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Sensory properties are an essential quality aspect when the consumption of fresh tomato is under consideration. The flavor of tomato is defined as a combination of taste sensations (sweetness, sourness), aroma (volatile compounds), and texture (firmness, mealiness), some of which are proven to be affected by insufficient nutrient supply -- especially potassium (K). This study intends to undertake a holistic assessment of the K fertilization effect on the flavor of tomato by connecting the use of sensorial and instrumental methods. An optimal K supply significantly increased the sensory descriptors sweetness, sourness, and aroma as well as the instrumental estimated color, firmness, total soluble solids (TSS), titratable acids (TA), and dry matter (DM) in a cultivar-specific manner. The volatile organic compounds (VOCs) were not significantly affected by K fertilization. The evaluation by the panelists confirmed the results of the instrumental analyses, by which an increment in the fruit quality with rising K supply could be detected. An optimal K supply of 3.66 g/plant could be suggested to increase tomato flavor in the cocktail cultivars studied: Primavera and Yellow Submarine. Cultivar effects should, therefore, be considered for defining the optimal K fertilizer dose that favors high tomato fruit quality and, hence, better flavor. [ABSTRACT FROM AUTHOR]

Tomatoes are an important source of benefcial phytochemicals, which act as antioxidants. These include ascorbic acid, phenolic compounds, carotenoids, and tocopherols. The concentration of anti-oxidants is infuenced, among others, by abiotic stress factors like nutritional status. Potassium (K) is a macronutrient, which is essential for several physiological functions in plants -- for example, translocation of assimilates, activation of enzymes, maintenance of turgescence, and stomata regulation. This study aims to investigate the effect of increasing K fertilization on the concentration of anti-oxidants in cocktail tomatoes. Therefore, two tomato cultivars (Primavera and Resi) grown in an outdoor pot experiment were ferti- lized with increasing K doses for two consecutive years. It has been confrmed that antioxidants in tomato fruit can be affected by the K regime, but it is also shown that other factors may reduce or even reverse those effects when cultivation takes place in an uncontrolled outdoor environment. The most consistent K fertilization effects were found for naringenin, p-coumaric acid, and caffeic acid. However, the enrichment of tomatoes with antioxidants by K fertilization is cultivarependent and therefore general statements should be avoided. [ABSTRACT FROM AUTHOR]

BACKGROUND The market for cocktail tomatoes is growing continuously, mainly because of their good taste. Titratable acids (TA), total soluble solids (TSS) and dry matter (DM) contents correlate positively with good taste. So far, the impact of different potassium (K) applications on yield and consumer‐oriented quality traits has not been comprehensively described for cultivars of smaller fruits. To fill this gap, we tested the effect of different K fertilization regimes on three cultivars of small‐sized or cocktail tomatoes. RESULTS: A positive impact on quality parameters (TSS, TA, DM, color and firmness) was detected by raising the K fertilizer application for the cocktail tomato cultivars Primavera and Yellow Submarine. The cultivar Resi showed no response to fertilization, except for TSS and TA. Yield increased significantly by higher K application only in Primavera, the most productive cultivar. The K concentration in tomato rose with increasing K application. CONCLUSION: Because TSS and TA increased in all cultivars, whereas only one cultivar showed an increase in yield, the results of the present study emphasize the importance of the application of cultivar‐specific mineral fertilizers on yield‐ and consumer‐oriented quality traits. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The demand for organically grown tomatoes has rapidly increased on the consumer side. However, there is a lack of tomato cultivars suitable for organic farming that are both high yielding and of superior fruit quality. In the present study, the variation in plant growth and fruit quality of tomato cultivars was assessed to identify the traits associated with higher yield and improved fruit quality. Sixty tomato cultivars, cocktail and salad tomatoes, were grown under organic low-input conditions in 2015 and a subset of 20 cultivars for further evaluation in 2016. The results revealed a high variability among 60 cultivars in all 28 traits that were observed. Salad cultivars that have been selected for intensive indoor cultivation exhibited the highest yield components. A cross-year evaluation of the 20 cultivars showed that salad cultivars had 10-70% lower fruit quality including minerals, dry matter, total soluble solids, and total phenolic compounds (TPC), but 10-60% higher fruit yield and leaf minerals than cocktail cultivars. Cocktail cultivars with improved yield performance were derived from organic breeding. Depending on the cultivar, there was a trade-off between fruit yield and fruit quality. Interestingly, salad cultivars with high magnesium (Mg) concentration in the leaves also contained high Mg concentration in the fruits. Moreover, fruit Mg correlated positively with titratable acidity and TPC of the salad cultivars, as well as with fruit phosphorus, potassium, and sulfur in both cocktail and salad cultivars. The results indicate the contribution of Mg in improving flavor, health related-compound and nutritional quality of tomato fruits. This information provides a novel path for further studies to improve plant-available Mg in organic tomato production to enhance fruit mineral concentration and fruit quality. [ABSTRACT FROM AUTHOR]

There is evidence that potassium (K) fertilization enhances the yield of medium and large-sized tomato cultivars. Many authors observed positive effects of K fertilization on fruit color, texture, total soluble solids (TSS) and titratable acids (TA) [3, 6]. The market for small-sized cocktail tomatoes is currently growing due to their preferable taste [5] which is positively related to increasing levels of TSS and TA [1, 2, 4]. We hypothesize, that K improves yield and quality of cocktail tomatoes. In order to test our assumption, we carried out pot experiments in two consecutive years. In a pot (6 L) experiment, three cocktail tomato cultivars (Primavera, Resi and Yellow Submarine) were fertilized with five K levels (3.1, 6.3, 9.4, 12.5 and 18.7 g K/pot applied in total over 19 weeks) to find out ideal dosages for well and deficient fertilized plants. Interestingly, the K effect on yield and most quality parameters was highly cultivar specific: while Primavera and Yellow Submarine reached a yield increase of more than 100% from the lowest to the highest K dose, no response of Resi was observed. In contrast to Primavera and Yellow Submarine, Resi showed only weak K fertilization effects on fruit quality aspects. Therefore, in a second experiment we grew the cultivars Primavera and Resi with two K doses (deficient and well-fertilized). In a third treatment, we interrupted K fertilization in order to induce a response in the cv. Resi to a sudden shortage of K. In contrast to Primavera, Resi showed no yield response to K fertilization like in the first experiment. The low yielding cv. Resi seemed to be more K efficient compared to Primavera. We conclude that the effect of K on yield and quality of cocktail tomatoes depends on the cultivar. [ABSTRACT FROM AUTHOR]

The macronutrient potassium (K) has vital physiological functions in plants and its availability can strongly impact quality of crops like tomato. The impact of K nutrition on conventional tomato fruit quality parameters has been described several times, but detailed investigations on the effect of K supply on the fruit metabolite profile are still rare. To fill this gap, we investigated the influence of K fertilization on the metabolite profile of tomato fruits. For this purpose, an outdoor pot experiment with three different cocktail tomato cultivars was performed. A fertilization regimen with five K levels was applied, ranging from deficiency to sufficient supply. Fruit samples were analyzed by untargeted GC×GC-MS to cover the primary metabolite profile as well as some secondary metabolites. As verified using ICP-OES, fruit K content was highly proportional to the supplied amount of K. At the metabolite profile level, the most prominent and cultivar-independent effect of increased K fertilization was the rise of tricarboxylic acid (TCA) cycle intermediates. Further effects were more cultivar-specific, for example an increase of the mobile nitrogen pool (e.g. amines like putrescine and amides like asparagine), changes in the profile of minor sugars (especially disaccharides) as well as higher levels of some secondary metabolites. Pronounced response patterns were mainly observed in the cultivars Primavera and Yellow Submarine that were recently characterized as higher yielding, demanding a stronger consideration of cultivar differences in future studies. • The impact of potassium (K) supply on tomato fruit metabolome was evaluated. • In a pot experiment with 5 K levels, 3 cocktail tomato cultivars were assessed. • Metabolites and minerals were determined by GCxGC-MS and ICP-OES, respectively. • Some TCA cycle intermediates were correlated with K supply in all cultivars. • Other metabolites exhibited a more cultivar-specific K effect. [ABSTRACT FROM AUTHOR]