Venue : Niamey , Niger

Fourth Agricultural Science Week of West and Central Africa and 11th CORAF/WECARD General Assembly • Venue : Niamey, Niger • Date: 16 – 20 Juin 2014

Effect of inoculation with exogenous Bradyrhizobium japonicum strains and phosphorus application on soybean [Glycine max (L.) Merrill] productivity in two agro-ecological zones of Benin Theme

OUTLINE • 1- Introduction • 2-Methods • 3-Results • 4-Conclusion

1- INTRODUCTION

1-INTRODUCTION • Agriculture = base of Beninese economy • Main agricultural constraints in sub-Saharan Africa = constant decrease of soil fertility and inadequacy of cropping systems (Saïdou et al., 2012). • Result = continuous decline in crop yields • To improve crop yields, use of chemical fertilizers whose needs became increasingly important (World Bank, 2008). • risks for the environment (pollution of groundwater) in addition to the expensive cost of manures and the obligation to repeat fertilization

1- INTRODUCTION • Alternative: Crop-livestock integration systems

INTRODUCTION • But if animals don’t have a quality diet, they couldn’t produce good dejection for soil fertilization. • Legumes residues are the most beneficial • So, interest of the use of dualpurpose legumes like soybean [Glycine max (L.) Merrill] in crop-livestock integration systems • Soybeans, a major source of inexpensive vegetable protein for human and animal consumption (FAO, 2010) • The fixation of soybean as much as 300 kg of N ha – 1 in addition to the release, in the soil, of nearly 80% for the followingcrop are currentestimate (Hungria et al., 2006). • To improvebiological nitrogen fixation, inoculation with efficients strains of soils bacterialikerhizobia is very important (Hussain et al., 2011).

2- OBJECTIVES • General objective: to assess if exogenous Bradyrhizobium japonicum strains can improve soybean productivity in Benin.

2- OBJECTIVES • Specific objectives: • (i) to study the eﬀect of exogenous Bradyrhizobium japonicum strains on yield and yield-related parameters of soybean, • (ii) to determine the main interaction eﬀects of Bradyrhizobium japonicum strains and phosphorus on soybean productivity • (iii) to identify the most effective strain to introduce in crop-livestock integration systems in Benin.

3- METHODS

3- METHODS Experimental site: Two Agro-Ecological Zones (AEZ) producers of soybean • Cropfood-producing zone of southernBorgou (Northern Benin: Savè, Glazoué) • Climate: soudanian • Annualrainfall: 1100 mm and 1200 mm

3- METHODS Experimental site: Two Agro-Ecological Zones (AEZ) producers of soybean • Cotton zone of central Benin : Bembérèkè et N’dali • Climate: soudano-guinnean • Annualrainfall: 1000 mm In both zones, experiments were established in ferruginous degraded soils.

3- METHODS • Plant material: One variety of soybeans (TGX 1910-14F) • Microbiological material: Four exogenous strains of Bradyrhizobium japonicum were used for inoculums production: • FA3, STM3043 and STM3045 obtained from Laboratory of Mediterranean and tropical symbiosis of Montpellier (France). • USDA110 from Laboratory of soils Microbiology of Nairobi University (Kenya). These strains were cultivated in Yeast-Mannitol-Broth medium and were fixed in peat.

3- METHODS T: témoinI1: FA3,I2: STM 3043,I3: STM 3045, I4: USDA 110 • Experimental design: in each zone, split plot withtwofactors Six soybeanproducers in each zone

3- METHODS • Data collection • Soil sampling from fieldsbeforesowing for assessement of Soil texture, pH, total carbon, CEC, available P, total Nitrogen etc of soil on surface (0-15 cm) • At flowering time (10 weeksaftersowing): nodulation, mycorrhizalcolonization, biomass dry weight and nitrogen content • At harvest (4 monthsaftersowing): straw and grain yield

3- METHODS • Statistical analysis • All statistical analysis was carried out using SAS software version 9.2. • One-way analysis of variance (ANOVA) was performed to determine the statistical differences among the different strains of Bradyrhizobium japonicum. When significant differences (p < 0.05) were noticed, a Student-Newman-Keuls test was used to compare the means

4- RESULTS

4- RESULTS Physico-chemical properties of the soil before the starting of the experiment

4- RESULTS Effect of Bradyrhizobium japonicum strains and phosphorus supply on soybean productivity parameters

4- RESULTS Nodule number Bars followed by a same letter are not significantly different at p < 0.05 according to Student Newman-Keuls test.

4- RESULTS Mycorrhizal colonization Bars followed by a same letter are not significantly different at p < 0.05 according to Student Newman-Keuls test.

4- RESULTS Shoot dry weight Bars followed by a same letter are not significantly different at p < 0.05 according to Student Newman-Keuls test.

4- RESULTS Biomass aspect and color

4- RESULTS Nitrogen yield Bars followed by a same letter are not significantly different at p < 0.05 according to Student Newman-Keuls test.

4- RESULTS Straw yield 71% 75% Bars followed by a same letter are not significantly different at p < 0.05 according to Student Newman-Keuls test.

4- RESULTS Grain yield 73% • Bars followed by a same letter are not significantly different at p < 0.05 according to Student Newman-Keuls test.

5- Conclusion • Results obtained showed that inoculation with exogenous Bradyrhizobium japonicum strains and phosphorus supply had improved productivity of soybean in Benin • The best strains were FA3 in Food producing zone of southern Borgou and STM3043 in cotton zone of central Benin • FA3 and STM3043 strains could be used in crop-livestock integration systems for improving soybean productivity and its quality in Benin. • However, phosphorus supplementation could be reduced by a co-inoculation of soybean with Mycorrhizae and Rhizobia.

ACKNOWLEDGMENTS • This work was funded by the University of Abomey-Calavi through the project “Programme de Fonds Compétitifs de Recherche ’’ • The authors would like to acknowledge the producers and other actors encountered during the study for their valuable and fruitful collaboration.

Thankyou for yourkind attention

Venue : Niamey , Niger