Indigenous rhizobia strains: The silver bullet for enhanced biological nitrogen fixation and soybean (Glycine max (L.) Merr. ) yield under different soil conditions in South Kivu province, Democratic Republic of Congo (original) (raw)
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Advances in Microbiology
Soybean [Glycine max (L.) Merrill] is an important crop known to improve population nutritional status and increase soil fertility and its productivity through biological nitrogen fixation. In Côte d'Ivoire, the introduced Bradyrhizobium japonicum used as inoculum had slight compatibility to several soybean varieties compromising their vulgarization. Therefore, the present study was conducted to examine the infectiveness and the effectiveness of indigenous rhizobial isolates on three soybean varieties (Canarana, Doko and Piramana) cultivated in Côte d'Ivoire. The experiment was conducted with potted plant filled with sterilized sand and was statistically laid in Completely Randomized Design (CRD) with sixteen (16) natives rhizobia, one (01) reference strain and uninoculated control (with or without nitrogen) with three replications. The results showed that inoculation significantly improved nodule number, nodule dry weight, plant height and total dry matter of soybean over the negative control treatment. Among the inoculated treatments, five indigenous rhizobia RSC119, RSC324, RSC502, RSC504 and RSC508 significantly (P < 0.05) increased the nodulation and plant growth parameters than B. japonicum (IRAT FA3) with Doko and Piramana. RSC502 produced highest nodule number (64) on Piramama, nodule dry weight was most promoted with RSC504 (321 mg•plant −1) compared to IRAT FA3 strain (95 mg•plant −1) on Doko. The higher effectiveness was recorded with RSC119, RSC504 and RSC502 with 206.73%; 201.79% and 200.
Soybean-Nodulating Rhizobia: Ecology, Characterization, Diversity, and Growth Promoting Functions
Frontiers in Sustainable Food Systems
The worldwide increase in population continues to threaten the sustainability of agricultural systems since agricultural output must be optimized to meet the global rise in food demand. Sub-Saharan Africa (SSA) is among the regions with a fast-growing population but decreasing crop productivity. Pests and diseases, as well as inadequate nitrogen (N) levels in soils, are some of the biggest restrictions to agricultural production in SSA. N is one of the most important plant-limiting elements in agricultural soils, and its deficit is usually remedied by using nitrogenous fertilizers. However, indiscriminate use of these artificial N fertilizers has been linked to environmental pollution calling for alternative N fertilization mechanisms. Soybean (Glycine max) is one of the most important legumes in the world. Several species of rhizobia from the four genera, Bardyrhizobium, Rhizobium, Mesorhizobium, and Ensifer (formerly Sinorhizobium), are observed to effectively fix N with soybean a...
Identifying Elite Rhizobia for Commercial Soybean (Glycine Max) Inoculants
2013
Existence of highly effective rhizobia in African soils is under exploited since commercial inoculants still contain exotic cultures from United States of America. Bio-prospecting was conducted in Kenya to identify elite strains of rhizobia capable of effectively nodulating and fixing large amounts of nitrogen with commonly grown soybean varieties. One hundred isolates were recovered from nodules of wild and cultivated legume hosts growing in different agro-ecological zones, namely coastal sand dunes and mangrove swamps, the uplands and Rift Valley highlands, to the Afro-montane zone of Mount Elgon and the Lake Victoria Basin, covering about 1045 km transect. These isolates were authenticated and tested for effectiveness on soybean (Glycine max) var. SB 19 in sterile vermiculite, and the twenty-four most promising isolates screened in potted soil to assess their competitive abilities using two contrasting varieties of soybean ("promiscuously nodulating" SB 19 and specific ...
International Journal of Plant & Soil Science
Legumes such as soybean establish symbiotic relation with nitrogen fixing bacteria such as Rhizobia. Nitrogen fixation via legume-rhizobium symbiosis is the most important source of Nitrogen in agro-ecosystems. But environmental stresses are important limiting factors for this process. Hence, the aim of this study is to evaluate the physiological characteristics and Plant Growth Promoting (PGP) properties of soybean rhizobia. A total of 28 Rhizobia strains obtained from soybean root nodules collected in from three Agro-Ecological Zones (zones 3, 4 and 5) producers of soybean in Benin were used. The physiological characteristics include utilization of carbon source, tolerance to temperature, salinity and pH, resistance to antibiotics and heavy metals. The PGP properties were relative to production of indole, hydrogen cyanide and ammonia and catalase test. The results revealed that, irrespective of their geographical regions, the 28 isolates were grouped into five Clusters. Most of th...
Agriculture, Ecosystems & Environment
The soybean-Bradyrhizobium symbiosis can be very effective in fixing nitrogen and supply nearly all plant's demand on this nutrient, obviating the need for N-fertilizers. Brazil has been investing in research and use of inoculants for soybean for decades and with the expansion of the crop in African countries, the feasibility of transference of biological nitrogen fixation (BNF) technologies between the continents should be investigated. We evaluated the performance of five strains (four Brazilian and one North American) in the 2013/2014 and 2014/2015 crop seasons in Brazil (four sites) and Mozambique (five sites). The experimental areas were located in relatively similar agro-climatic regions and had soybean nodulating rhizobial population ranging from ≪ 10 to 2 × 10 5 cells g −1 soil. The treatments were: (1) NI, non-inoculated control with no N-fertilizer; (2) NI + N, non-inoculated control with 200 kg of N ha −1 ; and inoculated with (3) Bradyrhizobium japonicum SEMIA 5079; (4) B. diazoefficiens SEMIA 5080; (5) B. elkanii SEMIA 587; (6) B. elkanii SEMIA 5019; (7) B. diazoefficiens USDA 110; (8) SEMIA 5079 + 5080 (only tested in Brazil). The best inoculation treatments across locations and crop seasons in Brazil were SEMIA 5079 + 5080, SEMIA 5079 and USDA 110, with average grain yield gains of 4-5% in relation to the non-inoculated treatment. SEMIA 5079, SEMIA 5080, SEMIA 5019 and USDA 110 were the best strains in Mozambique, with average 20-29% grain yield gains over the non-inoculated treatment. Moreover, the four best performing strains in Mozambique resulted in similar or better yields than the non-inoculated + N treatment, confirming the BNF as an alternative to N-fertilizers. The results also confirm the feasibility to transfer soybean inoculation technologies between countries, speeding up the establishment of sustainable cropping systems.
Journal of Plant Nutrition, 2019
Soybean cultivation in Ethiopia is dominated by smallholder farmers who use little or no inputs, often resulting in low yields. The use of effective rhizobia strains was considered as an ecologically and environmentally sound approach for soybean production. Field experiments were conducted during 2015/16 cropping seasons at two different agro-climatic regions in Ethiopia to investigate the effectiveness of local soybean isolates for improving nodulation, growth, yield and quality of soybean. Ten treatments comprising of seven indigenous rhizobia isolates, one exotic strain, nitrogen fertilized treatment and uninoculated control were arranged in randomized complete block design in three replications. Results of the experiment revealed that nodule number and nodule dry weight significantly increased from nil in the uninoculated control to 14-34 and 110-521 mg plant À1 , respectively due to inoculation with different isolates. Furthermore, inoculation significantly increased shoot dry weight by 24-46%, shoot nitrogen concentration by 20-30%, shoot N content by 29-49%, plant height by 14-41%, pods per plant by 12-38%, seeds per pod by 7-19%, thousand seed weight by 15-24%, grain yield by 22-115% and protein content by 7-39% compared with the uninoculated control. Generally, isolates Jm-1-Bo, As-5-Aw, Bk-3-Aw, Cw-6-Aw and MAR 1495 performed better than the others in most yield parameters at both locations of which Jm-1-Bo and As-5-Aw were the local isolates performing best irrespective of location, and were superior to the effective exotic standard strain. Therefore, isolates Jm-1-Bo, As-5-Aw and Bk-3-Aw could be utilized as candidates for inoculant production at large scale in areas with similar agroecology.
2016
Inoculation of promiscuous soybean with rhizobia has been proven to improve yield. Screenhouse pot experiments were conducted to assess the response of promiscuous soybean, TGx1448-2E to rhizobia inoculation and to determine the relative efficiency of indigenous rhizobia from soils collected from the Northern and Southern Guinea and Sudan Savanna agro-ecological zones of Nigeria. Soils were collected at 0 to 20 cm depth from 45 sites spread in 15 local government areas of Kaduna and Kano states. The treatments used were uninoculated control, mineral nitrogen and Legumefix, a commercial rhizobia inoculant which were arranged in randomized complete block design and replicated three times. Nodulation and biomass were assessed at eight weeks after planting. Response to inoculation and relative efficiency were also determined. The results showed that response to inoculation was higher in the Sudan Savanna than in the Northern Guinea Savanna. These were observed in 12 out of 21 and 9 out ...
The potential for rhizobial inoculation to increase soybean grain yields on acid soils in Ethiopia
Soil Science and Plant Nutrition, 2017
In Ethiopia, inoculation of soybean with rhizobial inoculants is not common practice, but could provide an option to increase grain yields in low nitrogen (N) acidic soils. In these acid soils, the selection of acid tolerant rhizobia is one strategy that may increase the performance of soybean. In this study, rhizobial strains isolated from Ethiopian soils were evaluated for their acid tolerance and symbiotic N fixation efficiency with soybean, in controlled environments. Following this, four isolated rhizobial strains were evaluated in six field experiments in major soybean growing areas of Ethiopia. Inoculation with the commercial strain or with one of two locally sourced isolates, that were developed as inoculants, improved soybean yield. The yield increase due to inoculation with the commercial strain was consistent and greater than other treatments, while the increase due to the two locally sourced strains was comparable to, or greater than, application of 46 kg N/ha in soils, where the resident rhizobial population was ≤1.4 × 10 3 cfu/g soil. For soils with high background rhizobial populations, there was no response to inoculation. In one of the experimental sites (Bako), the percentage of N fixed (%Ndfa) was 55 for the commercial strain and 35 for the local strain, ES3. This study demonstrated that field validation is a necessary step in the selection of acid-tolerant strains of rhizobia to increase soybean production for Ethiopia.
International Journal of Agronomy, 2016
Identification of effective indigenous rhizobia isolates would lead to development of efficient and affordable rhizobia inoculants. These can promote nitrogen fixation in smallholder farming systems of Kenya. To realize this purpose, two experiments were conducted under greenhouse conditions using two common bean cultivars; Mwezi moja (bush type) and Mwitemania (climbing type) along with soybean cultivar SB 8. In the first experiment, the common bean cultivars were treated with rhizobia inoculants including a consortium of native isolates, commercial isolate (CIAT 899), a mixture of native isolates and CIAT 899, and a control with no inoculation. After 30 days, the crop was assessed for nodulation, shoot and root dry weights, and morphological features. In the second experiment, soybean was inoculated with a consortium of native isolates, commercial inoculant (USDA 110), and a mixture of commercial and native isolates. Remarkably, the native isolates significantly (p<0.001) incre...