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Tomato (Solanum lycopersicum) fruit quality and yield are highly dependent on adequate uptake of nutrients. Potassium, magnesium and calcium are essential elements that influence fruit quality traits such as colour, uniformity of ripening, hollow fruit, fruit shape, firmness and acidity. Sodium is not an essential element for tomato and can detrimentally compete with the absorption of potassium and calcium. Daily intakes of potassium, magnesium and calcium in human diets are typically below healthful levels, while sodium intake is often excessive. The objective of this study was to compare 52 diverse commercially important varieties of tomato for concentrations of potassium, magnesium, calcium and sodium in fruits. The tomatoes were produced in replicated plots in Geneva, NY in 2010 and 2011. Multiple fruits per plot were harvested vine-ripe, homogenized and assayed for cations. Analysis of variance showed significant differences among the 52 varieties for all four traits, i.e. cation concentrations (df = 51, P < 0.0001–0.0034) and no significant differences between years for any trait (df = 1, P = 0.3432–0.6770). Factor analysis showed a strong interrelationship between potassium and magnesium that was independent of calcium and sodium. Potassium and magnesium were highly significantly correlated with each other (r = 0.64, P < 0.0001). No other correlations between pairs of traits were observed. Results supported a genetic basis for potassium, magnesium, calcium and sodium concentrations that was consistent across environments (i.e. years). Results can contribute to the development of cultivars with favourable cation profiles in terms of human health and fruit quality. [ABSTRACT FROM AUTHOR]

This study evaluates the agronomic and morphological traits, chemical composition and traits related to consumer perception of local tomato landraces mostly collected in the suburban area of Madrid. Results showed remarkable variability at all the studied levels in this small area – intra- and inter-accession variability, and in morphological, agronomical and quality traits – and was often dependent on the environmental conditions where the crop was grown. However, few morphotypes could be defined. Some morphological traits of the studied samples seemed to be associated. For instance, ribbed fruits ripened with green shoulder and dark flesh accumulated more soluble solids. Consumer appreciation and fruit morphology, i.e. traits related to fruit size and shape, seemed to be the main determinants of tomato-type definition, although nutrient content also played an important role. Consumers positively received heirloom tomatoes, especially when they were cultivated in the open-field near their area of selection where they express their full potential in the nutrient synthesis and sensory properties. Although total soluble solids content seems to be the main trait related to appreciation, some morphological traits could be determinant in consumers’ choice. Furthermore, some consumers were more interested in different tomato typologies and nutritional characters like acidity. [ABSTRACT FROM AUTHOR]

The importance of plant genetic resources for the future of agricultural production and for achieving food security necessitates the study of the factors affecting their most efficient exploitation, particularly in breeding programmes. The established negative correlation between competitive and yielding ability is emerging as an important, yet overlooked cause of seed and variety degradation. Because of this negative correlation, the low yielding, strong competing plants within the variety or the germplasm under study acquire a survival advantage over the high yielding, weak competing plants when propagated under dense stands, leading to a gradual cultivar degeneration and identity loss. Moreover, this gradual degeneration prevents selecting for the positive and novel adaptive variation that is endlessly released by the genome in response to biotic (e.g. mutating pathogens) and abiotic stresses. The application of nonstop selection on individual plants grown in the absence of competition using a novel selection equation demonstrates an effective means to counteract the negative effects and accelerate progress through selection. [ABSTRACT FROM AUTHOR]