(1) The seedlings of paddy rice (about 35 cm in height), the root of which had been cut off by a knife, were put, for 24 hours in the laboratory, in the 1% solution of straw-ash, 0.5% of Ca(OH)2, 0.l% KC1 and water (control), respectively, and then all were cultured in water for a few days, during which the root-growth being wxamined every day. It was noticed that the root-growth during the water culture was hastened in the treatment with either straw-ash or KC1, compared with the control, but not in that with Ca(OH)2. (See Table 1.) (2) The root-growing activity of the leaf-stalks of sweet potato were tested in the same way as explained above, resulting in that the root-growth was accelerated in either the straw-ash or KC1 treatment while it was rather reduced in that with Ca(OH)2. (See Table 2 and Fig. 1.) (3) The stems of chrysanthemum were cut off and put in straw-ash solution and also in the Ca(OH)2 solution, for 24 hours, the KC1 treatment being omitted in this case, then they were planted on the field, all of which being proved alive, and they were tested with regards both the root-forming and the plant growth with the results that the root-growth promoted in the straw-ash treatment, accompanied with the vigorous vegetative growth, but the reverse was the case in the Ca(OH)2 treatment. (See Table 3 and Fig, 2.) (4) Judging from the results noted above, the hasting of the root-growth by straw-ash seems to due to the Physiological action of Potassium but not of calcium, contained in the material. (5) Furthermore, the hasting of the root-growth by potassium, it is supposed, is drived from the high assimilaten products by the above-noted material. (6) In cultivation practice, straw-ash is widely used in our country, at least, on the nursery, and this seems recommendable in favour of hasting the root-growth of plants concerned after the transplantation. But it is worth while that the straw-ash treatment with seedlings or cuttings is studied in regard to the modes of its application with various crops for increasing the efficiency of its hasting action of the root-growth.
