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Photosynthesis • What is it ? • Where it occurs ? • How ? • How is its important ? • How to measure ? Photosynthesis ประกอบด้วย 3 กระบวนการย่อย • CO2 diffusion A = Cg d[CO2] • Photochemical process (light reaction) 4H2O + 2ADP+2NADP+ +2pi O2+2H2O+2ATP+2NADPH +2H+ • Biochemical process 3CO2+9ATP+6NADPH+6H+ P+6NADP+9ADP+8Pi+3H2O triose- The overall chemical reaction • CO2 + 2H2O H2O light / atenna ADP +Pi +NADP+ CO2 (CH2O) + H2O + O2 PSII PSI Cytochrome enzymes/ stroma RuBPcarboxylase : CO2receptor O2 + H+ +Pi ATP + NADPH (CH2O) CHLOROPLAST • 1- 10 mm • Lamellae (membranes) : light reaction – stroma lamella (double lamella) – grana lamella (stacked lamella) • Stroma : dark reaction Leaf anatomy of C3 vs. C4 plants Chloroplast and Chlorophyll structure Electron transportation • Chlorophyll a ,b Carotenoid • Reaction centers : absorbed PHOTONS from light energy • PSII : ground stage excited stage • PSI : Q , Photophosphorylation Energy diagram of the photosynthetic electron transport system Light Light O2 Chlorophyll a/b Chlorophyll a P680 Electron transfer P700 Electron transfer NADPH ATP H2O Photosystem II Photosystem I Energy diagram of the photosynthetic electron transport Redox potential Fd-Ub -800 e- -600 NADP+ Fd -400 -200 Q 0 200 Solar eradiation Solar radiation e ADP e- Cty f 400 ATP 600 800 H2O Photo system II H+ O2 NADPH Photo system I CO2 reduction Radiation vs Photons • E = hv = speed of light/wave length • E = energy content of the quantum (J/quantum) • h = Planck ‘s constant (6.626 x 10-34 J s) 400 500 25 20 7.5 6 5 4 600 700 (nm) 16.7 14.3 (x103 cm-1) 5 4.5 (x1014 s-1) 3.3 2.9 (x10-19 J quantum-1) Conversion factors for energy units used in the text • • • • • • • • • • = 1.602 x 10-19 J = 1 J s-1 = 3.6 x 106 J = 0.239 calories = 6.242 x 1018 eV 1 cal. = 4.184 J 1 kJ mol quantum -1 = 1.036 x 10-2 eV Plank’s constant = 6.62 x 10-34 Js = 4.136 x 10-15 eVs 1 mol quantum of photon contains Avogadro’s number 6.023 x 1023 particles = 1 Eistein 1 electron volt (eV) 1 watt 1 kWh 1 Joule Radiation & Light Carbondioxide fixation Biomass or Dry weight = Photosynthesis Respiration - Dead - Translocation Carbon Balance • C3 species : Calvin cycle ; RUBP 3-PGA • C4 species : Hatch & Slack cycle ; PEP Oxaloacetic Acid etc. • Crussulation Acid Metabolism (CAM) : CO2 fixed during night C3 vs C4 : Kranz anatomy C3 C4 and CAM plant PEP Carboxylase CO2 C4 Organic acids RuBP Carboxylase CO2 CO2 PGA RUBP PEP C3 C4 CAM C3 acids Mesophyll Mesophyll Bundle sheath Dark Light (CH2O) พืช C3 vs C4 • ลักษณะทางกายภาพต่ างกัน C3 ไม่ มีVascular sheath แต่ C4 มี (Kranz anatomy) • เอนไซม์ PEPase มีความสามารถจับ CO2 ดีกว่ า เอนไซม์ RUBPase • C4 มีอัตราการสังเคราะห์ แสงสูงกว่ า C3 (ในสภาพแสงจัด) • C4 ใช้ พลังงานมากกว่ า C3 ในการตรึง CO2 1 โมเลกุล • C4 มี RUBP น้ อยกว่ า C3 • C3 ปรับตัวได้ ดีในสภาพ เย็นชืน้ และ ร้ อนชืน้ ส่ วน C4 ปรับตัวได้ ดี ในสภาพ ร้ อน แห้ ง หรือ ชืน้ • C3 มี Photorespiration ส่ วน C4 ไม่ มี Cellular respiration • The process by which active cells obtain energy. It occurs in mitochondria, there are two coditions : aerobic & anaerobic respiration. • The obtained energy was used for maintenance and growth of the cell or organ. • Growth respiration : catabolism provides the energy required for biosynthesis and constructive reactions leading to form cellular products used in the crop growth Aerobic respiration has 3 stages : C6H12O6 + 6O2 6CO2 + 6H2O + energy Sucrose NAD+ Glycolysis Pyruvic acid e transport chain TCA NADH, ATP 2 Oxidative phosphorylation Krebs’ cycle NADH NADH+, ADP O H2O Respiration • MITOCHONDRIA • C6H12O6 + 6O2 6CO2 + 6H2O +637 kcal • Glycolysis : anaerobic respiration • aerobic respiration : Krebs cycle ; Oxidative phosphorylation • Electron transport chain : ATP, NADPH formed and available for other synthesis of other moplecules for growth, active transport, and metabolic processes. Major plant metabolisms O2 STRUCTURAL compounds • cellulose • hemicellulose • pentosans • pectin, ect. STORAGE compounds • starch • fructosans • proteins • lipids, ect. ACTIVE CELL compounds • nucleic acids • enzymes • cytochrome • chlorophyll • phospholipids, ect. Chloroplast : Photosynthesis Synthesis / Translocation Glycolysis CO2 ATP, NADP Mitochondria : Respiration; Krebs cycle O2 CO2 Photosynthesis vs Respiration • Photophosporylation • Oxidative phosphorylation • NADPH formed • NADP formed • CO2 reduction • O2 reduction • CO2 as substrate • CO2 is product • H2O as substrate • H2O is product • O2 is product • O2 is substrate • CH2O is product • (CH2O)n is substrate and product Photosynthesis vs Respiration if ……. • Down • Up if + O2 • Up • Down if + CO2 • Up • Up if + light • Up • Up if + temperature • Stop • Burst if dark เครือ่ งมือทีใ่ ช้วดั การสังเคราะห์ดว้ ยแสง Ce Reference IRGA Analyser Co Data logger Environments SOIL CLIMATE AGRONOMY Character of CROPS Water route Photosynthesis Yield potential Etr/Etm Pst Pst * Etr/Etm -Res P pot X HI BAMnut model (Azam-Ali Sayed et.al, 2001. A Global Mapping Systems for Bambara Groundnut Production. FAO Agricultural Information Management Series) Weather data Water limited growth (WLG) Radiation limited growth (LLG) seed Intercepted radiation Bambara groundnut Water uptake Soil water Root PodW Leaf LeafW RootW ShootW