrigation water regimes in cultivation management of a potato crop in a Mediterranean environment, a two-year experiment was conducted in Sicily (South Italy). The effects of four irrigation regimes (irrigation only at plant emergence, irrigation during the whole cycle, irrigation from tuber initiation up to 50% of tuber growth, irrigation from 50% of tuber growth to the end of tuber growth), on the tuber yield and yield components, on irrigation water productivity (IWP) and on tuber quality, were studied. Our results showed a marked and significant effect of the irrigation regime on tuber yield, IWP, source/sink relationships and dry matter content of tubers. We also demonstrate that high yield levels of potatoes, high IWP and good tuber quality can be reached by irrigating with 100% maximum evapotranspiration (ETm) supply from tuber initiation up to 50% of tuber growth. Compared to irrigation with 100% ETm supply throughout the whole cycle, this allows making savings of irrigation water of roughly 77 mm year-1, which is a significant reduction for the semi-arid areas.