Mitigating Iron Toxicity by Using Rock Phosphate to Improve Rice Productivity

Iron toxicity is a major constraint to rice production, particularly in highly weathered soils of inland valleys in Sub-Saharan Africa where the rice growing area is rapidly expanding. This study aimed to improve the productiveness of iron toxicity sensitive’s rice fields as well as in the unsensitive fields by using local phosphate fertilizers. Eighteen (18) rice genotypes were been assessed in a split plot design in two areas: without iron toxicity and with iron toxicity. NPK, NK, Rock Phosphate, Triple super phosphate, Calcined phosphate and Acidulated phosphate were used as fertilizers. Data collection was focused on agronomic traits and yield (g/m2). The best fertilizers in the area without iron toxicity were NPK (820.2 g/m2) and triple super phosphate (751.7 g/m2). In the iron toxicity area, the best yields were performed by NPK (785.5 g/m2) and raw calcined phosphate (698.3 g/m2). Yet, the Accessions 15, Accessions 225, Accessions 226 and Accessions 270 were rainfed rice genotypes while CC109 A, HB 46 and HB 62 were low-land/irrigated rice genotypes. NPK, NK and acidulated phosphate fertilizers alleviate the best, iron toxicity in both sensitive and unsensitive rice fields.

Evaluation of Soybean Genotypes (Glycine max L. Merr.) Susceptibility to Parasitic Nematodes in Western Part of Burkina Faso

Parasitic nematodes have been reported as one of the major constraints to soybean production worldwide. The majority of nematodes are so-called “free-living” and feed mainly on bacteria, fungi, protozoa and other nematodes. In Burkina Faso, the presence of parasitic nematodes has been reported in crops such as rice and sorghum. The objective of this study was to identify the genera and species of nematodes associated with soybean production in Burkina Faso. Investigations were carried out on 24 genotypes of a medium-maturity group of soybean at the Farako-Ba research station. Soil samples were taken from the trial soil before its installation. At harvest, soil samples with roots were taken from each genotype in the elementary plots. The composite sample is represented by 4 lots of soil samples with roots. Extractions and counts of nematodes were performed on the different lots. In total, 7 genera of plant-parasitic nematodes associated with soybean were identified. Among these genera, Pratylenchus (100% of infected genotypes), Helicotylenchus (97.28%) and Scutellonema (94.44%) were the most prevalent in terms of frequency and abundance. Some soybean genotypes were less susceptible to the genus Pratylenchus is known to be highly pathogenic in soybean. These were mainly the genotypes TGX2025-10E, TGX2023-3E and TGX2025-14E.

Induced Resistance to <i>Striga hermonthica</i>in Sorghum by Gamma Irradiation

Striga species affect the potential productivity of cereals in sub-Saharian Africa due to the lack of durable Striga-resistance in host crops. This study aimed at inducing the new source of resistance in sorghum using gamma irradiation. Dry seeds of three Sorghum varieties;Grinkan, ICV1049 and Sariaso14 were gamma-irradiated with 200 Gy, 300 Gy, 400 Gy and 500 Gy. Screening strategies involved a 2-year field and greenhouse experiments, where mutant Sorghum families, their parents and resistant control were artificially infected with Striga hermonthica seeds. Field screenings revealed induced genetic variability among them, forty families significantly reduced the number of emerged Striga plants or showed good Sorghum grain yield performance despite the infection by S. hermonthica ecotype from Burkina Faso. The induced putative resistant mutants were identified across the four applied gamma-irradiation doses. Greenhouse experiment confirmed Striga resistance in seven mutant Sorghum families leading to no emergence of Burkina’s S. hermonthica ecotype along with high resistance index (RI) and low Striga damage score. Among them, two mutants SA38M5 and IC47M5 withstood S. hermonthica ecotype from Sudan. The induced mutants will be evaluated for the release to farmers for commercial production. Further studies are ongoing on confirmed mutants to highlight their Striga resistance mechanisms and explore the potential of pyramiding different mechanisms to produce durable resistance to S. hermonthica in sorghum.

Molecular Characterization Using Microsatellites of Bambara Nut (<i>Vigna subterranea</i>[L] Verdcourt) Landraces Cultivated in Burkina Faso

Voandzou is a seed legume cultivated in Burkina Faso with significant nutritional potential. The objective of this study was to assess the genetic diversity of Bambara nut cultivated in Burkina Faso using microsatellite markers. For the study, fifteen SSRs markers were used for molecular characterization of 90 Bambara nut landraces from three agro-climatic zones of Burkina Faso. All markers were 100% polymorphic with an average value of 4.81 for effective alleles. The polymorphism information content (PIC) ranged from 0.654 to 0.867 with a mean of 0.775. Dendrogram classified the accessions in four mixed groups independently of the three agro-climatic zones. This distribution is consistent with the results on the agro-morphological characterization of the same landraces. This information was served as a basic model for breeding and conservation programs of V. subterranea in Burkina Faso.

Physical and Cooking Characteristics of Six Cowpea Varieties Seeds Cultivated in Burkina Faso

Cowpea is essential in the diet in Burkina Faso. The information on their physical properties and cooking quality is important for consumer acceptance. This study has therefore been undertaken in order to fill the gap. Thus, six cowpea varieties were evaluated for their physical and cooking properties. The seeds had between 9% to 12% moisture. For physical proprieties, the result revealed that the variety Makoyin had the highest seed length (9.65 mm), the variety Gourgou recorded the highest seed width (7.08 mm), seed thickness (5.13 mm), and seed area (153.29 mm2), and 100-seeds weight (21.1 g). The lowest seed sizes were presented by the variety Teeksongo with values of 7.88 mm, 6.34 mm, 4.88 mm, 122.68 mm2, and 16.87 g for respectively the length, the width, the thickness, the area, and the 100-seeds weight. The variety Makoyin produces seed elliptical form and varieties Neerwaya, Gourgou, Yipoussi and Issa-sosso, and Teek-songo the seeds spherical form. For cooking proprieties, the highest value of the bulk density of the seeds was presented in the variety Teek-song (1.51 g/ml). The highest hydration and swelling capacity were observed in varieties Gourgou (0.22 g/seed and 0.24 ml/seed respectively) and Yipoussi (0.22 g/seed and 0.21 ml/seed respectively). The seed with large size, greater hydration, and swelling capacity is preferred by consumers and processors for food products. Varieties Makoyin, Neerwaya, Gourgou, Yipoussi, and Issa-sosso presented cooking time of unsoaked seeds equal to one hour (from 60 to 68 min) excepted Teek-songo which had 46 min. These cooking times are acceptable for consumers. Seed length, surface area, thickness, the weight of seeds, hydration capacity, and cooking time have been the most discriminating among the cowpea varieties studied.

Genetic Relationship between Sweet Grain Sorghum and the Other Sorghum Types Cultivated in Burkina Faso Assessed with Nuclear Microsatellite Markers SSRs

In Burkina Faso, sweet grain sorghum [Sorghum bicolor (L.) Moench] is generally cultivated in association with several other types of sorghum. However, the lack of information on the genetic relationship between this sorghum and grain sorghum as well as sweet stalk sorghum hinders the efficient management of its genetic resources. Thus, 34 sorghum accessions consisting of 14-grain sorghum, 10-sweet stalk sorghum, and 10 sweet grain sorghum were evaluated using 15 nuclear microsatellites markers (SSRs) to determine their genetic relationship. Results revealed significant genetic diversity within each sorghum type and a significant index of genetic differentiation per pair of sorghum types (0.017) between sweet grain sorghum and sweet stalk sorghum. The minimum Nei distance was also high (0.12) between these two sorghum types. Sweet grain sorghum indeed showed the lowest values of theoretical heterozygosity (0.35), of observed heterozygosity (0.13). Structuring of the accessions of the three types of sorghum cultivated in two distinct groups, one of grain sorghum and sweet stalk sorghum and another consisting of accessions of grain sorghum and sweet grain sorghum was also obtained. The low differentiation observed would suggest greater genetic proximity between the three types of sorghum. The differences observed would be more of a physiological and biochemical nature. These results could contribute to better management of the genetic resources of sweet grain sorghum.

Agromorphological Characterization of Introgression Lines Derived from Wild and Exotic Sorghum Germplasm to Climate Change Challenges

Sorghum (Sorghum bicolor (L.) Moench) is vitally important for food security in semi-arid West Africa. The introgression of wild- and high transpiration efficiency genotypes may contribute genes for abiotic stress tolerance or novel traits. Characterizing the introgressed lines can help researchers in the process of varietal improvement. The objectives of this study are (i) To learn if introgression of wild sorghum (CWR) and high transpiration efficiency (HTE) lines into a very early maturing (photoperiod insensitive) local land-race variety can create useful variation for grain yield in drought-prone Sahelian environments, (ii) To determine if grain yield advantages (and putative drought tolerance traits) obtained from introgression of CWR and HTE germplasm are expressed differently in moderately to highly moisture-limited environments, and (iii) To understand the relationship between putative drought tolerance traits. These populations were developed from crosses between the CSM63E (Jakumbe, a high grains quality variety) and two wild parents (accessions) and five high transpiration efficiency (TE) sorghum accessions. Phenotyping was conducted using an alpha lattice design with three replications in two environments for agronomic traits (grain yield and components), flowering time and physiological traits (stay-green, chlorophyll content and lodging). A total of 669 BC1F5 progenies were developed. Genetic variation for grain yield and putative drought tolerant traits were evaluated. Both populations derived from wild parents exhibited in Cinzana a grain yield (>300 g/m2) greater than CSM63E (245 g/m2). In Bema, more than 75% of the progenies of all populations indicated a chlorophyll content at physiological maturity (>30 SPAD) higher than CSM63E (20 SPAD) chlorophyll content. The estimated broad sense heritability was generally high (≥0.50) for all traits. The results also showed a very significant interaction between genotype and environment for grain yield, flowering time, chlorophyll content, stay green and lodging. There was a strong correlation between stay green and chlorophyll content (0.60) on the one hand and between stay green and lodging (0.48) on the other. This great variability could help improve the grain yield of sorghum for farmers in the Sahelian zone.

Genetic Diversity of Local Rice Accessions Cultivated in Guinea Based on Agro-Morphological Traits and Identification of Sources of Tolerance to Iron Toxicity

In Guinea, traditional rice varieties are the most widely cultivated in rural areas despite their low yield and high susceptibility to iron toxicity. Moreover, the introduction of new improved varieties tolerant to iron toxicity poses a serious threat to the preservation of the genetic resources of these traditional varieties, whose genetic diversity remains poorly known. The present study therefore aims at a better valorisation of these local rice cultivars through the evaluation of their agromorphological diversity and the identification of genotypes potentially tolerant or resistant to iron toxicity. Thus, 90 accessions collected in the regions of Kindia and Macenta and six controls susceptible or resistant to iron toxicity (AZUCENA, BOUAKE 189, CK 73, IR64, NERICAL 19 and AURYLUX 6) were evaluated in three replicate alpha lattice designs in two sites (Sérédou and Kilissi) using 16 agromorphological traits. The results showed significant agromorphological variability of the traditional accessions at both sites for all qualitative and most quantitative traits studied. In addition, 30 local cultivars expressed similar or higher grain yields than the resistant or tolerant controls at both sites, of which 12 were found to be stable at both sites. Of the 12 cultivars identified, five were resistant and seven tolerant to iron toxicity. These 12 accessions could be used in the varietal improvement of lowland rice in Guinea Conakry.