Effect of different nitrogen rates on some quality parameters of greenhouse tomatoes

This investigation was carried out in order to determine the effects of four nitrogen rates (0, 120, 240 and 360 kg/ha) on yield and fruit quality characteristics of tomatoes grown in an unheated glasshouse. Seed sowing, transplanting and planting dates were September 14, September 27 and October 26, 1993; respectively. The plants were spaced at 80 * 40 cm and the trial was set up according to the randomized blocks using three replicates for each treatment. Total soluble solids (TSS), pH, titratable acidity (TA), total dry matter, TSS/TA PWTA and vitamin C contents were determined in fi-Liit samples taken at 20 days interval. Organic acids (citric, oxalic, malic, aketo) and sugar fractions (maiuiose, fi-Lictose, a-glilcose, B-glucose, sorbite) were determined, as well. Eventhougly the effect of nitrogen rates on fruit quality parameters were not followed statictically significant, yield results were noteworthy in this aspect. The results were discussed in terms of changes occurring during the harvest period.