1. In the culture solution, which was purified from heavy metal impurities by the adsorption procedure with calcium phosphate, and to which Fe was then added,
Spirodela and
Lemna could not grow and sooner or later died, if Mn was not added.
2. The minimum concentration of Mn in the culture solution, which was enough to permit the new growth of Mn-deficient plants of
Spirodela, was about 5×10
-10mol.
3. In the medium containing Mn in concentration of 10
-9mol, the vegetative propagation occurred continuously, but fronds remained very small, the growth of roots was extremely retarded and chlorosis occured. In the medium in which the concentration of Mn was increased to 5×10
-9 mol, fronds were still smaller than the normal ones, but in other appearances they were almost similar to each other. For the normal growth of
Spirodela Mn was required in the concentration of 10
-8mol. In the medium with more Mn (10
-7mol and 10
-6mol) no difference was visible from the case of 10
-8mol, concerning the rate of vegetative propagation, the size of frond, the growth of root and other appearances.
4. From the culture experiment of
Spirodela, it may be concluded that the culture solution, which was purified by the adsorption treatment with calcium phosphate, does not contain Mn in a higher concentration than 5×10
-10mol.
5. Mn is reserved in the body of
Spirodela, and the amount contained in one plant of 4 or 5 fronds, is sufficient to cause a new growth and vegetative propagation from a Mn-deficient plant, which is cultured in 100cc. solution. Its concentration corresponds to 10
-8mol.
6. Dry weight of
Spirodela and
Lemna in the culture with Mn amounted to 40-300 times as much as that in the Mn-deficient culture.
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