|Budget Amount *help
¥2,200,000 (Direct Cost : ¥2,200,000)
Fiscal Year 1994 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1993 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1992 : ¥1,200,000 (Direct Cost : ¥1,200,000)
It have been reported by the present author that characters of photoperiodism have playd an important role in process of distribution in the genus Oryza. The object of the present investigation was to study the ontogenetic development and the differentiation of photoperiodic response and to investigate their intra-and interspecific variations within in the genus Oryza.
1. More than 300 strains belonging to 5 species, including 2 cultivated and 3 wild species were used, in viewpoints of locality, ecological condition, collection year and others as the materials, i.e., New Guinea, Philippens (1961), Borneo, Malaya, Java (1963), India, Ceylon (1971), India, Assam (1978), Indonesia, Thailand (1981), Fiji, Solomon Islands (1982), Ivory Coast, Nigeria, Kenya, Tanzania (1994), Kenya, Madagascar, Liberia, Senegal, Gambia (1985), Madagascar, Tanzania (1988), which were directly collected in the fields by the present author.
2. Photoperiodic sensitivity can be determined by classifying the strains
into "sensitive" and "insensitive" on the basis of their short day response, and by more exactly measuring their photoperiodic sensitivity. The measurement was started at the 40 days old seedlings and 28 cycles continuity. There were very large varietal variations from strong sensitive to completely non-senstive. The response-patterns were not disturbed by abnormal meteorological conditions both in 1993 and 1994.
3.Critical day lengths of relatively strong sensitive strains were detected as slightly shorter than those of strains collected in southeast and east Asia. Strains collected in East Africa showed large varietal variations than those of West Africa.
4.Aging effect was detected to be sufficiently appeared from 40 days old seedlings but not 30 days ones in the most strains of the whole of the materials used.
5.Accumulation effect was looked upon to be found at 24 cycle treatments in general. However, strains showing accumulation effect only by 20 cycle treatment were preliminarily expected to some extent. Less