Yield and water use efficiency of early potato grown under different irrigation regimes

Potato grown for early or off-season production plays a crucial role in theeconomy of several areas in the Mediterranean countries. Irrigation is important fordetermining yield and earliness, thus a better investigation of plant response undervarious pedo-climatic conditions can help to improve resource use efficiency andfarmer income. A two-year field research (2009-2010) was carried out in Apuliaregion, southern Italy, on cv Spunta grown under three irrigation regimes: fullirrigation (I100), 50% of full irrigation (I50) and rainfed (I0). Treatments werearranged in a randomized complete block design with three replicates. Plant waterstatus, plant growth and, at harvesting, water use efficiency, yield and qualityparameters were quantified. Water stress significantly affected yield response: asan average of the two years, a marketable yield decrement of 25.9 and 63.6% wasobserved in I50 and rainfed compared with I100 treatment, respectively. On thecontrary, tuber dry matter and specific gravity increased moving from irrigatedtreatments to the rainfed one and varied also as a function of experimental year.The results confirmed that irrigation is required for early potato cultivation becauserainfall is not sufficient to meet crop water needs. In addition, the study indicatedthat the irrigation regime reduced by 50% of crop water requirements was able tofurnish satisfactory yield, with tuber quality characteristics similar or even betterthan those obtained under full irrigation.