天狗巣病

The purpose of this paper is to show the abnormality of the starch decomposition to sugars in paulownia tree leaves affected by witches'-broom. The experiment was designed to compare the velocity and the amount of starch accumulation of in the leaf disks of the diseased tree with that of the healthy each floated on various sugar solutions. The leaf starch was detected with iodine reaction. The results were as follows. 1. Both the diseased and healthy leaf disks much synthetized starch from each 10 per cent solution of glucose, fructose, galactose, and sucrose, and less from each 10 per cent solution of xylose, maltose, and lactose; but not from each of the same per cent solution of arabinose, rhamnose, and glycogen. 2. The amount of starch synthetized in healthy and diseased leaf disks was related to the concentration of sugar solution upto 20 per cent and to floating times, but it was independent of leaf disk size. The widths of zones of starch accumulation in both healthy and diseased leaf disks (Fig. 1) were related to the kind of sugars and their concentrations, but were independent of leaf disks sizes and floating times. The diseased leaf disks had always wider starch accumulation zones than that of healthy ones without showing any definite forms. 3. The healthy leaf disks synthetized starch from sugar solutions after 4 hrs. treatment, while the disease ones after 6 hrs. Young leaf disks from healthy shoots synthetized starch from sugar solutions than old ones, but this tendency was not found in the diseased leaves. Above data showed that the starch synthesis from sugars in that diseased leaves was lower than in the healthy ones. This facts indicated that the gradation of starch of the diseased leaves decreased than that of healthy, because the gradation and the synthesis of starch are reversible reactions in leaves. It was concluded that the fact that abnormal, formerly reported by the author was due to the unbalanced degeneration of sugar translocation against the decrease of starch gradation.