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+ triose-P+6NADP+9ADP+8Pi+3H2O

The overall chemical reaction CO2 + 2H2O (CH2O) + H2O + O2 H2O light / atenna O2 + H+ +Pi ADP +Pi +NADP+ PSII PSI Cytochrome ATP + NADPH CO2 enzymes/ stroma (CH2O) RuBPcarboxylase : CO2receptor

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 Chlorophyll a Chlorophyll a/b P700 P680 Electron transfer O2 Electron transfer NADPH ATP H2O Photosystem II Photosystem I

Energy diagram of the photosynthetic electron transport 800 200 400 600 -600 -200 -400 -800 H2O Photo system I H+ O2 Q system II ATP ADP Fd-Ub Fd NADP+ NADPH CO2 reduction e- Solar radiation Cty f Redox potential

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) 400 500 600 700 (nm) 25 20 16.7 14.3 (x103 cm-1) 7.5 6 5 4.5 (x1014 s-1) 5 4 3.3 2.9 (x10-19 J quantum-1)

Conversion factors for energy units used in the text 1 electron volt (eV) = 1.602 x 10-19 J 1 watt = 1 J s-1 1 kWh = 3.6 x 106 J 1 Joule = 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

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 CO2 C4 Organic acids CO2 CO2 PGA (CH2O) RUBP PEP PEP Carboxylase RuBP Carboxylase CO2 C4 Organic acids CO2 CO2 PGA (CH2O) RUBP PEP C3 acids C3 C4 CAM Mesophyll Bundle sheath Dark Light

พืช C3 vs C4 ลักษณะทางกายภาพต่างกัน C3 ไม่มีVascular sheath แต่ C4 มี (Kranz anatomy) เอนไซม์ PEPase มีความสามารถจับ CO2 ดีกว่า เอนไซม์ RUBPase C4 มีอัตราการสังเคราะห์แสงสูงกว่า C3 (ในสภาพแสงจัด) C4 ใช้พลังงานมากกว่า C3 ในการตรึง CO2 1 โมเลกุล C4 มี RUBP น้อยกว่า C3 C3 ปรับตัวได้ดีในสภาพ เย็นชื้น และ ร้อนชื้น ส่วน C4 ปรับตัวได้ดีในสภาพ ร้อน แห้ง หรือ ชื้น C3 มี Photorespiration ส่วน C4 ไม่มี

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+ O2 e transport chain Oxidative phosphorylation Pyruvic acid Glycolysis TCA Krebs’ cycle H2O NADH NADH+, ADP NADH, ATP

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 STRUCTURAL compounds cellulose hemicellulose pentosans pectin, ect. STORAGE compounds starch fructosans proteins lipids, ect. ACTIVE CELL compounds nucleic acids enzymes cytochrome chlorophyll phospholipids, ect. O2 Chloroplast : Photosynthesis Synthesis / Translocation Glycolysis ATP, NADP CO2 Mitochondria : Respiration; Krebs cycle CO2 O2

Photosynthesis vs Respiration Photophosporylation NADPH formed CO2 reduction CO2 as substrate H2O as substrate O2 is product CH2O is product Oxidative phosphorylation NADP formed O2 reduction CO2 is product H2O is product O2 is substrate (CH2O)n is substrate and product

Photosynthesis vs Respiration if ……. Down Up Stop Up if + O2 Down if + CO2 Up if + light Up if + temperature Burst if dark

เครื่องมือที่ใช้วัดการสังเคราะห์ด้วยแสง

Character of CROPS Pst Environments SOIL CLIMATE AGRONOMY Water route Photosynthesis Yield potential Etr/Etm Pst P pot X HI Pst * Etr/Etm -Res

Water limited growth (WLG) Radiation limited growth (LLG) 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 Leaf Soil water PodW Root LeafW RootW ShootW