Photosynthesis apparatus meter

一、Introduction to photosynthesis

1、A brief introduction to photosynthesis

1. Definition of photosynthetic rate (Pn)

The photosynthetic rate is the amount of CO₂ fixed or O₂ released or accumulated dry matter per unit time and photosynthetic mechanism (dry weight, area or chlorophyll). If CO₂ is used as a measurement index, the unit of the photosynthetic rate is: μmolCO₂•m^-2•s^-1. This instrument uses the CO₂ absorption of plant leaves to measure the photosynthetic rate of plant leaves.

2、Measurement principle of photosynthesis

Photosynthesis and transpiration are the internal and external exchange processes of CO₂ and water vapor molecules through leaves respectively, and the main channels are stomata. The driving force of gas diffusion is the concentration difference between inside and outside the leaf. According to Fick's diffusion law, the diffusion flux of the gas in the diffusion path is directly proportional to the concentration difference of the diffusion path, and inversely proportional to the diffusion resistance. For the photosynthetic rate Pn, the relationship is as follows:

△C —CO₂ concentration difference at both ends of diffusion pathway；

It is the difference between the CO₂ concentration in the air and the CO₂ concentration in the mesophyll space

∑r—The total diffusion resistance of the diffusion pathway to CO₂ molecules。

3、Measurement method

CO₂ absorption method is divided into two measurement methods: closed circuit measurement and open circuit measurement.

二、 (Water Use Efficiency)

Water use efficiency (instantaneous water use efficiency) (wue) is equal

to the ratio of photosynthetic rate to transpiration rate:

三、 Transpiration

1、Definition of transpiration:

The loss of water in gaseous form through the surface of the plant to the outside is called transpiration, which is different from ordinary evaporation in that the former is the diffusion of water through the living organism, while the latter is a simple physical process. Transpiration is a physiological process, which is not only affected by environmental factors but also regulated by plant structure and stomatal behavior.

Transpiration rate definition:

The amount of water lost by transpiration per unit leaf area is called transpiration rate.

四、PAR( photosynthetically active radiation )

The radiation that plants use for photosynthesis in a specific wavelength range (400-700nm) is called photosynthetically active radiation.for short: PAR

五、Parameter annotation

Rni:  Humidity of the air before entering the leaf chamber

Rout: The humidity of the air after leaving the leaf chamber

RHc: The difference between Rout and Rni. RHc is used to calculate the transpiration rate

Flow: air flow rate

PARin: Photosynthetically active radiation sensor in the leaf chamber (with red and blue light source optional)

PARout: External photosynthetically active radiation sensor

△CO₂: The CO₂ difference before and after the air passes through the leaf chamber

TC: leaf chamber temperature

TL: leaf temperature

RH: leaf chamber humidity

P: Atmospheric pressure

Pn: Photosynthetic rate

Tr: Transpiration rate

Wue: Water Use Efficiency

Gs: stomatal conductance

Ci: Intercellular CO₂

六、Technical Parameters:

CO2 analysis:

A temperature-tuned dual-wavelength infrared carbon dioxide analyzer was added, measuring range: 0-3000 ppm, resolution: 0.1 ppm; accuracy 3 ppm. Carbon dioxide measurement is not affected by temperature changes, it is stable, high precision, and sensitive. The carbon dioxide difference can be collected within 1 second.

Leaf chamber temperature:

Germany Heraeus high-precision digital temperature sensor, measuring range: -20-80 ° C, resolution: 0.1 ° C, error ± 0.2 ° C

Blade temperature:

Platinum resistance, measuring range: -20-60 ° C, resolution: 0.1 ° C, error ± 0.2 ° C

humidity:

Swiss imported high precision digital humidity sensor:

Measuring range 0-100%, resolution: 0.1%, error ≤ 1%

Photosynthetically active radiation (PAR):

Silicon photocell with correction filter

Measuring range: 0-3000μmol m 2 / sec, accuracy<1μmolm m2 / sec. Response wavelength range: 400 ~ 700nm

Flow measurement: glass rotor flowmeter, flow rate is arbitrarily set within the range of 0-1.5L, error: 1%, <±0.2% in the range of 0.2~1L/min, the pump flow can be set according to needs, can measure different gases The effect of photosynthesis under flow, the gas flow is stable.

Leaf chamber size: standard size 55×20mm, other sizes are customized according to customer needs

Operating environment: temperature -20 ° C -60 ° C, relative humidity: 0-100% (no condensation)

Power supply: DC8.4V lithium battery, can work continuously for 10 hours

Data storage: 16G memory, expandable to 32G.

Data transfer: USB connected to the computer can directly export data.

Display: 3.5" TFT true color LCD color display, resolution 800 × 480, clearly visible under strong light

Volume: 260 × 260 × 130mm