Influence of Salinity and Fertilization Level on Greenhouse Tomato Yield and Quality

The objective of this study was to evaluate the effects of two irrigation water qualities and three different levels of nitrogen-phosphorous-potassium (NPK) rates applied by fertigation on yield and quality of tomato fruit. The experiment was carried out in a polyethylene greenhouse on 'Pitenza' tomato grown on a sand-mulched sandy loam soil using a trickle irrigation system. The treatment consisted of two irrigation water qualities (C2S1 and C3S2) and three fertilization levels: 50%, 100%, and 200% [7.1 mmol L-1 nitrate (NO3) N, 0.5 mmol L-1 P, and 3.1 mmol L-1 K] for each water quality category. The dry-matter content of fruit (DMC), number of fruit, fruit weight per period (g), weight per fruit (g), number of trusses, fruits per truss, and unmarketable fruit were monitored. Quality was evaluated using fruit firmness (Kg), total soluble solids (°Brix), pH, and tritable acidity (meq citric acid L-1 of juice). The increased salinity of the irrigation water did not affect the marketable and unmarketable yield of fruit but did produce an increase in the number of fruits per truss at 127 days after transplanting (DAT) (10%) and in the DMC percentage at 127 and 179 DAT, being 9 and 6.8% respectively. High-salinity irrigation water reduced the firmness of the fruit at 127 and 179 DAT (9% and 22%, respectively); it increased the soluble solids for all the dates analyzed as well as the fruit's tritable acidity with significant differences at 127 and 206 DAT. The fertilization level increased the marketable yields, fruit number, and number of trusses during all stages. Treatment F1 produced a yield 28% lower than F2, whereas F3 was 10% higher than F2. The results show that irrigation water electrical conductivity (EC) of 2.2 dS m-1 is adequate for high yield and quality of tomato in the commercial cycle.