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Current Status of BNI Research at JIRCAS


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A Collaborative effort with CIAT, ICRISAT and CIMMYT
GV Subbarao, JIRCAS, Japan

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Current Status of BNI Research at JIRCAS

  1. 1. Current Status of BNI Research at JIRCAS GV Subbarao JIRCAS, Japan A Collaborative effort with CIAT, ICRISAT and CIMMYT Collaborators CIAT CIMMYT ICRISAT Tottori University Scottish Crops Research Institute Colleagues contributed from JIRCAS 1. T. Ando 2. K. Nakahara 3. T. Yoshihashi 4. T. Watanabe 5. T. Ishikawa 6. Y. Yamanaka 7. H. Y. Wang (PDF) 8. S. Gopalakrishnan (PDF) 9. Stuart Pearse (PDF) 10. A.K.M. Hussain (PDF) 11. Yiyong Zhu (PDF) 12. Zhu Yiyong (PDF) 13. T. Tsehaye (PDF)
  2. 2. Nearly 70% of the N fertilizer applied is lost to the environment Amounts to a direct annual economic loss of US$ 90 billion* [*based on - a) world annual N fertilizer production is 150 million Mg; b) 0.45 US$ kg-1 urea] Nitrogen fertilizer consumed in 1930s - < 1.0 Tg (million metric tons) Nitrogen fertilizer consumed in 1960s – 10 Tg Nitrogen fertilizer consumption worldwide in 2010 – 150 Tg (million metric tons) Energy cost of nitrogen fertilizer – 1.8 to 2 L diesel oil per kg N fertilizer To produce 150 million metric tons of Nitrogen fertilizer requires 1.70 billion barrels of diesel oil (energy equivalent) Nitrogen fertilizers – Some facts
  3. 3. Year 1950 1960 1970 1980 1990 2000 2010 2020 Nitrogenefficiencyincerealproduction (megatonnescerealgrain/megatonnsfertilizerapplied) 20 30 40 50 60 70 80 Trends in N-fertilization efficiency in cereal production (annual global cereal production divided by annual global application of N-fertilizer) (Source: FAO 2012) Global food production has tripled during this period, but N-fertilizer applications have increased 10-fold (Tilman et al., 2001)
  4. 4. Why NUE is <30% in most agricultural systems? Nitrification and denitrification processes associated with uncontrolled rapid nitrification are largely responsible for the massive N leakage (>70% of the N fertilizers) and for the low-NUE
  5. 5. Nitrogen Cycle in Typical Agricultural Systems Soil OM Organic N NH4 + Microbial N NO3 - >95% of the total soil inorganic N pool Plant N uptake & Assimilation Mineralization Nitrification Inorganic N Crop Residues N Fertilizer
  6. 6. Soil incubation period in days 0 10 20 30 40 Nitrification(%) 0 20 40 60 80 100 120 Intensively managed Alfisols Watersheds Conservatively managed Alfisols Alfisol fields at ICRISAT WS HP Nitrificationrate(gNO3 -g-1soild-1) 0 1 2 3 4 5 Alfisol fields at ICRISAT WS HP Nitrificationrate(gNO3 -g-1soild-1) 0 1 2 3 4 5 Conservatively managed Watershed Alfisols Intensively managed High-precision Alfisols Agricultural intensification led to acceleration of nitrification in intensively-managed production systems
  7. 7. How to achieve low-nitrifying agricultural soils? Switch to low-nitrifying agricultural systems
  8. 8. Ammonium (NH4 +) Nitrite (NO2 -)  Leaching Nitrate (NO3 -)  N2O, NO, N2  Greenhouse gases  Global warming  Nitrification OM mineralization  Denitrification Ammonia-oxidizing Bacteria Nitrite-oxidizing Bacteria Biological Nitrification Inhibition (BNI) Brachiaria spp. root-produced nitrification inhibitors Microbial Immobilization of NH4 + Low-Nitrifying Natural Ecosystems High-Nitrifying Modern Agricultural Systems BL BL BL BL BL BL BL BL BL BL BL NFertilizer BNI Function and its potential impacts to N-cycling
  9. 9. How to detect and quantify nitrification inhibitors ? pHLUX20 9763 bp (Bg/II/ BamHl) kat Trrn Phao luxAB PstI (BamHI/Bg/II) PstI PstI BamHI Physical map of pHLUX20 (source: Iizumi et al. 1998) OM IM NH2OH + H2O NO2 - + 5H+ + 4e- NH3 + O2 HAO c554 c554 UQ UQH2 NAD(P)H + H+ NAD(P)+ FMNH2FMN H2O hv RCOOH RCHO O2 Luciferase NAD(P)+ reductase Cytaa3 oxidase NAD(P)H-FMN AMO oxidoreductase Hypothetical model of interaction between the electron transfer pathways and the luciferase reaction in N. europaea (source Iizumi et al. 1998) BNI activity is expressd in ‘ATU’ Inhibitory effect from 0.28 M AT is defined as one ATU
  10. 10. Pasture grasses 0 1 2 3 4 5 6 7 BNI-activityreleasedfromroots (ATUg -1 rootdrywt.d -1 ) 0 2 4 6 8 10 12 14 16 18 1. B. humidicola 2. M. minutiflora 3. P. maximum 4. L. perenne 5. A. gayanus 6. B. brizantha BNI capacity of pastures JIRCAS-CIAT partnership
  11. 11. Plants release two categories of BNIs Hydrophobic Hydrophilic BNI Activity Mostly confined to Rhizosphere May move out of Rhizosphere Plant -root produced nitrification inhibitors BL BL BL BL BL BL BL BL BL BL BL BL BL BLBL BL BL BL BL
  12. 12. Plant Species BH Sorghum Wheat BNIactiviity(%oftotalBNIactivity) 0 20 40 60 80 100 Hydrophobic-BNI Hydrophilic-BNI Relative importance of hydrophobic- and hydrophilic- BNI activity in three plant species at 8 d old plants 40 d old plants 8 d old plants
  13. 13. BNI activity added to the soil (AT g-1 soil) 0 5 10 15 20 25 NO3concentrationinsoil(ppm) 0 50 100 150 200 250 Threshold Releases about 200 to 400 ATU hydrophilic BNI d-1 BNIs provide stable inhibitory effect on soil nitrification 55 d soil incubation
  14. 14. 14 A bioassay-guided purification of BNI activity led to isolation of Brachialactone, identified as the major nitrification inhibitor released from the roots of B. humidicola. Atricyclic terpenoid with a unique 5-8-5 ring system and a g-lactone ring Similar 5-8-5 ringsystem Fusicoccins are produced in some fungi (Geranylgeranyl diphosphate) Patented by JIRCAS GGDPis a precursorin thebiosynthesisof terpenoids;also thisis theprecursorfor thesynthesis ofcarotenoids, gibberllinsand chlorophylls in plants 11 Subbarao G V et al. PNAS 2009;106:17302-17307 ©2009 by National Academy of Sciences
  15. 15. 0.0 2.5 5.0 7.5 10.0 12.5 15.0 min 0 5000 10000 15000 20000 25000 30000 35000 40000 45000 uV sample: brachialactone standard (mixture of a and b), 75 μg column: TSK gel super ODS (4.6 x 100 mm) mobile phase: water (A) – acetonitrile (B) flow rate: 1.0 ml/min gradient program: 23% - 43%B (10 min), 43% - 48%B (8 min) Time (min) Detectorresponse Brachialactone b Purified Brachialactone HPLC chromatogram
  16. 16. GC-MS-SIM based brachialactone quantification 16 Progesterone (IS:1 ppm) Brachialactone (48 ppm) 19.78min Identification: m/z 334 Quantification: m/z 137 18.65min Identification: m/z 314 Quantification: m/z 314 Quantification & identification was achieved. Brachialactone showed 2 peaks, which might be caused by keto-enol tautomerism. ‘Keto’form ‘Enol’form
  17. 17. GC-MS-SIM based analytical methodology can have major implications to genetic improvement efforts directed at brachialactone-trait into root systems of Brachiaria sp. Brachialactone is detected in root tissues and quantification using GC- MS-SIM analysis could be a possibility in future Preliminary results suggest brachialactone concentration in root tissues can be as high as 0.27  0.01% (dry weight basis) Brachialactone levels in root tissues could be up to 10 times higher than in root exudates (i.e. about 10% of brachialactone in the root tissues may be released per day from exudation) GC-MS-SIM analysis improves the detection thresholds for brachialatone levels in the samples and may give better quantification in root tissues and root exudates.
  18. 18. Brachialactone release is highly influenced by growing season Spring season in Japan appears to have a major influence on brachialactone release in B. humidicola 020004000600080001000012000 11.01.04(No.31) 11.01.18(No.32) 11.02.01(No.33) 11.02.14(No.34) 11.03.03(No.35) 11.03.23(No.36) 11.03.26(No.36… 11.04.01(A-1) 11.04.05… 11.04.11(A-3) 11.04.14(A-5) 11.04.18(A-6) 11.04.21(A-7) 11.04.25(A-8) 11.05.10(May-1) 11.05.17(May-2) 11.05.25(May-3) 11.06.07(No.37) 11.06.21(No.38) 11.07.06(No.39) 11.07.25(No.40) 11.08.08(No.41) 11.08.23(No.42) 11.09.08(No.43) 11.09.26(No.44) 11.10.11(No.45) 11.10.24(No.46) 11.11.07(No.47) 11.11.25(No.48) 11.12.05(No.49) 11.12.19(No.50) 12.01.04(No.51) 12.01.16(No.52) 12.01.30(No.53) 12.02.16(No.54) 12.02.27(No.55) 12.03.05(Marc… 12.03.14(Marc… 12.03.21(Marc… 12.03.26(Marc… 12.04.02(April-1) 12.04.09(April-2) 12.04.13(April-3) 12.04.18(April-4) 12.04.23(April-5) 12.05.8(May-1) 12.05.18(May-2) 12.05.29(May-3) 12.06.05(june-1) 12.06.05(june-2) 12.06.18(june-3) 12.06.25(june-4) 12.07.06(july-1) 12.07.24(july-2) 12.08.06(aug-1) 12.08.20(aug-2) 12.09.03(sep-1) 12.09.18(sep-2) 12.10.11(oct-1) 12.10.16(oct-2) 12.11.06(nov-1) 12.11.19(nov-2) 12.12.03(dec-1) 12.12.18(dec-2) 13.01.07(jan-1) 13.01.22(jan-2) 13.02.04(feb-1) 13.02.18(feb-2) 13.03.05(mar-1) 13.03.18(mar-2) 13.03.25(mar-3) 13.04.01(apr-1) 13.04.08(apr-2) 13.04.22(apr-3) 13.05.08(may-1) 13.05.20(may-2) 13.06.03(jun-1) 13.06.17(jun-2) 13.07.01(july-1) 13.07.16(july-2) 13.07.22(july-3) 13.08.20(aug-1) 13.09.03(sep-1) 13.09.17(sep-2) peakarea mAU*sec. date Annualfluctuationrootexdate standardBH highBNIBH 2011 20132012 We need to understand whether these seasonal influence on brachialactone release from root due to production in root tissues or only release from roots is influenced?
  19. 19. Brachialactone’s mode of inhibitory action on Nitrosomonas Compound Concentration in the in vitro assay, mM AMO pathway HAO pathway Crude-root exudate (methanol extract) 63.4 + 0.8 63.8 + 0.8 Brachialactone 5.0 59.7 + 0.9 37.7 + 0.9 Nitrapyrin 3.0 82.3 + 1.5 8.1 + 1.2 Inhibition (%) Outer Membrane Inner Membrane Periplasm Nitrosomonas
  20. 20. Regulating factors for the Release of BNIs from roots
  21. 21. BNI synthesis and release from roots requires presence of NH4 + N treatment (NO3-N vs NH4-N grown plants) NO3-grown NH4-grown BNIactivityoftheroottissue(ATunitsg-1rootdrywt) 0 50 100 150 200 Root tissue from RE-water treatment Root tissue from RE-NH4 treatment Nitrogen treatment (i.e. NH4-N vs. NO3) of the plants NO3-grown NH4-grown TotalBNIactivityreleasedduring10dperiod(ATunits) 0 200 400 600 800 1000 RE-collected using distilled water RE-collected using 1 NH4Cl (1 mM)
  22. 22. Functional link between NH4 +-uptake and BNI release A hypothesis NH4 + Cytoplasm pH >7 NH4 + NH4 + H+ H+ ATP ADP + Pi BNIn- BNIn- BNI Glutamine + H+ glutamate
  23. 23. Is there potential for genetic improvement of BNI capacity in pastures? Genetic variability is the primary requirement for genetic improvement in trait/s of interest using traditional breeding
  24. 24. Is there a genetic variability for BNI capacity? High-BNI and low-BNI genetic stocks in B. humidicola B. humidicola Accession BNI released ATU g-1 root dry wt. d-1 CIAT 26159 46.3 CIAT 26427 31.6 CIAT 26430 24.1 CIAT 679 17.5 CIAT 26438 6.5 CIAT 26149 7.1 CIAT 682 7.5 Panicum maximum 0.1 LSD (0.05) 6.0 Based on evaluation of 40 germplasm accessions in B.humidicola CIAT’s Collaboration Note 11 sexuals from a total of 40 germplasm accessions were evaluated for BNI capacity; Most sexuals evaluated have BNI capacity similar to the CIAT 679. A bi-parental population using high-BNI (CIAT 16888) and low-BNI (CIAT 26146) has been developed to identify genetic regions associated with BNI-function using a mapping population derived from crosse between apomictic and sexual germplasm accession of BH that differ in BNI-capacity – CIAT-JIRCAS ongoing collaboration
  25. 25. Date of Root exudate collection during Spring 2012 2nd March 3rd March 4th March 1st April Brachialactonereleaseperplant (peakarea) 0 2000 4000 6000 8000 10000 12000 CIAT 679 CIAT 26159 CIAT26159 CIAT679 Genetic differences in Brachialactone release capacity High-BNI genotype releases several times higher brachialactone than standard cultivar 25
  26. 26. Parental lines of RIL population PVK 801 296-B BNIactivity/Sorgoleonereleaseperplant 0 10 20 30 40 50 BNI activity (ATU) Sorgoleone (g) Total BNI activity and sorgoleone levels in root-DCM wash after 8 d growth in root boxes with hydroponic system (based on 6 times evaluation of 20 seed lings each over a 6 month period) Parental lines of RIL population characterization JIRCAS-ICRISAT partnership
  27. 27. HPLC chromatogram of purified sorgoleone BNI activity detected only in this peak NO BNI activity detected in any of these peaks O O OH O Chemical structure of sorgoleone, Molecular Weight - 358 a P-benzoquinone exuded from sorghum roots BNI activity released from sorghum roots Hydrophobic BNIs Hydrophilic BNIs Isolation of the major BNI constituent of hydrophobic BNI activity ED80 = 1.0 ppm Adroplet of sorgoleone exuding from root tip
  28. 28. 296B PVK 801 Sorgoleone-phenotyping system is now developed JIRCAS-ICRISAT partnership
  29. 29. Bi-Parental Sorghum RIL population (PVK 801 x 296B) 0 50 100 150 200 Sorgoleoneproduced(gplant-1) 0 10 20 30 40 50 PVK801 296B RIL phenotyping for sorgoleone levels in root-DCM wash JIRCAS-ICRISAT partnership
  30. 30. Introducing high-BNI capacity into wheat Is it possible or feasible? JIRCAS-CIMMYT partnership
  31. 31. Plant species 0 1 2 3 4 BNIactivityreleasedfromroots (ATUg-1rootdrywt.d-1) 0 5 10 15 20 25 30 35 NH4-N grown NO3-N grown Nobeoka Chinese Spring L. racemosus Releases about 150 to 200 AT units of BNI da-1 under optimum conditions Wild-wheat has high-BNI capacity JIRCAS-CIMMYT partnership
  32. 32. Leymus racemosus 2N=4X =28; genome Ns NsXmXm Triticum aestivum L. cv. Chinese Spring 2N=6X =42; genome AABBDD F1 hybrid Triticum aestivum L. cv. Chinese Spring 2N=6X =42; genome AABBDD BC1F1 hybrid BC7F1 hybrid Production of wheat-Leymus racemosus-addition lines Two Lr#n L. racemosus chromosomes in wheat detected by florescence in situ hybridization with probe of L. racemosus genomic DNA (green color) 3.9LSD (0.05) 4.97Lr-1-2DtA7Lr-1-2 6.47Lr-1-1DtA7Lr-1-1 6.65Lr-1DA5Lr-1 3.22Lr-1DA2Lr-1 3.7Lr-HDALr-H 4.1Lr-FDALr-F 5.5Lr-kDALr-k 6.4Lr-1DALr-1 13.0Lr-IDALr-I 13.5Lr-jDALr-j 24.6Lr-nDALr-n BNI released (ATU g-1 root dry wt d-1) L. racemosus chromosome introduced Genetic Stock 3.9LSD (0.05) 4.97Lr-1-2DtA7Lr-1-2 6.47Lr-1-1DtA7Lr-1-1 6.65Lr-1DA5Lr-1 3.22Lr-1DA2Lr-1 3.7Lr-HDALr-H 4.1Lr-FDALr-F 5.5Lr-kDALr-k 6.4Lr-1DALr-1 13.0Lr-IDALr-I 13.5Lr-jDALr-j 24.6Lr-nDALr-n BNI released (ATU g-1 root dry wt d-1) L. racemosus chromosome introduced Genetic Stock BNI released from Chromosome-addition lines derived from L. racemosus and cultivated wheat (Chinese Spring) Can the high-BNI capacity of wild-wheat be Transferred/Expressed in cultivated wheat? Would this be the first step to develop low-nitrifying and low-N2O emitting wheat production systems? BA JIRCAS-CIMMYT partnership
  33. 33. Lr#nS.3BL Lr#nS.7BL Leymus chromosome ‘N’ The short-arm of the Leymus ‘N’ chromosome is translocated to either 7B or 3B wheat chromosome (short-arm) for BNI evaluations Short arm long arm centromere Courtesy - Kishi Courtesy - Kishi JIRCAS-CIMMYT partnership
  34. 34. Lr#n addition Lr#nS.3BL Wheat-Leymus genetic stocks CS N - add N - sub-3A N - Tr-3B N - Tr-7B BNIactivityreleasedfromroots (ATUg-1rootdrywt.d-1) 0 100 200 300 400 500 RE-NH4 + BNI activity release from roots in the presence of NH4 + in the collection solutions Courtesy - Kishi Courtesy - Kishi BNI activity release is two-fold higher in Lr#N addition and Lr#N translocation line (on 3B wheat chromosome) compared to Chinese Spring The above results strongly confirm that BNI-capacity in Leymus is controlled by Lr#N and expressed in wheat background; further the BNI-trait is controlled by short-arm of Lr#n chromosome and its expression depends on the translocation position on wheat JIRCAS-CIMMYT partnership
  35. 35. Can the BNI function be effective to control nitrification and nitrous oxide emissions under field conditions? JIRCAS-CIAT partnership
  36. 36. Roots of B. humidicola release a powerful nitrification inhibitor Brachialactone Ammonium (NH4 +) Nitrite (NO2 -) Nitrate (NO3 -)Ammonia-oxidizing Bacteria Nitrite-oxidizing Bacteria BL BL BL BL Microbial-N Immobilization Mineralization By blocking the Nitrosomonas function, B. humidicola facilitates NH4 + to move into mocrobial pool and to remain in the soil system and act as a slow-releasing nitrogen source for Brachiaria growth
  37. 37. Estimations for the BNIs release from B. humidicola • Active root biomass in a long-term BH pasture being 1.5 Mg ha-1 •(Root mass up to 9.0 Mg ha-1 has been reported in BH pastures) • BNI release rates can be 17 to 50 ATU g-1 root dry wt. d-1 • Estimated BNI activity release d-1 could be 2.6 x 106 to 7.5 x 106 ATU (CIAT 679) (CIAT 26159) •1 ATU being equal to 0.6 g of nitrapyrin • This amounts to an inhibitory potential equivalent to the application of 6.2 to 18 kg of nitrapyrin application ha-1 yr-1
  38. 38. 38 Soil ammonium oxidation rates (mg of NO2− N per kg of soil per day) in field plots planted with tropical pasture grasses (differing in BNI capacity) and soybean (lacking BNI capacity in roots) [over 3 years from establishment of pastures (September 2004 to November 2007); for soybean, two planting seasons every year and after six seasons of cultivation] Brachiaria pastures suppressed soil ammonium oxidation Subbarao G V et al. PNAS 2009;106:17302-17307 ©2009 by National Academy of Sciences JIRCAS-CIATpartnership CIAT-Palmira field study 2004-2007 0 0.5 1 1.5 2 2.5 3 3.5 4 Control - Bare soil BH- 16888 ppmofnitrateproducedday-1 CIAT-Palmira field study 2013
  39. 39. 39 Cumulative N2O emissions (mg of N2O N per m2 per year) from field plots of tropical pasture grasses (monitored monthly over a 3-year period, from September 2004 to November 2007) Subbarao G V et al. PNAS 2009;106:17302-17307 ©2009 by National Academy of Sciences Brachiaria pastures suppressed N2O emissions from the field Can BNI function in plants be exploited to develop low-N2O emitting systems then? JIRCAS-CIATpartnership
  40. 40. BNI capacity of the species (ATU g-1 root dry wt. d-1) 0 10 20 30 40 50 60 CumulativeN2Oemission (mgN2O-Nm2y-1) 0 100 200 300 400 500 Con Soy PM BHM BH-679 BH-16888 High BNI capacity leads to low-N2O emitting systems? A 3-year field study with soybean and pasture grasses with varying BNI capacities Can we develop low-nitrifying and low-N2O emitting pasture-production systems through genetic exploitation of BNI trait? The new MAFF-BNI project (starts from 2014) will test this hypothesis further using genetic stocks of B. humidicola with diverse BNI capacity in root systems JIRCAS-CIATpartnership
  41. 41. Photo: J. W. Miles Exploitation of BNI function in BH for the sustainable agro-pastoral systems? Characterization of residual effect of BNI from B. humidicola pasture on maize productivity and Nitrogen use efficiency Ongoing JIRCAS-CIAT partnership
  42. 42. How long the BNI-suppressive effect on nitrification persists? Ongoing JIRCAS-CIAT partnership Land Management 0 1 2 Nitrificationrate (mgNO2-Nkg-1soild-1) 0.00 0.02 0.04 0.06 0.08 0.10 0.12 Native savanna BH Cultivated fields Maize BH-BNI effect Time in years 0 1 2 3 4 5 6 Ammoniumoxidationrateinsoil (mgNO2kg -1 soild -1 ) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 Cultivated soils control BH-residual scenario-4 BH-residual scenario-3 BH-residual scenario-2 BH-residual scenario-1
  43. 43. Characterization of residual BNI impact on NUE in maize systems An agro-pastoral systems perspective Ongoing JIRCAS-CIAT partnership
  44. 44. Maize crop established in a high-BNI field by clearing B. humidicola Field site – Taluma, Iianos, Colombia JIRCAS – CIAT collaborative study – CIAT field site at Llanos Ongoing JIRCAS-CIAT partnership
  45. 45. 120 kg N/ha 240 kg N/ha B. humidicolafieldThe BH-BNI benefits on Maize growth Beneficial effects of BNI on subsequent maize crop Land Management 0 1 2 Nitrificationrate (mgNO2-Nkg-1soild-1) 0.00 0.02 0.04 0.06 0.08 0.10 0.12 Native savanna BH Cultivated fields Maize BNI-Field Ongoing JIRCAS-CIAT partnership
  46. 46. 120 kg N ha-1 Beneficial effects of BNI on subsequent maize crop A healthy maize crop in BNI-field with 120 kg N application Land Management 0 1 2 Nitrificationrate (mgNO2-Nkg-1soild-1) 0.00 0.02 0.04 0.06 0.08 0.10 0.12 Native savanna BH Cultivated fields Maize JIRCAS – CIAT collaborative study – CIAT field site at Llanos BNI-Field Ongoing JIRCAS-CIAT partnership
  47. 47. 120 kg N ha-1 Land Management 0 1 2 Nitrificationrate (mgNO2-Nkg-1soild-1) 0.00 0.02 0.04 0.06 0.08 0.10 0.12 Native savanna BH Cultivated fields Maize JIRCAS – CIAT collaborative study – CIAT field site at Llanos Non-BNI-Field Beneficial effects of BNI on subsequent maize crop A nitrogen-deficient maize crop in non-BNI-field with 120 kg N application Ongoing JIRCAS-CIAT partnership
  48. 48. BNI-Field Non-BNI-Field 2012 Field study at Iianos, Colombia Nitrogen fertilizer application (Kg ha-1 ) 40 60 80 100 120 140 160 180 200 220 240 260 Maizegrainyield(tha -1 ) 0 1000 2000 3000 4000 5000 High nitrifying - cultivated fields Low nitrifying - BH-BNI Beneficial effects of BNI on subsequent maize grain yields BNI is more effective on maize yields at low to moderate N applications but not high-N environments BNI function is effective in improving NUE only under low- to moderate-N environments and not at high-N environments BNI-field Non-BNI-field Ongoing JIRCAS-CIAT partnership
  49. 49. Maize plant tissues from various land-use systems Ear Shoot Root 15N/14Nratioinplanttissues 4.5 5.0 5.5 6.0 6.5 BH-BNI cont.Maize Native savannah Beneficial effects of BNI on N recovery by Maize BNI is effective in improving N recovery by maize in the field (from 15N studies) BNI-Field Non-BNI-Field Ongoing JIRCAS-CIAT partnership
  50. 50. Land use treatments on Maize BH-BNI cont.Maize Native savannah 15N/14Nratioinsoils(0-60cmsdepth) 0.35 0.40 0.45 0.50 0.55 Beneficial effects of BNI on soil-N retention BNI is effective in improving soil-N retention after maize harvest (from 15N studies) BNI-Field Non-BNI-Field Ongoing JIRCAS-CIAT partnership
  52. 52. 175 Tg N N-Fertilizer inputs into Agriculture 53.5 Tg N Plant protein from Agriculture 3.5 Tg N Animalprotein from Livestock 0.27Tg N Human system N-retention 123.5 Tg N LOST (70%) FromAgriculture 48.0 Tg N LOST (90%) From Livestock 5.0 Tg N LOST (95%) From Municipal Sewage systems N-Fertilizer inputs into Agriculture Plant protein-N Animal protein-N Human-N Nitrogen flow in Human-centric Ecosystems Annual
  53. 53. Nitrogen pollution epidemic in China Nitrification facilitates movement of N from agricultural soils to water-bodies (ground water, freshwater lakes, rivers and to oceans) and cause algal blooms Second Green Revolution?
  54. 54. NH4 + NO3 - Plant uptake Soil- microbial uptake Nitrification SOM Mineralization N-Fertilizers Microbial-N Immobilization Plant litter and Root exudates Nitrification opens several pathways in N-cycle for fertilizer-N to escape into the larger Environment
  55. 55. A fundamental shift towards NH4 +-dominated crop nutrition is possible? Retention of soil-N in agricultural soils is critical for the sustainability of production systems and to prevent N from entering into water-bodies Nature 2013, 501:291 BNI function in plants should be exploited to facilitate retention of soil-N within agricultural systems
  56. 56. We must develop new technologies to keep N to remain and recycle within the agricultural systems and not allow into water systems – Nitrification control is key BNI function can be one such mechanism that can be exploited from a breeding perspective and from a system’s perspective Take Home Message
  57. 57. Strategic Research Partner – CIAT (Drs. IM Rao; Manabu Ishitani; John Miles; Joe Tohme; Jacobo Arango, Marco Rondon; Maria Pilar Hurtado; Danillo Moreta; Gonzalo Borrero) Other participating research institutes ICRISAT (India) CIMMYT (Mexico) Tottori University (Japan) Yokohama City University (Japan) Scottish Crops Research Institute (UK) Biogeochimie et ecologie des milieux continentaux (France) CIAT Tropical pastures-BNI MAFF GTZ Forage-CRP(?) JIRCAS BNI Research CIMMYT Wheat-BNI MAFF Wheat-CRP ICRISAT Sorghum-BNI MAFF (?) Dryland cereals-CRP(?) Thank you for the attention