Experiment 35 Improved half-leaf method to determine the intensity of the lump joint in The field

Experiment 35 Improved half-leaf method to determine the intensity of the field photolyticprinciple the modified half-leaf system will be part of the plant symmetrical blades to block or remove the light and place in the dark, the other part is left in the light for photo-cooperation, after a certain period of time, in these two parts of the corresponding parts of the blades to take the same area, drying weighing. Because the dry weight of the equal area of the two corresponding parts of the symmetrical blade is initially considered equal, the weight of the lighted blade exceeds the weight of the dark leaf, the output of the part is photosynthel products, and the photosynthelation strength can be obtained by certain calculations.。Instrument druganalysis
balanceoven scissors weighing container blade metal templategauze tin paper threci chloroacetic acid operating steps 1. Select 20 measuring samples select representative plant blades in the field (e.g., the part of the leaves on the plant, leaf age, light conditions, etc.), with a small card number.2. Leaf base treatment In order not to allow photocodesic products in the selected blades to be shipped out, and affect the accuracy of the measurement results, the following methods can be used to deal with: (1) can damage the skin part of the leaf conduction system. For example, the leaves of gemel plants, such as cotton, can be used blades to cut the outer ring of the leaf handle about 0.5cm wide.(2) Such as wheat, rice and other single leaf plants, due to the tough skin and wood part is difficult to separate treatment, can be used just soaked in boiling water gauze or cotton made of clips, the leaf base burns a small section can be (generally with more than 90 degrees C of boiling water hot 20 seconds).(3) Because of the low woodness of the cotton leaf handle, the leaf handle is easily broken. With boiling water hot, but also difficult to grasp the degree of burns, often either hot enough or too hot and leaves drooping, changing the angle of the blades. Therefore, chemical methods can be used between circumcision, the appropriate concentration of triclosan, point-coated leaf handle to prevent the output of photochemical products. Tachloroacetic acid is a strong
protein
sedimentation agent that penetrates into the shank of the leaf and kills the sieve living cells, while acting as a way to prevent the transport of
organic
nutrients. The concentration of triclosan acid, depending on the degree of tenderness of the leaves. To be able to obviously burn the shank, without affecting the water supply, do not change the angle of the blade is appropriate. 5% triclosal acetic acid is generally used.in order to make hot or ring cut after treatment of the blades do not sagging, affecting the natural growth angle of the blades, can be surrounded by tin paper or plastic tubes. Keep the blades at their original raw angle.3. After cutting the sample the leaf base part is finished, the sample can be cut, the time is recorded, and the photometric determination is started. Generally cut half of the symmetrical blades in numbered order (the main vein is not cut), in numbered order in a wet gauze, stored in the dark. After 4-5 hours, cut off the other half of the leaves in turn, also according to the number clamped in the wet gauze, the speed of the two leaf shears should be as consistent as possible, so that each blade experienced equal light hours.4. Weighing comparisonThe two halves of the same blades are stacked together according to their corresponding parts, and a metal template of a known area (e.g. cotton can be used for 1.5×2cm) is placed at the non-coarse leaf veins, and two blades are cut along the edge with the blade, respectively, placed in the light and dark weighing vessels, 80-90 degrees C baked to constant weight (about 5 hours), weighing on the analytical balance.5. The resultsthe part of the blade dry weight difference and (mg) divided by the leaf area (converted to dm
2
, 1dm
2
x 100cm
2
) and light hours, i.e. the intensity of photosynthelation, expressed as dry matter, mg/(dm
2
h). the calculation formula is as follows: Since the photochemide products stored in the leaves are generally sucrose and starch, the weight of the dry matter can be multiplied by 1.5, the amount of carbon dioxide assifilation, in CO
2,
,mg/(dm
2
.h). 。