Studies on the saline injury on crops(III) : On the relations between the air supply to the root zones on wheat and the appearance and the development of the saline injury.

The author has investigated the relation between the air supply to the root zones and the appearance and the development of the toxicity symptoms resulting from salinization on wheat, the variety used being a local variety "Norin No. 52 ". The results obtained can be summarized as follows : In the experiment for about two weeks, the degree of the development of the toxicity symptoms resulting a from salinization was significantly greater in the plants under the anaerobic condition than under the aerobic condition at the critical level of concentration for growth but at higher concentration than above, the difference was not significant. This relationship was equally shown in the reduction of top and root growth, hydration ratio and number of leaves. It was shown strikingly that sodium accumulation in leaf blades was lower under the aerobic condition than under the anaerobic condition. The accumulation of the other elements decreased in the plants treated by saline solution under the aerobic condition, but under anaerobic condition this relationship was not clear. In regard to the growth and maturity on the polder fields, it was found that the yield of wheat as backcrops on the paddy field was extremely poor than that of either upland wheat or of wheat at the field cultivated for the first time in spite of the lapse of the same time after reclamation from sea. It was also found that leaf length, leaf width and size of stoma on top leaves were significantly reduced and found at the same time that the number of stomata increased on wheat as backcrops on the paddy fields. The percentage of air space and porosity in the soils of upper layer on the fields after harvesting rice were distinctly smaller than that on the other fields. Therefore, it might be considered that the appearance and the development of the toxicity symptoms resulting from salinization is markedly promoted by lowered aerobic condition around the roots as far as this experiment goes.