agronomy
Article Teff Grain Physical and Chemical Quality Responses to Soil Physicochemical Properties and the Environment
Anteneh Abewa 1,2, Enyew Adgo 2 , Birru Yitaferu 1, Getachew Alemayehu 3, Kebebew Assefa 4, Juan K. Q. Solomon 5,* and William Payne 6
1 Amhara Agricultural Research Institute (ARARI), Bahir Dar, Ethiopia; [email protected] (A.A.); [email protected] (B.Y.) 2 Department of Natural Resource Management, Bahir Dar University, Bahir Dar, Ethiopia; [email protected] 3 Department of Plant Science, Bahir Dar University, Bahir Dar, Ethiopia; [email protected] 4 Ethiopian Institute of Agricultural Research, Debre Zeit Agricultural Research Center, Bishoftu, Ethiopia; [email protected] 5 Department of Agriculture, Veterinary & Rangeland Sciences, University of Nevada, Reno, NV 89557, USA 6 College of Agriculture, Biotechnology & Natural Resources, University of Nevada, Reno, NV 89557, USA; [email protected] * Correspondence: [email protected]; Tel.: +1-775-784-6888
Received: 24 March 2019; Accepted: 29 May 2019; Published: 31 May 2019
Abstract: Teff is the only cultivated cereal crop from the genus Eragrostis and it is the major staple food of Ethiopians. In Ethiopia, the quality of teff and its market price are primarily determined by its grain color. The objective of this study was to evaluate the effects of soil physicochemical characteristics across multiple locations in the two main teff growing regions of Amhara and Oromia states in Ethiopia on teff grain color and nutritional quality of a single variety. Grain and soil samples were collected from 24 field sites cultivated with the popular teff variety ‘Quncho’ (DZ-Cr-387/RIL-355). The teff grain samples collected from the 24 locations were evaluated for grain color, proximate composition, amino acid composition, and grain mineral concentration and the soil samples were analyzed for their physicochemical properties. Sample location means were considered different p < 0.05. Teff grain color indices of hue (H), saturation (S), and brightness (V), grain proximate composition, amino acid composition, and mineral concentration differed among locations (p < 0.05). There were significant negative correlations between grain S color value and soil pH, SOC, Ca, Mg, S, and Na. Soils with greater pH, SOC, Ca, Mg, and S generally had lower S values and thus, whiter color teff grains. There were considerable variations in the measured parameters for soil and teff grain physicochemical properties. The results indicated an opportunity for management interventions necessary to obtain uniformity in grain color and chemical composition for the same variety of teff grown in the two major regions in Ethiopia.
Keywords: teff; grain color; grain mineral nutrient; grain proximate composition; amino acids; soil physicochemical properties
1. Introduction Teff [Eragrostis Tef (Zucc.) Trotter] is the only cultivated cereal crop from the genus Eragrostis [1–4]. It is believed that pre-semantic inhabitants of the Ethiopian highlands domesticated teff around 4000 BC as a food crop [1,5,6] and it has served as the major staple food for Ethiopians for thousands of years.
Agronomy 2019, 9, 283; doi:10.3390/agronomy9060283 www.mdpi.com/journal/agronomy Agronomy 2019, 9, 283 2 of 19
In Ethiopia, the main teff-producing areas have been concentrated in the Amhara and Oromia regional states (the northwestern and central highlands of Ethiopia). Teff cultivation in Amhara and Oromia regional states covered 1.45 (47.8%) and 1.14 million ha (37.6%) of land, respectively, for a combined 2.59 million ha or 87.5% of the total teff cultivation in Ethiopia during the 2017 to 2018 main growing season [7]. Teff grain production from these two main cultivated regions of Amhara and Oromia states were 2.6 (48.9%) and 2.04 million tons (38.6%), respectively, for a total of 4.64 million tons or 87.5% of the total teff production in Ethiopia during the 2017 to 2018 main growing season [7]. Teff grain production ranged from 0.84 to 1.75 tons per hectare annually in Ethiopia depending on location of cultivation and agronomic practices [7]. Almost all the teff grain produced in Ethiopia is mainly used for local consumption in the form of “injera” (a thin, malleable, with many eyes, fermented bubbly spongy type Ethiopian bread) [8]. The major determinants of quality variation of cereal grains are derived from the nutrient composition and physical attributes of the grain [9]. The grain color of teff varies from pale white to ivory white, light tan to dark brown to reddish-brown purple [10–12] and in Ethiopia, the quality of teff grain is determined primarily by its physical attribute of color [13,14]. There are four major categories of teff grain colors specified by the Ethiopian Standard Agency (ESA) and the grains are classified as very white (magna), white (nech), mixed (sergegna) and brown (key) teff [13]. In Ethiopia, grain color is a measure of quality that also dictates the market demand and value. The very white and white teff fetches the highest price and is consumed by the wealthiest individuals whereas, the brown teff is sold at a lower price to low-income communities [8,15–17]. In Ethiopia, the production area and soil type which is closely correlated with grain color, are intricately linked to the market price of teff grain [8,18,19]. For example, teff cultivated on black and brown soils in Ethiopia has brighter grain color than those produced on red soils and are most preferred by consumers and traders [19]. However, even with the same grain color, there has been a wide range of variability in the nutrient content reported for teff [20–22]. Further, teff has been proposed as an important dietary source of mineral nutrients to combat malnutrition for the populace of developing nations [22]. In particular, the concentrations of calcium, iron, copper, zinc, carbohydrates, and fiber are generally greater than those of other cereal crops [21,23]. Micronutrients such as iron and zinc are considered the most limiting nutrients for children in many communities in developing countries [24] and teff may be the ideal crop for biofortification as a sustainable and cost-effective strategy to curtailed micronutrient malnutrition that affects approximately 2 billion people globally [25,26]. Further, among female athletes from developing nations, only Ethiopian athletes are free of anemia and this was attributed to the consumption of teff [27]. Teff has the potential in reducing iron deficiency anemia diseases by its iron richness [21,28,29] and it is also reported to have a complete set of essential amino acids with excellent composition [21,30–33] and richer in lysine than most other cereals [34]. The qualitative value of teff as a gluten-free grain combined with its nutritional value and health benefits have attracted global interest in its consumption [14,35–37]. Compared to the other major cereal crops, the crude protein, crude fiber, fat and starch concentrations of teff grain are either similar or superior to those of maize, oat, sorghum, wheat and quinoa (false cereal) in general [38]. Globally, the demand for teff grain has increased over the last decade due to the many health benefits of this gluten-free product and as a result of the demand, the Ethiopian government has prohibited the export of teff grain raw material to ensure food security and protection of local markets in Ethiopia. However, the government of Ethiopia did not place a ban on value-added teff hence, teff bread (injera) is exported to the Middle East, Europe, and the United States of America [39]. It is possible that the reported variability in the nutrient content of teff in Ethiopia could be attributed to environmental factors (climatic and edaphic variations) rather than genetic variations. However, there are no studies that have reported on the influence of different environmental factors on variability in teff grain quality in Ethiopia. Most reported research focused on teff nutritional quality based on color [21,22,30,40] and did not address the influence of environmental factors on Agronomy 2019, 9, 283 3 of 19 Agronomy 2019, 9, x FOR PEER REVIEW 3 of 20 physicochemicalgrain nutritional characteristics composition. across Therefore, multiple the locations objective in the of this main study teff growing was to evaluate regions theof Ethiopia effects of soil on teffphysicochemical grain color and characteristics nutritional quality across of multiple a single locationsvariety. in the main teff growing regions of Ethiopia on teff grain color and nutritional quality of a single variety. 2. Materials and Methods 2. Materials and Methods 2.1. Description of the Study Area 2.1. Description of the Study Area This study was carried out in 24 major teff producing areas of Amhara and Oromia regional states of ThisEthiopia study (northwestern was carried out and in 24 central major tehighlandsff producing of areasEthiopia, of Amhara respectively). and Oromia The regional specific states locationsof Ethiopia and known (northwestern names listed and in central parentheses highlands were of Abrja Ethiopia, (Denbia), respectively). Abshem The (Debre specific‐Elias), locations Adet and 1, Adetknown 2, Akaki, names Alemtena, listed in parentheses Arerti 1 (Minjar), were Abrja Arerti (Denbia), 2 (Minjar), Abshem Atsedemariam (Debre-Elias), Adet(Este), 1, AdetBichena, 2, Akaki, BirzakaniAlemtena, (Metekel), Arerti Bishoftu 1 (Minjar), (Ad’a), Arerti 2Bitiejersalafo (Minjar), Atsedemariam (Welenkomi), (Este), Demdengay Bichena, Birzakani(Gonj‐Kollela), (Metekel), FetlokuskuamBishoftu (Ad’a),(Yilmana Bitiejersalafo Densa), Gejagedanba (Welenkomi), (Sebeta), Demdengay Gumdri (Gonj-Kollela), (Dangila), FetlokuskuamSimada (Simada), (Yilmana KosheshilaDensa), (Shebel), Gejagedanba Kudmi (Sebeta), (Mecha), Gumdri Motta, (Dangila), Wondata Simada (Bahir (Simada),Dar), Yubodegabati Kosheshila (Dedi), (Shebel), and Kudmi Zenzelima(Mecha), (Bahir Motta, Dar) Wondata (Figure 1). (Bahir Dar), Yubodegabati (Dedi), and Zenzelima (Bahir Dar) (Figure1).
FigureFigure 1. Grain 1. Grainand soil and collection soil collection sites in sites the intwo the main two teff main growing teff growing regions regions of Amhara of Amhara and Oromia and Oromia states statesin Ethiopia. in Ethiopia.
The areasThe areaswere selected were selected based basedon their on variability their variability of altitude of altitude(1670–2570 (1670–2570 m above msea above level), sea soil level), typessoil (Nitisols–Vertisols), types (Nitisols–Vertisols), annual rainfall annual rainfallamount amount(1000–1960 (1000–1960 mm) and mm) temperatures and temperatures (Table (Table 1). 1). MaximumMaximum temperatures temperatures range range from from39.5 °C 39.5 at◦ CDebre at Debre Elias Eliasto 29 to °C 29 at◦ CMotta at Motta with witha minimum a minimum temperature of 9.8 C at Debre Elias to 1.5 C at Dangla. Rainfall amount varies from 1964 mm (Debre temperature of 9.8 °C at ◦Debre Elias to −1.5 °C− at Dangla.◦ Rainfall amount varies from 1964 mm (Debre Elias)Elias) to 779 to mm 779 (Bishoftu) mm (Bishoftu) (Table (Table 1). The1). areas The areas were were also selected also selected from from the two the regions two regions based based on the on the informationinformation gained gained from fromAddis Addis Ababa Ababa and other and other regional regional markets markets surveyed surveyed [19] and [19] from and frompersonal personal communicationcommunication with withresearchers researchers and zonal and zonal agricultural agricultural experts. experts.
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Table 1. Altitude, rainfall, minimum and maximum temperatures of the two main teff growing regions of Amhara (northwestern highlands) and Oromia (central highlands) in Ethiopia.
Temperature ( C) Annual ◦ Soil Altitude Region Sites Met Station Rainfall Maximum Minimum Type (m) (mm) max Ave min average Amhara Vertisols Abrja Gorgora 1852 1153 36.5 25.2 6.5 11.4 Amhara Nitisols Abshem D/Elias 2234 2291 32.4 24.5 7.0 14.2 Amhara Nitisols Adet 1 Adet 2207 1372 35.5 26.8 3.0 11.0 Amhara Vertisols Adet 2 Adet 2174 1372 35.5 26.8 3.0 11.0 Oromia Vertisols Akaki Akaki 2205 979 32.0 26.7 1.0 10.3 Oromia Vertisols Alemtena Alemtena 1652 809 37.2 29.4 1.0 14.1 Oromia-Amhara Vertisols Arerti 1 Arerti 2152 957 35.0 28.1 4.0 13.6 Oromia-Amhara Vertisols Arerti 2 Arerti 2152 957 35.0 28.1 4.0 13.6 Amhara Vertisols Atsedemariam Este na na na na na na † Amhara Vertisols Bichena Bichena 2543 1130 33.0 23.7 5.0 11.5 Amhara Regosols Birzakani Chagni 1677 1856 36.2 28.6 3.0 13.4 Oromia Vertisols Bishoftu Bishoftu 1887 779 39.5 27.0 1.0 11.5 − Oromia Vertisols Bitiejersalafo Wolenkomi 897 na na na na na Amhara Regosols Demdengay Adet 2261 1372 35.5 26.8 3.0 11.0 Amhara Vertisols Fetlokuskuam Adet 2192 1372 35.5 26.8 3.0 11.0 Oromia Vertisols Gejagedanba Sebeta 2148 917 na na na na Amhara Nitisols Gumdri Dangla 2218 1848 32.0 25.5 1.5 10.5 − Amhara Vertisols Kosheshila Bichena 2389 1130 33.0 23.7 5.0 11.5 Amhara Nitisols Kudmi Merawi 1977 1580 33.0 na 2.0 na Amhara Nitisols Motta Motta 2419 1286 32.2 24.5 1.5 10.4 Amhara Vertisols Simada Simada 2574 1017 32.1 na 2.5 na Amhara Vertisols Wondata Bahir Dar 1816 1491 38.5 28.4 0.4 12.7 Oromia Vertisols Yubodegabati Dedi 2172 897 na na na na Amhara Nitisols Zenzelima Bahir Dar 1920 1407 38.5 28.4 0.4 12.7 na, not available. † 2.2. Data Collection, Grain and Soil Nutrient Analysis At each of the 24 field sites, the popular teff variety named ‘Quncho’ (DZ-Cr-387/RIL-355) was earmarked for grain collection due to its white grain color, adaptability to the different agro-ecological zones, and its widespread cultivation across Ethiopia [41]. The recommended fertilizer rate for Vertisols, 1 in Ethiopia, is 60 kg N and 80 kg P2O5 ha− by Debre Zeit Agricultural Research Center and for Nitisols 1 (red soils), is 40 kg N and 60 kg P2O5 ha− by Adet Agricultural Research Center (AARC) in Ethiopia. Diammonium phosphate (DAP) and urea fertilizer materials are the typical sources of the nutrients. While DAP is usually applied once at the time of sowing, split application of urea is the general N management practice, one half at sowing and the other at early tillering. However, in the study areas, the extent to which farmers follow these fertilizer recommendations is not verifiable. Grain sampling was carried out at each of the selected field site (approximately 1 ha in size) and a total of five 1-m2 quadrat samples were collected randomly along a diagonal transect across the field at fixed steps intervals at the time of harvest or physiological maturity (November to December, 2017). The five quadrats samples from each field were then stored separately in a moisture-free area in preparation for seed cleaning. The samples were hand threshed inside cloth bags in order to reduce soil contamination. The threshed grain samples were then manually cleaned by sifting and winnowing to remove dust, chaff, and other materials. Soil samples were randomly collected down to a depth of 20 cm from each field site at the time of grain sampling using a 1.9-cm diameter probe and composited. Further, independent undisturbed core soil samples were taken for bulk density determination to help in soil characterization. The collected samples for soil nutrient analysis were air-dried while those for bulk density determination were oven-dried at 110 ◦C for 24 h at the Adet Agricultural Research Center Soils Laboratory. The soil samples were then ground and sieved through a 2-mm screen before chemical analysis. The soil pH, soil organic carbon (SOC) and cation exchanging capacity (CEC) were determined at the same Laboratory. Total nitrogen (TN) was determined using the Kjeldahl method [42] at Horticoop Soil and Water lab, Bishoftu, Ethiopia. The soil color at each site was determined using the Munsell color chart Agronomy 2019, 9, 283 5 of 19 in dry soil bases. Each sample was analyzed in triplicates for macro and micronutrients (phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), and sodium (Na)) using the Mehlich 3 extraction method (0.2M CH3COOH, 0.25M NH4NO3, 0.015M NH4F, 0.013M HNO3, and 0.001M EDTA adjusted to pH 2.5) [43]. The soil samples were analyzed using inductively coupled plasma atomic emission spectroscopy (Spectro CIROS ICP–AES, Spectro Analytical Instruments, Kleve, Germany). Grain color images were captured using a Tecno-Camon mobile 24 mm pixel camera (Techno Mobile, Hong Kong). The images were first analyzed using RGB (red, green, blue) color detector free software. The RGB color was then converted to HSV (hue, saturation, and value) by RGB to HSV color converter software. The preference for HSV color space was out of the ease of understanding color with the human eyes than other color spaces [44,45]. Ibraheem et al. [45] and Deswal and Sharma [44] described HSV color space as H (hue) measures the purity of a particular color, S (saturation) measures the degree of white color embedded in a specific color and V (value or brightness) detects the intensity of colors. They also noted that V can be used as a luminance which detects what the color brightness is (brightness/lightness or darkness). The value of H is in degree and the S and V values are in percent. In preparation for nutrient analysis, 100 g of teff grain from each field site sample was ground separately using a RIRIHONG high-speed multifunction rotary grain grinder (Shanghai Yuanwo Industrial and Trade Co. LTD, Shanghai, China). One half (50 g) of the ground sample was used for nutrient analysis [43] at the Horticoop Soil and Water Laboratory, Bishoftu, Ethiopia and the other for composition analysis (crude fiber, fat, crude protein (CP), and starch analysis at the Ethiopian Agricultural Research Institute (Addis Ababa, Ethiopia). Grain proximate and amino acids composition were analyzed using 3 g of homogenized teff flour in duplicate. The flour samples were scanned using a Near Infrared Reflectance Spectrophotometer (NIRS) spinning system (FOSS, Model: NIRS system 5000, Hilleroed, Denmark). Samples were placed in ring cups and their spectra were recorded in reflectance mode in the range from 400 to 2500 nm, at 2 nm intervals as described by Agza et al. [46]. The prediction for the collected spectra was carried out using plant-based and aqua feed calibrations developed by the International Livestock Research Institute in collaboration with Ethiopian Institute of Agricultural Research. As described by Agza et al. [46] the coefficient of determination (R2) for the calibration and validation ranged between 0.93-0.99 and 0.93–0.98 with corresponding standard error values ranging between 0.03–0.25 and 0.04–0.37. The grain mineral elements determination was carried out using Mehlich 3 extraction method (0.2M CH3COOH, 0.25M NH4NO3, 0.015M NH4F, 0.013M HNO3, 0.001M EDTA and adjusted to pH 2.5) [43] and gas chromatography-mass spectrometry.
2.3. Statistical Analysis Soil physicochemical parameters were not subjected to ANOVA because samples collected were composited for each location thus excluding replications. Therefore, location means for each soil physicochemical parameters were presented based on the triplicate analysis in the laboratory. Analysis of variance was performed to detect differences in grain parameters among the different locations and block (northwestern vs. central highlands) using PROC GLM in SAS software [47]. Location and block mean for grain nutrient and color data were separated using the Fisher’s protected least significant difference at alpha = 0.05. Pearson’s correlation coefficients among soil physicochemical and teff grain parameters were generated using the PROC CORR procedure in the SAS software [47].
3. Results
3.1. Soil Physicochemical Properties Based on the Munsell color chart, soil color varied across the different sample collection sites in the two main teff growing regions of Ethiopia however, the majority were black colored soils (Table2). Soil pH based on the numerical value did not vary widely, however, six out of the 24 locations were considered slightly acidic (Table2). The CEC value varied widely among locations and for Abrja, Agronomy 2019, 9, 283 6 of 19
Arerti 2, Bichena, and Simada the values were above 60 but for the Kudmi location, CEC was relatively low (Table2). Both SOC and TN also varied across locations and the SOC values were considered high at the Birzakani, Gumdri, and Abshem locations relative to Wondata location (Table2). Total N based on numerical value was highest at Abshem followed by Akaki location and some of the lowest values were obtained at Abrja, Atsedemariam and Kosheshila locations (Table2).
Table 2. Soil physicochemical parameters sampled during November 2017 at 24 field sites in the two main teff growing regions of Amhara and Oromia in Ethiopia.
Bulk CEC SOC Soil TN Locations Soil Texture Soil Color Density pH (meq/100g) (g/kg) (mg/kg) (g/cm3) Abrja Clay Loam Black 1.4 7.6 62.6 5.8 488 Abshem Clay Red 1.2 5.3 28.9 23.5 1825 Adet 1 Clay Red 1.2 5.4 31.2 10.7 966 Adet 2 Clay Black 1.2 6.6 58.8 13.4 747 Akaki Clay Black 1.4 7.8 41.7 4.3 555 Alemtena Loam Yellowish Brown 1.4 6.9 34.8 8.0 1682 Arerti 1 Clay Black 1.3 7.7 31.7 16.3 757 Arerti 2 Clay Loam Black 1.3 7.7 60.5 12.8 887 Atsedemariam Clay Black 1.4 7.0 56.4 8.7 471 Bichena Clay Black 1.2 6.4 66.0 12.1 917 Birzakani Clay Dark Grayish Brown 1.3 6.3 49.8 27.7 1819 Bishoftu Clay Black 1.3 6.8 41.9 8.8 774 Bitiejersalafo Loam Black 0.9 7.0 47.9 16.4 644 Demdengay Clay Loam Dark Reddish brown 1.4 6.2 60.5 16.2 1185 Fetlokuskuam Clay Black 1.2 6.7 48.3 10.9 569 Gejagedanba Clay Black 1.3 7.8 30.2 10.4 517 Gumdri Clay Loam Reddish brown 1.3 5.3 20.3 25.1 1420 Kosheshila Clay Black 1.3 7.9 35.1 11.0 450 Kudmi Clay Red 1.3 5.3 12.8 19.3 1263 Motta Clay Red 1.3 5.4 31.3 13.8 1225 Simada Clay Black 1.3 7.8 61.2 10.0 1435 Wondata Clay Black 1.3 6.5 58.7 3.3 681 Yubodegabati Clay Black 1.3 7.7 28.1 10.9 506 Zenzelima Clay Red 1.3 5.3 28.1 13.3 1333 Average 1.3 6.7 42.8 13.0 963 Minimum 0.9 5.3 12.8 3.3 450 Maximum 1.4 7.9 66.0 27.7 1825 SD 0.1 1.0 15.3 6.1 444 † SD; Standard deviation. †
In this study, the numerical values for mineral concentration varied across locations (Table3). For example, the concentration of soil P ranked highest at the Bishoftu location (43 mg/kg) followed by Arerti 2, Alemtena (almost 24 mg/kg), and Arerti 1 (about 15 mg/kg) respectively, while the numerical values for P concentration at most other locations were relatively close (Table3). The K concentration values showed wider variations at the different locations relative to P, and K concentration numerical values were greatest at Alemtena followed by Arerti 1, Arerti 2, and Bishoftu locations respectively and the lowest was from Kudmi location (Table3). The Ca concentration numerical value was greatest at Kosheshila and lowest at Gumdri and Zenzelima locations while for Mg concentration, the numerical value was highest at Abrja and lowest at Abshem and Gumdri locations (Table3). For S concentration, wide variations also occurred across locations based on numerical value and soil S concentration at Abrja, Adet 2, Akaki, Areti 1, Areti 2, Atsedema, Birzakani, Fetlokus, Gejageda, Kosheshila, Simada, Wondata, and Yubodegabati were among the lowest (Table3). In relation to the concentration of soil Fe concentration, the greatest numerical value was obtained from soils collected from Bichena and lowest at Arerti 2 location (Table3). There were also, di fferences in numerical value for all other soil micronutrient concentrations across the locations used in this study and there were wider variations in Mn, Zn, and Cu compared to the variation among locations for soil Mo concentration (Table3). The numerical values for soil Na concentration varied across locations and were ranked highest at Abrja field site and lowest at Gumdri and Kudmi locations (Table3). Agronomy 2019, 9, 283 7 of 19
Table 3. Soil extractable mineral concentration sampled during November 2017 at 24 field sites cultivated with the teff variety Quncho in the two main teff cultivation regions of Amhara and Oromia in Ethiopia.
Soil Extractable Nutrient Location P K Ca Mg S Fe Mn Zn Cu Mo Na mg/kg Abrja 9.2 226.0 8349.0 2845.4 9.0 128.0 103.6 1.3 5.8 0.3 93.4 Abshem 10.0 382.1 1618.2 241.1 23.7 106.5 183.3 1.6 4.5 0.3 13.9 Adet 1 7.9 225.7 2302.1 517.8 21.6 123.8 149.8 1.4 4.8 0.3 12.9 Adet 2 7.8 293.0 6031.8 1302.5 8.2 153.8 106.3 1.4 4.1 0.3 31.1 Akaki 8.6 451.9 10653.9 1259.0 8.6 80.5 122.9 1.8 3.6 0.3 42.4 Alemtena 23.8 850.7 2862.7 414.8 12.9 106.2 279.2 2.8 1.5 0.4 44.2 Arerti 1 14.6 777.6 8694.6 998.0 8.6 85.0 263.5 1.6 4.5 0.3 25.0 Arerti 2 29.7 646.7 8543.6 869.1 9.0 58.7 247.4 1.5 3.9 0.3 23.3 Atsedemariam 8.4 320.3 9073.6 2189.0 7.9 124.1 136.0 0.9 4.7 0.3 33.1 Bichena 11.5 348.9 6966.1 1361.6 11.4 168.3 95.9 1.1 5.1 0.3 34.7 Birzakani 10.3 337.3 3358.9 985.0 9.3 99.6 30.3 1.3 3.3 0.3 16.8 Bishoftu 43.0 540.0 5495.4 1135.2 12.7 157.6 245.8 2.0 3.7 0.3 45.2 Bitiejersalafo 10.8 367.7 7231.1 1737.9 12.3 146.8 112.9 1.4 3.9 0.3 71.9 Demdengay 9.9 102.9 3608.5 1072.3 11.9 102.4 76.1 0.8 4.6 0.3 20.8 Fetlokuskuam 6.9 279.5 6680.8 1343.5 8.0 147.2 129.8 1.0 4.1 0.3 34.5 Gejagedanba 10.6 468.6 11719.1 779.0 8.2 69.4 192.0 1.1 3.2 0.3 21.5 Gumdri 9.3 224.0 1350.3 260.7 20.0 110.0 56.6 0.8 3.6 0.3 11.3 Kosheshila 8.6 358.5 12607.5 821.0 9.1 124.5 237.2 1.2 3.1 0.3 18.8 Kudmi 7.2 70.9 1612.1 379.5 30.1 96.1 188.3 1.1 4.9 0.3 11.8 Motta 8.2 267.4 1850.6 407.8 19.0 164.7 153.7 1.5 4.4 0.3 13.1 Simada 10.3 260.9 11115.0 1073.6 8.6 118.3 150.1 1.1 3.6 0.3 19.7 Wondata 9.4 224.7 5670.1 1468.5 10.2 158.0 141.0 1.9 4.8 0.3 24.6 Yubodegabati 10.8 508.3 8632.0 1118.6 8.3 99.5 110.9 1.2 3.6 0.3 30.8 Zenzelima 8.2 231.4 1297.5 324.3 21.3 74.8 113.4 0.9 2.4 0.3 13.2 Average 12.3 365.2 6138.5 1037.7 12.9 116.8 589.5 1.4 4.0 0.3 29.5 Minimum 6.6 70.9 1297.5 241.1 7.9 69.4 30.3 0.8 1.5 0.3 11.3 Maximum 43.0 850.7 12607.5 2845.4 30.1 168.3 279.2 2.8 5.8 0.4 93.4 SD 1.9 6.7 106.5 20.2 1.6 1.6 2.8 0.03 0.6 0.5 0.6 † SD; Standard deviation. † 3.2. Teff Grain Physical and Chemical Quality The grain of the teff variety Quncho sampled across the main regions of its cultivation in Ethiopia varied in color (Figure2). There was a significant e ffect of location (p < 0.05) on teff grain color indices of hue (H), saturation (S), and brightness (V) in this study (Table4). Based on the color space classification scheme, grains which showed high V and low S were generally very bright white and those with low V and high S values were generally darker in color based on Deswal and Sharma, [44] color classification. The pureness of the teff grain color represented by the H value was generally higher in the locations Adet 1, Akaki, and Alementa than most other locations (Table4). In relation to the S values, te ff grown in Abshem and Kudmi had the highest values among the different locations and were of a pale white color while the lowest S value was for teff grain collected from the Bishoftu location and the grains were very white (Table4). Other locations that had te ff grain classified as very white based on the S value were Abrja, Arerti 1, Arerti 2, Atsede Mariam, and Kosheshila (Table4). Te ff grain V value was greatest for teff grain collected from the Bishoftu location (brighter color) and lowest for grain sampled from Zenzelima location (darker color) while for all other locations, the values were intermediate (Table4). Te ff grown on red colored soils (Nitisols) had lower V and higher S values while teff grown on the black colored soils (Vertisols) had higher V and lower S values (Table4). Pertaining to grain color of teff grown in the two main regions (northwestern highlands vs. central highlands) both the S(p = 0.004; SD = 5.3) and V (p = 0.001; SD = 3.7) color value were different. However, the H color value was not different (p = 0.237; data not shown) between the two main teff growing regions in Ethiopia. The greater grain S color value was obtained from teff grown in the northwestern highlands (39%) compared to teff grown in the central highlands (32%) and this indicates that the lower saturated grain color of teff was linked to locations within the central highlands while the higher saturated grain color was from locations within the northwestern highlands. The greater grain V value of 81% was Agronomy 2019, 9, 283 8 of 19 obtained from teff grown in the central highlands compared to the northwestern highlands (75%) and is indicative of whiter grains from the central highlands of Ethiopia. In our study, there were significant negative correlations between grain S value and soil pH, SOC, Ca, Mg, S, and Na (Table5). Therefore, the soils in our study with greater pH, SOC, Ca, Mg, and S generally exhibited lower S values and thus very whiter color teff grains were observed. For the V value, there were significant positive correlations with black soil color, pH, Ca, Mg, Na, and a negative association with SOC and S (Table5). Agronomy 2019, 9, x FOR PEER REVIEW 9 of 20
Figure 2. Grain color of the teff variety Quncho collected from 24 field sites in the two main teff cultivation Figure 2. Grain color of the teff variety Quncho collected from 24 field sites in the two main teff regions of Amhara and Oromia in Ethiopia. cultivation regions of Amhara and Oromia in Ethiopia. Table 4. Teff grain HSV (H, hue; S, saturation; V, value) color values and proximate composition (CP, Incrude addition, protein) there concentration was some for significant the variety Quncho negative collected relationships from November between (2017) H to color January value (2018) and grain starch (r = 0.41; p < 0.05), S value and CP (r = 0.44; p < 0.05), V value and fiber concentration (r at 24 −locations in the two main teff cultivation regions− of Amhara and Oromia in Ethiopia. = 0.48; p < 0.05) but a significant positive association between S value and grain fat (r = 0.44; p < − Location H S V Fiber 0.05). The higher V value indicates(°) brighter(%) color(%) and lower V value, darkerg/kg color teff grain. Only the S valueAbrja was significantly36.66h† associated 25.64 withj the81.05 aminodefg acids26.3 alanineh 25.5 (r lm= 0.50;111.4p c< 0.05),554.3 argininek − (r = 0.45;Abshemp < 0.05), aspartic43.12bc acid (r =59.140.56;a P < 64.580.01),l methionine33.9d (r33.0= ab 0.51; p92.6
Agronomy 2019, 9, 283 9 of 19 at the Birzakani location and lowest at Simada location (Table4). Te ff grain sampled from the locations Adet 2, Alemtena, and Zenzelima were ranked highest in starch concentration and those collected from Abrja, Adet 1, and Demdengay locations were among the lowest in starch concentration (Table4). Overall, there was no consistent trend where anyone location ranked highest in all the proximate composition parameters in this study which indicated how variable these proximate composition parameters were in this study. Among the proximate composition parameters, only crude fat was different (p = 0.009; SD = 4.4) between the two main teff growing regions and was greater for teff grown in the northwestern highlands (29.0 g/kg) relative to those grown in the central highlands (23.0 g/kg). The grain CP concentration was positively correlated with SOC, and TN but negatively associated with soil Mg, Fe, and Na (Table6). Te ff grain crude fiber concentration was positively correlated with TN and S, but negatively correlated with soil pH, K, Ca, Mg, and Na while grain fat concentration was only negatively correlated with SOC and positively associated with Cu (Table6). However, grain starch had no significant associations with any of the soil physicochemical properties (Table6). There was a significant effect (p < 0.05) of location on all 18 amino acids analyzed in the teff grain of this study (Table7).
Table 4. Teff grain HSV (H, hue; S, saturation; V, value) color values and proximate composition (CP, crude protein) concentration for the variety Quncho collected from November (2017) to January (2018) at 24 locations in the two main teff cultivation regions of Amhara and Oromia in Ethiopia.
Location H S V Fiber
(◦) (%) (%) g/kg h j defg h lm c k Abrja 36.66 † 25.64 81.05 26.3 25.5 111.4 554.3 Abshem 43.12 bc 59.14 a 64.58 l 33.9 d 33.0 ab 92.6 h 605.2 de Adet 1 47.84 a 52.43 b 70.0 k 37.3 c 30.0 efg 95.1 g 552.9 k Adet 2 41.06 cdefg 32.38 fghi 77.90 hi 34.7 d 31.6 bcd 93.6 gh 623.8 ab Akaki 45.46 ab 36.85 de 78.88 ghi 21.0 j 31.1 cde 88.8 ij 605.7 de Alemtena 45.99 ab 46.44 c 77.65 i 26.0 h 29.8 efg 86.8 k 628.1 a Arerti 1 41.28 cdefg 27.95 j 81.31 cdefg 18.5 k 31.7 bcd 87.8 jk 574.2 j Arerti 2 37.82 gh 28.64 hij 80.33 efgh 25.7 h 28.8 ghi 115.8 b 617.1 bc Atsedemariam 43.41 bc 28.28 ij 83.66 bc 27.7 g 28.3 hij 104.6 e 589.8 gh Bichena 38.72 fgh 33.26 defg 82.87 bcd 18.6 k 29.5 fgh 92.4 h 605.5 de Birzakani 36.54 h 43.45 c 69.67 k 29.5 f 21.0 n 126.2 a 581.0 ij Bishoftu 43.45 bc 15.87 k 87.19 a 18.3 k 28.1 hijk 103.1 e 615.7 bc Bitiejersalafo 40.81 cdefg 34.49 def 84.18 b 23.8 i 33.5 a 84.8 l 598.3 efg Demdengay 42.86 bcd 37.42 d 80.65 defg 25.9 h 24.6 m 113.0 c 560.8 k Fetlokuskuam 40.95 cdefg 33.58 defg 82.67 bcde 21.3 j 27.2 jk 101.2 f 588.1 ih Gejagedanba 39.54 defgh 29.72 ghij 80.00 fghi 22.1 j 29.8 efg 93.0 h 591.2 fgh Gumdri 41.51 cdef 46.86 c 63.92 l 30.6 ef 32.8 ab 88.9 ji 581.7 ij Simada 40.01 cdefgh 35.63 def 80.00 fghi 25.2 h 31.9 bc 84.9 l 604.0 de Kosheshila 37.96 fgh 26.81 j 81.83 bcdef 40.7 b 28.6 ghij 103.4 e 599.3 fe Kudmi 42.65 bcde 58.68 a 64.57 l 18.9 k 28.1 hijk 99.7 f 582.7 hij Motta 39.19 efgh 52.60 b 75.03 j 31.8 e 30.3 def 92.1 h 601.9 de Wondata 39.53 defgh 32.89 efgh 80.72 defg 36.7 c 28.0 ijk 90.2 i 609.5 cd Yubodegabati 38.81 fgh 33.59 defg 79.54 fghi 18.0 k 26.9 kl 93.3 h 599.8 ef Zenzelima 37.89 gh 32.65 efgh 55.04 m 42.3 a 25.2 1m 107.8 d 621.0 ab LSD (0.05) 3.6 4.3 2.4 1.3 1.4 1.6 8.6 Within columns, means followed by same lowercase letters superscripts are not different (p > 0.05). †
No one location ranked highest for all the 18 amino acids analyzed in the teff grain collected, however, teff grain collected from the Bishoftu location ranked highest for 12 out of the 18 amino acids evaluated (Table7). Also, between the two main te ff growing regions (northwestern vs. central highlands), none of the amino acids were different (p > 0.05). There was a location effect (p < 0.05) on teff grain minerals concentration in this study (Table8). Among the macronutrients, grain P concentration was ranked highest for teff grown at Fetlokuskuam and Yubodegabati and lowest at Zenzelima location (Table8). The grain K concentration followed a similar trend like P and grain Ca Agronomy 2019, 9, 283 10 of 19 concentration was highest at the Yubodegabati location and lowest at Gejagedanba and Zenzelima locations (Table8). The grain Mg concentration was highest at Fetlokuskuam and Yubodegabati locations and lowest at Zenzelima location while for grain S concentration, highest at Atsedemariam and lowest at Akaki and Zenzelima locations (Table8). Additionally, the grain Na concentration ranked highest at Atsede Mariam, Bishoftu, and Simada but lowest at Akaki, Bichena, Gejagedanba, Wondata, and Zenzelima while all other locations were intermediate and also varied (Table8). In relation to the teff grain micronutrients, Fe concentration was greatest at Abrja location and ranked lowest at Abshem, Alemtena, Arerti 1, Bichena, Birzakani, Bitiejersalafo, Demdengay, Gumdri, Kosheshila, Wondata, Yubodegabati, and Zenzelima locations (Table8). There were di fferences in all other grain micronutrients concentration with wider variations in micronutrients concentration for B and Cu and the least variation occurred for Mo across locations (Table8). Between the two main te ff growing regions, grain Mg concentration differed (p = 0.011; SD = 12.1) and it was greater for teff grown in the northwestern highlands (160.2 mg/100 g) compared to those grown in the central highlands region (144.5 mg/100 g). There were trends for both grain P (p = 0.07; SD = 25.9) and grain S concentration (p = 0.06; SD = 2.9) difference between the two main teff growing regions. Both grain P (320.7 mg/100 g) and S (26.5 mg/100 g) for teff grown in the northwestern highlands region tended to be greater than those grown in the central highlands regions P (291.1 mg/100 g) and S (23.9 mg/100 g) respectively. For teff grain minerals concentration, the significant correlations that occurred with soil physicochemical parameters were all below the 50% threshold and indicated that other external variables would have played a more significant role in the variation of grain mineral concentration among locations (Table6)
Table 5. Correlation coefficients among soil physicochemical properties and HSV (H, hue; S, saturation; V, value) grain color value of the teff variety Quncho grown on 24 field sites in the main teff cultivation regions of Amhara and Oromia in Ethiopia during November of 2017.
HSV Soil Color 0.287 0.398 0.634 ** − − pH 0.218 0.690 ** 0.742 ** − − ‡ SOC 0.117 0.499 * 0.540 ** † − − P 0.164 0.391 0.302 − K 0.16 0.282 0.337 − Ca 0.241 0.663 ** 0.700 ** − − Mg 0.285 0.599 ** 0.645 ** − − S 0.294 0.789 ** 0.787 ** − Na 0.143 0.442 * 0.518 * − − Cu 0.058 0.106 0.197 − Fe 0.045 0.074 0.359 − Mn 0.288 0.129 0.24 − Mo 0.307 0.092 0.07 − Zn 0.367 0.062 0.207 SOC, soil organic carbon. *, **, significant at the 0.05, and 0.01 levels respectively. † ‡ Agronomy 2019, 9, 283 11 of 19
Table 6. Pearson’s correlation coefficients among soil physicochemical properties, grain proximate parameters, and grain mineral nutrients for the teff variety Quncho grown on 24 field sites in the main teff cultivation regions of Amhara and Oromia states in Ethiopia during November of 2017.
Proximate Composition Grain Mineral Concentration Soil CP Fiber Fat Starch P K Ca Mg S Fe Mn Zn Cu B Mo Na Properties pH 0.02 0.70 ** 0.03 0.06 0.12 0.15 0.29 0.12 0.18 0.20 0.06 0.25 0.15 0.41 ** 0.13 0.29 − − − − SOC 0.54 ** 0.34 0.47 * 0.33 0.29 0.21 0.26 0.14 0.07 0.37 0.40 0.08 0.19 0.03 0.07 0.05 † − − − − − − − − − − TN 0.50 * 0.47 * 0.35 0.18 0.36 0.19 0.31 0.34 0.11 0.34 0.14 0.11 0.04 0.01 0.25 0.09 − − − − − − − − − − P 0.27 0.35 0.27 0.06 0.01 0.08 0.01 0.12 0.18 0.10 0.01 0.16 0.14 0.10 0.30 0.30 − − − − − − − − − K 0.46 0.52 * 0.30 0.01 0.16 0.13 0.01 0.31 0.13 0.06 0.03 0.14 0.10 0.08 0.281 0.08 − − − − − − − − − − − Ca 0.17 0.64 *** 0.09 0.04 0.16 0.14 0.32 0.17 0.24 0.29 0.01 0.27 0.20 0.42 * 0.01 0.23 − − − − Mg 0.43 * 0.50 * 0.31 0.26 0.23 0.20 0.31 0.32 0.12 0.34 0.15 0.06 0.17 0.29 0.33 0.22 − − − − S 0.13 0.55 ** 0.08 0.01 0.23 0.15 0.33 0.23 0.19 0.03 0.07 0.18 0.01 0.36 0.06 0.17 − − − − − − − − − − − − Fe 0.53 ** 0.07 0.28 0.11 0.39 0.27 0.43 * 0.30 0.12 0.14 0.05 0.16 0.05 0.09 0.16 0.16 − − − − − Mn 0.18 0.33 0.02 0.11 0.01 0.07 0.00 0.19 0.14 0.18 0.02 0.01 0.08 0.17 0.14 0.20 − − − − − − − Zn 0.20 0.27 0.06 0.20 0.11 0.10 0.08 0.33 0.35 0.10 0.25 0.09 0.36 0.25 0.34 0.08 − − − − − − − − − − − − − Cu 0.51 * 0.08 0.49 * 0.23 0.43 * 0.31 0.07 0.34 0.08 0.33 0.17 0.10 0.11 0.11 0.09 0.05 − − − − − − Mo 0.30 0.17 0.13 0.01 0.08 0.01 0.08 0.09 0.12 0.18 0.11 0.30 0.05 0.07 0.41 * 0.07 − − − − − − − Na 0.26 0.62 ** 0.163 0.28 0.01 0.02 0.15 0.07 0.10 0.15 0.19 0.07 0.07 0.10 0.38 0.15 − − − − − − − SOC, soil organic carbon; TN, soil total nitrogen. *, **, and ***, significant at the 0.05, 0.01, and 0.001 levels respectively. † Agronomy 2019, 9, 283 12 of 19
Table 7. Amino acids concentration for the teff variety Quncho collected from November (2017) to January (2018) at 24 locations in the two main teff cultivation regions of Amhara and Oromia in Ethiopia.
Location Ala Arg Asp Cys Glu Gly His Ile Leu Lys Met Phe Pro Ser Thr Trp Tyr Val † mg/100 g
Abrja 500ij ‡ 570i 720fgh 160m 1890hi 290h 219hi 270gh 760j 250def 180hi 450jk 580ij 370hi 270hi 70jk 300klm 370klmn Abshem 610c 760b 920c 220a 2810a 300fghi 320a 430b 1080b 320bc 210d 640b 770ab 501b 400b 120c 390bc 550b Adet 1 450n 610fgh 720fgh 170ijk 2110g 340cd 210j 280fgh 710lm 230fgh 180hi 480h 640g 380gh 260i 80hi 330h 380jkl Adet 2 500i 570i 790e 160klm 1790kl 360bcd 190lm 280gh 750jk 240fgh 190g 460ij 570jk 370hi 250j 80hi 310ijkl 360mn Akaki 500i 590ghi 740f 190ef 1640m 330defg 200kl 270hi 750jk 210ghi 180hi 430l 600hi 360ij 260ih 80hi 300klm 370j-m Alemtena 460mn 520j 660jk 175hi 1630m 330def 190n 230lm 690n 200ij 170kl 410m 610h 330kl 230k 70kl 280no 330o Arerti 1 490jk 610efg 710ghi 202cd 1650m 320efgh 210ij 240jk 760ij 190ji 170lm 430l 650g 350j 270ih 70kl 290lm 360lmn Arerti 2 590d 740b 990b 194de 2680bc 380ab 270d 430b 990c 340b 220b 610c 710d 500b 370c 120c 400b 510c Atsede Mariam 550e 620def 820r 177gh 2420d 350bcd 250e 360d 890e 300c 210de 550e 700de 450e 320e 90f 360f 444ef Bichena 530g 610fgh 740f 202cd 1820jkl 380av 230fg 280fg 790hg 270d 180gh 460ij 680ef 390gh 290g 80h 310ij 390hi Birzakani 480kl 540j 660k 174hij 1470n 270i 200k 220m 700mn 190ij 160m 390n 560k 330l 240jk 60n 270ef 330o Bishoftu 680a 820a 1140a 190ef 2710b 360bc 280c 490a 1100ab 340b 240a 670a 640g 550a 420a 140a 420a 580a Bitiejersalafo 580d 630dce 880d 216a 2460d 370ab 300b 380c 990c 370a 200e 580d 780ab 480c 360c 100e 380d 480d Demdengay 630b 760b 930c 211ab 2820a 270i 320k 430b 1110a 310c 210c 640b 740c 510b 410ab 130b 390de 560b Fetlokuskuam 540ef 640cd 820e 206bc 2470d 380ab 280c 350d 930d 320bc 190f 560e 790a 470cd 340d 90g 370ef 450ef Gejagedanba 510hi 580hi 730fg 185fg 1900h 340cde 230fg 280gh 780hi 270d 180i 4700hi 650g 390g 280gh 70ij 310ijk 380jk Gumdri 480l 580i 680ijk 166jkl 1770l 280i 210j 260ji 740kl 210ih 170k 430l 590hij 350j 260i 70l 290mn 360n Simada 480kl 570i 690hij 167i-l 1440n 280i 180mn 230klm 690n 180j 170jk 390n 510l 320l 240jk 60lm 260q 340o Kosheshila 510h 620def 820e 162klm 2300e 370ab 210j 330e 810g 260de 200de 530f 640g 410f 290fg 90fg 350g 410g Kudmi 550ef 660c 820e 213ab 2180f 390a 270d 320e 870ef 310c 190g 530f 760bc 440e 330e 90f 350g 440f Motta 500i 610efg 740f 165klm 1870hij 300ghi 230gh 280gh 750jk 250def 180hi 450k 570k 360ij 280gh 80h 300jkl 390ij Wondata 460m 570i 730fg 140n 1620m 320efgh 160o 240kl 680n 150k 170k 420l 510l 350jk 230k 60mn 280op 330o Yubodegabati 550ef 620def 820e 205bc 1840ijk 330defg 240f 290f 860f 250def 180ij 490g 660fg 400f 300f 80h 310i 400gh Zenzelima 540fg 630def 880d 159lm 2630c 330cd 230gh 390c 940d 270d 210c 580d 680ef 460de 320e 110d 380de 450e LSD (0.05) 10 30 30 10 60 30 10 10 10 30 10 10 30 20 20 40 10 14 Ala; alanine; Arg, arginine; Asp, aspartic acid, Cys, cysteine; Glu, glutamic acid; Gly, glycine; His, histidine; Ile, isoleucine; Leu, leucine; Lys, lysine; Met, methionine; Phe, phenylalanine; Pro,† proline; Ser, serine; Thr, threonine; Trp, tryptophan; Tyr, tyrosine; Val; valine. Within columns, means followed by same lowercase letter superscripts are not different (p > 0.05). ‡ Agronomy 2019, 9, 283 13 of 19
Table 8. Grain mineral nutrients concentration for the teff variety Quncho collected from November (2017) to January (2018) at 24 locations in the two main teff cultivation regions of Amhara and Oromia in Ethiopia.
Grain Mineral Nutrient Location P K Ca Mg S Fe Mn Zn Cu B Mo Na mg/100 g
Abrja 317.3g† 458.4f 123.8g* 169.6de 24.6g 96.2a 4.0hi 2.04fgh 0.50efg 0.45de 0.087b 9.9ef Abshem 315.5g 413.8h 123.8g 146.8hi 27.4ef 8.1g 8.0f 2.33e 0.43ij 0.39defg 0.193a 8.9fgh Adet 1 319.0g 432.1g 113.9hi 154.7gh 21.3ij 35.2bc 19.4a 2.40e 0.51efg 0.20jk 0.030bcd 9.8ef Adet 2 370.5b 420.9h 124.3fg 176.6cd 20.5jk 23.2f 6.8f 2.55d 0.39kl 0.38efg 0.047bcd 8.6fgh Akaki 270.6ij 291.4l 109.2ijk 122.2k 16.7l 22.5f 19.9a 2.04fgh 0.36lm 0.23ijk 0.020d 7.2ij Alemtena 281.5i 432.0g 129.2efg 134.2j 24.7g 6.3g 3.9hi 2.72c 0.43ij 0.30ghi 0.083bc 11.7cd Arerti 1 356.6cd 519.0b 114.3hi 166.6e 30.0cd 11.2g 13.8c 2.12fg 0.45hij 0.80b 0.020d 11.0de Arerti 2 243.1k 289.4l 107.1jk 111.8l 15.4lm 24.4ef 2.3ijk 2.11fg 0.49fgh 0.01m 0.053bcd 9.3fg Atsede Mariam 343.8ef 461.1ef 154.7b 184.1bc 34.7a 40.2b 4.3h 2.91ab 0.56cd 0.65c 0.083bc 14.7a Bichena 354.5cde 459.1f 136.4cd 150.8gh 27.0f 11.1g 7.1f 2.33e 0.46hij 0.23ijk 0.027bcd 7.9ghij Birzakani 225.6l 337.6j 106.3k 124.5k 24.6g 4.9g 2.0jk 1.99gh 0.51efg 0.48d 0.087b 10.0ef Bishoftu 320.9g 436.9g 130.9de 152.9gh 18.7k 32.8bc 4.6h 1.98gh 0.42jk 0.07lm 0.087b 14.4ab Bitiejersalafo 238.8k 318.3k 129.9ef 135.5j 24.2gh 10.3g 3.5hij 2.16f 0.54de 0.61c 0.033bcd 12.1cd Demdengay 364.2bc 487.6c 130.0ef 183.7c 26.9f 7.6g 6.9f 1.94h 0.37lm 0.31ghi 0.030bcd 11.9cd Fetlokuskuam 395.1a 589.2a 131.6de 194.4a 32.1b 26.4def 1.9jk 2.56d 0.65b 0.28hij 0.030bcd 12.8bc Gejagedanba 269.1j 412.2hi 100.0l 141.6ij 26.0fg 20.1f 9.8e 2.17f 0.44ij 0.34fgh 0.010d 8.0ghij Gumdri 297.0h 403.6i 116.8h 176.0cd 30.7bc 8.3g 4.4h 2.73c 0.58c 0.41def 0.037bcd 9.9ef Simada 300.2h 469.6de 138.4c 157.9fg 32.0b 31.9cde 4.9gh 2.85bc 0.70a 1.26a 0.047bcd 14.7a Kosheshila 341.2f 432.2g 155.8b 169.9de 31.7bc 7.2g 4.2h 2.55d 0.45hij 0.39efg 0.043bcd 12.4cd Kudmi 314.9g 472.3d 112.5hij 154.9gh 24.2gh 22.0f 1.6k 2.10f 0.52def 0.20jk 0.013d 11.4cde Motta 324.5g 418.3h 138.6c 155.8fg 28.9de 24.8ef 11.9d 2.37g 0.42jk 0.15kl 0.037bcd 12.3cd Wondata 350.7def 457.9f 126.1efg 163.5ef 22.8hi 7.2g 16.0b 2.06fgh 0.34m 0.34fgh 0.027cd 7.4hij Yubodegabati 396.0a 519.3b 170.9a 192.4ab 36.0a 8.2g 6.7f 3.01a 0.47ghi 0.47de 0.030bcd 12.9bc Zenzelima 196.6m 220.1m 100.0l 100.3m 14.1m 7.2g 6.5fg 1.60i 0.34m 0.18k 0.017d 6.6j LSD (0.05) 11.5 9.1 5.8 8.6 1.8 7.7 1.8 0.14 0.04 0.10 0.58 1.62 Within columns, means followed by same lowercase letters superscripts are not different (p > 0.05). † Agronomy 2019, 9, 283 14 of 19
4. Discussion The characterization of soil properties helps provide an understanding of the variation in crop production and quality in different agro-ecological zones [48]. While Na is not an essential nutrient element required for plant growth its presence in high concentration in the soil can hinder nutrient uptake, growth, and development of crop plants [49]. The common trend of spatial variation in soil physicochemical properties are generally the result of soil formation factors and variation in agricultural soil management in cultivated areas [50] and this may have been the principal factors responsible for the variation in soil physicochemical properties among the locations evaluated. Our results for teff grain color evaluated across multiple locations in the main teff growing regions of Ethiopia is in confirmation with the results of Wu et al. [51] who reported significant color variation in wheat grain from a single variety cultivated over diverse production conditions. Further, Baye [14] reported that the very white and white teff are grown on the vertisols of the central highlands of Ethiopia which corresponds to our results. The results suggested that there could be a direct relationship between grain nutrient and grain color of teff. Ta´nskaet al. [52] reported that variation in grain color of wheat was reflected by changes in its chemical composition but not the environment which is in partial agreement with the results of our study. In addition, the accumulation of carotenoids and anthocyanins pigments in wheat grain accounted for the large variation in its grain color [52–55] and may have played a role in the grain color differences for the single variety of teff sampled across multiple locations in our study. Overall, the average of 63.5% of the variation in grain color can be attributed to the variation in the soil physicochemical properties that influenced several parameters that were correlated with grain color in this study (Table5). For the proximate composition parameters, the grain crude fiber, crude fat, CP, and starch concentrations were aligned with the range reported in several studies for different varieties of teff across different geographic locations [20,22,32,55]. This result is indicative of how these nutritional parameters are highly variable in space. In this study, the seven out of the 18 amino acids had significant correlations with soil P, while only four out the 18 correlated with Mg, and 10 out of the 18 correlated with Na (Table9). However, with the exceptions of aspartic acid and soil P, and cysteine and soil Na, all other significant correlations were below the 50% threshold (Table9) and indicates that other environmental variables may have played a role in the differences in teff grain amino acids concentration. The amino acids concentration of teff grain in this study were in line with those reported for the same variety of teff in a study by Daba [22]. For teff grain minerals concentration, the significant correlations that occurred with soil physicochemical parameters were all below the 50% threshold and indicated that other external variables would have played a more significant role in the variation of grain mineral concentration among locations (Table6). In our study, high soil mineral concentration did not necessarily correspond to high grain mineral concentration particularly, the grain micronutrients of Fe and Zn showed no significant correlations with soil physicochemical properties and may be indicative of a dilution effect because of higher grain yield in those nutrient-rich locations similar to the trends reported by Fan et al. [56]. The grain mineral concentration in this study was similar to those reported for both white and red teff [57] but often times lower grain mineral concentration than that of the major cereal crop wheat [58,59]. These variabilities in the grain proximate composition parameters, amino acids, and mineral concentration are generally modified by the unique soil physicochemical characteristics, climatic conditions, and the type of agronomic management practices instituted at the location of crop plants cultivation [58–60]. Agronomy 2019, 9, 283 15 of 19
Table 9. Pearson’s correlation coefficients among soil physicochemical properties and grain amino acids for the teff variety Quncho grown on 24 field sites in the main teff cultivation regions of Amhara and Oromia states in Ethiopia during November of 2017.
Amino Acids Ala Arg Asp Cys Glu Gly His Ile Leu Lys Met Phe Pro Ser Thr Trp Tyr Val † Soil 0.381 0.32 0.32 0.49 0.17 0.445 0.33 0.24 0.30 0.35 0.19 0.26 0.33 0.31 0.32 0.25 0.27 0.29 color BD 0.13 0.12 0.17 0.07 0.20 0.01 0.08 0.19 0.16 0.10 0.21 0.17 0.06 0.15 0.14 0.20 0.16 0.16 ‡ − − Texture 0.16 0.15 0.10 0.03 0.20 0.27 0.23 0.18 0.20 0.17 0.13 0.15 0.09 0.14 0.20 0.18 0.13 0.17 − pH 0.174 0.13 0.15 0.30 0.02 0.16 0.05 0.07 0.12 0.05 0.07 0.06 0.09 0.08 0.09 0.11 0.06 0.10 − SOC § 0.12 0.20 0.24 0.01 0.15 0.29 0.02 0.18 0.11 0.02 0.23 0.18 0.05 0.17 0.10 0.22 0.19 0.16 − − − − − − − − − − − − − − − − − P 0.47 * 0.49 * 0.57 ** 0.12 0.25 0.20 0.18 0.42 * 0.35 0.25 0.47 * 0.35 0.01 0.39 0.37 0.47 * 0.38 0.41 * − K 0.073 0.10 0.03 0.08 0.22 0.13 0.20 0.14 0.13 0.13 0.10 0.16 0.11 0.14 0.14 0.10 0.11 0.14 − − − − − − − − − − − − − − − − Ca 0.118 0.07 0.10 0.21 0.02 0.24 0.02 0.04 0.06 0.08 0.07 0.04 0.08 0.06 0.05 0.05 0.04 0.05 − Mg 0.416 * 0.34 0.32 0.42 * 0.31 0.10 0.41 * 0.35 0.41 * 0.32 0.27 0.36 0.36 0.38 0.39 0.33 0.32 0.38 S 0.175 0.08 0.13 0.19 0.01 0.06 0.05 0.08 0.13 0.03 0.08 0.06 0.03 0.07 0.08 0.09 0.04 0.09 − − − − − − − − − − − − − − − − − Fe 0.063 0.03 0.07 0.10 0.01 0.15 0.01 0.03 0.01 0.07 0.08 0.03 0.10 0.03 0.01 0.02 0.02 0.03 − − − − Mn 0.017 0.14 0.17 0.03 0.06 0.39 0.09 0.08 0.02 0.05 0.16 0.07 0.01 0.08 0.02 0.11 0.14 0.05 − − − − Zn 0.182 0.14 0.07 0.19 0.28 0.04 0.34 0.20 0.25 0.28 0.15 0.24 0.34 0.22 0.25 0.14 0.21 0.21 − − − − − − − − − − − − − − − − − Cu 0.238 0.37 0.15 0.32 0.22 0.04 0.39 0.20 0.24 0.24 0.10 0.23 0.27 0.24 0.30 0.18 0.20 0.28 Mo 0.285 0.31 0.32 0.23 0.24 0.22 0.33 0.26 0.29 0.33 0.20 0.29 0.22 0.32 0.29 0.20 0.27 0.27 − − − − − − − − − − − − − − − − − − Na 0.46 * 0.36 0.38 0.53 ** 0.34 0.15 0.47 * 0.40 0.47 * 0.42 * 0.30 0.40 0.44 * 0.42 * 0.45 * 0.41 * 0.38 0.44 * Ala; alanine; Arg, arginine; Asp, aspartic acid, Cys, cysteine; Glu, glutamic acid; Gly, glycine; His, histidine; Ile, isoleucine; Leu, leucine; Lys, lysine; Met, methionine; Phe, phenylalanine; † § Pro, proline; Ser, serine; Thr, threonine; Trp, tryptophan; Tyr, tyrosine; Val; valine. *, **, significant at the 0.05, and 0.01 levels respectively. ‡ BD, Bulk density; SOC, Soil organic carbon. Agronomy 2019, 9, 283 16 of 19
5. Conclusions Grain color of teff dictates its quality and demand in Ethiopia and was influenced by location for the same variety. In this study, teff grown on the red colored soils of the five locations in Amhara (Abshem, Adet 1, Kudmi, Motta, and Zenzelima), had higher S (saturation) and lower V (brightness) color space values, which indicates the production of pale white grains compared to the whiter grains produced on the black colored soils of several locations in both Amhara and Oromia regional states. The soil properties of pH, soil organic carbon, Ca, Mg, and S were strongly associated with grain S value, however, among those soil variables based on the correlation coefficient, soil S concentration had the strongest relationship with teff grain color S value and a similar trend occurred for grain V (brightness) value. The locations of Abshem, Adet 1, Gumdri, Kudmi, Motta, and Zenzelima with high soil S concentration were all in Amhara state which indicates that these locations produced pale white teff grains and for the lower soil S recorded in the other locations in both Amhara and Oromia regional states produced whiter teff grains based on the significant positive correlation between grain S color space value and soil S concentration. There was no strong association between grain proximate composition parameters (grain fiber, fat, CP, starch) and grain color in this study. The grain amino acid concentration of teff was only associated with grain color S value particularly, for aspartic acid and alanine. Grain crude fiber was strongly associated with soil pH and Ca but not crude fat, crude protein, and starch. Also, in this study, soil physicochemical properties had minimal influence on grain mineral concentration and since those relationships were below the 50% threshold level, it is indicative that other factors had played a more significant role in altering grain mineral nutrient concentration. Soil P, Mg, and Na were the only soil properties associated with grain amino acids concentration but none of these relationships were considered strong and therefore, suggested that other major factors were involved in determining the level of grain amino acid concentration present in teff grain. Based on the results of this study, grain color and nutrient concentration were influenced by location within the two regional states of Amhara and Oromia and this may help dictate management interventions necessary to obtain uniformity in grain color, chemical composition, and market equity for the same variety of teff in these two major teff cultivation regions in Ethiopia.
Author Contributions: A.A. Graduate student work on the development of the proposal, implementation of the project, data collection, data analysis, and manuscript preparation.; E.A., the conceptualization of project from proposal development to implementation on fieldwork, and editing.; B.Y., involved in proposal development and fieldwork. G.A., involved in proposal development, statistical advising, and editing. K.A., involved in proposal development and fieldwork. J.K.Q.S.; data analysis, reviewing, and writing of the manuscript, W.P.; review and editing, supervision, and funding acquisition. Funding: This research was funded by the College of Agriculture, Biotechnology and Natural Resources, University of Nevada, Reno. Acknowledgments: The authors would like to acknowledge Amhara Agricultural Research Institute, Agricultural Growth Program II (AGP II), Debre Zeit Agricultural Research Center, Adet Agricultural Research Center, Bahir Dar University, Ethiopia Institute of Agricultural institute quality lab, and University of Nevada Reno College of Agriculture Biotechnology and Natural Resources for their financial and logistic support to accomplish this study. Conflicts of Interest: The authors declare no conflict of interest.
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