Sponsoring Institution
National Institute of Food and Agriculture
Project Status
Funding Source
Reporting Frequency
Accession No.
Grant No.
Project No.
Proposal No.
Multistate No.
Program Code
Project Start Date
Oct 1, 2001
Project End Date
Sep 30, 2004
Grant Year
Project Director
Kopsell, D. A.
Recipient Organization
Performing Department
Non Technical Summary
The vegetables Brassicas are significant sources of RDA nutrients as well as beneficial health promoting phytonutrients, such as carotenoids. But, there is limited information on the genetic and environmental factors affecting the nutritional content of these crops. The purpose of this study is to determine the potential for nutreint and phytonutrient enhancment within B. oleracea L.
Animal Health Component
Research Effort Categories

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
Goals / Objectives
Identification of genetic contributions and environmental influences on the nutritional and phytonutritional content of vegetable Brassica species. Specific project objectives include: 1) Evaluate Brassica species for members with the genetic predisposition to accumulate high concentrations of essential mineral elements beneficial to human diets when grown in New England soils; 2) Determine the potential for enhancement of Ca and K in cultivars within B. oleracea subgroups: and 3) Identify genetic and environmental influences on phytochemical accumulation patterns, specifically the carotenoids, within B. oleracea L.
Project Methods
Plant selections of commercially viably Brassica cultivars will be selected and grown during two separate years of cultivar evaluations. The experimental design will be a randomized complete block with 30 plants per replication. Special focus will be placed on both Ca and K accumulation in the edible plant tissues of the crops surveyed. Analysis will consist of biomass evaluations and nutrient analysis. Harvested samples will be oven dried, ground into tissue, and digested for nutrient analysis. After sample preparation and digestion, elemental nutrients will be measured by Inductively Coupled Plasma (ICP) analysis. Two hydroponic greenhouse experiments will determine the potential for Ca and K enhancement within the Brassicas. Plants will be grown in containers holding modified Hoagland's nutrient solutions. Chloride salts of Ca will be used to amend Ca levels in the solution culture experiment. In a second study, chloride salts of K will be used to amend K treatment levels. Treatment concentrations both above and below Hoagland's original solution level will determine the possibility of Ca and K enhancement. Studies will be replicated in randomized complete blocks. Nutrient solutions will be changed periodically to maintain original solution concentrations and quantify nutrient influx into plant tissues. Plants will be measured periodically for nutrient accumulation over the growth cycle. Plants will be separated into different tissues to determine nutrient partitioning patterns. Tissues will be cleaned, dried, and digested before nutrient analysis via ICP. Field experiments will determine the effects of traditional fertilizers on the Ca and K content of the same Brassica subspecies selected for the nutrient solution study. Traditional fertilizer sources of calcium sulfate (gypsum) and potassium sulfate (sulfate of potash) will be used to increases in Ca and K fertility in field evaluations. The experiment will involve two separate years of evaluations. The experimental design will be a randomized complete block with 30 plants per replication. Two separate years of evaluations will be conducted. Differences in yield between treatments will be measured at harvest and tissues will be collected for nutrient analysis using ICP. Cultivars grown under the first objective will also be measured for carotenoid compounds. Carotenoids are plant pigments and are usually found in highest concentrations in leaf tissues. Representative leaf tissue samples will be taken from each plant and extracted with acetone and hexane. After extraction, the plants will be measured for carotenoid compounds through HPLC analysis. Reduction in plant S would reduce the bitter flavors that may influence consumer acceptance. Kale will be hydroponically grown in a modified Hoagland's nutrient solution under decreasing S fertility levels. Treatments will be arranged in a randomized complete block under greenhouse environmental conditions. Total S and other nutrients in leaf tissues will be analyzed using ICP. Carotenoid compounds will be identified using reverse phase HPLC.

Progress 10/01/01 to 09/30/04

Projects have determined the impacts of genetic and environmental influences on elemental and phytochemical contents of vegetable Brasscias. Twenty-two kale and collard cultivars and selections suitable for the NE were evaluated for elemental accumulation over two growing seasons. On average, a two-fold difference in Ca, Mg, K, Fe, and Zn elemental concentrations among the cultivars and selections was measured. 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 did not change from year 1 to year 2. Information on genotypic variability for elemental accumulation and opportunities for cultivar selection has been provided to NH and NE producers through publications, presentations, and web-page dissemination. Kale and other Brassicas can deliver high amounts of bioavailable Ca to human diets. The potential to enhance Ca in kale tissues was evaluated in both field and greenhouse studies. Kale leaf tissue Ca increased significantly when Ca soil applications increased from 75 to 300 kg Ca per hectare. However, there were no differences in leaf tissue Ca among three different Ca fertilizer carriers (CaNO3, CaSO4, and CaCl2). Results indicate that producers can modify the levels of Ca in kale leaf tissue through higher Ca application rates. The treatment dose response in Ca leaf tissue accumulation was confirmed in greenhouse studies using nutrient solution culture. The same 22 kale and collard cultivars were screened for levels of carotenoid phytochemicals. The cultivars differed significantly for lutein and beta-carotene accumulation. There was a significant difference in carotenoid accumulations between two consecutive years of field evaluations, but rank order among the cultigens for both lutein and beta-carotene did not change between the years. Stability in the rank order of the cultivars for leaf tissue carotenoids has been shared with stakeholders and will allow them to make educated decisions on appropriate kale cultivar selections for their operations. We also measured the environmental influence of sulfur fertility on the carotneogenesis. Sulfur is responsible for the characteristic flavors found in the Brassica crops. We showed that the flavor compounds present in kale were influenced by sulfur fertility. The more sulfur present, the more bitter, or stronger the taste perception. However, the carotenoid phytochemicals were not affected by sulfur fertility. People list objectionable taste as the main reason for not eating more Brassica vegetables. Our study showed that flavor intensity can be modified through fertility management, while retaining high levels of valuable carotenoids. This research was demonstrated on three separate NH farms in conjunction with annual vegetable grower twilight extension meetings during the summer of 2003. These activities were attended by over 200 people. These results may also be applicable to other production areas and growers who wish to produce green-leafy Brassica vegetables with enhanced levels of nutritionally-valuable carotenoid phytochemcials.

Information from these studies has made an impact on cultural management practices and cultivar selections made by NH and NE vegetable producers. Research results have been provided to stakeholders through publications and web-site dissemination. On-farm research demonstrations on three NH farms were attended by over 200 people during the summer of 2003. Our results continue to highlight the nutritional value of the vegetable Brassicas and both genetic and environmental influences that impact nutritional value.


  • Kopsell, D.A., D.E. Kopsell, M.G. Lefsrud, J. Curran-Celentano, and L. Dukach. 2004. Variation in lutein, beta-carotene, and chlorophyll concentrations among Brassica oleracea cultigens and seasons. HortScience 39(2):361-364. Kopsell, D.E., D.A. Kopsell, M.G. Lefsrud, and J. Curran-celentano. 2004. Variability in elemental accumulations among leafy Brassica oleracea cultivars and selections. J. Plant Nutr. 27(10):1813-1826.
  • Kopsell, D.E., D.A. Kopsell, W.M. Randle, T.W. Coolong, C.E. Sams, and J. Curran-Celentano. 2003. Kale carotenoids remain stable while flavor compounds respond to changes in sulfur fertility. J. Ag. Food Chem. 51(18):5319-5325. Kopsell, D.E. and D.A. Kopsell. 2004. It's in the leaves: high levels of carotenoids are found in dark-green leaves of spinach and kale. American Vegetable Grower May 2004:28.
  • Kopsell, D.E., D.A. Kopsell, and J. Curran-Celentano. 2004. Carotenoid variability among kale and spinach cultivars. HortScience 39(2):458.
  • Kopsell, D.E., D.A. Kopsell, J. Curran-Celentano, W. Randle, T. Coolong, and C. Sams. 2004. Sulfur fertility influences kale flavor but not carotenoid content. HortScience 39(2):458-459.

Progress 10/01/02 to 09/30/03

We have finished evaluation of Brassica oleracea germplasm for the accumulation of Ca, Mg, K, Fe and Zn. We have also screened the germplasm for phytonutrient carotenoids, such as lutein and beta-carotene. Work is now complete on the potential for Ca enhancement in kale (Brassica oleracea var. Acephala). Lastly, we have participated in outreach activities to demonstrate our research finding and educate the stakeholders of the state of New Hampshire. Twenty-three different B. oleracea cultigens showed significant genetic variation for mineral element accumulation of Ca, Mg, K, Fe, and Zn. On average, a 2.4-fold difference in mineral accumulation between the B. oleracea cultigens was measured over two separate years of evaluation. The same cultigens also differed significantly for lutein and beta-carotene accumulation. Most notable for both studies was the fact that the rank order of the cultigens did not change from year to year for the accumulation of Ca, Mg, K, Fe, Zn, lutein, or beta-carotene. Separate research manuscripts have been published on the results. Information on the genotypic variability present within cultigens of leafy B. oleracea may be important for plant breeders, producers, and consumers. Choice of B. oleracea cultigen will influence nutritional and phytonutritional qualities. Results from these studies have been made available through publication and web-site dissemination. Kale leaf tissue Ca did not differ between three commercial Ca fertilizer sources, but did respond to increases in Ca application rates from 75 to 300 kg per hectare between two separate years of evaluation. Kale plants were also grown in nutrient solutions under 1.0, 2.5, 4.0, 5.5, and 7.0 mmol Ca to determine Ca uptake, accumulation, and partitioning in plant tissues. Mean total Ca depletion from solutions was increased with increasing Ca treatment concentrations. Ca accumulation in leaf tissues was significantly higher for the highest three levels at the final harvest date compared to the lowest two levels. Results indicate it is possible to enhance Ca levels in kale by increasing the concentration of Ca in the nutrient solutions. These studies are part of a thesis project which we anticipate will be completed in the upcoming year. Results from our previous studies on the influence of sulfur on carotenoid and glucosinolate production in kale were demonstrated on three separate NH vegetable farms last summer. Research demonstration plots were planted in conjunction with annual vegetable grower twilight meetings in Moultonboro, Peterborough, and Dalton, NH. Growers and public stakeholders were allowed to taste the flavor differences between three commercial kale cultivars grown under increasing S fertility. Research results and background information on the nutritional values of kale were also presented. Results demonstrated that decreases in S fertility decreased bitterness in kale, but did not decrease the concentration of beneficial carotenoid compounds.

Results for the current projects have directly impacted vegetable growers in New Hampshire and the New England region. Results for the cultigen evaluations have been provided to stakeholders through publications and web-site dissemination. We have also demonstrated important research projects directly to NH growers during annual vegetable grower organizational meetings. We made a significant impact through farm demonstrations and taste evaluations of kale plants grown in commercial settings. Our results continue to highlight the nutritional value of the vegetbale brassicas. We have enforced both genetic and environmental influences that impact the nutritional value of leafy brassicas. Simple cultivar selection and fertility modifications are cultural practices that are easily manipulated by commercial growers in order to provide the highest quality produce.


  • Kopsell, D.A. and D.E. Kopsell. 2003. Variability in lutein and beta-carotene accumulation among leafy Brassica oleracea cultigens. HortScience 38(5):677.
  • Kopsell, D.E. and D.A. Kopsell. 2003. Kale carotenoids remain stable while flavor compounds respond to sulfur fertility. HortScience 38(5):830.
  • Hunt, L. and D.A. Kopsell. 2003. Calcium application rates significantly increased leaf tissue Ca in filed-grown kale. HortScience 38(5):766.
  • Kopsell, D.A., D.E. Kopsell, and J. Curran-Celentano. 2003. Iron fertility affects chlorophyll and carotenoid pigments in kale (Brassica oleracea L. Acephala Group). HortScience 38(3):489-490.
  • Kopsell, D.E., D.A. Kopsell, and J. Curran-Celentano. 2003. Magnesium fertility affects elemental content but not carotenoid pigments in kale. HortScience 38(3):490.
  • Hunt, L. and D.A. Kopsell. 2003. Uptake and accumulation of calcium in kale (Brassica oleracea L. Acephala Group). HortScience 38(3):488.
  • Kopsell, D.A., J. Curran-Celentano, and J. Sheehan. 2002. Influences of nitrogen form on elemental content, pigmentation, and carotenoid accumulation among kale (B. oleracea Acephala Group) cultivars. HortScience 37(3):442.

Progress 10/01/01 to 09/30/02

There has been great progress towards the research goals of my AES Hatch (H-422) project. We have completed several of the proposed studies and many more are on-going and approaching a conclusion. We have prepared several manuscripts from these projects and have plans for submission to scientific journals in the upcoming year. We have recently completed our genetic/cultivar evaluation of commercially viable Kale (Brassica oleracea L. Acephala Group). We evaluated 23 different Kale cultivars for beneficial lutein and beta-carotene carotenoids. Our analysis revealed a 2.4 fold difference in lutein and a 2.5 fold difference in beta-carotene among the Kale cultivars. More significant was the fact that the rank order of the cultivars for lutein and beta-carotene accumulation did not change during our two-year evaluation. Results from this study demonstrate that vegetable growers can maximize the nutritional attributes of kale through proper cultivar evaluation. Recommendations to commercial growers will be made in the upcoming year. We have also assessed the influence of environmental growing factors on the accumulation of lutein and beta-carotene carotenoids in Kale. We have successfully completed a study which measured the effect of increased sulfur (S) fertility on the production of beneficial carotenoids. Our results showed no significant changes to lutein and beta-carotene production in Kale over a wide range of sulfur treatment concentrations. Collaborative research during this study also helped to measure the flavor attributes associated with different sulfur fertility levels. Sulfur produces the characteristic bitter flavors associated with members of the Brassica family. Our results revealed decreases in methyl cysteine sulfoxide and glucosinolate flavor compounds in Kale under low S fertility. Most consumers report a dislike of Brassica crops due to their bitterness and off-flavors. It is possible to decrease these offensive flavors through S fertility modification. Our results were significant in the fact that decreases in S fertility decreased bitterness in Kale, but did not decrease the concentration of beneficial carotenoid compounds. This may result in greater consumer acceptance of Kale and increase the delivery of carotenoid compounds to the diet. Research is continuing on projects assessing the potential for nutrient enhancement in Kale. The physiological makeup of Kale allows for high bioavailability of important nutrient elements, such as calcium (Ca), magnesium (Mg), and potassium (K). Field and greenhouse studies focusing on the potential for Ca enhancement in Kale are now complete and are in the initial stages of data analysis. Two separate years of a field study measured the effects of Ca fertilizer form and concentration on Ca enhancement in Kale. A similar hydroponic greenhouse study was conducted to measure Ca uptake, accumulation, and partitioning in the tissue of Kale. Information from these studies will be helpful to growers who wish to produce and market value-added Kale, or other green-leafy vegetables, as phytonutritionally enhanced for improved human health.

Current results for this project will directly impact commercial vegetbale growers in the state of New Hapmshire and the New England region. We have demonstrated that cultivar selection is vital to producing Kale that has high levels of nutritionally benefical lutein and beta-carotene carotenoids. Proper fertility management by producers will also affect flavor and nutritional attributes of Kale. This information will allow commercial vegetbale growers to produce superior leafy vegetbale crops that can establish a advantagious marketing nitch.


  • No publications reported this period