|Budget Amount *help
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1990: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1989: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1988: ¥1,300,000 (Direct Cost: ¥1,300,000)
Using the materials collected in several tropical and sub-tropical regions in the world, the plants belonging to the genus Oryza were analyzed their varietal variations shown in species, strains, regional and ecological statuses, in view of fundamental characters of agricultural terms. The main purposes were focused on evolutional processes of the genus and on advanced techniques of rice cultivation in the future. The results were summarized as follows :
(1) Amylose contents of endosperm starches of brown rice ranged from 12.4% to 29.1%, with a mean of 24.1%. The strains were classified into 4 types, i. e., very low, low, intermediate and high types. The large varietal variations were found between species, strains and localities. The same tendency was found in storage proteins.
(2) The intercellular spaces ranged from 40% to 70% and from 5% to 52% in root and leaf, respectively. The differences are especially clear in young seedlings and became later obscure. The occurrence of the spaces were used as index for adaptability to water conditions.
(3) Flowering habits were detected using photoperiodic responses in the present studies. Most of the responses were looked upon as adaptability for the respective habitats in the practical fields. However, the several problems were remained for introduce the new varieties in the developing countries, and suggested as important results for breeding works.
(4) Leaf emergence intervals were measured during the flower promordia formation to heading period. The intervals changed under short day condition, and clearly delayed according to the growing processes. The tendency became dull following annual to perennial species in the genus Oryza, and was not found in African species.
(5) The large variations were found in the species, variety, locality and habitat in the whole characters. The findings were looked upon as useful informations for rice cultivations in the world.