Efficiency of water use in sugar beet and processing tomato cropped in Southern Italy

A more efficient crop water use in biomass and yield accumulation can represent great water saving in the waterlimited environments. Crop management – irrigation, sowing time, fertilization – could affect water (and irrigation water) transformation efficiency in dry matter and commercial yield of beet and tomato in Southern Italy. This field research, carried out in two locations of Southern Italy (Foggia and Vasto) in 1998-2002 period, compared for sugar beet irrigation regimes (optimal, 100% of ETc and reduced, 60% of ETc) and sowing times (autumnal and spring); for tomato three irrigation regimes were compared, re-establishing 100% (ET100), 66 (ET66) and 33% (ET33) of crop evapotranspiration. Water and irrigation water transformation efficiency in harvestable yield (WUEhdm and IRRWUE hdm), in total dry matter (WUEdm and IRRWUEdm) and sucrose (WUEsuc) were calculated both at harvest and during crop cycle. The results showed a significant effect of sowing date on WUEhdm and WUEsuc of sugar beet (respectively 2.44 and 2.12 for autumnal sowing and 1.08 and 0.84 kg m-3 for spring sowing). Irrigation regimes did not show significant differences. “Irrigation x sowing times” interaction was significant for WUEdm, with a superiority of reduced vs. optimal only in spring sowing time. In tomato, WUEdm was not affected by the irrigation regime, while WUEhdm in ET66 treatment was more efficient treatment than ET100 (1.19 vs. 1.00 kg m-3). “Year” effect was significant for WUEdm and WUEhdm with lowest values in the driest year. IRRWUE was higher in tomato than in sugar beet, considering dry matter, fresh harvestable product and also from an economic point of view. The temporal analysis of water use efficiency showed WUEdm and WUEhdm greater in the middle of crop cycle in autumnal than in spring sugar beet, but not between the irrigation regimes. In tomato, the ET66 treatment resulted the most efficient in water using, especially at the end of crop cycle. This information can be useful in the crop management of sugar beet and tomato in Southern Italy and to better address the scarce irrigation water resources.