IN INOCULANTS Nodulaid - 17th International Nitrogen Fixation ...

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17 th International Congress on Nitrogen Fixation Fremantle, Western Australia 27 November – 1 December 2011 Title Efficiency of Bradyrhizobium japonicum in different formulations and when co-inoculated with bacillus subtilis on soybean in a Kenyan soil Authors Mary Atieno 1, 2 , Laetitia Herrmann 2 , Robert Okalebo1 , Didier Lesueur 2, 3 Poster Board Number 19 1 Moi University, Department of Soil Science, PO Box 1125-30100, Eldoret, Kenya 2 Tropical Soil Biology and Fertility Institute of the International Centre for Tropical Agriculture (TSBF-CIAT), United Nations Avenue, PO Box 30677-00100, Nairobi, Kenya 3 CIRAD, UMR Eco&Sols (CIRAD-IRD-INRA-SupAgro), Land Development Department, 2003/61 Paholyothin Road, Lardyao Chatuchak, Bangkok 10900 Thailand The major setback in successfully obtaining an effective inoculant is overcoming difficulties in formulating a viable and user-friendly final product as the live nature of the active ingredient underscores the importance of formulation in maintaining the microbial cells in a competent state. Co-cultures of rhizobia and PGPR (Plant Growth Promoting Rhizobacteria) are also known to influence the efficacy of the symbiotic bacteria on plant biological nitrogen fixation. A greenhouse experiment was set to assess the formulation effect of one strain i.e. Bradyrhizobium japonicum, 532c (granules, liquid and broth) and to determine the efficiency of co-inoculation of Bacillus subtilis with two strains of Bradyrhizobium japonicum (532c and RCR 3407). The objectives were evaluated on 2 soybean (Glycine max L.) varieties: Nyala, a non-promiscuous variety and TGx1740-2F, a promiscuous test variety. A non sterile soil from Central Kenya (Chuka) classified as a Nitisol was used. Nodule occupancy was determined by PCR-RFLP. Most of the inoculants showed increased nodulation and biomass yields as compared to the un-inoculated controls with a higher response seen in the promiscuous TGx1740-2F variety as compared to the non-promiscuous variety. The liquid and granule-based inoculants had higher biomass yields suggesting an impact of formulation on the effectiveness of the inoculants. The co-inoculants also gave higher yields but showed no significant differences to the rhizobial inoculants alone. Nodule occupancy was 100 % for all the rhizobial inoculants as well as the co-inoculants emphasizing the infectivity and high competitiveness of 532c and RCR 3407 strains even in the presence of indigenous strains (80-113 cell/g of soil). These inoculants, though not initially made for SSA countries, showed promising increased yields in a Kenyan soil containing significant populations of native rhizobia nodulating soybean, signifying a possibility of their adoption in increasing soil fertility and crop yields in the poor SSA soils. 134 2011
17 th International Congress on Nitrogen Fixation Fremantle, Western Australia 27 November – 1 December 2011 Title Potential of indigenous Bradyrhizobia versus commercial inoculants to improve cowpea and green gram yields in Kenya Author Samuel Mathu 1, 2 , Pieter Pypers 1 , Laetitia Herrmann 1 , Viviene Matiru 2 Romano Mwirichia 2 and Didier Lesueur 1,3 Poster Board Number 20 1. Tropical Soil Biology and Fertility Institute of CIAT, World Agroforestry Center, P.O. Box 30677-00100 Nairobi – Kenya. 2. Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200 Nairobi- Kenya. 3. CIRAD, UMR Eco&Sols Land Development Department, 2003/61 Paholyothin Road, Lardyao Chatuchak, Bangkok 10900 Thailand. Limited information is available on reduced cowpea and green gram yields in Kenya. Declining soil fertility or presence of ineffective indigenous rhizobia? In regards to this, soils were collected from Western province (Bondo, Bungoma) to Eastern (Isiolo), Central (Meru) and at the Coast (Kilifi) to trap indigenous rhizobia nodulating both legumes under greenhouse condition. Highest nodule fresh weights of 4.63 and 3.32 g plant -1 for cowpea and green gram were observed in soil from Isiolo site A and Kilifi site A respectively suggesting significant populations of indigenous strains in such soils. Lowest nodule fresh weights of 2.17 and 0.72 g plant -1 were observed in soil from Bungoma site B for cowpea and green gram respectively. Genetic diversity of indigenous strains nodulating both legumes was assayed using PCR-RFLP of the 16S-23S rDNA IGS and 19 IGS groups were identified with I and II predominating for both legumes. A second greenhouse experiment was set up to evaluate if commercial inoculants significantly improve cowpea and green gram yields in soils with significant populations of native rhizobia. Rhizobial inoculation did not significantly (p
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PrinciPal SPonSor: SPonSorS: Progra
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INVENTING THE FUTURE IN INOCULANTS
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17 ICNF Organising Committee Graham
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Cottesloe Beach © Tourism Western
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GeNeRAl INfoRmATIoN aTM’s Automat
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16:30 - 16:50 Felix Dakora Tshwane
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Thursday 1 December 2011 08:00 - 12
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