抄録
This experiment was carried out to define the effect of nitrogen fertilization at the different growth stages on the long stem yield of mat rush. For that purpose, watercultured mat rushes, cv. Asanagi, were treated to grow under the low (20 ppm N), the medium (60 ppm N) and the high (180 ppm N) nitrogen levels of culture solution at the early tillering stage (stage II), the tillering stage of the long stem (stage III) and then the elongating stage of the long stem (stage IV), respectively. The results are summarized as follows : 1. Number of tillers and the long stem (>105 cm) per hill at the harvest time increased under the high or the medium N levels for stage II and stage IV. On the contrary, for stage III, i.e. the middle growing stage which was defined as the tillering stage of the long stem, number of the long stem per hill increased under the low N level. 2. Moreover, it was found that the nodal position of the long stems on the stolons were changed and lowered basipetally under the low N level at stage III and the mean dry weight of the long stems was also increased by that treatment. 3. The utilization efficiency of the applied nitrogen during whole growth period of mat rush was estimated on the basis of the dry matter weight and nitrogen content of each part and it was found as low as about 50%. The result of this experiment suggested that 1) at the early tillering stage and the elongating stage of the long stem, the sufficient amout of nitrogen fertilizer should be topdressed to promote the early tillering and the long stem elongation but 2) at the tillering stage of the long stem, the smaller amount of nitrogen fertilizer shoud be applied for getting higher yield of mat rush.
