Morphological Variations in Scirpus juncoides Roxb. var. ohwianus T. Koyama Collected from Various Regions in Japan
1983 Volume 28 Issue 1 Pages 35-42
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1983 Volume 28 Issue 1 Pages 35-42
Twentyfive strains of a noxious weed growing in Japanese paddy fields, Scirpus juncoides Roxb. var. ohwianus T. Koyama, were collected from different locations from Hakkaido to Kyushu and were compared morphologically. The effect of chlornitrofen on these weeds was also evaluated.
1. Maximum and minimum tiller number was determined in strains collected in Shimane Prefecture and Hokkaido, respectively. The stem number of the Shimane and Hokkaido strains was 132 and 32 respectively 70 days after transplanting of a hill composed of 3 stems of which height was cut to 5cm. (Table 2)
2. The tillering patterns were classified into three groups according to the period of active tillering in each strain, which in 4, 19 and 2 strains took place within 7 weeks after transplanting, 7 to 10 weeks after transplanting and throughout the growing period, respectively. (Fig. 1)
3. The notrhern strains showed earlier heading than the southern strains. The heading of the three strains of Hokkaido began within 3 weeks after transplanting whereas that of the others trains began 4 to 10 weeks after transplanting. (Table 2, Fig. 2)
4. The ratios of bract to stem length were nearly constant (ratio; 0.30-0.40) in all the strains except for those of Hokkaido (ratio; 0.19-0.21) and Shimane Prefecture (ratio; 0.51). The bract length of the strains of Hokkaido was less than that of the other strains and the stem of the strain of Shimane was rather short. (Table 3)
5. The thousand-kernel-weight of the strains of Hokkaido was higher than that of the other strains. (Table 3)
6. There was a high positive correlation between the seed weight and length of spikelet.
7. The effect of granules of chlornitrofen applied before emergence at the rate of 3.6kg (a. i.)/ha on the 25 strains of S. juncoides var. ohwianus varied with the strains but was comparatively low in all the strains. No correlation between seed weight and the effect of chlornitrofen could be recognized. (Table 5)
