ISHS Acta Horticulturae 542: VII International Symposium on the Processing Tomato
EFFECTS OF REDUCED IRRIGATION AND NITROGEN FERTIGATION RATE ON YIELD, CARBOHYDRATE ACCUMULATION, AND QUALITY OF PROCESSING TOMATOES |
| Authors: | G. Colla, A. Battistelli, S. Moscatello, S. Proietti, R. Casa, B. Lo Cascio, C. Leoni |
| Keywords: | Drip irrigation, fertilization, Lycopersicon esculentum, fruit quality, leaf testing |
| Abstract:
Processing tomatoes were grown in 1999 at Viterbo in central Italy on a sandy loam soil to evaluate the effects of four irrigation regimes and three nitrogen fertigation rates (0, 80, and 160 kg·ha-1) on productivity, accumulation of storage carbohydrates, leaf nitrogen concentration, and quality of fresh and processed product. Irrigation treatments were based on different percentages of crop evapotranspiration (ETc) at two plant growth phases (planting to fully formed first fruit, and first fruit to harvest). The four irrigation treatments during the two growth phases were 75–50%, 75–75%, 100–75%, and 100–100% ETc. Marketable yield was highest in the 100–75% ETc and 100–100% ETc treatments, and was significantly lower in the 75–50% ETc and 75–75% ETc treatments. Irrigation and nitrogen independently affected the percentage of fruit dry matter at very early stages of fruit growth. Fruit storage capacity was constant throughout the season and was not affected by treatments. Deficit irrigation increased fruit sugar concentration and decreased fruit size, so that the amount of sugars per fruit was unaffected. The highest soluble solids content was found in the lowest irrigated treatments (75–50% ETc and 75–75% ETc). However, taking into account the decrease in marketable production, soluble solids yield was not significantly different among the treatments. Yield, soluble solids content, and titratable acidity were higher in the fertilized treatments than in the unfertilized treatment, but no differences were found between the 80 and 160 kg·ha-1 fertilization levels. No significant interactions between fertilizer and irrigation were found. Leaf nitrogen concentration declined during the season and was greatly affected by nitrogen applications. Post-processing fruit quality data showed the highest canned tomato quality with the 75–50% ETc treatment. | |
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