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Plant Nitrogen Assimilation and Use Efficiency

Plant Nitrogen Assimilation and Use Efficiency. 03/21/2012. relative amount of nitrate. Nonlegume plants: 20–50 g of N 1 kg of dry biomass 44 million tons for 9 billion people by 2050. ( Dechorgnat J, et al., 2011) . Pathway of nitrogen from rhizosphere to seeds. N efflux and

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Plant Nitrogen Assimilation and Use Efficiency

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  1. Plant Nitrogen Assimilationand Use Efficiency 03/21/2012

  2. relative amount of nitrate • Nonlegume plants: 20–50 g of N 1 kg of dry biomass • 44 million tons for 9 billion people by 2050 (Dechorgnat J, et al., 2011)

  3. Pathway of nitrogen fromrhizosphere to seeds • N efflux and • N transportation and remobilization • N assimilation • N acquisition • Rhizosphere

  4. N forms and concentration changes in Rhizosphere • aerobic soils nitrate • flooded/acidic soils ammonium (Kirk GJD, Kronzucker HJ. 2005)

  5. Nitrogen acquisition low external concentrations (1 μM to 1 mM) • transport system : • high affinity transport system (HATS) • constitutive system (cHATS) • inducible system (iHATS) • low affinity transport system (LATS)

  6. Nitrogen assimilation (Masclaux-Daubresse C, et al., 2010)

  7. Nitrogen remobilization • 95% of seed protein is derived from amino acids

  8. Nitrogen transportation • NTR1s: nitrate transporter (Kirk GJD, Kronzucker HJ. 2005)

  9. Nitrogen efflux • ATP-dependant H+-pumping activity • low-affinity (Kirk GJD, Kronzucker HJ. 2005)

  10. Volatile nitrogen losses • imbalance between N accumulation and N assimilation • gaseous N losses: 40 kg of N/ha (soybean and maize)

  11. outline • GENETICALLY CONTROLLED DIFFERENCES IN NITROGEN USE EFFICIENCY • AGRONOMY EFFICIENCY OF SOIL NITROGEN AND FERTILIZER NITROGEN

  12. Natural Variation in DifferentGenotypes of the Same Plant Species • Genetic variation • total N uptake • postanthesisN uptake • N translocation • N assimilation • Accurate fertilizer Nfor different cultivars • developmental stages • harveststage Ex: tillers, HI↑ NpUE↑

  13. Favorable alleles for breeding • N uptake & remobilization genes are independently inherited traits • Modulating the activities of enzymes which related to high NUE • Ex:GS1&GS2in wheat

  14. Variation of Nitrogen Use Efficiency at Limited and Sufficient Nitrogen Conditions • genotype & genotype N fertilization level

  15. Strategy of breeding high-NUE cultivars • high-yield breeding in Chinese maize Root growth was improved only under N-sufficient conditions • root growth traits have been inadvertently selected to adapt to the increasing N supply in the environment • Genetical materials of Arabidopsis was unaffected by N supply levels at the vegetative stage • breeding high-NUE cultivars should occur under conditions of moderate N supply

  16. AGRONOMY EFFICIENCY OF SOIL NITROGEN AND FERTILIZER NITROGEN • Soil and Fertilizer Nitrogen Use Efficiency • Integrated Nutrient Management in Intensive Agriculture

  17. Soil and Fertilizer Nitrogen Use Efficiency • Mismatching of N availability with crop needs is probably the single greatest contributor to excess N losses Soil surface • Leaching • Ground water • Denitrification to N2 • Soil erosion Fluxes to atomosphere Volatilization

  18. fertilizer application • Base on leaf chlorophyll level & N concentration deep placement, controlled release materials multiple-split applications • biological sources of supplement fertilizer N Azollaand legumes

  19. Integrated Nutrient Management in Intensive Agriculture • management tools Rotations Intercropping perennial crops • site-specific conditions to decrease N losses and optimize crop performance • remote sensing of the visible light reflected

  20. Root & NUE In previous review • a root system that is more efficient at taking up N • maintaining root activity enhance NUpE Nitrate and ammonium transporter (NRT, AMT) (Werner, 2010)

  21. Cytosolic pH Balance Rice prefer ammonium than nitrate • alkalinization in the cytoplasm • influences pH homeostasis • ammonium and nitrate uptake

  22. A tonoplastdicarboxylate (malate and fumarate) transporter (AttDT) • C-N metabolism • pH balance, N & organic acid metabolism

  23. Increasing Yield and Nitrogen Harvest Index • NUpEN losses from soil • NUtEand NpUEN concentration • Target : improve the grain yield per unit of N application • A low seed N concentration • HI and NHI are highly correlated

  24. Gln1-3 : specific to grain production (Martin, 2006) • Gpc-B1 :enhancing N remobilization from source leaves to the seeds (Uauy, 2006) • Asnsynthetase 1 : enhancing HI and N remobilization from vegetative tissues to the seeds (Masclaux-Daubresse, 2010)

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