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A Plus for Pulses: Symbiotic Nitrogen Fixation for Sustainable Intensification in the Drylands

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Oral Presentation 09 by Rachid Serraj at the International Conference on Pulses in Marrakesh, Morocco, 18-20 April 2016

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A Plus for Pulses: Symbiotic Nitrogen Fixation for Sustainable Intensification in the Drylands

  1. 1. A Plus for Pulses: Symbiotic Nitrogen Fixation for Sustainable Intensification in the Drylands Rachid Serraj Outline • Pulses & SNF challenges in a nutshell • N2 fixation, Abiotic stress & Climate Change • SNF for sustainable intensification • Take home messages International Conference on Pulses – Marrakech, April 2016
  2. 2. “ Chemical fertilizer is the fuel that powered the Green Revolution's ” Norman Borlaug Is this sustainable/generalizable? What are the alternatives? Africa accounts for <1% of global fertiliser market and cost of fertiliser can vary significantly between and within countries. e.g., a farmer will pay ~ $330 per t of fertiliser in Kenya vs. $830 in Angola [Montpellier Panel Report, 2013]
  3. 3. Excess N in the environment
  4. 4. FAOSTAT Database, Oct. 2014 Evolution of Global Cereal & Legume Production (pulses + groundnut + soybean)
  5. 5. Annual global pulse production, harvested area and yield in 2008–10 & annual rate of change from 1991 to 2010 Fischer, Byerlee & Edmeades (2014) Crop yields and global food security, ACIAR
  6. 6. Slow Productivity growth Yield gap Price relative to other commodities Shift in diet Income growth Demand static Low profitability & competitiveness No technological breakthroughs Pulses pushed into marginal lands (Kelley & Paratharasathy, Chickpea competitivenes in India, (1994)
  7. 7. March 2016: price of pulses skyrocketing… « Ce projet inédit vise à faire du pays un hub pour exporter les trois-quarts de sa production en Europe et en Afrique.. »
  8. 8. Slow Productivity growth Yield gap Price relative to other commodities Shift in diet Income growth Demand static Low profitability & competitiveness No technological breakthroughs Pulses pushed into marginal lands Policy (LCA): subsidies, Research Protein production & health; Sustainability effects on soil & people (Kelley & Paratharasathy, Chickpea competitivenes in India, (1994)
  9. 9. Life cycle and economic assessment of Western Canadian pulse systems: The inclusion of pulses in crop rotations
  10. 10. Factors underlying legume yield gaps e.g. reasons for the decline in grain legumes in North Africa include:  non-availability of improved seed,  lack of suitable varieties for mechanical harvesting,  low prices,  high production costs,  orobanche infestation + other pests & diseases  climatic stress, especially severe droughts,  losses of human capacity to conduct R4D. Morocco and Tunisia were formerly exporters of food legumes but have now become importers! From CRP on Grain Legumes  Only 25% of legume crop area in the developing world is high input/irrigated, compared to 60% of the cereal area.  Only 6% of fertilizer in SS Africa is used on grain legumes, compared to 26% for maize. CGIAR SPIA - From Akibode & Maredia (2011)
  11. 11. Examples: • Drought • Nitrate • Low P • Salinity • Temperature • Climate change? SNF Agronomic constraints: Serraj & Adu-Gyamfi, 2004  How much progress are-we making in the search for molecular / physiological mechanisms? (late 70ies, 90ies, 2000,….)
  12. 12. Strategy: Physiological dissection & screening Breeding & Genetics Agronomy, on-farm testing & adoption SNF Response to Drought SNF extremely sensitive to stress:  Nitrogenase more sensitive than PS, NRA.. Limitation of legume yield, protein production..
  13. 13. Relationship between Leaf and Nodule Metabolism O2N2 ATP ADP Ureides Amino acids Ureides Amino acids NH4 + N2 H2O H2O CO2 hn Sucrose Feed Back Inhibition Serraj et al. (1999). Plant Physiol .119: 289-296
  14. 14. Species No. Of Observations Fraction with RDN: RTR > 1.0 Sap Ureide (mM) Soybean cv. Biloxi 51 0.10 458 Cowpeacv. CB9 21 0.14 216 Black gram cv. Regur 10 0.30 ^ Common Bean cv. Roma 29 0.86 45 Pea cv. Sugar snap 41 0.95 15 Lupine cv. Ultra 44 0.77 0 Peanut cv. Florunner 80 0.94 ‡ Faba beancv. F223 23 0.96 0 Chickpea cv . Sombrero 37 0.97 0 Sinclair & Serraj (1995). Nature 378: 344 Species Comparison of sensitivity of N2 fixation to drought
  15. 15. Combined CO2 and Drought effects on growth parameters, BNF & WUE USDA-Univ. Florida, Gainesville
  16. 16. Response of Plant Growth, PSR, Transpiration and N2 Fixation to FTSW under ambient & Elevated CO2 Exp. 2 FTSW 0.00.20.40.60.81.0 NormalizedARA 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 Exp. 1 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 y = 1/[1 + 7.1 exp(-13.8 x)], r 2 = 0.75 y = 1/[1 + 1.7 exp(-18.7 x)], r 2 = 0.39 y = 1/[1 + 4.7 exp(-8.3 x)], r 2 = 0.73 y = 1/[1 + 0.8 exp(-6.5 x)], r 2 = 0.27 360 mmol mol -1 700 mmol mol -1 Exp. 2 FTSW 0.00.20.40.60.81.0 NormalizedARA 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 Exp. 2 FTSW 0.00.20.40.60.81.0 NormalizedARA 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 Exp. 1 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 y = 1/[1 + 7.1 exp(-13.8 x)], r 2 = 0.75 y = 1/[1 + 1.7 exp(-18.7 x)], r 2 = 0.39 y = 1/[1 + 4.7 exp(-8.3 x)], r 2 = 0.73 y = 1/[1 + 0.8 exp(-6.5 x)], r 2 = 0.27 360 m Exp. 1 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 y = 1/[1 + 7.1 exp(-13.8 x)], r 2 = 0.75 y = 1/[1 + 1.7 exp(-18.7 x)], r 2 = 0.39 y = 1/[1 + 4.7 exp(-8.3 x)], r 2 = 0.73 y = 1/[1 + 0.8 exp(-6.5 x)], r 2 = 0.27 360 mmol mol -1 700 mmol mol -1 Serraj et al., PCE, 1998 Serraj et al. Global Change Biol., 1999
  17. 17. Dynamics of Ecosystem Biodiversity under Climate Change: N-Fixers vs. non-N-Fixers Will N2-fixing plants benefit more from atmospheric CO2 enrichment than non-N-fixers, leading to a competitive advantage, thereby changing the dynamics of ecosystems biodiversity? Little evidence to suggest that N-fixing legumes will out- compete non-N-fixing plants in ecosystems. worth revisiting in drylands? Few studies of species competition in mixed ecosystems: Arnone, Functional Ecology (1999); Matthis & Egli, Oecologia (1999); Stocklin & Korner, Functional Ecology (1999); Navas et al, New Phytologist (1999),..
  18. 18. The Brazilian success story: Area planted, total production, productivity & total N exported on soybean grains in Brazil. Year Area planted (ha) Grain Prod (ton) Productivity (kg/ha) N exported4 (1000 t) 1970-711 1,716,420 2,014,291 1,174 121 20003 12,773,272 31,195,344 2,442 1,946 1 IBGE (1992); 2 IBGE (October 97, July 98), FIPE AGRÍCOLA (1997, 1998); 3 Agrianual, (1999,2000); 4 N Considering 6% N on grain. Price of N-fertiliser in Brazil ~$0.79 per kg >> ~ $1.5 Billion py?? Franco et al., 2002
  19. 19. C:N Ratio in different soils under No-till, conventional tillage and forest Sisti, Santos, Urquiaga, Alves, Boddey, 2001 NitrogênioTotal(g.kg-1) 0 1 2 3 4 Carbonoorgânicototal(g.kg-1) 5 10 15 20 25 30 35 40 45 R2=0,94 Y=0,5+12,37.X (n=420) p<0,001 Nitrogen (g.kg-1) Carbon x N in the Soil: To accumulate 1 Mg of C as SOM it is necessary to also incorporate about 80 kg of N. overall N balance of crop rotation/cropping system will have a major influence on long-term C accumulation or C loss.
  20. 20. A Holistic approach: • Legume-Rhizobium Biodiversity & Genomics • Integrated Soil Fertility Management • Breeding-Physiology – Agronomy • Participatory Research, Systems & Modeling • Socioeconomics, Political Economy From Genes to Farmers’ Fields CPBNF Vision CPBNF Workshop -Montpellier, June 2002
  21. 21. A successful model for SSA and WANA? Full adoption of the N2Africa package increases yield, but to close the yield gap between current average and attainable yield and to achieve the yield increases stated in the Vision of Success more than the use of N2Africa technologies alone is needed.
  22. 22.  Untapped potentials: promising crops, traits and opportunities (niches, germplasm & genetic variation)  Legumes & SNF in the heart of “CSA” practices: Prospects for increased role of legumes/NF in cropping systems under CC  Future thrusts of agroecological approaches in the drylands – Need to broaden the scope of R&D. SNF research should proceed along the process-component-systems continuum, demand-driven and on-farm problem solving Take home messages Thank you!

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