Interactions of OM and fertilizer (WPW2002) - ETH - North-South ...

Plan1. Introduction2. Breeding for Improved grain legumes adaptedto low P soils2.1. Field selection2.2. Mechanism of P acquisition efficiency2.3. Benefit of legumes to maize crops3. Management of AMF4. Conclusions

The humid forest area of southern CameroonApproximately 80 % of thepopulation lives with less than 2dollars per day. (World bank)The problem of malnutrition ispresentAgricultural production remains themost important source of incomefor the smallholders (85 % of thepopulation)

Farmers slash and burn secondary and oldforests to establish new fieldsForest clearanceCrops areestablishedShort fallow

Soil fertility decreases rapidly after forestclearanceCropCrop yield grownimmediately afterforest clearanceCrop yield on short fallow(few years afterforest clearance)yield decrease(%)Soybean 0.88 ± 0.30 0.30 ± 0.08 66Cowpea 1.12 ± 0.40 0.73 ± 0.21 35Maize 2.20 ± 0.40 1.30 ± 0.17 41Plantain 7.68 ± 2.70 2.32 ± 1.80 70Hauser, 2001; Jemo et al 2006 a,b,c

The annual cropping system in the farmers fieldis mixed food crop where groundnut is only theN 2 fixing grain legumesIt is grown inassociation withother crops suchas:MaizeCassavaBut groundnut yield is poor and N 2 fixation is weak

Current attempts to improve cropping systemproductivity and stabilize yield focus in theintroduction of new grain legumesSoybeanCowpeaThey have high N 2 fixation capacity compared togroundnut.Grains contain high diet proteins.The market is available with high economic impact.

The major questions we asked were:Are these grain legumes able to grow on low P soils?Can they fix sufficient N 2 from the atmosphere?Can they provide good yield?Do they provide benefit to the subsequent and/orassociated maize?

Plan1. Introduction2. Breeding for Improved grain legumes adaptedto low P soils2.1. Field selection2.2. Mechanism of P acquisition efficiency2.3. Benefit of legumes to maize crops3. Management of AMF4. Conclusions

2.1. Selection for P efficiency8 cowpea genotypes:DANILA, IT82-816, IT82D-849, IT86D-715, IT89KD-349, IT89KD-391, andIT90K-59Two soils: typic kandiudult (TK): forest soilsrhodic kandiudult (RK): short fallow soilsThree P rates: OP, 30 kg P as TSP, and 90 kg P asphosphate rock from Togo.

Grain yield of cowpea2000Grain yield [kg ha -1 ]16001200800400TKRK0IT 89KD-349IT 82D-849IT 82D-716IT 81D-715IT 90K-59Dan’ila IT 89KD-391GenotypeGrain yield varied significantly amonggenotypes

N 2 fixation of cowpea70N2 fixation [kg ha -1 ]605040302010TKRK0IT 89KD-349IT 82D-849IT 82D-716IT 81D-715IT 90K-59Dan’ilaIT 89KD-391GenotypeN 2 fixation significantly varied amonggenotypes

Relationship between N 2 fixation and P uptake ofcowpea.80---- y TK= 6.5 x + 12.9, r 2 = 0.34 **__ y RK= 7.0 x + 12.0, r 2 = 0.44 **N 2 fixation [kg N ha -1 ]60402000.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0P content [kg P ha -1 ]0P, TKPR, TKTSP, TK0P, RKPR, RKTSP, RKSource: Jemo et al.2006, J Plant Nutr. Soil Sci. acceptedN 2 fixation increases with P uptake

Similar work was done for soybean…12 soybean genotypes :TGm1420, TGm1511, TGm1293, TGm1360, TGm1566,TGm0944, TGm1540, TGm1196, TGm1251,TGm1419, TGm1039, and TGx1456-2E

Partial conclusion 1.Two groups of P-efficiency were distinguished:High P-efficient genotypessoybean: TGm 1511, TGm 1566cowpea: IT89KD-391, IT90K-59Low P-efficient genotypes:soybean: TGm 1251, and TGm 1196cowpea: IT89KD-349, IT82D-849.

Plan1. Introduction2. Breeding for Improved grain legumes adaptedto low P soils2.1. Field selection2.2. Mechanism of P acquisition efficiency2.3. Benefit of legumes to maize crops3. Management of AMF4. Conclusions

Overview on P mechanismsUtilisation efficiency (PUE)Exploration of soils P pool:Root architectureRoot densityFine rootsRoot hairsSurface:volume ratioP uptake rateSymbiotic effectiveness:AMF dependencyNitrogen source – BNFPhosphate solubilizing microbesRoot exudates:ProtonsOrganic acidsEnzymesP acquisition efficiency (PAE)

P uptake and root length soybean and cowpeaP uptake [mg g plant -1 ]20161284Soybean0 100cowpeaP uptake of the soybeanincrease with P application0TGm1196TGm1251TGm1511TGm1566IT82D-849IT 89KD-349IT90K-59IT89KD-391GenotypeLower genotypicvariation was observedfor root growthRoot lenght [m plant-1 ]161412108642Soybean0 100cowpea0TGm1196TGm1251TGm1511TGm1566IT82D-849IT 89KD-349IT90K-59IT89KD-391Genotype

Root surface phosphataseRoot surface phospahatase activity [[nmolh-1 (cm root) -1 ]76543210TGm1196SoybeanTGm1251TGm1511TGm1566IT82D-8490 100cowpeaIT 89KD-349IT90K-59IT89KD-391GenotypeLow genotypic variation in phosphatase exudation

Among the soybean cultivars used, TGm 1511was found to be infected by AMF and theinfection rate was related to P content.25.0y = 0.4541x + 6.3662, r 2 = 0.38 **P content [mg plant -1 ]20.015.010.05.00.00.0 5.0 10.0 15.0 20.0 25.0 30.0AMF root colonisation [%]But the we could not know the species or strainsresponsible for the increase in P content.

Organic acid exudation9.0(a) Malate25.0(c) Succinate8.07.020.06.05.015.00µM P 100µM POrganic acid-anion exudation rate[ρmol (cm root) -1 h -1 ]4.03.02.01.00.01.41.21.00.80.60.4Tgm1196Tgm1251(b) CitrateTgm1511SoybeanTgm1566IT82D-849IT89KD-349IT90K-59CowpeaIT8KD-39110.05.00.09.08.07.06.05.04.03.02.0Tgm1196Tgm1251(d) OxalateTgm1511SoybeanTgm1566IT82D-849IT89KD-349IT90K-59CowpeaIT8KD-3910.21.00.0Tgm1196Tgm1251Tgm1511Tgm1566GenotypeIT82D-849IT89KD-349IT90K-59IT8KD-3910.0Tgm1196Tgm1251Tgm1511Tgm1566GenotypeIT82D-849IT 89KD-349IT90K-59IT8KD-391Source: Jemo et al.2006, Plant Soil, in press

Organic acid exudation: How it’s work?Soluble Pavailable in theroot zoneFe, Al, CaphosphateDesorption andcomplexationOrganic acidsynthesis(Malate, citrate,succinate, etc(Source: Neumann et al. Planta (1999)

Partial conclusion 2.Different mechanisms for P acquisition were observed.These include:Organic acid exudation (IT89KD-391),Colonization by AMF fungi (TGm 1511),Root surface phosphatase exudation (TGm 1566).

Plan1. Introduction2. Breeding for Improved grain legumes adaptedto low P soils2.1. Field selection2.2. Mechanism of P acquisition efficiency2.3. Benefit of legumes to maize crops3. Management of AMF?4. conclusions

3. Benefit of the preceding grain legumes torotational maize3.5(a), TK-1 ]Maize grain yield [Mg ha3.02.52.01.51.00.50.0MAIZELSDTGm1196TGm1251TGm1511TGm1566IT 82D-849IT89KD-349IT 90K-59IT89KD-391TK, Typic kandiudult soils,(Forest soils)RK, Rhodic kandiudult soil(short fallow soils)3.0(b), RK-1 ]Maize grain yield [Mg ha2.52.01.51.00.5LSD0.0MAIZETGm1196TGm1251TGm1511TGm1566Preceding cropIT 82D-849IT89KD-349IT 90K-59IT89KD-391Source: Jemo et al 2006 Plant soil. In press

Relationship between grain yield and P uptakeby maize grown after he grain legumes species5------ y TK= 0.16 x + 0.06, r 2 = 0.75 ***__ y RK= 0.15 x + 0.07, r 2 = 0.78 ***Maize grain yield [Mg ha -1 ]432100 5 10 15 20 25 30 35P uptake [kg P ha -1 ]0P, TKPR, TKTSP, TK0P, RKPR, RKTSP, RKSource: Jemo et al 2006, Plant soil. In press

Maize takes up P from the residues of legumesMaize shoot P uptake[kg P ha -1 ]20.018.016.014.012.010.08.06.04.02.0----- y TK= 1.57 x - 0.39, r 2 = 0.33 **__ y RK= 2.05 x - 1.75, r 2 = 0.44 **TGm 15110.00.0 2.0 4.0 6.0 8.0 10.00P, TKPR, TKTSP,TK0P, RKPR, RKTSP,RKCrop residue P [kg P ha -1 ]Source: Jemo et al 2006 Plant soil. In press

Partial concl. 3.The benefit of grain legumes to the maize willincrease if P is applied to the legumes.

Plan1. Introduction2. Breeding for Improved grain legumes adapted to low P soils.2.1. Field selection2.2. Mechanism of P efficiency2.3. Benefit of legumes to maize crops3. Management of AMF4. conclusions

In most P-deficient soils, the transport of P to the root isthe main limiting factor for P acquisition rather P uptake(Barber 1995)Therefore, enhancing the P transport and favoring thesoil/contact will lead to increase P pool and P uptake bythe plant.AMF are know to play important role in nutrient transferfrom distance far away from the roots (Jansa et al 2003).

Are AMF present in the humid Forest soils?25.020.0y = 0.4541x + 6.3662, r 2 = 0.38 **P content [mg plant -1 ]15.010.05.00.00.0 5.0 10.0 15.0 20.0 25.0 30.0AMF root colonisation [%]But their composition and communities remain unknownto fully explore their functional role

On- going workJoining ETHWork on AMFCurrently on NIDECO scholarshipRFPP project submitted

By G.G.Mur tha(CSIR O)andTch ienkoua( IRAD) basemap :roadma pofCame ron,scal e1:1,50,0 0fie ldworkfro m19Marc hto25Ap ril 191soil sketc hmapbas edonfield observati A ons bongMbangPoumaYaounde 1314 15717 16 90 95919193 94 9921 20 18 9231 78 76 Akono 80 8179 linga 82 98979 63º30’12165 4 87 Mbalm ayo 83 8945 24 2325 109 2 86878848554Sa Ak ngmelima onolingas3º0’Bipindi 4342 46 E 50bolowa 11757472 5212535MbEbolowasoil almayosoKribi 4 40 1 3839 4748 2726 49 73 Sa 71 56 ngmelima 585759 Ya oundesoi3 37 328 2 30 69 9 68676 D65joum 61 602º30’Campo3 34 5Amba31 m 70 64 63 623610º12ºSamplingForest fieldFallow fieldCropped fieldPlant model : the soybean TGm 1511 from breeding program of IITA Ibadan1. It was successfully screened on the acid soil ofSC.2. It fixes considerable N from the atmosphere,3. It colonized by indigenous AMF species(Jemo et al. 2006 a, b)

Activities proposed1. AMF identification (spores and DNA methods)2. Cross inoculation of forest and cropped soilswith indigenous AMF.3. Functional diversity of indigenous AMF –selection of beneficial strains.4. Competitiveness of selected strains

Preliminary resultsScutellosprora sp.unknownS. cerradensisS.spGlomus nanolumenSclerocystis S. sp. G.microaggregatumAMF trap culturesScutellospora sp.Gigaspora(death)Scutellospora (cellwall layer)Gigaspora sp.(cell wall layer)

Plan1. Introduction2. Breeding for Improved grain legumes adapted to low P soils2.1. Field selection2.2. Mechanism of P efficiency2.3. Benefit of legumes to maize crops3. Management of AMF?4. Conclusions

conclusionsP-efficient grain legumes for the acid and P deficient soil ofSC selected.The potential mechanisms of P efficiency studyandthe benefit they provide to the rotational maize known.The role of AMF in improving growth and P uptake ofsoybean are now being approaching.

AcknowlgementsInternational Institute of TropicalAgriculture, CameroonDr. C. NolteDr. R. AbaidooInstitute of Plant Nutrition, ETHProf. Dr. E. FrossardDr. J. JansaInstitute of Plant Nutrition, University ofHanoverProf. Dr. W. J. HorstMs T. EdlerFrau I. Dusy.Thanks to the NIDECO and ETH for the financialsupport.