Effect of the Night-Illumination by Electric Lamps on the Growth and the Yields of Paddy Rice

[摘要] Authors examined the relation between the illumination by the all-night street fluorescent lamps, and its effects on the growth and yields of paddy rice. The results obtained are as follows: 1. In case of 2 luxes or less, neither the growth nor the yields were affected at all, but in case of 5 luxes, they were affected, though quite slightly, while in case of 10 luxes or more, they were affected markedly, and in case where the all-night illumimation exceeds 50 luxes, the yields were completely nil. In an extreme case of as high as 70 luxes or more, rice plants never even came int o ears. 2. The plant growth stage affected most remarkably by all night illumination was the duration from the 40th to the 20th day before the heading, which corresponds to the duration of 20 days after the differentiating stage of flag-leaf primodium. 3. The varietal differences in the delaying effect on the heading dates caused by all-night illumination are given belows. The growth and the yields of the extremely early maturing varieties for the early season cultivation (Honenwase, Reimei) were affected quite slightly. However, considerable injuries caused by night illumination were observed in those for ordinary season cultivation, i.e., the early maturing (Yamahosi, Ukonnisiki), the middle maturing (Harima, Kinmaze), and late maturing varieties (Siranui, Tokai No. 28). Among them the early maturing varieties were affected most seriously by all-night illumination. And in any cases, the varietal differences were also confirmed clearly. 4. Among varieties for ordinary season cultivation, which were greatly affected by illumination and showed the great delay in the heading, authors could discover some individuals which were affected little by all-night illumination. By examining the characteristics of their subsequent generations, it was found that they were the very strains which could bear ears and fruits even under a considerably high illumination. This phenomenon is meaningful, because the study on such an ecotype may suggest the possibility of breeding up some non-responsible varieties to all-night illumination.

[学科分类] 农业科学（综合）