Nitrogen availability and genotype affect major nutritional quality parameters of tef grain grown under irrigation

Abstract

Worldwide demand for tef (Eragrostis tef) as a functional food for human consumption is increasing, thanks to its nutritional benefits and gluten-free properties. As a result, tef in now grown outside its native environment in Ethiopia and thus information is required regarding plant nutrition demands in these areas, as well as resulting grain health-related composition. In the current work, two tef genotypes were grown in Israel under irrigation in two platforms, plots in the field and pots in a greenhouse, with four and five nitrogen treatments, respectively. Nutritional and health-related quality traits were analyzed, including mineral content, fatty acid composition, hydrophilic and lipophilic antioxidative capacity, total phenolic content and basic polyphenolic profile. Our results show that tef genotypes differ in their nutritional composition, e.g. higher phenolic contents in the brown compared to the white genotype. Additionally, nitrogen availability positively affected grain fatty acid composition and iron levels in both experiments, while negatively affecting total phenolics in the field trials. To conclude, nitrogen fertilization is crucial for crop growth and productivity, however it also implicates nutritional value of the grains as food. These effects should be considered when fertilizing tef with nitrogen, to optimize both crop productivity and nutritional effects. Tef (Eragrostis tef) is an annual tropical Poaceae cereal, grown in a wide range of environments, and used throughout the world as grain for human consumption 1. Tef is indigenous to Ethiopia 2 , where it is a staple food for majority of Ethiopians and for millions of people in the semi-arid regions of the world 1. From a nutritional point of view, tef is naturally gluten free 3,4 , with a low glycemic index 5. It is rich in important minerals such as iron (Fe), calcium (Ca), potassium (K) and zinc (Zn) 6-10 as well as in copper (Cu), phosphorous (P) and magnesium (Mg) 11. Tef also contains remarkable levels of vitamin C, niacin, vitamin A, riboflavin and thiamin 12,13. It has an average of 10.4% protein, 2.3% fat and 3.3% fiber 12,13 and is rich in oleic and linoleic acid 14 , unsaturated essential fatty acids. Tef protein has an excellent amino acid composition, including all 8 essential amino acids and relatively high in lysine 15. These data suggest that tef is as nutritious as or better than the major western staple cereals such as wheat, rice, oats and barley. It is preferred by celiac disease patients as it is consumed as a whole grain, and thus provides much higher nutritional value compared to other components of gluten-free diets 16. It was also suggested to be incorporated into bread made of other cereal, to increase their health benefits 17,18 and sensory quality 19. Furthermore, tef is rich in phenolic acids and flavonoids, which consumption was correlated with lower incidence of chronic diseases (diabetes, cardiovascular, cancer) possibly thanks to their bioactivity as antioxidants and anti-inflammatory 20. Tef genotypes v...

Durum Wheat Grain Yield and Quality under Low and High Nitrogen Conditions: Insights into Natural Variation in Low- and High-Yielding Genotypes

“…Few studies have analyzed the effect of N fertilization on polyphenols in grains, with their results being divergent. Engert et al [2] and Ma et al [28] found that total phenolics increased in wheat grains due to N fertilization, while N availability affected negatively total phenolics in tef grains [64] and sesame seeds [65]. Stumpf et al [66] found, on the contrary, that total phenolic concentration was not affected by N treatment in wheat grains.…”

Nutritional Values of Teff (Eragrostis tef) in Diabetic Patients: Narrative Review

“…51 Available studies support the idea that diabetic patients can get enough amount of essential fatty acids from teff and it is a promising food type used to manage acute and chronic diabetic complications. 2,20,52,53…”

Water-soluble total sugars and total free amino acids of the two varieties of teff [Eragrostic tef (Zuccagni) Trotter] cultivated in different regions of Ethiopia

“…Teff is a warm-season annual cereal and the only cultivated species in the genus Eragrostis which has originated in Ethiopia [14][15][16][17]. It is a whole grain and superior than other cereals due to being naturally gluten free and is the dominant source of nutrients like carbohydrates, amino acids, minerals, dietary fibers, proteins, dietary polyphenols, starch, and vitamins [5,16,18,19], volatiles like aldehydes, ketones and alcohols [16], and is rich in unsaturated fatty acids like linoleic, oleic and linolenic acids [17,20]. The ratio of ω-6/ω-3 found in the white and brown teff flour was almost consistent with the suggested 1-2:1 ratio and is recommendable for the normal human growth and development.…”