Biochemical Characterization of Ethiopian Black Cumin (Nigella sativa L.).

Black cumin (Nigella sativa L.) seed oil has been used for its medicinal and aromatic values. Some studies revealed the presence of variability among N. sativa genotypes in seed oil content and yield. In Ethiopia, very few studies were conducted to investigate the variability of N. sativa genotypes by using biochemical traits. Thus, this study was conducted at Debre Zeit and Kulumsa Agricultural Research Centers' experimental sites under field conditions during the 2021 cropping season to investigate the variability of Ethiopian N. sativa genotypes based on biochemical traits. Sixty-four genotypes were used and arranged in an 8 × 8 simple lattice design with two replications. Essential oils (EOs) and fixed oils were extracted by the respective methods of hydro distillation and solvent extraction. The univariate, bivariate, and multivariate analyses of the collected data were performed. Combined analysis of variance (ANOVA) revealed significant differences among genotypes in fixed oil yield per hectare (FOY), EO content (EOC), and EO yield per hectare (EOY). EOY had a significant positive correlation with FOY and EOC. It is expected to improve all biochemical traits by 17.39%-94.62% over the improved varieties by selection of the top 5% landraces. Therefore, genotypes 90504, 219970, and 013_ATH were the top 5% best performed landraces by FOY and EOY over the improved varieties. So, through selection, it would also be possible to improve the studied biochemical traits of the genotypes. The principal component (PC) analysis (PCA) of four biochemical traits showed 85.86% of the total variance captured by the first two PCs. EOY and FOY were the main contributor traits to the variation in the first PC, whereas FOC and EOC were the main contributor traits to the variation in the second PC. The genotypes were grouped into three different clusters based on four biochemical traits with significant intercluster distance. This showed that there was sufficient diversity among the genotypes which can be exploited for the future N. sativa improvement program in Ethiopia.

Influence of nitrogen fertilizer rate and variety on tef [Eragrostis tef (Zucc.) Trotter] nutritional composition and sensory quality of a staple bread (Injera).

In Ethiopia, tef is one of the major staple crops used as a basic raw material for food development such as stable bread called injera. Studies reported that imbalanced N fertilizer reduces the overall deliciousness of grains. Nowadays nitrogenous fertilizers are considered as the source of variation for the quality of injera, Ethiopian traditional flat bread. Therefore, a field experiment was conducted to assess the effects of N fertilizer rates (0, 30, 60, 90, and 120 kg N ha-1) on grain nutrition and sensory quality of injera of three tef varieties of (Kora, Boset, and Asgori). The experiment was conducted in main cropping season in Randomized Complete Block Design with three replications and Di-ammonium Phosphate was used in the same dose. Crop attribute parameters were determined using standard methods. Sensory quality and color of injera were determined by panelists and injera eye software respectively. Results showed that only protein content increased with nitrogen rates, while carbohydrate decreased significantly at (P < 0.05). Kora at the control plot (K0) had better color, flavor, texture, and taste values of injera, but they decreased with nitrogen rates. Injera from white tef varieties had a better acceptance as compared with Asgori red tef variety. Injera eye software indicated that the color of injera was significantly affected by varieties. Kora had a higher (55.74) lightness value followed by Boset (54.71), and Asgori (51.26). Injera from the Asgori variety had a maximum red color. Kora and Boset had higher yellow color on the control plot, but for Asgori it increased with the nitrogen rate.

Preference and perception of value chain actors to quality parameters and factors affecting the quality of tef (Eragrostis tef (Zucc. Trotter) in Central and Northwestern Ethiopia.

Tef grain color is considered as the dominant parameter in the trading and price setting on the local markets. However, there are no comprehensive studies conducted so far on the preference and perception of actors on tef grain quality attributes and factors affecting it. Its implicitly assumed that other quality parameters also play a role in the value chain of tef. Using semi-structured questionnaires, this study researched the parameters and factors affecting the quality of tef, perceived by farmers, traders, and consumers in central and northwestern highlands of Ethiopia. Results from this survey indicated that grain color, size, density, shininess, cleanness, purity, and hulledness were the perceived tef grain quality attributes by all respondent groups'. Grain color followed by grain size, cleanness, and purity were the most perceived and directly or indirectly affected the price setting of tef. Farmer and trader respondents' perception for tef color was mainly dependent on their clients' (consumers). However farmer preferred the brown color tef for their consumption. Trader respondents categorized their client's preference of grain color on the income level as high, medium and low-income consumers. The high-income consumers mostly preferred the whitish color; middle-income for the mixed and brown color; and low-income for the brown color tef. The perception between farmer and trader, farmer and consumer, and trader and consumer as well as the same group of respondents living in different areas showed significantly (p < 0.05 to p < 0.0001) different on most of grain quality attributes. Nevertheless, there was no preference variability on grain color and density between farmer and trader respondents. While there were considerable differences in the color of tef between farmer and consumer and trader and consumer respondents. However, between the central and northwestern highland farmers (grain color, density and cleanness, traders, (color and cleanness), and consumer (color, density, purity, and hulledness) did not show considerable differences. From respondents, 100% of farmers, 97.7% of traders, and 93.3% of consumers perceived that grain quality variability comes from the variability of production area. Soil types, topography, and climatic factors were the main perceived causes for the variability of quality. Ninety eight percent of farmer and 100% of trader respondents perceived that black and brown color soils produced tef had highest quality in terms of whiteness or brightness as compared to tef produced on red soils. All respondent groups were also perceived that the quality of injera affected by tef grain quality. To better connect the value chain actors to the needs and preferences of tef grain and the economy in Ethiopia; the quality attributes like grain size, density, and shininess which affect the price of tef needs consideration in Ethiopian tef breeding program. The effects of soil type, agroecology, and crop variety should also be tested experimentally for a better understanding of factors influencing tef grain physical quality.