Variability in Elemental Accumulations Among Leafy Brassica oleracea Cultivars and Selections

Abstract

The vegetable brassicas are consumed in part for their nutritional values of calcium (Ca), magnesium (Mg), potassium (K), iron (Fe), and zinc (Zn). However, information on the genetic variability of elemental accumulation within kale and collards (Brassica oleracea L. var. acephala DC) is limited. Therefore, 22 kale and collard cultivars and selections suitable for the northeastern United States were field grown under similar fertility regimes over two years and evaluated for elemental accumulation. Leaf tissues were analyzed using inductively coupled argon plasma–atomic emission spectrometry. Significant variability among cultivars and selections was observed for tissue Ca, Mg, K, Fe, and Zn. On average, a two-fold difference in elemental accumulation among the cultivars and selections was measured. Tissue Ca levels ranged from 1.2 (“Crimson Garden”) to 3.1% (“NZ Thousand Head”), tissue Mg ranged from 0.3 (“Crimson Garden”) to 0.6% (“NZ Thousand Head”), tissue K ranged from 2.1 (“NZ Thousand Head”) to 3.5% (30665-96G11), tissue Fe ranged from 53.1 (“Winterbor F1”) to 114.2 mg/kg (“Giant Jersey Kale”), and tissue Zn ranged from 29.1 (“Shetland”) to 71.9 mg/kg (“Redbor F1”). Significant year-to-year variability occurred for Ca, Mg, Fe, and Zn accumulation. Despite these yearly changes, ranking of the cultivars and selections for elemental accumulation, as determined by Spearman's rank correlation coefficient, did not change from year 1 to year 2. Overall, the cultivar with the highest elemental leaf accumulation was “Redbor F1”. Information on genotypic variability for elemental accumulation may be important for producers and consumers looking to select kale and collards with higher nutritional levels of beneficial dietary elements.

Keywords:

• Collards
• Human health
• Inductively-coupled plasma spectrophotometry
• Kale
• Macronutrients
• Micronutrients

Acknowledgments

This article was funded by a grant received from the Cooperative State Research, Education, and Extension Service, U.S. Department of Agriculture, under Agreement No. 2001-52102-11254. This publication is Scientific Contribution Number 2197 from the New Hampshire Agricultural Experiment Station. The authors thank the Northeastern Regional Plant Introduction Station, USDA-ARS Plant Genetic Resources Unit, Cornell University, Geneva, NY, for seed used in this study, and John McLean, Evan Ford, and the Woodman Horticultural Research Farm at UNH for their technical support of this research.