A more complete definition for promiscuous soybean

Open Access JournalAbstract Following a series of research on promiscuous nodulation, it came out that it is incomplete to define ‘promiscuous soybean’ as soybean cultivars with the sole ability to form nodules freely with indigenous Bradyrhizobium strains without requiring the specific type, Bradyrhizobium japonicum. This paper proposes a more complete definition which caters for both nodulation and biological nitrogen fixation ability. Keywords : Promiscuous soybean; Nodulation; Biological nitrogen fixation; Bradyrhizobiu

Mode of inheritance of promiscuous nodulation and combining abilities in soybean genotypes

Article purchasedKnowledge of the mode of inheritance of a trait can be a powerful decision-making tool in a breeding program, as it helps predicting selection gain, defining breeding strategy and choosing parental lines. This study aimed at estimating genetic parameters to infer the mode of inheritance of promiscuous nodulation in soybean. Half diallel crosses were made among nine parental lines. F2 progenies were field evaluated together with parents for nodulation characteristics and grain yield in response to Bradyrhizobium sp. strain USDA 3456. Data on nodule number (NN), percent of effective nodules (NE), fresh and dry weight of nodules (NFW and NDW), and grain yield were subjected to analysis of variance, and progenies’ means regression against parents’ was performed following Griffing’s Method2/Model 1. General and specific combining abilities, broad and narrow sense heritabilities, and Baker’s ratio were estimated. The study showed predominant GCA effect for all measured traits except NE. Broad and narrow sense heritabilities were high for grain yield and NDW, moderate for NN and NFW, and low for NE. Baker’s ratio was high for all measured traits except for NE. Overall, additive gene action was more important for all measured traits, except NE where non-additive gene action was more important. The high to moderate heritabilities for most traits showed that substantial gain can be achieved through selection

Influence of biogas digesters on faecal indicator organisms in digestate and around homesteads In ethiopia

Acknowledgement: This work was funded by AUC/EUC (Afri-flame network); the authors would like to thank the laboratory and field assistants who participated in this study. The Scottish Government for funding Dr Avery’s contribution to co-authouring.Peer reviewedPostprin

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

Leveraging biological nitrogen fixation and soybean yield by planting duration under varying onset of rainy seasons in Uganda

Rainfall distribution and onset of rainy seasons, both of which are key determinants of the decision to plant most annual crops in sub-Saharan Africa (SSA), are increasingly difficult to predict due to climate change. Consequently, planting schedules affect both crops and vital natural systems such as biological nitrogen fixation in legumes. The objective of this study was to establish the optimum planting duration for soybean ( Glycine max L.), from the onset of the rainy season, in the context of nodulation and grain yield, and diversity of rhizobia in rhizosphere soil and nodules. A field experiment was set up with treatments, Bradyrhizobia inoculated and non- inoculated soybean variety Maksoy3N planted at four dates; 0, 10, 20 and 30 days from the onset of rain season. Diversity of rhizobia in the rhizosphere soil and nodules were fingerprinted using Single Strand Conformation Polymorphism (SSCP) method. Inoculation significantly (P<0.05) increased the number but not effectiveness of nodules and grain yield; which was attributed to presence of native strains in the soil. Planting after 10 days following the onset of a rainy season significantly (P<0.05) reduced grain yields and total yield loss was realised when seasonal cumulative rainfall was about 500 mm. Planting after 20 days from onset of rainy season significantly (P< 0.05) reduced the total number of nodules. A total of 8 and 12 clusters of bacteria from the soil and nodules at 5% dissimilarity, respectively, were recorded. The Bradyrhizobia species consisted of B. japonicum, B. japonicum (USDA 6), B. elkanii, B. liaoningense, B. canariense, and B. yuanmingense.La distribution des pluies et le d\ue9but des saisons pluvieuses, \ue0 la fois sont des d\ue9terminants cl\ue9s dans la d\ue9cision de semis de la plupart des cultures annuelles en Afrique sub-sahariennes (SSA), sont progressivement difficiles \ue0 pr\ue9dire \ue0 cause des changements climatiques. EN cons\ue9quence, le calendrier agricole affecte \ue0 la fois les cultures et les syst\ue8mes naturels vitaux tels que la fixation biologique d\u2019azote dans les l\ue9gumineuses. L\u2019objectif de cette \ue9tude \ue9tait d\u2019\ue9tablir la dur\ue9e optimale de culture pour le soja ( Glycine max L.), au d\ue9but de la saison pluvieuse, dans le contexte de la nodulation et du rendement en grain et la diversit\ue9 en rhizobia dans la rhizosph\ue8re du sol et les nodules. Une exp\ue9rimentation au champ a \ue9t\ue9 mise en place avec les traitements, la vari\ue9t\ue9 Maksoy3N inocul\ue9e et non inocul\ue9e avec Bradyrhizobia sem\ue9e en quatre dates\ua0; 0, 10, 20 et 30 jours depuis le d\ue9but de la saison. Les empreintes digitales de la diversit\ue9 de rhizobia dans la rhizosph\ue8re du sol et les nodules ont \ue9t\ue9 \ue9valu\ue9es en utilisant la m\ue9thode de recherche du polymorphisme de conformation (SSCP). L\u2019inoculation a significativement (P<0,05) fait augmenter le nombre mais non n\u2019effectivit\ue9 des nodules et le rendement en grain\ua0; qui est attribu\ue9e \ue0 la pr\ue9sence des souches natives au sol. Le semis 10 jours apr\ue8s le d\ue9but de la saison pluvieuse a significativement r\ue9duit (P< 0,05) r\ue9duit les rendements en grain et la perte totale du rendement a \ue9t\ue9 observ\ue9e lorsque la pluie cumulative saisonni\ue8re a \ue9t\ue9 environ 500mm. Le semis 20 jours apr\ue8s le d\ue9but de la saison pluvieuse a significativement (P< 0.05) r\ue9duit le nombre total de nodules. Un total de 8 et 12 groupes de bact\ue9ries du sol et des nodules \ue0 une dissimilarit\ue9 de 5%, respectivement ont \ue9t\ue9 observ\ue9s. Les esp\ue8ces de Bradyrhizobia sont consist\ue9 B. japonicum, B. japonicum (USDA 6), B. elkanii, B. liaoningense, B. canariense, et B. yuanmingense

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

SCREENING SOYBEAN GENOTYPES FOR PROMISCUOUS SYMBIOTIC ASSOCIATION WITH Bradyrhizobium STRAINS

The current low soybean ( Glycine max L. Merrill) yields in Sub-Saharan Africa can be alleviated by developing promiscuous genotypes. The research trend in Africa is towards developing promiscuous varieties for less labour and high yields in soybean production. A greenhouse experiment was conducted at Makerere University Agricultural Research Institute, Kabanyolo (MUARIK) with the aim of screening of soybean germplasm for promiscuous symbiotic association with Bradyrhizobium sp. in order to identify genotypes with potential to be used as parents to initiate a breeding programme focusing on promiscuous nodulation. The response of 65 soybean genotypes from different origins to cowpea-type inoculant, Bradyrhizobium sp. strain USDA 3456 were evaluated. Soybean seeds inoculated with both Bradyrhizobium sp. strain USDA 3456 and Bradyrhizobium japonicum strain USDA 110 were planted in buckets filled with steam-sterilised soil. Significant differences in the number of nodules, effective nodules, fresh and dry weight of nodules were observed among genotypes (P<0.001). Twelve of the 65 genotypes were highly responsive to Bradyrhizobium sp., with over 10 nodules per plant, over 50 mg dry weight of nodules, and 50% effective nodules. A highly positive correlation was shown between dry weight of nodules and nodule number. This study proposes the soybean genotypes NamII, WonderSoya, Bulindi 48C, NamSoy 4M, MakSoy 3N, NamSoy 3, K-Local, Kabanyolo 1, UG 5, Soprano, MakSoy 2N, and MakSoy 5N as potential parental materials for subsequent breeding work.La s\ue9lection de vari\ue9t\ue9s de soja \ue0 nodulation facile peut contribuer grandement \ue0 l\u2019am\ue9lioration des rendements de production en Afrique sub-Saharienne. Les vari\ue9t\ue9s de soja \ue0 nodulation facile rendent superflus l\u2019utilisation d\u2019engrais azot\ue9s, l\u2019application d\u2019inoculum aux fins de fixation biologique d\u2019azote, am\ue9liorent le rendement de soja, ainsi que la qualit\ue9 du sol pour les cultures subs\ue9quentes. Une exp\ue9rimentation en serre a \ue9t\ue9 conduite \ue0 l\u2019Institut de Recherche Agricole de l\u2019Universit\ue9 de Makerere \ue0 Kabanyolo (MUARIK). L\u2019objectif \ue9tait d\u2019\ue9valuer l\u2019habilet\ue9 des accessions de soja \ue0 r\ue9aliser la symbiose avec Bradyrhizobium sp. En vue d\u2019identifier les cultivars qui peuvent constituer de potentiels parents \ue0 utiliser pour initier un programme d\u2019am\ue9lioration g\ue9n\ue9tique du soja visant la nodulation facile. 65 accessions d\u2019origines diverses ont \ue9t\ue9 \ue9valu\ue9es pour leur r\ue9action en pr\ue9sence de rhizobium de type ni\ue9b\ue9 (Bradyrhizobium sp. souche USDA 3456). Les graines de soja inocul\ue9es avec le rhizobium de type ni\ue9b\ue9 (Bradyrhizobium sp. souche USDA 3456) ou de type soja ( Bradyrhizobium japonicum souche USDA 110) ont \ue9t\ue9 plant\ue9es dans des pots en plastic soigneusement remplis de terre arable st\ue9rilis\ue9e \ue0 base de vapeur surchauff\ue9e. Des diff\ue9rences significatives ont \ue9t\ue9 observ\ue9es entre accessions, au niveau des nombres de nodules, pourcentages de nodules actives, poids frais et secs des nodules (P<0.001). Douze accessions ont notablement r\ue9agi face \ue0 Bradyrhizobium sp. avec chacune plus de 10 nodules par plante, 50 mg comme poids sec de nodules, et 50% de nodules actives. Une corr\ue9lation positivement tr\ue8s significative a \ue9t\ue9 observ\ue9e entre poids sec et nombre de nodules. Cette \ue9tude propose les accessions NamII, WonderSoya, Bulindi 48C, NamSoy 4M, MakSoy 3N, NamSoy 3, K-Local, Kabanyolo 1, UG 5, Soprano, MakSoy 2N, and MakSoy 5N comme potentiels parents \ue0 utiliser dans un programme ult\ue9rieur d\u2019am\ue9lioration g\ue9n\ue9tique

Biophysical potential of crop residues for biochar carbon sequestration, and co-benefits, in Uganda

Open Access Journal; Published online: 27 July 2019Increasing organic matter/carbon contents of soils is one option proposed to offset climate change inducing greenhouse gas (GHG) emissions, under the auspices of the UNFCC Paris Agreement. One of the complementary practices to sequester carbon in soils on decadal time scales is amending it with biochar, a carbon rich byproduct of biomass gasification. In sub‐Saharan Africa (SSA), there is a widespread and close interplay of agrarian‐based economies and the use of biomass for fuel, which makes the co‐benefits of biochar production for agriculture and energy supply explicitly different from the rest of the world. To date, the quantities of residues available from staple crops for biochar production, and their potential for carbon sequestration in farming systems of SSA have not been comprehensively investigated. We assessed the productivity and usage of biomass waste from maize, sorghum, rice, millet, and groundnut crops; specifically quantifying straw, shanks, chaff, and shells, based on measurements from multiple farmer fields and household surveys in eastern Uganda. Moreover, allometric models were tested, using grain productivity, plant height, and density as predictors. These models enable rapid and low‐cost assessment of the potential availability of feedstocks at various spatial scales: individual cropland, farm enterprise, region, and country. Ultimately, we modeled the carbon balance in soils of major cropping systems when amended with biochar from biomass residues, and up‐scaled this for basic scenario analysis. This interdisciplinary approach showcases that there is significant biophysical potential for soil carbon sequestration in farming systems of Uganda through amendment of biochar derived from unused residues of cereals and legume crops. Furthermore, information about these biomass waste flows is used for estimating the rates of biochar input that could be made to farmlands, as well as the amounts of energy that could be produced with gasifier appliances

Water use efficiency of maize (Zea mays L.) crop under selected soil and water conservation practices along the slope gradient in Ruzizi watershed, eastern D.R. Congo

Open Access Journal; Published online: 18 Oct 2022Maize (Zea mays L.) productivity is constrained by water shortages in the predominantly rainfed agriculture of the tropical semi-arid Ruzizi Plain, in the eastern Democratic Republic of Congo (DRC). The region is characterized by a high seasonal and inter-annual rainfall variability and a frequent occurrence of consecutive dry days within growing seasons. Consequently, planning water utilization in rainfed agriculture has become complex, as appropriate soil water conservation (SWC) practices are lacking among most smallholder farmers. Identifying practices that increase water use efficiency (WUE) along the slope gradient is crucial for supporting maize production in the region. In this study, we assessed, for three growing seasons, the effectiveness of two SWC practices (tied ridges and Zai pits) in improving the WUE of two maize varieties along three slope gradients (0–2, 2–8, and 8–15%) in the tropical semi-arid Ruzizi Plain. In this area, rainfall amounts (142–289 mm) were consistently below the evapotranspiration demands (356–533 mm) across the three growing seasons. Tied ridges recorded the highest grain yield (2.16 t ha−1) and WUE (15.23 kg mm−1), especially at low slopes, when compared to Zai pits and conventional tillage. For all SWC practices, WUE decreased with the slope gradient (p < 0.01). Furthermore, a decrease in stored soil water (SWS) at silking and maturity stages (milk, dough, and dent stages) negatively affected the WUE. The variety had no significant effect on grain yield and WUE. Root biomass (RBM), shoot biomass (SBM), and leaf area index (LAI) at the flowering stage were the most associated with the WUE (R2 = 58.5%). In conclusion, tied ridges showed potential for improving maize WUE and yield in the water-deficient conditions that characterize the Ruzizi Plain, and could be promoted to improve the maize productivity among smallholder farmers