Studies on Yield-Forecast in Main Crops : 15. On the regional differences of meteorological and other natural conditions in the Chugoku district.

[摘要] The regional differences of the meteorological and other natural conditions, having influence upon the productivity of paddy rice in the Chugoku district were investigated. The results obtained are summarized as follows: 1. The configuration of the district forms a great slope on either side of the Chugoku mountain range and its rivers are short with small quantity of water. Accordingly, many paddy fields distribute themselves over the inclined planes along the coast, depending the water supply on the irrigation ponds and rainwater. 2. Since the soil of the paddy field in this district can hold little water and fertilizer because of its basic constituent mainly consisting of acid rock, the basis contained in the soil are liable to be quickly melted and washed away. This becomes also the cause of acceleration of superannuation and "Akiochi" (Autumnal low-crop) due to unusual deoxidation under high temperature, as we have often experienced in many paddy fields. 3. The meteorological condition shows little difference among the regions when viewed from the civil day. But when the growth stage of the paddy rices are compared, it is found that the deeper the district is located in the mountains, the lower the temperature at the former half-stage of growth becomes, and the duration of sunshine at a maximum tillering stage becomes the shorter and the more unstable. Therefore, the mountainous regions may be said unfavourable for securing proper number of panicles.

[学科分类] 农业科学（综合）