On the Damage of Upland Rice by the Cool Weather in Kanto District

Abstract

1. The growth and yield of upland rice have been reduced by the cool weather in summer as severely as that of paddy rice in Kanto district.2. The yield of upland rice was more severely reduced by the cool weather during the earlier part of growing season than by that during the later part of season. The rate of yield reduction of upland rice by the former was greater than that of paddy rice, and the damage was seen all over the district, but especially severe in the northern part.3. The comparison of the growth and yield of upland rice in 1953 (the year of cool weather) with those in 1952 (the normal year) showed that the low temperature during the earlier part of season reduced the height of plants and delayed the tillering, reducing the ear length and number of grains, what was more, the percentage of sterile grain increased and 1, 000-kernel weight decreased by the delayed heading. The reason why the injury of upland rice is severer than that of paddy rice seems to be as follows:a) As upland rice is sown and grown between the row of barley or wheat, the tillering is apt to be restricted, especially under unfavorable weather conditions.b) As the growing season is shorter than that of paddy rice, it is difficult to recover from the cool weather injury even under the favorable weather condition during the later part of the growing season.4. For these reason, the cultural methods as continuous cropping, light dressing of fertilizer, and sparse standing, or law and wet field condition make the injury severe.5. The yield reduction of upland rice in the years when the yield of paddy rice was severely reduced by the low temperature during the later part of growing season was rather small as compared with those of paddy rice and those by the cool weather during earlier part of season. This is due to the earliness of heading and the resistant property of upland rice to leaf blight that prevail in the cool weather condition.