Composition and spore abundance of arbuscular mycorrhizal fungi in sweet potato producing areas in Uganda

IntroductionFarming systems influence composition and abundance of microbial communities.MethodologyA study was conducted using morphotyping and enumeration methods to determine the composition and spore abundance of Arbuscular Mycorrhizal Fungi (AMF) in sweet potato producing regions in eastern Uganda. Sampling was done from fields with crop types (CTs) including legumes (groundnuts, common beans, cowpea, soybeans, green grams), sorghum, sweet potato, and fallowed fields which were used as a control. Three agro-ecological zones (AEZs) i.e., Mt. Elgon High Farmlands (MEHF), Lake Victoria Crescent (LVC), and Southern and Eastern Lake Kyoga Basin (SELKB) were considered.Results and discussionA total of 6 AMF genera comprising of Glomus, Acaulospora, Scutellospora, Entrophospora, Archaeospora, and Gigaspora were isolated from the study sites. Agro-ecological zones had a significant (p<0.05) effect on Entrophospora spp. while crop types had a significant (p<0.05) effect on Gigaspora spp. although all the AMF genera were present in all AEZs and CTs. Spore abundance was similar across the AEZs except for MEHF (177) which was lower while spore abundance lowest in sweet potato (177) and largest in fallow (224), attributed to soil properties and similar crops included in the crop rotation program. The AMF can be isolated, identified, and multiplied to produce bioinoculants for the regions

Production and use of arbuscular mycorrhizal fungi inoculum in sub-Saharan Africa: challenges and ways of improving

Article purchasedUse of inorganic fertilizer is an essential practice to optimize crop productivity in the poor fertility soils in sub-Saharan Africa, but it has been linked to high cost of crop production, contamination of surface and/or ground water by nitrate leaching and eutrophication of surface water by phosphate run-off. Besides, secondary effects on soil biotic community and soil impoverishment have weakened cropping systems making them increasingly dependent on external chemical fertilizers. Efficient plant nutrition management should ensure both enhanced and sustainable agricultural production and safeguard the environment. Improved production and adoption of bio-inoculants such as arbuscular mycorrhizal fungi is an emerging soil fertility management practice with potential to increase and cheaply improve crop yields. Arbuscular mycorrhizal fungi inoculum production and adoption in sub-Saharan Africa smallholder systems is however, still limited mainly by research capacity and technological challenges. This study provides the state of the art in production and use of the technology and highlights the challenges and opportunities for its advancement. To experience the benefits of arbuscular mycorrhizal fungi, sound investment on research in low input systems and technical support from the government, the public and the private sectors should be considered. Nevertheless, adequate training of extension workers, agro-dealers and smallholder farmers through agricultural, academic and research institutions will solve the challenges of production and adoption of arbuscular mycorrhizal fungi inoculum technology hence improve crop production

Combined application of biofertilizers and inorganic nutrients improves sweet potato yields

Open Access JournalSweet potato [Ipomoea batatas (L) Lam] yields currently stand at 4.5 t ha−1 on smallholder farms in Uganda, despite the attainable yield (45–48 t ha−1) of NASPOT 11 cultivar comparable to the potential yield (45 t ha−1) in sub-Saharan Africa (SSA). On-farm field experiments were conducted for two seasons in the Mt Elgon High Farmlands and Lake Victoria Crescent agro-ecological zones in Uganda to determine the potential of biofertilizers, specifically arbuscular mycorrhizal fungi (AMF), to increase sweet potato yields (NASPOT 11 cultivar). Two kinds of biofertilizers were compared to different rates of phosphorus (P) fertilizer when applied with or without nitrogen (N) and potassium (K). The sweet potato response to treatments was variable across sites (soil types) and seasons, and significant tuber yield increase (p 30 t ha−1. The results also show that to realize significance of AMF in nutrient depleted soils, starter nutrients should be included

Biological inoculants for sustainable intensification of agriculture in sub-Saharan Africa smallholder farming systems

Land degradation in the smallholder farming systems in sub-Saharan Africa is mainly related to insufficient adoption of sustainable agriculture technologies. This study was aimed at investigating the potential of biological inoculants to improve crop yields and control plant diseases in a profitable manner. Three rhizobia inoculants for soybean or common bean, 2 arbuscular mycorrhizae fungi (AMF) for sweet potato, and 2 Trichoderma products for tomato were applied to determine their effect on yields and tomato late blight disease. The study was conducted in Ghana, Kenya, Tanzania, and Uganda, but the treatments varied among the countries. The Rhizobia inoculants produced significant soybean or common bean yield increases in Ghana, Kenya, and Tanzania at p ≤ 0.05 when compared to the untreated control, and an economic analysis of the Ghanaian data found that Legumefix was profitable with a value–cost ratio of >3. There was significant spatial variability in crop yields (coefficients of variation: 37–64 %), indicating a need for further investigation to correct the limiting factors. The sweet potato response to AMF was variable across sites and seasons, and a significant response (p ≤ 0.05) was shown only under drought conditions in a soil with low organic matter content (1.2 %). The Trichoderma inoculants controlled late blight disease in tomatoes significantly better than Ridomil (p ≤ 0.05), a synthetic fungicide currently used by farmers in Kenya. Biological inoculants can therefore improve the productivity of the sub-Saharan Africa smallholder farming systems, and awareness of them should be created for relevant stakeholders to increase understanding and adoption of technologies for sustainable agricultural intensification