Abstract
In order to examine the agricultural characteristics of colored-kernel rice varieties, which included red rice and purple-black rice, 45 strains collected from Japan and 7 other Asian countries, as well as 17 leading varieties (common rice) of Hiroshima Prefecture, were cultivated under 2 soil fertility levels. The red rice strains from Japan could be divided into a short-grain type or long-grain type by the width/length ratio of hulled rice. The two groups were also different in regard to other morphological traits. The red rice strains from foreign countries varied widely in width/legth ratio. Concerning purple-black rice, there was no short grain-type among the strains from foreign countries. The red rice and purple-black rice strains were, as a rule, taller in plant height, lower in panicle number and lower in paddy yield than the leading varieties. The red rice strains from foreign countries also showed wide variations in plant height, panicle number and paddy yield. Responses to different soil fertilities were similar for most traits among the strains. One notable exception, though, was harvest index which increased slightly with high soil fertility in the case of the leading varieties, while decreasing for the other strains under the same conditions. The kernel colors of red rice, purple-black rice and common rice could be distiguished through their L value (lightness) as determined from a color difference meter. Also, the red rice showed continous variation in its kernel colors.
