Japanese Journal of Breeding

Using the data of the performance test for recommendable varieties in Toyama Prefecture, the influence of the environments (year, Iocation) on the yields of the rice varieties was analyzed during the 10 year-period from 1961 to 1970. These data were divided into 3 periods, and common varieties and locations were extracted (Table 1). The variances of the main effects and the interactions of the factors were examined by analysis of variance at each period, and then, the adaptability and the features of each variety were evaluated by FlNLAY and WILKlNSON (1963)'s regression analysis, principal component analysis (PCA) and cluster analysis.

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Dimensions (length, breadth and thickness) of carbonized rice grains excavated from 12 archeological sites were measured to investigate the origin of ancient Japanese rice . The ages of rice grains excavated were from the late Jomon to the Yayoi eras (from c.500 B.C. to c.300 A.D.). The excavation sites were located in the northern part of Kyushu, Japan. The 13 different materials from 12 excavations were analyzed for variations of the grain dimensions and were compared with those of 16 modern rice cultivars. The twelve sites were located in three geographical regions: three sites in the north-western Kyushu sea-shore region facing the Sea of Genkai, seven sites in the Chikushi alluvial plain region, and one of other two sites in the northern inland and the north-eastern sea-shore facing the Sea of Suo. The oldest sites were located in the north-western Kyushu sea-shore region. About 100 grains randomly sampled from the large masses excavated were measured using scaled photographs. In the cases where fewer than 180 grains were excavated, all available grains were measured. Results are as follows: 1.) The lengths of grains from the three sites in the northwestern efyushu sea-shore region were all shorter than those from the other nine sites.

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There was clear difference in stomatal chloroplast number between haploid and diploid tobacco plants. In this experiment, chimeral structure of colchicine-treated tobacco plants was analyzed on the basis of stomatal chloroplast number as an indicator of ploidy level. Colchicine treatment on haploid plantlets which were derived from anther culture resulted in haploid, diploid, tetraploid and aneuploid plants. However, of the colchicine-treated plants, 13 - 36 percent showed chimera, because the ploidy level was different between lower and upper leaves of the plant. Difference in ploidy level was also observed between floral organs and the leaves (Table 1).

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Chinese arrowhead (Sagittaria trlfolia L.), an aquatic plant, is a tuber crop, cultivated in paddy fields in East Asia. In Japan, there are only three cultival varieties, 'Aokuwai', 'Shirokuwai' and 'Suitakuwai'. 'Aokuwai' is the most popular in most areas of the country because of the good quality in tuber shape and color. But, this variety shows low yield and has a slightly bitter taste. On the other hand, 'Shirokuwai' shows high yield but the tuber shape and tuber color are not good for market sale . 'Suitakuwai' produces tubers with good taste, but the tubers are too small to be sold. Therefore, 'Shirokuwai' and 'Suitakuwai' are considered to be useful gene sources to improve 'Aokuwai'. To gather fundamental data for the breeding of 'Aokuwai', diallel crosses were made among the three varieties and the F₁ hybrids were raised. The morphological characters were investigated in the parents and F₁ hybrids in this experiment.

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