Abstract
The writer has already reported that, in the seed-bed of rice in tidal paddy-field of Tyosen where sulphate-reducing bacteria, Microspira desulfuricans (BEIJERINCK) van DELDEN, took an active and vigorous part, and that the rotting of rice-seeds and seedlings prevailed as the consequence of a great lack of oxygen.
This paper reports that injury in the same manner occurs also in common paddy-fields.
The injured soils investigated by the writer contain much of organic matters in addition to stagnation of water, and the reaction of soil is weak alkaline (pH 7.17.3). The symptom appears on germ elongated to 13 cm of cotyledon as a germ with curvature and check of the elongation of the first leaf, which becomes dead and rots with age, and the growth of its root is checked, and then withers with a black colouration of the precipitation of iron sulphite.
In the injured soils, sulfate-reduction is very visible, and sulfate-reducing bacteria and the specially associated organisms have been isolated. Those bacteria are found to be identical with Microspira desulfuricans (BEIJERINCK) van DELDEN, and Pseudomonas sp. respectively which had been isolated by the writer from tidal paddy-fields, after comparing their morphological, cultuarl, and physiological characters.
From the results of experiments, these injurious soil conditions are not only closely resembles to those of tidal paddy-fields, but they are also similar to the conditions produced by the inoculation of sulfate-reducing bacteria, Microspira desulfuricans (BEIJERINCK) van DELDEN, in sterilized soil.
