Characterization of Mineral Nutrients in National Plant Germplasm System (NPGS) Tomato Varieties

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 color, uniformity of ripening, hollow fruit, fruit shape, firmness, and acidity.  Sodium is not an essential element for tomato and can detrimentally compete with 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 commercial 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.  ANOVA showed significant differences among the 52 varieties for all four traits, i.e., cation concentrations (df = 51, p < 0.0001 to 0.0034) and no significant differences between years for any trait (df = 1, p = 0.3432 to 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.   Results will provide insight for development of cultivars with favorable cation profiles in terms of human health and fruit quality.