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CO2 on the roots part 3


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Kursanov, A.L. , Kuzin A.M. and Mamul, Y.V. 1951.

Doklady Akademii Nauk SSSR 79: 685-687


Since the invention of green plants assimilation of CO2 more than 170 years (1) have gone. In space of this period among a great amount of literary works, which appeared in connection to this problem, the most numerous were the works, dedicated to the definition of the intensity of plant photosynthesis depending on the outside and inside conditions. On this way the biologists and agronomists aspired to form a conception of the productivity of the plants, they cultivated, and to find out the methods for its future increase. However in all these works much attention is paid to the assimilation of CO2 of oxygen and in consequently to the process of getting the notion “air nutrition” of the plants.
Meanwhile, many kinds of soil, especially carbonate soil, have a great amount of free and bound carbonic acid, that may be probably, absorbed by the plant roots together with a soil solution. In account of the fact, that the water motion in the plant, caused by the transpiration, is performed towards the leaves, and at that takes place especially in the day time, we can expect, that the carbonate acid solution, going from the soil to the leaves through the root age, is assimilated by the plant, just like the other, that diffuses in the leaves from the air.
The specific gravity of each of these CO2 sources will change depending on the conditions. But, undoubtedly, in a number of cases the carbonic acid introduction through the root may become the vital source of carbon for the plants.
Unfortunately, the researchers almost didn’t study this second way of CO2 entering the plants. As a result, today we have only single observations, herewith they are still deficient to cover widely the side of this phenomenon. (2-7)
Whereas, it’s expected, that the extra carbon acid feeding of the plants through the roots especially by the agriculture with artificial irrigation, will increase greatly the plant productivity. It is indeed very interesting now because of the large irrigation systems construction, owing to which the specific gravity of the agriculture with artificial irrigation in the USSR considerably rise.
Under these considerations, we undertook this research, using the modern isotope methods, and tried to establish the fact of CO2, entering the plant through the roots, and also to define the possibility of its assimilation by the green plant by the light. The experiments are to reveal the specific gravity of the CO2 source in the plant feeding.
For our research of carbon utilization from the carbonates of the soil solutions we used Knop’s feeding solution, which consisted of sodium bicarbonate with C14. The total amount of bicarbonate was 0.2%. The amount of radio active carbon was rather small. Such amount was taken on purpose, it was for the plants not to be exposed. Therefore 10 ml of feeding solution contained only 0,5 µC.
We took 30-day haricot (phaseolus vulgaris) for the research. We put the plant roots into a wide test tube with the feeding solution so that the stem almost at the bottom went through the plug, which hermitically locked up the tube.
Owing which there was no way for the radio active CO2 to the atmosphere in which the stem and the leaves were. The plant was placed under the lamps of 300 Watt, the distance between the plant and the lamps is 20 sm. After the three hour under the lamps one leaf was removed, and in 18 hours he research was over. We had washed the plant out in the running water for 10 minutes, after which we dried it by laying it between the filter paper sheets.
According to the results of the autoradiography we got the following scheme, shown on the picture 1 (see the attachment).
On the autoradiography results it is understood that all parts of the plant contain the radio active carbon: The greater amount of it is in the stem, and the less- is in the leaf. The leaf, torn in 3 hours after the research had been started, didn’t contain any carbon. To define the magnitude determination the leaf, the stem and the root were separately pounded and the relative activity was determined on the end window counter (we took 10 mg of tissue on the disk with the radius of 2 sm). Having the purpose to determine what part of the radiation was induced by the absorbed carbonates, we heated the tissues together with the 10% of hydrochloric acid, then we dried it in vacuum and again tested their activity. The results of this process are shown in table 1.

Table 1:

Activity ИMII / MИH HA 10 mg / Tissue
Before HC1 treatment After the HC1 treatment
The leaf after 3 hours under the lamps 56 44
Leaf 18 292 279
The stem after 18 hours under the lamps 3246 2969
Stem 18 1463 1407

As it seen, the quantity of assimilated carbon in the stems (the stems, we took, are rich of chlorophyll) is twice larger than the quantity in the roots, herewith these amounts will not change if we use the hydrochloric acid. This points to the transformation of the carbonates into the non-volatile organic substances. We had to show, that the absorbed ions CO3 were utilized by the plant the same way as CO2 of atmosphere, that is they took part in photosynthesis. For this we repeated our experiments, at that one plant had been lighted for 10 hours, and another plant had been kept in the dark. The auto radiographies of this plants are represented on pictures 2 and 3.
This auto radiographies show that during the period of 10 hours the absorbed carbonates are not disclosed in the dark in the stem, but by the light the carbonates are saved in the tissues of the green stem, at that carbon here is discovered higher in the stem, where the stem is of green colour. The dependence of the CO3 disclose on the photosynthesis is observed more clearly in the following experiment, where the plant with its roots in the nutrient solution, containing carbonates with marked carbon, had been in light for 5 hours, then the half of the leaf was taken and was tested. After this the plant had been in the dark for the whole night and then the second part of the leaf was found and the plant had been lighted for 3 hours and only after this the whole plant was found. The received auto radiographies are on picture 4.
As it is seen from the auto radiographies, after the 5 hours of light the carbonates didn’t come to the leaves yet. And as it goes from the previous experiment, they are энергично фиқсируются by the green stem. For the night of being in the dark the carbonates are built up in the leaf- the amount of them is still rather little. But we can already see the feedle stamp of the half of the leaf. The further lighting runs to the active assimilation of the absorbed carbonates, that is distinctly seen by the intense radiation of the third leaf. Just to become certain that the поступившие through the roots carbonates are assimilated by the plant the same way CO2 is, that is they turn to the carbohydrates, we isolated them from the plant, being given of labelled carbon through the roots for 24 hours. The pounded dries plant (the stem and the leaf) had been boiled for 30 minutes with 1N of hydrochloric acid. The received muriatic extract was run through the anionite and cation to eliminate the acids and the bases, then was concentrated in vacuum and to this solution 100 mg of chemical glucose, as a carrier, was added. After glucose had been dissolved, it was precipitated with phenyl hydrazine. Precipitation of osazone looking like bunches of needles, was isolated, flushed up and recrystallized from the aqueous alcohol. Its activity is 112 imp/min. (10 mg on the disk of diameter 2 sm). Osazone had been recrystallized from the aqueous alcohol for 5 times. The activity was 100 imp/min under the same conditions. Osazone activity points out the activity of carbohydrates, that is the formation of the carbohydrates from the carbonates, given to the plant through the roots.
The conducted experiment showed, that the carbonates of the soil solutions may be assimilated as much as CO2 of the air is.

The Institute of Biochemistry of A.N. Bakh and the laboratory of biophysics and isotones and radiance of the Academy of Sciences of USSR.


1 J. Ingen-Housz, Experiments upon Vegetables, London, (1779)
2 M. Bergamaschi, Atti Institude Bot. University. Pavia, 4,1,117 (1929)
3 E.A. Livingston and R. Bealf, Plant Physiology, 9, 237, (1934)
4 O. Overkott, Zs. F. Gesamt, Naturwiss., 3, 480 (1938)
5 O. Hartel, Jahrb. Wiss. Bot., 87, 173 (1939)
6 V. Kudrevich, Sov. Bot., 1, 70 (1940)
7 R. Overstreet, S. Ruben and T. Broyer, Proc. Natton. Academy of Sciences, 26, 688 (1940)

Source : No Mercy Seeds
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Again....My english isn't good enough to answer on all questions correctly.
If you don't become a right answer by me...please take a look at my website, where you find 90% of your answers in english. No Mercy Supply
Since I'm a Dutch guy who's 53....My english is totally poor.
Al what's written here by me was translated by a pro.
But the official documents about soilplants and the way they pick up CO2 out of their growmedium....I did get for myself during a 3 times trip tu Russia.


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