Breeding of Setonami, a new variety of mat rush by gamma ray irradiation

A new variety of mat rush, Setonami, was obtained from Asanagi by the following procedure. 24 growing plants of Asanagi were irradiated with the gamma ray from a Co-60 source at the distance of 9 m. The cumulative dose was 68 KR, and the dose rate was 363 R/day. It was carried out in a gamma field at the Institute of Radiation Breeding from April to December, 1963. They were brought back to the Tobu Branch, Hiroshima Prefectural Agricultural Experiment Station, divided into 480 individuals, and planted in a paddy field. Thereafter, they were selectively cultivated by clonal separation from December, 1964. In December, 1969, the cuttings of one of the strains were distributed among the prefectures concerned, and their productivity and local adaptability were tested. It was found in these tests that they were excellent, and they were named Setonami in June, 1982. Although the growth pattern is of a tiller type, Setonami produces long stems exceeding 105 cm with a large number of tillers. It bears very few flowers, and its florescence is short. The dried stems show beautiful luster. The stems are as thick as Asanagi, but supple. The yield of Setonami is more than that of Asanagi. The tatami-facing production with Setonami per unit planted area is more than that of Asanagi, and the quality is superior. (Kako, I.)