This poster was presented by David Byrnes of Rutgers, the State University of New Jersey, at the 2017 National Association of Plant Breeders meeting in Davis, California. Byrnes is a collaborator on the Horticulture Innovation Lab project focused on improving nutrition with African indigenous vegetables in Kenya and Zambia. Co-authors on the poster include Fekadu Dinssa, Ondego Nyabinda, Steve Weller, and James Simon.
Genotype, environment, and genotype x environment interaction effects on elemental micronutrient content in vegetable amaranth grown in the United States, Kenya, and Tanzania
Vegetable amaranth (Amaranthus spp.) is a leafy green vegetable consumed in over 50 countries across Sub-Saharan Africa, South Asia, Southeast Asia, and the Caribbean (National Resource Council, 2006). High rates of micronutrient deficiencies in these regions have attracted attention to vegetable amaranth and other culturally preferred vegetable crops as easily available and economically sustainable sources of micronutrients (Weller et al. 2015). The utility of vegetables to maintain or improve micronutrient health status in humans for Feed the Future initiatives and to be marketed as a “source” or “high source” of one or more essential micronutrients by international labeling practices is determined by the values reported in the USDA Nutrient Database for Standard Reference (Codex Alimentarius, 1997; Feed the Future. 2014). This nutrition information is not disaggregated by crop, yet recent observations have shown significant genotype effect in vegetable amaranth for Fe, Ca, Mg, and Zn contents (Byrnes et al., 2017). Assessing the effect of genotype x environment interaction (GEI) is necessary to evaluate the capacity for selecting genotypes for nutrition delivery.
Materials and Methods
All field experiments were arranged in randomized complete block design with three replications. Plants were grown in double rows spaced 30 cm between plants within rows with 14 plants per plot. Five of the 10 interior plants were randomly selected, oven-dried at 40°C, and mill-homogenized. Elemental micronutrient analysis was conducted on foliar subsamples from each genotype by inductively coupled plasma (ICP) mass spectrophotometry.
- NJ13 and NJ15=field-grown Northern New Jersey (Pittstown, NJ); TZ14= field-grown Arusha, Tanzania; KY17=field-grown Turbo, Eldoret County, Kenya
Iron (Fe): Three genotype means exceeded 4.2 mg Fe·100g -1 : ‘Ex-Zan’, ‘Madiira 2’, and ‘RUAM24’.
- RUAM24 had highest mean and insignificant GEI in all trials except for positive GEI in TZ14.
- Ex-Zan had a high mean complemented by low PC score, ‘AC-45’ and ‘Commercial’ had low PC scores but moderate and low Fe content, respectively, each below high source threshold.
- Madiira 2 had the second highest mean due largely to a strong positive GEI in NJ13, yet low stability with all other data points falling below threshold (Fig. 2.), demonstrated by negative GEI in NJ15 and KY17 (Fig. 3.).
Calcium (Ca): All genotypes in all environments were above 300mg Ca·100g -1 threshold, with the exception of KY17, in which only ‘Commercial’ and ‘Local’ entries had means above threshold.
Magnesium (Mg): All genotypes in all trials were above 90mg Mg·100g -1 , GEI effect was significant (P value < 0.001); data not presented.
Zinc (Zn): All genotypes in all trials were below 4.2mg Zn·100g -1 , GEI effect was significant (P value < 0.01); data not presented.
Selection for high and stable elemental micronutrient content is both feasible and necessary in vegetable amaranth. Genotypes ‘Ex-Zan’ and ‘RUAM24’ can be considered candidates to deliver high source levels of three elemental micronutrients commonly associated with deficiencies in humans (Fe, Ca, Mg).
Results from this study show higher Fe, Ca, and Mg content for raw amaranth leaves than USDA Standard Reference data from 2016.