Experiments on the detection of plant respiration rate by the air flow method
Experiments on the detection of plant respiration rate by the air flow method
The principles and techniques of determining the rate of plant respiration by the airflow method will be mastered through experiments.
Operation method
Experiments on the detection of plant respiration rate by the air flow method
Principle
The principle of the air flow method to determine the plant respiration rate is to make a stable air flow without CO2 through the respiration chamber equipped with plant materials, the CO2 released from plant respiration into the CO2 absorption bottle, which is absorbed by the barium hydroxide quantitatively, generating a white precipitate of barium carbonate, and then the remaining barium hydroxide is titrated with standard oxalic acid. According to the difference between the amount of oxalic acid measured twice before and after the experiment, the amount of CO2 released from the plant samples can be found out, and accordingly the plant respiration rate can be found out. The reaction formula is as follows: Move I. Material Instruments and Reagents Record the experimental data and results of plant respiration rate measurement in the following table For more product details, please visit Aladdin Scientific website.
1. Materials: tomatoes; potatoes; other plant materials such as fruits.
2. Instrumentation: balance; pump (or atmospheric sampler); respirometry device (as shown in the figure); 10ml potbelly pipette;
25 ml acid burette; ear-wash ball; burette holder; 100 ml triangular flask; 100 ml measuring cylinder; 100 ml volumetric flask.
3. Reagents and preparation: sodium lime
1 / 44mol-L-1Ba(OH)2 solution preparation: weigh Ba(OH)2-8H2O 7.25g dissolved in distilled water, dissolved to 1000ml, shaking well.
Preparation of 1/44mol-L-1 standard H2C2O4 solution: accurately weigh the recrystallized H2C2O4-2H2O 2.865g dissolved in distilled water, dissolved and volume to 1000ml, shake well.
Preparation of 1% phenolphthalein solution: weigh 1g of phenolphthalein, dissolve in 100ml of 75% ethanol.
Experimental method
1. First determination (gas washing)
1.1 As shown in the diagram of the respirometry setup, add about 1 / 44mol-L-1Ba(OH) to each of the two gas-washing flasks 3 and 4 with a measuring cylinder.
solution 150 ml; and 200 ml of 1 / 44mol-L-1 Ba(OH)2 solution was added to each of the two CO2 absorption flasks at 7 and 8 using a volumetric flask.
1.2 Weigh 1Kg of the sample and fill the breathing chamber with the lid.
1.3 Connect the atmospheric sampler, gas buffer bottle, CO2 absorption bottle, respiratory chamber, gas washing bottle and CO2 absorption tower with each rubber pipeline, then start the pumping device and check the joints to prevent gas leakage. Atmospheric sampler flow meter gas flow rate to 0.5 L / pumping 5 min after stopping pumping (Note: record the first stop pumping time), and the breathing chamber before and after (11, 12) and the two ends of the clamp.
1.4 First titration
Remove the small plugs on the caps of the two CO2 absorption bottles, and use a 10 ml pot-bellied pipette to draw 10 ml of Ba(OH)2 solution from each of the two CO2 absorption bottles and inject it into the same triangular flask (take two repetitions of the titration.). Note: After taking the sample solution immediately plug tightly cover the small plug), and add 3 drops of phenolphthalein as an indicator, with 1 / 44mol-L-1 standard oxalic acid from the triangular bottle stopper on the small hole for titration, titration to the red solution just disappeared for the end of the titration, record the amount of oxalic acid (ml). The average of the two repeated titration values was calculated by substituting into the formula.
2. Second determination (respirometry)
2.1 Open the clamps at both ends of the respiratory chamber before and after (11, 12), start the pumping device, adjust the gas flow rate of the atmospheric sampler to 0.1-0.2 L/min (adjust the gas flow rate to release about 120 bubbles per minute), and check whether there is any leakage of the caps and nozzles of the bottles. Breathing measurement 30min, stop pumping, record the second stop pumping time, and will breathe before and after the chamber (11, 12) clamps at both ends of the clamp.
Note: The difference between the second stopping time and the first stopping time is the respiration measurement time.
2.2 Second Titration
The method is the same as for the first titration. Take the average of the two repeated titrations and substitute it into the formula.
Calculation
Calculate the respiration rate of the plant according to the following formula: 
Record the results
Record the experimental data and results in the following table
