Physicochemical Characterization of Nine Cassava (<i>Manihot esculenta</i>Crantz) Cultivars from Chad

In Chad, despite the multiple culinary uses of cassava leaves and tubers, their nutritional values are untapped. In this study, the physicochemical compositions and structure of nine cultivars were assessed. The proteins were obtained by Kjeldahl’s method. Total sugars were determined according to the Luff-Schoorl method. For starch content, the polarimetric method of Earle and Milner was used. Mineral elements were carried out using an atomic absorption spectrophotometry. The cyanide was evaluated by the method of Williams and Edwards. Significant variability has been demonstrated in the leaves and dry tubers except for water content and dry matter. Analysis of the variances of the components of the tubers reveals that the water contents of the cultivars vary from 5.01% to 5.86%. The ash contents vary from 4.23% (cultivar DVA2) to 8.32% (cultivar DVL2). For total sugars, the values are between 53.63% (cultivar DVL2) and 57.99% (cultivars DVL12 and KA0303). The fiber contents are lower and vary from 1.74% (cultivar DVL12) to 1.92% (cultivars SB1366, DVA2, TL0101 and PG1314). The starch content varies from 28.93% (cultivar DVL12) to 31.05% (cultivar SB1366). The variations in mineral constituents of the tubers in mg/100g are Ca (145.21 - 250.08), Mg (83.89 - 165.22), P (147.34 - 360.78), K (1534.50 - 3064.09), Zn (0.75 - 0.82) and Mn (0.78 - 0.89). Iron concentrations are from 7.72 mg/100g (cultivar BA0909) to 60.62 mg/100g (cultivar DVA2). Analysis of the variances of the leaf constituents reveals high contents of Calcium for SB1366 (2108.41 mg/100g), of iron (Fe 54.26 mg/100g) and potassium (K 1866.86 mg/100g) for DVL12, of phosphorus for TL0101 (471.87 mg/100g), of phosphorus (470.36 mg/100g) and protein (30.74%) for PG1314, for magnesium for DVA2 (383.41 mg/100g) and Copper for KA0303 (0.0147 mg/100g). The concentrations of hydrocyanic acids are high in both leaves than fresh tubers (85 - 150 ppm). Lowest values are observed in tubers (10 - 15 ppm) for cultivar DVA2. Principal component analysis of the physicochemical characteristics of the leaves revealed four groups: the first very rich in calcium, magnesium and average potassium contents. Groups 2 and 3 are poor in calcium and magnesium but Group 2 has the highest potassium content while Group 3 has an intermediate content. Group 4 is very rich in calcium but low in magnesium and potassium. According to tubers, three groups have been identified which are characterized by low, intermediate and high contents in phosphorus. Cultivars SB1366, DVA2, DVL2, TL0101 and PG1314 show promising nutritional values and chemical constituents even if some have high levels of hydrocyanic acids. They could be recommended for the national selection program and for various applications.

Agro-Morphological Characterization of Cassava (Manihot esculenta Crantz) Cultivars from Chad

Cassava is a considerable source of food and income for the rural community of the south of Chad. Despite the importance of the diversity of cultivars in situ, their morphological traits and agronomic performance are under investigated. The aim of this study is to characterize and analyze the variability structure of the cassava’s germplasm. Fifty nine cultivars collected from five main cassava growing regions, were evaluated by forty five agro-morphological descriptors in a Fisher design replicated three times. Data were collected at three, six, nine and twelve months after planting. High phenotypic variability was shown within the collection for the color of apical leaf, vein leaf, petiole, roots and pulp. The same case was observed for the root peduncle, the shape of the central leaflet and the root, the cortex root thickness and the texture of root epidermis. Significant to highly significant differences were observed for all the quantitative traits. High variability were shown for the size of the leaf lobe, petiole length, plant height, root number and length, harvest index, above-ground biomass and fresh root weight. Positive correlations were found between the leaflet and leaf lobe number. Fresh root weight was also positively correlated to the root number, length and diameter. Principal component analysis (PCA) on quantitative variable revealed four groups with two of them containing performant cultivars: Group II with small root, high potential yield but less leaflet and leaf lobe and group III characterized by some cultivars with high productivity, more leaflet and leaf lobe, more and bigger roots. At regional level, significant differences were shown within cultivars which were discriminated in relation to their origin region by the number of the leaf lobes. The better cultivars and the interesting traits could be used to improve cassava production in Chad.

Local Taxonomy and Diversity of Chadian Sorghum [<i>Sorghum bicolor</i>(L.) Moench] Accessions

The integration of local plant genetic resources into the breeding program is an asset for research. The objective of this study is to assess the diversity and analyze the management practices of cultivated sorghum. A questionnaire following a participatory approach was submitted to 675 producers in 45 villages. The cultivars collected were characterized using 9 qualitative descriptors. In total, 151 accessions and 191 names were inventoried. On average, 25.17 accessions per department and 3.36 accessions per village. Local taxonomy is based on many criteria expressed in different local languages. The most common method of naming is that to the word sorghum is added either the color of the grain, the precocity, or any element deemed relevant by the farmers. Significant variability in grain and panicle traits was observed within the collection, except the color of the endosperm. The rate of diversity loss is 11.52% and red grain sorghums are the most threatened with extinction. Five accessions groups are differentiated by the presence or absence of awns, the color of glumes, and amount of grain covered by glumes, grain plumpness, and form. Based on productivity, precocity, plant size, seed shape, and color, the farmers identified seven promising accessions. This potential will be preserved and developed in the sorghum varietal improvement program in Chad.