Mots clés : Zones agro-écologiques, éléments minéraux, analyse des sols, manioc, rendement. TEMEGNE et al. / Int. J. Biol. Chem. Sci. 9(6): 2776-2788, 2015 2777 Effect of soil chemical composition on nutrient uptake and yield of cassava (Manihot esculenta Crantz, Euphorbiaceae) in two agro-ecological zones of Cameroon ABSTRACT A study was conducted to evaluate the effect of soil chemical composition on nutrient uptake and yield of cassava in two agro-ecological zones of Cameroon. Soil and plant samples were obtained from twelve month old pure culture cassava fields at Ekona (zone 4) and Ongot village (zone 5). An improved variety (8034) and two local varieties (Local Red at Ekona and Bassa Noire at Ongot) were used. Results showed that the soil from Ekona (Andosol) was significantly higher in nutrients (total nitrogen: 1.34%; phosphorus available: 15 mg.kg -1 ) than the soil from Ongot [(Ferralsols), (total nitrogen: 0.11%; phosphorus available: 4 mg.kg -1 )]. The improved variety accumulated significantly more total fresh biomass and root yield than the local varieties, irrespective of the site. Similarly, nutrient uptake was higher with the improved variety across the zones. A positive and highly significant correlation (r 2 :0.999, p<0.001) was observed between nutrient uptake by cassava and soil nutrient availability. Thus, it may be concluded that the quantity of nutrient in the leaves and roots of cassava is proportionate to the quantity of nutrient elements in the soil. This preliminary result constitutes a solid base for the determination of an appropriate fertilizer scheme for cassava cultivation in Cameroon.

Increasing yields in agriculture and management of soil fertility are becoming a major issue in view of the malnutrition problems. Tropical ferralitic soils are phosphorus (P)-deficient. The arbuscular mycorrhizal fungi (AMF) must form symbiotic associations with plants to enhance their hydro-mineral nutrition. The objective of this study was to evaluate the effect of mycorhization on growth of Vigna subterranea. Seedlings of two landraces were inoculated withAMF composite (Gigaspora margarita and Acaulospora tuberculata). P was administered by Hoagland solution (0 and 1000 MP i ). Two months after sowing, plants were harvested. The results show that,with or without phosphate, the number of nodules was three times (p<0.001) higher in mycorrhized plants compared to controls.Phosphate increased (p<0.001) the leaf P-content by 21 and 54% for the control and mycorrhized plants, respectively. Soluble phosphate did not affect the frequency and intensity of mycorhization. Soluble phosphate and mycorhizationsignificantly improve growth and leaf P-content.

Many strains of arbuscular mycorrhizal fungi (AMF) have the ability to improve the water and mineral nutrition of plants and in particular the supply of phosphorus (P). The objective of this study was to determine the influence of mycorrhization and simple superphosphate (SSP) on growth of Voandzou, also called Bambara groundnut (Vigna subterranea (L.) Verdc.). Five SSP doses (0, 30, 60, 90 and 120 mg P 2 O 5 .kg-1 of substrate) were administered on seedlings of two Voandzou landraces inoculated with AMF composite (Gigaspora margarita and Acaulospora tuberculata). Plants were harvested eight weeks after sowing. The results showed that mycorrhization and SSP favored vegetative growth and increased biomass. Thus, the number of leaves of mycorrhized plants was significantly higher than that of control by 5.0%. The highest leaf P-content was observed with 60 mg P 2 O 5 + AMF treatment; but was reduced with 120 mg P 2 O 5 + AMF treatment. Mycorrhizal intensity was highest without SSP. High P levels were observed to reduced mycorrhizal efficiency. However, low SSP doses could be associated with AMF to optimize Voandzou growth. In conclusion, mycorrhization and SSP enhance the growth of Voandzou.

In order to improve the production and commercialization of Bambara groundnut (Vigna subterranea (L) Verdc.) in Cameroon, an inventory on the use of available resources and peasant agronomic practices is a necessary prerequisite. Their understanding can help to establish efficient strategies to enhance this neglected crop. The objective of this work was therefore to identify the uses and the peasant knowledge on the Bambara groundnut in Cameroon. To this effect, a survey on the use of Bambara groundnut was carried out through interviews and direct discussions with farmers in the main production areas (Far North, Adamawa, Littoral (Coastal), Centre, North-West and West) of Cameroon. The survey revealed that in Cameroon, Bambara groundnut is mainly grown by women (74%). Monoculture (60%) is the most widely used cropping system; 40% of farmers associate it with other crops such as groundnuts, maize, sesame, okra, millet, sorghum, beans, egusi or pumpkin, and tubers. It is produced mainly on small land areas by the elderly. It is mainly cultivated by the poor peasants and without soil amendments. Several landraces are cultivated, the preferred varieties varying according to the production basins. Seed storage is mainly done with chemicals in closed containers. Weeds, lack of improved varieties, low yields, diseases and pests (insects, rodents) are the main production constraints identified. Results of this study could be exploited for the improvement and vulgarization of Bambara groundnut in Cameroon.

Background: Cassava (Manihot esculentaCrantz

Background: Development of high yielding and disease resistant cassava (Manihot esculenta Crantz) varieties, coupled with the promotion of efficient processing technologies, is the principal intervention aimed at changing the cassava sector in Cameroon. National research and extension programs have been spearheading efforts to disseminate these varieties alongside improving farmer's access to other technologies. Methods: This paper investigated the rate of adoption of the disseminated cassava varieties and processing technologies on adopting households. Survey of 100 households was done in 5 villages (Mbankomo, Akono, Okola, Ngoumou and Nkoldoum) in the Center Region of Cameroon. Results: The results showed that in all the study sites 40% of the farmers cultivate improved variety. They process cassava at home using small processing commercial processors. It is noted that the farmers prefer the improved variety because of their high dry matter content and most common processed cassava products were found to be "Baton" and "Fufu". Moreover, farmers that were able to obtain the improved variety appreciate this variety so much because of its yield and disease tolerant and most of all of because of their high dry matter content which the farmers appreciate a lot. The farmer's adhesions in community organizations or cooperative organizations have a higher tendency of obtaining credits for their farms seeds and other technical support. Thus the introduction of new cassava varieties would be enhanced by farmers' access to these facilities and services. Conclusion: The size of the farm, the availability and the adoption of improved planting material play a critical role on cassava tuber production in Center Region of Cameroon.

The objective of this study was to investigate appropriate fertilization schemes to improve the production of maize and sorghum in the Sahel agroecological zone of Cameroon. The experiment was carried out in 2018 at IRAD (Institute of Agricultural Research for Development) Kismatari experimental field. The experimental setup was a complete randomized block design in four replicates and four treatments for each crop. For maize, treatments were: T1 (No input), T2 (100 kg NPK + 100 kg Urea.ha-1), T3 (150 kg NPK + 150 kg Urea.ha-1), and T4 (200 kg NPK + 200 kg Urea.ha-1). For sorghum, treatments were: T1 (No input), T2 (50 kg NPK + 50 kg Urea.ha-1), T3 (100 kg NPK + 100 kg Urea.ha-1), and T4 (150 kg NPK + 150 kg Urea.ha-1). All fertilizer treatments NPK and urea were applied to both crops respectively at 3 and 5 weeks after sowing. Nine weeks after sowing, the plant height was highest at T3, following by T2 and T4 for the two crops. The treatment T1 exhibited the lowest grain yield while T2 and T3 showed intermediate grain yield. The treatment T4 produced the highest biomass, number of ears.plant-1, and grain yield (maize: 3.3 t. ha-1, sorghum: 2.9 t.ha-1) for the two crops and thus appears to be the most appropriate fertilizer recommendation for maize and sorghum production in the Sahel zone. However, costs-benefits studies for the use of fertilizer NPK and urea are warranted to facilitate adoption by farmers in the agroecological zone.

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