Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 15, 2000
Publication Date: N/A
Interpretive Summary: Calcium and magnesium are essential minerals in the human diet. Calcium is particularly important because a lack of this mineral can lead to increased risk of osteoporosis late in life. Although Americans meet most of their calcium and magnesium needs by consuming dairy products, a significant amount of these minerals can be obtained by eating certain vegetables, like broccoli that are rich sources of them. Indeed, vegetables like broccoli are important sources of calcium and magnesium for people that consume little or no dairy products. It is possible that plant scientists could improve the calcium and magnesium content of this crop through breeding and genetics. However, it is important to first determine if different varieties of broccoli have different concentrations of calcium and magnesium and if the environment in which a variety is grown influences the concentration of these minerals. Our results indicate that both the variety and the environment influence mineral concentration of broccoli heads. We also found that on average, people derive about 30 milligrams of calcium and 20 milligrams of magnesium when 100 grams of broccoli is consumed although this can very by as much as two times depending on the source of broccoli. These findings provide plant scientists with basic information necessary to initiate the improvement of broccoli for calcium and magnesium content. Such efforts will ultimately lead to the enhancement of broccoli as an even more nutritious vegetable for human nutrition and health.
Technical Abstract: Broccoli is a good vegetable source of calcium (Ca) and magnesium (Mg), two critical minerals in human nutrition. Bioavailability of Ca from broccoli is comparable to that from milk, and thus, broccoli is an alternative source of Ca for people that consume limited amounts of or no dairy products. Nothing is known about the influence of genetics and environment on Ca or Mg concentration of broccoli heads. Thus, the goal of this research was to examine head Ca and also Mg concentrations in a collection of USDA inbreds and commercial hybrids in field environments. In 1996 and 1997 field studies, significant differences among inbred entries and among hybrid entries were observed for Ca and Mg concentrations of broccoli heads. With hybrids and inbreds, mean head Ca concentrations were approximately 3.0 mg/g DW, and entries with lowest and highest Ca concentrations differed more than two-fold. Mean Mg concentrations of hybrid heads was 2.3 mg/g DW (range 1.8 to 2.6) and 2.8 mg/g DW (range 2.2 to 3.7) in 1996 and 1997, respectively. Inbred lines had mean head Mg concentrations of 2.0 and 2.6 mg/g DW in the two respective years and ranges in concentration were similar as for hybrids. Analysis of variance indicated significant environment and entry by environment effects for Ca and Mg concentrations of hybrids. With inbreds, a significant entry by environment effect for Ca concentration and environment effect for Mg concentration was also observed. Significant environment and entry by environment effects indicate that the environmental influence on phenotypic expression of Ca and Mg concentrations may complicate genetic improvement of head mineral concentration.