水田多年生雑草オモダカ繁殖体の生存状態と出芽に関する生態学的研究 : 第4報水田における塊茎の休眠覚醒時期

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In order to determine the time when the dormancy of arrowhead tubers (Sagittaria trifolia L.) was broken in paddy fields in normal season cultivation, the studies were carried out by changing the sampling time as under dark and light-sprouting conditions. The degree of dormancy breaking was estimated from the sprouting percentage for the first ten days. The results obtained were as follows ; 1 ) The dormancy of tubers formed in well-drained paddy fields was less deep at a low temperature (2-5℃) during winter. However, the tubers were still partially dormant in the field even in the beginning of March. 2 ) As the temperature (5-17℃) rose in spring, the dormancy of the tubers located at the soil surface and exposed to light was completely broken until the middle of May, while dormancy breaking of the tubers within the soil was broken in the end of June. 3 ) The above results suggest that light required for the breaking of dormancy of arrowhead tubers, as observed in the seeds of other weed species. 4 ) The dormancy of tubers formed in ill-drained paddy fields and under submerged conditions was gradually broken at a low temperature in winter. However some tubers with deep dormancy did not awake until the middle of May. 5 ) The above results of experiments under natural conditions confirmed the experiments of storage treatments in which the period of storage, temperature and soil water conditions were modified by the use of incubators.
1989-08-30