Determination of plant transpiration rate
The speed of transpiration is related to the speed of mineral salt transportation in the plant and leaf temperature, etc. The transpiration rate can be used as an important index to determine the degree of water demand. The main purpose of this experiment is to master the principle and method of determining the transpiration rate of plants under natural conditions by using the isolated rapid weighing method.
Principle
The basic principle of the determination of plant transpiration rate is that plants lose water by transpiration to reduce the weight, so the weighing method can be used to measure a certain leaf area (or a certain weight of leaves) in a certain period of time, the amount of water lost, so as to find out the transpiration rate. Plant branches and leaves although cut from the mother, but a short period of time in the physiology of the physiological changes are not yet obvious, the measured transpiration rate and the actual situation is similar. The disadvantage of this method is that the plant material must be lost, and the transpiration rate cannot be continuously measured and automatically recorded over a long period of time.
Operation method
Determination of plant transpiration rate
Principle
The basic principle of the determination of plant transpiration rate is that plants lose water by transpiration to reduce the weight, so the weighing method can be used to measure a certain leaf area (or a certain weight of leaves) in a certain period of time, the amount of water lost, so as to find out the transpiration rate. Plant branches and leaves although cut from the mother, but a short period of time in the physiology of the physiological changes are not yet obvious, the measured transpiration rate and the actual situation is similar. The disadvantage of this method is that the plant material must be lost, and the transpiration rate cannot be continuously measured and automatically recorded over a long period of time.
Materials and Instruments
Materials: plant leaves with stalks or small branches. Move The basic procedure for the determination of plant transpiration rate can be divided into the following steps: 1. cut off the leaves or twigs with stalks, weigh them and record W1. 2. Fill a triangular vial with water and cover with a perforated rubber stopper. Insert the prepared leaf or branch through the perforated rubber stopper into the water in the triangular vial and close it. Dry the outside of the vial, weigh it, and record the weight W2. 3. 3. Weigh the leaves or branches after 1-2 h indoors or outdoors and record the weight W3. 4. 4. Subtract this from the amount of water transpired. 5. 5. The following two methods can be used to find the transpiration intensity. (1) Calculate the leaf area ( cm2 ) of the measured leaves and branches using a transparent checkerboard, and calculate the transpiration intensity [calculated as the mass of water transpired per hour per square meter of leaf area (g)] according to the following formula. Transpiration intensity (g H2O・m-2・h-1 ) = amount of water transpired (g) × 600,000/leaf area ( cm2 ) × measurement time (min) (2) For plants such as trees, where it is not convenient to calculate the leaf area, the transpiration intensity [mass of water transpired per hour per gram of leaf (mg)] can be obtained by weighing the original fresh weight. Transpiration intensity (g H2O・m-2・h-1 ) = transpiration amount (g) × 60/tissue fresh weight (g) × measurement time (min) Caveat 1. The balance should be sensitive and have a wide weighing range (0.01-100 g) to monitor changes in the weight of plant material at any time. 2. When calculating transpiration intensity on the basis of fresh weight, the shoot tips should be included in the weight of transpiring tissues. For more product details, please visit Aladdin Scientific website.
Equipment:
① Palletized torsion balance
② Setting
③ Scissors
③ Scissors ④ Triangular bottle
⑤ Rubber stopper with hole