Mineral Concentration of Broccoli Heads in Relation to Year of Cultivar Release

It has been suggested that breeding for yield in agronomic and horticultural crops has resulted in decreases in mineral nutrient (e.g., calcium, magnesium) concentration of the harvested part of these crops.   Broccoli has been cited as one horticultural crop that has exhibited such nutrient declines.   Most of the claims regarding nutrient decline are based on historical data from United States and European nutrient databases that represent samples taken over many years assayed using variable methods and analytical equipment.   Using historical data to evaluate possible changes over time has been criticized as a use of this data that was never intended.   A better assessment of nutrient changes over time would be accomplished by conducting field tests of different cultivars released in different years but grown in the same environment(s).    Thus, we undertook a study to evaluate mineral concentration of broccoli heads harvested from field-grown hybrids released over the last 30 years as well as from one older open-pollinated population.    Broccoli heads from 14 cultivars were harvested from three replicated trials conducted in three fall environments in South Carolina.   Concentrations of Ca, Cu, Fe, K, Mg, Mn, Mo, Na, P, S, and Zn were determined on a dry mass basis using ICP-OES.   Observations indicate there were no consistent trends for all minerals as a function of year of cultivar release.    In some years and with some minerals, older cultivars had the highest concentrations, while for other minerals the newer cultivars had the highest concentrations.    Results do not appear to support a general concept of nutrient decline in broccoli associated with modern crop improvement.