Effect of water regime on physiological and quanti-qualitative parameters of processing tomato crop

Processing tomato is largely cultivated in Mediterranean areas. Nevertheless, these areas are often characterized by recurrent water scarcity. The aim of this study was to evaluate physiological and quali-quantitative response of processing tomato under water stress. The trial was conducted in Foggia on four processing tomato hybrids (Ercole, Genius, Tania and Ulisse) cultivated under six water regimes.The regimes consisted in three “fixeds” throughout the cycle (restoration of 100%, 75% and 50% of crop evapotranspiration - ETc) and three “variables” depending by different critical stages of tomato cycle: from transplanting to flowering of the first truss (f1), from flowering of the first truss to fruit breaking colors at the same truss (f2) and from this stage to harvest (f3). In these three stages the irrigation was 75-100-75% ETc, 50-100-50% ETc and 50-75-50% ETc. In order to monitor the leaf water status relative water content (RWC), leaf osmotic potential and crop canopy temperature were measured. At harvest, marketable tomato yield, water use efficiency (WUE: marketable tomato yield/total water used), total soluble solids content (TSSC) and titratable acidity were evaluated. All data were analyzed using the analysis of variance (ANOVA). Results from physiological parameters and marketable yield showed the importance of giving the highest water regime (100 or 75% Etc) to the crop especially in the critical period going from flowering to fruit breaking colours of the first truss (f2). In conclusion, the study show that the “variable” water regimes can save water with only marginal influence on physiological parameters producing only marginal yield reduction in tomato.