稲黄化萎縮病に関する研究 : 第 1 報疾病とその病原菌卵胞子に関する知見

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1. The present paper deals with some knowledge gathered from writer's observations and experiments on the downy mildew of rice, wheat, and other cereal crops, and certain wild species of grasses of Gramineae. Distribution of oospores of Phytophthora macrospora (SACC.) ITO et TANAKA in the tissues of rice plant is also considered. 2. Downy mildew infection of rice plant as well as that of others occurred mostly at the occasion of floods. The writer however have observed the disease year after year on young rice plant in some nursery-beds normally managed to be free from floods. 3. There are two seasons of infection for the disease; respectively, from the latter part of May to early July and from the middle part of October to about the middle of November. 4. The disease on the rice plant after transplanting originates from two sources, one from diseased seedlings in the nursery-beds and the other in the field. In the latter case the external symptoms of the diseased plant frequently do not appear, and only by the use of microscope and observing oospores and mycelia that the presence of the disease is ascertained. Some plants may be in the heading stage, and in this case it is believed that there will be considerably seed infection. 5. On the 10th of October 1952 the state of growth of diseased and healthy rice plants growing in the same field was studied. In this field the disease was observed year after year having been originated from diseased seedlings in the nursery-beds. The diseased plants presented severe dwarfing-36.1% of the height of the healthy ones. As the diseased plants showed much tillering they appeared like a small bush. The length and the width of the blade were both less on the diseased plant than the healthy plant. The percentage of width to the length was 24.23% for the former compared to the healthy ones of 9.85%. 6. Wheat plants were studied on the 17th of May 1952 which were infected from a flood last November. The diseased wheat plants were dwarfed 71.8% in height of the healthy plants. The disease did not affect the tillering as much. 80% had heads, 4% with deformed heads, and 16% without heads. The heads on the diseased plants were smaller. 7. The disease symptoms on the other cereal crops and wild grasses varied, and some of them were difficult to see with the naked eyes. The writer confirmed the following subjects involved : chlorosis or yellowing, dwarfing, deformed spikes, and zoosporangial and oospore formation. In many cases the zoosporangium were formed on the young plant when it dipped into the water after three or five hours. 8. On the distribution of oospores in the rice plant tissues, they were found most abundant in the lower parts of blade, consecutively less in the middle part of the blade or the upper part of the sheath, and very few in the tip of blade, the lower parts of stem and the deformed spike. No oospores were observed in roots, but were observed rarely in the leaf-sheaths about 3cm from ground level, which apparently indicates overwintering of the fungus in the rice stubble in the field.
京都府立大学の論文
1953-01-25

稲黄化萎縮病に関する研究 : 第 1 報疾病とその病原菌卵胞子に関する知見

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稲黄化萎縮病に関する研究 : 第 1 報 疾病とその病原菌卵胞子に関する知見

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稲黄化萎縮病に関する研究 : 第 1 報疾病とその病原菌卵胞子に関する知見