dc.description.abstracteng | The tomato (Solanum lycopersicum L.) is a worldwide important vegetable, with an annual
production of 170.8 million tons in 2014. Potassium (K) has several physiological functions
in plants, such as translocation of assimilates, activation of enzymes, maintenance of
turgescence, and stomata regulation and thereby contributes to fruit yield and quality. The
aim of all experiments was to investigate the impact of increasing K application on tomato
fruit quality for a better understanding of K’s physiological functions. Therefore, different
cocktail tomato cultivars (Primavera, Resi, and Yellow Submarine) were studied in two
consecutive years in outdoor pot experiments.
Total soluble solids (TSS), titratable acids (TA), dry matter (DM), color, and firmness are
important consumer-related quality traits. Especially high concentration of TSS and TA are
taste beneficial. In all studied cultivars TSS, TA, and partly DM increased with rising K
fertilization. Other parameters, such as color, firmness and yield increased in Primavera in
both years, whereas in Resi no further changes were detected. This clear cultivar
dependence shows that high K fertilization not necessary enhance these traits.
Tomatoes contain several important water- and fat-soluble antioxidants, like ascorbic acid,
phenolics, carotenoids, and tocopherols. The antioxidant concentrations in tomato fruit are
affected by K fertilization, but other abiotic factors may alter or even reverse those effects
in an outdoor environment. Nevertheless, the tendencies of ascorbic acid, naringenin, pcoumaric
acid, and caffeic acid are similar in both years for Primavera and Resi, indicating
a strong K fertilization effect.
The metabolome analysis provides a comprehensive overview of the induced changes by
increasing K fertilization on low weight metabolites in tomato fruits. The cultivarindependent
increase of TCA cycle metabolites and decrease of amines with rising K
fertilization was most prominent. Several other metabolites showed a cultivar-specific
effect. Indicating that the reaction towards macronutrient stress is quite different between
cultivars of one species. | de |