ảnh hưởng của CO2 đến quang hợp và sinh trưởng cây trồng

Nghiên cứu ảnh hưởng của khí Co2 lên sinh trưởng cây trồng

Controlling CO2

Introduction

• C is the most important element in plants

– 40-50 % of the dry matter

• The average CO2 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 CO2concentration in the air

(global change)

• CO2 is taken up by the plants through the

stomata

C3, C4 and CAM

• C3:

– Competition for binding to

photorespiration takes place

– Most greenhouse plants are

characterized by C3

metabolism

• C4:

• CAM:

– Stomata open during the

the plant as malate

– Kalanchoë, orchids, some

bromeliads

Uptake of CO2 by Alstroemeria

Time of the day

6 a.m 7.15 a.m 8.30 a.m.

0

20

40

60

80

100

-0,5 0,0 0,5 1,0 1,5 2,0 2,5 3,0

400

450

500

550

600

650

PPFD (leaf level) leaf net photosynthesis

CO2 concentration

Light response curve of tomato

Dry matter production in tomato:

CO2 interaction with temperature

Light – temperature interaction on CO2

uptake

CO2 rule of fist

• the CO2-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:CO2concentration)²xF

1.8

1.2

Influence of CO2 on the quality of pot plants

Influence of CO2 on dry matter production by

vegetables

Higher production and better quality in

Alstroemeria

Alstroemeria c v 'Tiara'

stengels

gewicht v/d stengel (g/100 cm)

aantal bloempjes/

bloeiwijze fotoperiodische

belichting

oorsprong variatie

Influence of CO2 on nursery stock seedlings

of forestry plants

Influence of CO2 (800 ppm) on rooting of cuttings

of Betula pendula ‘Purpurea’

1.8 1.5

54 45

23 July

2.1 1.6

71 64

19 June

3.2 2.0

92 72

23 April

+ CO2 ambient CO2

+ CO2 ambient CO2

Weight of cuttings (g) Rooting %

Date

Negative effects of CO2

• Too high leaf temperature due to lowered transpiration

(closing of the stomata) at high CO2-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 CO2

Applying CO2

• When ?

• What when windows are open ?

• Continuous or intermittent ?

Techniques of CO2-enrichment

• Enrichment with pure

CO2

• Enrichment with CO2

from flue gasses

– CO2from a central burner

– CO2enrichment with small

burners in the greenhouse

– CO2via combustion of

fossil fuels, f.e burning of

kerosene (oldest method)

Decrease in CO2 in function of photosynthesis

Influence of NOx (O.8-1.0 µl/l) on greenhouse

plants

Circulation of air in a greenhouse

Vertical distribution of CO2 in an open crop

(tomato) and a closed crop (chrysanthemum)

Tomato

Is the greenhouse closed? Leaks

Is the greenhouse closed? Ventilation rate

• Degree of ventilation in a greenhouse is determined by:

– Type of covering

– Age of the cover

– Wind speed

ÎThey influence the ventilation rate

2.00 tot 4.0 Old construction, glass less well

1.00 tot 2.0 Old construction, glass well maintained

0.50 tot 1.0 New cover: double glass

0.75 tot 1.5 New cover: single glass

Ventilation rate (Air changes/hour) Construction

Cost price in function of source of CO2

Cost price simulation for tomato:

pure CO2 from tank