The effect of deficit irrigation in processing tomato for the important industrial parameters

Two-year open field processing tomato experiment was conducted with different levels of irrigation and potassium fertilization. Four different water supply were combined with four different potassium levels were set in 2016 and 2017. The water supply levels (W) were 100, 75, and 50% of crop evapotranspiration (ETc) until the beginning of the ripening stage, compared to control (0%) without regular irrigation. Yield data were recorded, the soluble solids content (degrees Brix) lycopene, and total antioxidant capacity was determined and evaluated from red ripened fruits in laboratory. Aim of our study was to determine the effects of deficit irrigation and different levels of potassium on yield, Brix value, lycopene, and total antioxidant content as the main industrial processing parameters. In total yield there were remarkable differences among treatments in 2016, Highest yield was reached in the combination of "100% W 50%P", while the lowest value was observed in the case of "50%W 0%P". Differences among yield of the treatment combinations became much less articulated in 2017. The largest yield was reached in combination of "50%W 75%P", while the lowest amount was harvested in p "0% W0%P". Unirrigated plots showed higher Brix values compared to areas with good water supply in 2016. The highest and lowest numbers are detected at "50%W 100%P" and "100%W 50%P", respectively. No such tendencies were justified in 2017, medium-supply treatments resulted lower soluble solids, while the two extremities led to similar, higher Brix values. "0%W 100%P" resulted the highest Brix, while the lowest was measured at "75%W 50%P". We measured the highest lycopene content by the "50%W 100%P" treatment and the lowest amount was by the "75%W 0%P" treatment. We detected the highest antioxidant capacity by the "0%W 50%P" treatment, and the lowest by the effect of the "75% W 0%P" treatment. We realized the highest from lycopene in 2017 by the "0%W 50%P" combinations, and the lowest by the "75%W 50%P" treatment. In the case of the antioxidant capacity, we have found the highest amount by the treatment of "100%W 0%P", and the lowest by the "75%W 100%P" group. In concluded it can be said that the seasonal environmental effect influenced both the yields and Brix values more considerably than the applied treatments. It is important to highlight those optimal yields and soluble solids contents were reached by deficit water supply. Water supply induced larger differences in productivity and in soluble solids content than potassium supply. In case of lycopene in 2016 most of the highest amounts were in water deficient plots. The potassium top dressing has an influence of the amount of lycopene. In the amount of lycopene in 2017 and by the antioxidant capacity (in 2016 and 2017) the definite effect of the treatments was not detectable.