In the context of sustainable research aiming at improving seed yield and maintaining soil fertility, a study on cross-inoculation of groundnut (Arachis hypogaea L.) and Bambara groundnut (Vigna subterranea (L.) Verd.) with rhizobia strains from four crop legumes was carried out at Sarh (Chad) and Ngaoundere (Cameroon). The experiment was conducted in each site following a randomized complete block design with 6 treatments known as the control, and 5 cross-inoculation formulations (RA, RN, RS, RV and MR), each of which was replicated thrice. Results obtained show that cross-inoculation contributed to the improvement of growth (plant sizes and biomasses) of the two crop legumes, as well as their seed yield at harvest. The enhanced yield expressed in kg/ha varied from 9.83% to 63.73% for groundnut and 72.71% for Bambara groundnut. These findings suggest that groundnut and Bambara groundnut do have a symbiotic affinity with rhizobia from other crop legumes. Whereas Groundnut, Cowpea, Soybean, Bambara groundnut rhizobia (GR, CR, SR, BR) alone, and the fourth in a mixture (RM) could be used to help improving groundnut seed yields; this mixture would not be indicated for intensive cultivation of Bambara groundnut later.

This study was carried out to find out how dependent are two local rice varieties (Magitolngar and Tox-728-1) to inoculation with selected endogenous arbuscular mycorrhizal fungi (AMF) in a field where they were isolated. The multi-indigenous endomycorrhiza spores previously isolated and identified were the active ingredient in the production of bioinoculants used for this purpose. Spores massively multiplied from the rhizosphere of each rice variety in each of the four locally collected soils substrates were harvested to constitute 08 AMF inoculants (Kema = T1; Lama = T2; Latox = T3; Ndjatox = T4; Koloma = T5; Kolotox = T6; Ndjama = T7; Ketox = T8). These inoculants were field tested on the two rice varieties at Kelo, under a complete randomized block design, comprising 10 treatments (8 inoculants, 01 positive control = T9, 01 negative control = T10), each of which was repeated thrice. The analysis of data indicates that AMF-inoculated plants were taller, developed more tillers/plant, and produced more rice grains/panicle than non-AMFinoculated plants for both studied rice varieties. The rice variety Madjitolngar yielded more grains (7.5 t/ha) than the Tox-728-1 variety (5.8 t/ha). Moreover, inoculants Koloma (T1), Latox (T3) and Kolotox (T6) on the one hand, Koloma (T1) and Ketox (T8) on the other hand, were best suited for the improvement of growth and yield of the rice varieties Madjitolngar and Tox-728-1 respectively, tested under field conditions at Kelo. In this study, the two rice varieties have shown a dependency to endomycorrhizal symbiosis at Kelo, and therefore, an industrial-scale production of efficient endomycorrhal inoculants is necessary to sustainably boost the productivity of this important crop in Chad.

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In Chad, rice is grown for its starchy seeds or caryopses, but is also for consumption in the form of seeds pasta with soup. However, little or no work has been conducted in Chad to assess the composition of endomycorrhiza community inhabiting the plant rice rhizospheres. Hence, the main objective of this study was to investigate on native endomycorrhiza that are efficient to establish a symbiotic relationship with two rice varieties in the Sahelian zone in Chad. Two rice varieties were grown in a pot experiment on composite soils samples from Laï, Kelo, Kolobo and N’Djamena for 3 months. Parameters such as mycorrhizal frequency, intensity, specific density and richness were determined following to the standard methods. After spore extraction, species description and characterization were obtained through the informations provided by the International Vesicular Mycorrhizal fungi collection (INVAM): http://invam.caf.wv.edu/fungi/taxonomy/species ID.htm. The highest specific endomycorrhizal density (97.3%) and richness (11%) were registered respectively at kelo, Laï and Kolobo. The endomycorrhizal frequency and intensity were respectively between 4.33-7.33% and 0.8-2.9% for the two rice varieties. Eleven endomycorrhiza species belonging to six genera were identified from different soil samples. These include Septoglomus (S. constrictum, S. deserticola); Rhizophagus (R. aggregatus, R. fasciculatus, R. intraradices); Acaulospora (A. lacunosa, A. rugosa, A. trappei); Claroideoglomus lamellosum; Glomus pansihalos and Diversispora epigae. S. constrictum was the most dominant and frequent species found in all the soil sampling sites, while R. aggregatus was the less frequently encountered specimen. The lowest macorrhizal richness and frequency obtained is a proof that cultivation of rice dependent on endomycorrhiza in this zone. The multi-native endomycorhiza spores identified are the active principle to be included in the bioinoculants production in order to increase and improve the production of rice in the south of Chad.

The effect of microorganisms particularly those of bacteria on litter decomposition in the tropical savannahs of Adamawa Cameroon is poorly investigated. Litter decomposition was conducted in the field on the litter of Ficus sycomorus, Terminalia glaucescens, Daniellia oliveri, and Hymenocardia acida, and the dynamic of bacterial populationas well as their enzymatic activity during degradation of leaf litters was studied. For this purpose, bacteria were isolated from the litterof these plants at the initial time (zero), 12 and 24 weeks of degradation by serial dilution method and spreading onto nutrient agar culture medium. Identification of bacteria was done under photonic microscope after Gram staining and the production of enzymes was carried out on specific media. Results indicate that: 25 bacteria were isolated from distinct phenotypic characteristics on nutrient agar. Based on morphological appearance as observed under light microscope, 24% of isolates were found to be single bacilli; 28% bacilli cluster; 16% were found to be streptobacilli and 32% diplococci. For sugar fermentation test (TSI), 20% of isolates produced gas and acidic reaction, 40% produced acidic butt reaction, while only 20% produced H2S gas ; 76% of isolates were positive to citrate utilization (SIM) test; 20% of isolates were positive to catalase production test, whereas only 20% of isolates were motile. The aforementioned study of phenotypic, microscopic and biochemical enabled identification of two genera: the genus Bacillus and the genus Micrococcus representing respectively 68 and 32% of the isolates. The genus Bacillus consisted of Bacillus cereus (41.17%, with 7 phenotypes), Bacillus megaterium (17.64%, with 3 phenotypes), Bacillus subtilus (35.29%, with 6 phenotypes) and Bacillus sp. (5.88%, with 1 phenotype). The genus Micrococcusre grouped 08 phenotypes. The relative abundance of isolates demonstrated that in all leaf litters and soils, there was a great diversity of bacterial isolates at the initial time and then a considerable decrease in this diversity during litters degradation. The genus Bacillus was generally dominant at all decomposition periods of different plant species. A total of 64% of bacteria isolates produced at least one enzyme. 36% of the isolates produced amylase, 56% produced cellulase, 40% produced esterase, 48% produced lipase, while 48 % of the isolates produced protease. This strong enzymatic activity of the isolated bacteria suggests their competences in the degradation process of leaf litter, and therefore, the interest in exploiting them in litter degradation units for an efficient production of organic fertilizer.