Question

can the production of above-ground dry matter by the plant can be used for measuring photosynthesis.

Answer 1

Hi Answer:

Q. Can the production of above-ground dry matter by the plant can be used for measuring photosynthesis.

Answer: Yes, the above ground dry matter or mass can be used for measure photosynthesis. It is well known that the dry mass is increased with the process of photosynthesis. The concept of determination of dry mass was involved in Sachs half-leaf method. In this method, the half part of the leaf is cut down and its weight is recorded as (W1) and the second half is allowed to grow after a particular time the second half of leaf is also removed and its weight is also recorded (W2). The difference in weight W2 and W1 is a measure of net assimilation. In this method, the loss due to respiration and translocation is also calculated and its name is given W3 and W4 respectively. After that, the real carbon assimilation is calculated by (W2-W1) + (W3-W4). The total increase in dry matter in the overall experiment is expressed in grams in unit time per unit area of leaf surface.

It is found that the above method has some limitations such as the area of cut leaf is not similar to the area of the uncut leaf. So to overcome this limitation and or for more accurate calculation of the dry mass during photosynthesis the one part plant leaf was covered with a clamp instead of cutting it and the second part is exposed to sunlight for normal photosynthesis. This improvement in experimental method provides more accurate results and it proves that the photosynthesis rises the dry mass.