Product quality of greenhouse tomatoes: effect of cultivars organic N-fertilization and harvest time.
The aim of this project was to investigate the marketability limits of old tomato cultivars used in organic farming and to maintain their biodiversity by promoting consumption on regional markets. Four old and endangered tomato cultivars, ‘Ananas’, ‘Auriga’, ‘Green Zebra’ and ‘Lukullus’, were treated with 0 and 100 kg N ha-1 applied as horn splinters. Harvesting was performed at early and optimum fruit maturity. All cultivars clearly differed in colour, shape and maturity of fruits. Nutritional quality and health promoting compounds were analysed in terms of beneficial ingredients such as ascorbic acid (vitamin C) and carotenoids (lutein, b-carotene and lycopene). Significant differences in nutritional quality of cultivars were detected. The highest contents of ascorbic acid and carotenoids were determined in cv. ‘Lukullus’. High amounts of soil- borne nitrogen resulted in no significant effects of N fertilization on N uptake, ascorbic acid and carotenoid contents. Harvest at the optimal ripening stage showed a higher ascorbic acid content in comparison to an early harvest.
Kumar, R.; Klein, D.; Krumbein, A.; Köpke, U. 2007. Product quality of greenhouse tomatoes: effect of cultivars organic N-fertilization and harvest time. European Journal of Horticultural Science 72 (1), 46-51.