Growth efficiency of rice seed germinated under various oxygen conditions was investigated in an attempt to clarify whether respiration of seed coated with calcium peroxide (CaO_2) was aerobic or anaerobic when it was germinated in flooded soil. 1. Growth efficiency varied with oxygen conditions during germination and it declined under anaerobic conditions. 2. When CaO_2-coated seed was germinated in flooded soil, respiration of the seed before seedling emergence was, judging from growth efficiency, fairly anaerobic.

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This experiment was conducted to verify our previous observation that ferrous iron (Fe^<2+>) inhibited seedling emergence and establishment and to attempt prevention of Fe^<2+> harm. Paddy rice seeds coated with calcium peroxide (CaO_2) alone and with CaO_2 plus chemical which change Fe^<2+> into insoluble form were sown into flooded soil. Fe^<2+> (0, 150, 225 or 300mg/100g air-dried soil) was added to the soil prior to sowing. Seedling emergence and establishment tended to be more delayed and inhibited as the amount of added Fe^<2+> increased and especially when it exceeded 225mg. Chemicals which change Fe^<2+> into insoluble form (potassium hexacyanoferrate (III), potassium hexacyanoferrate (II)) brought certain improvement of seedling emergence and establishment, such as earlier seedling emergence.

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[in Japanese]

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A Turkish barley cultivar, Turkey 253, was found to be resistant to scald caused by Rhynchosporium secalis. The resistance in Turkey 253 was genetically investigated using the hybrids with a susceptible Japanese cultivar, Ban-Sekitori 1. Seedlings at 1-2 leaf stage of the F_2 and F_3 progenies were inoculated with a fungus strain originated from a single spore on affected Minorimugi which was susceptible to scald and the leading cultivar in Hokuriku district. In F_2 generation, resistant and susceptible plants segregated in the ratio of 3 : 1, and in F_3 progenies, homozygous resistant, heterozygous and homozygous susceptible lines segregated in the ratio of 1 : 2 : 1. These results indicate that the resistance of Turkey 253 was controlled by a single dominant gene. Also, the resistance gene was found to be linked with uz gene located on chromosome 3 with 36.0±2.5% in recombination value. It was already known that there were three close-linked genes, Rh, Rh-3 and Rh-4, located on chromosome 3, and one of them, Rh, linked to uz gene with 8-12%. It was concluded that the resistant gene involved in Turkey 253 was different with Rh, Rh-3 and Rh-4, although allelic test between them should be conducted.

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The effects of incubation at 0℃, wet and dark condition were studied on surviving of barley seedlings. Barley seedling died to be caused by more than 60 days incubation. Percentage of surviving were influenced by variety, growing period, cold acclimation and incubation period.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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Intercross between glyphosate sensitive and tolerant biotype of field bindweed and self pollination of each biotype were made. Seed set percentages of both biotypes by intercross were almost 100%. Seed set percentage by self pollination in sensitive biotype was 2.1% and that of tolerant biotype was 30.8%. Partial breakdown of self-incompatibility in glyphosate tolerant biotype of field bindweed was suggested.

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The distribution and size structure of Rumex obtusifolius in a pasture were investigated at the Experimental Farm, Faculty of Agriculture, Shinshu University. This weed produced clumped distribution (Iδ=1.79, P<0.01). The population consisted of 83 seedlings, 50 asexual individuals and 14 sexual ones. The larger the biomass of individual plant, the fewer the frequency.

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