The quality of tomato for canning as affected by combined chloride, nitrate and osmotic potential of the nutrient solution

Abstract

The quality of tomato fruit and juice (Lycopersicon esculentum L. cv. VF M82-1-8) grown in an aerohydroponic system in a greenhouse was affected by the level of Cl⁻ and NO ₃ ⁻ , and by the osrnotic potential (OP) of the nutrient solutions. The total suspended solids (degrees Brix) in the fresh juice increased from approximately 4.0 in the nonsaline solutions (OP ∼ −0.05 MPa) to approximately 5.6–5.8 in the saline solutions (OP ∼ −0.45 MPa). Juice acidity was similarly affected by the Cl⁻, NO ₃ ⁻ and OP levels in the nutrient solutions. Less affected, the ascorbic acid content of juice, was lowest (∼ 8–9 mg/100 cc) in the high-NO ₃ ⁻ -nonsaline solution treatments, and was between 10 and 12 mg/100 cc at OP levels greater than ∼ −0.2 MPa. NO ₃ ⁻ in the juice was high (∼ 60 mg/L) under low OP conditions (∼ −0.05 to −0.1 MPa), especially when combined with high NO ₃ ⁻ levels, and lower (between 8 and 30 mg/L) in plants exposed to saline conditions (low OP). Fruit puffiness (boxiness) was reduced markedly by salinity and was not considerably affected by the NO ₃ ⁻ /Cl⁻ ratio, while fruit firmness was influenced by both factors.