Determination of the photoresoluing rate of plant leaves (improved half-leaf method)

photosynthmic rate measurement is one of the basic research methods of plant physiology, and it has a wide range of applications in crop abundance theory, crop ecology, selection of new varieties, and basic theoretical research on photosynthmics.
based on the total reaction of photo-cooperation:
The C022H2O → (CH2O) O2H2O
photolycing intensity can in principle be expressed as the rate at which any reactant is consumed or the result is produced. Because the moisture content of the plant is very high, and the plant is constantly absorbing and dehydration at any time, the
national and chemical
reaction of water participation is very many, that is, the moisture content in the body often changes, so it is not actually able to use water content changes to determine the photolytic rate. In scientific experiments, the photosynthing rate can be measured and represented by the following methods (Table 9-1), the most commonly used of which are: improved half-leaf method, infrared CO-2 analysis method, and oxygen electrode method. The following introduction mainly introduces the "improved half-leaf method".
improved half-leaf method:
principle
the middle vein of the same blade, its internal structure, physiological function is basically the same. One side of the blade is shaded or part of the leaves removed and placed in the dark, the other side is left in the light for photo-cooperation, after a certain period of time, the corresponding parts on both sides of the blade to take the same area, dry weighing separately. The photosynthing rate can be calculated based on the increment of the dry weight of the lighting portion.
In order to prevent photochemists from being exported from the leaves, ring cutting can be used on the leaf handles of gemine-leaf plants, hot water on the leaf base of single-leaf plants, or damage to the living cells of the ligaments by treating the
protein
precipitate), which almost does not affect the delivery of water and inororgent salts to the leaves.
equipment and
reagents
equipment: FS scissors, analysis
balance
, weighing dishes (or aluminum boxes),
ovens
, blades, metal (
organic
glass also available) templates (or punchers), gauze, water bottles or other portable
heating
equipment, clips, enamel, etc.
reagents: fs tricloste, paraffin.
methods and steps
1. Select the measuring sample: the experiment can start at 8-9 o'clock in the morning on a sunny day, in advance in the field to select a representative blade (such as the part of the blade on the plant, age, light conditions, etc.) 10 sheets, listing number.
2. Leaf base treatment:
(1) cotton and other gemal leaf plants, can use a blade to cut the outer skin ring of the leaf handle about 0.5cm, cut off the ligament transport.
(2) wheat, rice and other single leaf plants, can be used just soaked in boiling water with gauze or cotton-wrapped clips to burn the leaf base for about 20 seconds, damage the ligament. Paraffin ironing can also be used at 110-120 degrees C.
(3) 5% to 10% of triclosal acetic acid for chemical circumcision, killing sieve tube living cells.
In order to prevent the natural growth angle of the blades from sagging after hot or circumcision, tin paper, rubber tubes or plastic tubes can be used to wrap the blades so that they remain at their original raw angle.
3. Cut sample: after the leaf base part is processed, you can cut the sample, the recording time is generally in the numbering order to cut half of the symmetrical blades (the middle vein is not cut), and in the numbered order of the blades clamped in the wet gauze, the leaves placed in the dark. After 4-5 hours (lighting, large leaves sample, can shorten the processing time), and then cut off the other half of the leaves in turn, the same number clamped in the wet gauze. The order of the two shears should be as consistent as possible with the time of the chemicalization, so that each blade experiences the same number of light hours.
4. Weighing comparison: With a template of the appropriate size and a single-sided blade (or puncher), place the light-darkly treated blades in two weighing vessels (or aluminum boxes) at the same size at the middle of each half-blade cut (dozen) (if necessary) In the weighing vessel, each sample is placed in a weighing vessel, baked at 80-90 degrees C to constant weight (about 5 hours), weighing (or weighing separately) on the analytical balance comparison, according to table 9-2 fill in the measurement data, and calculate the results.
photolyceration rate (mg dry matter, dm-2,h-1) - (light-dark) blade dry weight increment (mg)/leaf area (dm-2) × photolytic time (h)
because the in-blade photochemide products are mainly carbon water such as sucrose and starch
compounds
, while 1 molar amount of C 02 can form a 1 mole amount (CH-2O), so the weight multiplier coefficient of dry matter
1.47 (WC02/W (CH2O) s 44/30 s 1.47)
will get C02 assification amount, photolycation rate units into mgCO-2 dm-2 h-1.
1985
Shanghai Society of Plant Physiology, Handbook of Plant Physiology, Shanghai Science and Technology published 98-100