Tony Fischer, Derek Byerlee and Greg Edmeades

Transcription

1 Tony Fischer, Derek Byerlee and Greg Edmeades

2 Why cereal yield? Current situation with yield Prospects for yield progress Resource use efficiency

3 6 5?? Yield (t/ha) y = x R² = Slope (relative) = 1.3%

4 1. Case studies of key regions 2. Farm yield (FY), attainable yield (AY), potential yield (PY, PYw), and rates of change FY and CO 2 rise, + 0.3% for C3 crops 3. PY, from trials with protection PY measurements need same natural resource base as region

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7 Yield gap 50% of FY Constraints from surveys and satellite imagery Late planting Delayed irrigation Summer weeds Total 10-15% of FY Lobell and Ortiz-Monasterio (2008), Ortiz-Monasterio and Lobell (2007)

8 Summary key case studies wheat Region, megaenvironment Yield (t/ha) and gap (%) 2007 Rate of change (%) FY PY Gap FY PY Yaqui Valley, S Punjab State, S W. A. (Australia), S N. Dakota, S UK, W Kansas, W

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11 Summary key case studies rice Region, megaenvironment Farm and potential yield (t/ha) and gap (%) Rate of change (%) FY PY Gap FY PY C. Luzon, wet Irr Punjab, wet Irr ? Japan, wet Irr Central Luzon, dry Irr Egypt, Irr South Asia, Rainfed ? 0

12 Rainfed rice (28.5 M ha average yield 1.8 t/ha) One quarter could be eliminated by concerted breeding and extension in 15 years = 1.0% pa FY progress. Constraint Yield loss Nutrients 23% Diseases 15% Weeds 12% Drought 9% Problem soils 4% Total 68% Source: IRRI, 2008 = expert opinion

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14 Soil fertility Fertilizer use, soil organic matter very low Extension, soil testing, credit? Continued improvements in fertilizer markets Pest management Weeds (Striga), Insects (stem borer) Agronomy Intercropping, no conservation tillage Role of transgenics in pest management

15 Iowa maize yield 61-90; Maize yield (t/ha) b=95 kg/ha/yr R 2 =0.51*** b=206 kg/ha/yr R 2 =0.61*** Year

16 Potential yield y = 0.116x R² = Grain Yield (tlha) Farm yield y = 0.205x R² =

17 Summary some key case studies maize Region, megaenvironment Farm and potential yield (t/ha) and gap (%) Rate of change (%) FY PY Gap FY PY Kenya, Trop ? SSAfrica, Trop ? Brazil, Trop ? Iowa, Temp ,17? 15,60? USA, Temp China, Temp

18 Farm yields, FY, always less than, but follows PY or PYw Best estimate min PY-FY gap of 25% 2 of 17 case studies < 30% gap - Research should focus on increase in PY 6 of 17 cases > 100% largest in SSAfrica - Big scope to raise FY by closing gaps 9 of 17 cases between 30 and 100% - Scope for both Breeding also has gap closing role

19 FY progress is linked to PY and PYw progress, except in SSA. PY, PYw progress at < 1% - not enough! What is the scope for lifting PY, PYw progress in medium term? How has PY, PYw been raised and what are the theoretical limits?

20 PY = ʃ PAR i x RUE x HI where ʃ PAR i = Photosynthetically active radiation intercepted by crop over lifetime (MJ) RUE = Radiation Use Efficiency(gDM/MJ) HI = Harvest index Agronomy and breeding have raised all three HI approaching limit of RUE : best around 3g/MJ for C3 (4 g/mj for C4) theoretical limit 5 g/mj (C3) or 6.5 g/mj (C4)

21 Empirical yield selection, now aided by new biometric and molecular tools e.g., association mapping Further exploit heterosis (rice, wheat) Trait selection esp. linked to RUE, adaptn. higher temp: - Non GM e.g., leaf photosynthetic rate, and surrogates - GM (C4 rice and wheat, modified rubisco, etc) All of the above, but getting more difficult and GE very long term, high risk failure (20 years+, despite Monsanto claim)

22 PY W = (ET-Esoil) x TE x HI where ET = Evapotranspiration (mm) Esoil = Soil evaporation (mm), say 100mm ET-Esoil = Transpiration (mm) TE = Transpiration efficiency (kgdm/ha/mm) HI = Harvest index Agronomy has raised (ET-Esoil), breeding TE and HI HI often below upper limit, stress lowering seed no. TE has limits depending on vpd, C3 vs C4 Best TE x HI : about 40mm/ton (C3), 30mm/t (C4)

23 Empirical yield selection, now aided by new tools Exploit heterosis (rice, wheat) Trait selection linked to HI, ET, and TE, adaptn. higher temp - Non GM e.g., resistance seed no. to stress, root traits, early vigour, etc. - GM stress resistance of seed no to protect HI All of the above, getting more difficult but GE maybe a feasible route (Monsanto DR maize, Chinese DR rice)

24 France and Italy Transgenics not used Base germplasm includes US lines Yield gain zero; drier conditions? Iowa 90% area transgenic Gain 225 kg/ha/yr (2.0%/year)

25 Role of private sector in US maize huge Protocols - Gene and whole genome molecular marker seln. - High throughput precision phenotyping - High regulatory cost of GM - Expensive =Advantages of scale= MNCs Partnerships - Private sector: hybrids; IP protection, incl GM Policies to encourage private investment

26 N Fertilizer: 100 M t, 2% of world s fossil energy, efficiency has improved, and further scope Phosphorus fertilizer: essential also, peak 2034?, efficiency has improved, recycle? Fuel: substantial savings (60%+) with conservation tillage, but < 10% crop area. Water: improved irrigation efficiency Green house gases : potential reductions high Modern agronomy and breeding has improved all, policy also critical

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28 L.T.Evans (1998) Feeding the ten billion

29 Large yield gaps especially in developing countries Promising management technologies Conservation tillage Use of ICT and precision agriculture Breeding eg host plant resistance Improved policies possible in much of the world: Institutional innovations Risk management, market development, rural finance, farmer organizations Infrastructure important also

30 Potential for breeding gains to raise PY and PYw Physiology suggests continued linear gains possible for another 30% or so but more difficult Genomics and molecular techniques to speed the breeding will become standard Transgenics an important tool for pest and disease, abiotic stresses (including PYw), nutritional value - policy

31 Beyond the big three crops? Food security crops, high value agriculture Beyond global food security Countries with high population growth and poor capacity to import (many in Africa, Pakistan ) Rising energy and phosphate prices (and water scarcity) Climate change uncertainty

32 Investments in R&D essential Public sector still critical, but need to reverse investment trends - policy Private sector could make a big impact in crops other than maize and soybean - policy Accessing and adapting to small farms Long lag to pay offs to research requires investment today for 2050