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Nghiên cứu ảnh hưởng của khí Co2 lên sinh trưởng cây trồng
1 Controlling CO 2 Introduction • C is the most important element in plants – 40-50 % of the dry matter • The average CO 2 concentration of the ambiant air is ± 350 µmol/l on a yearly base – due to combustion it changes during the day and over the year – gradual increase of CO 2 concentration in the air (global change) •CO 2 is taken up by the plants through the stomata – Opening stomata 2 Photosynthesis C3, C4 and CAM •C3: – Competition for binding to Rubisco by CO 2 en O 2 – When O 2 is binding photorespiration takes place – Most greenhouse plants are characterized by C3 metabolism •C4: •CAM: – Stomata open during the night, CO 2 is internally fixed by the plant as malate – Kalanchoë, orchids, some bromeliads 3 Uptake of CO 2 by Alstroemeria Time of the day 6 a.m. 7.15 a.m. 8.30 a.m. PPFD (µmol m -2 s -1 ) 0 20 40 60 80 100 P n (µmol CO 2 m -2 s -1 ) -0,5 0,0 0,5 1,0 1,5 2,0 2,5 3,0 CO 2 concentration (µl l -1 ) 400 450 500 550 600 650 PPFD (leaf level) leaf net photosynthesis CO 2 concentration Light response curve of tomato 4 Dry matter production in tomato: CO 2 interaction with temperature Light – temperature interaction on CO 2 uptake CO 2 = 350 ppm CO 2 = 700 ppm 5 CO 2 rule of fist • the CO 2 -dose varies on average from 600-1000 ppm, in function of the light intensity • F= 1.2 low light • F= 1.5 average • F= 1.8 high light intensity % production increase = (1000:CO 2 concentration)²xF 1.8 1.2 Influence of CO 2 on the quality of pot plants 6 Influence of CO 2 on dry matter production by vegetables Higher production and better quality in Alstroemeria Alstroemeria cv 'Tiara' belichting CO 2 aantal stengels gewicht v/d stengel (g/100 cm) aantal bloempjes/ bloeiwijze fotoperiodische belichting 350 110.3 54.4 4.5 900 169.9 55.2 4.7 assimilatiebelichting 350 156.5 63.7 4.8 900 181.1 62.5 5.0 oorsprong variatie licht * *** *** CO 2 ** ns ** licht x CO 2 ns ns ns 7 Influence of CO 2 on nursery stock seedlings of forestry plants Influence of CO 2 (800 ppm) on rooting of cuttings of Betula pendula ‘Purpurea’ 1.81.5544523 July 2.11.6716419 June 3.22.0927223 April +CO 2 ambient CO 2 +CO 2 ambient CO 2 Weight of cuttings (g)Rooting %Date 8 Negative effects of CO 2 • Too high leaf temperature due to lowered transpiration (closing of the stomata) at high CO 2 -concentration • Accumulation of starch in the leaves followed by breakdown of chlorophyll; – This is stimulated by high light levels and low temperatures, e.g. tomato • Reduced uptake of nutrients due to decreased transpiration (closure of the stomata), especially with high RH Negative effects of high CO 2 9 Applying CO 2 • When ? • What when windows are open ? • Continuous or intermittent ? Techniques of CO 2 -enrichment • Enrichment with pure CO 2 • Enrichment with CO 2 from flue gasses –CO 2 from a central burner –CO 2 enrichment with small burners in the greenhouse –CO 2 via combustion of fossil fuels, f.e. burning of kerosene (oldest method) 10 Decrease in CO 2 in function of photosynthesis Influence of NO x (O.8-1.0 µl/l) on greenhouse plants . 2. 11.6716419 June 3 .22 .0 927 223 April +CO 2 ambient CO 2 +CO 2 ambient CO 2 Weight of cuttings (g)Rooting %Date 8 Negative effects of CO 2 • Too high leaf. 7.15 a.m. 8.30 a.m. PPFD (µmol m -2 s -1 ) 0 20 40 60 80 100 P n (µmol CO 2 m -2 s -1 ) -0,5 0,0 0,5 1,0 1,5 2, 0 2, 5 3,0 CO 2 concentration (µl l -1 ) 400