[in Japanese]

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[in Japanese]

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[in Japanese]

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The experiment was conducted to survey better eating quality which lower N% (Nitrogen content) in milled rice and lower A_1/A_3 value (Hardiness/Stickiness) in perboiled rice seemed to be shown in some fertilizer's treatments without reducing annual average yield. 1. In spite of cool summer (1993), each treatment of additional fertilizer application to deeper layer (AFADL) showed annual average yield. 2. A_1/A_3 value of AFADL-2 treatment was lower than that of conventional fertilizer as control (surface additional fertilizer application). And N% of all AFADL treatments was lower than that of control. From the above results, it was suggested to be eating quality improvement in some of AFADL treatments.

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About 1, 800 academic literatures and technological materials mainly from papers of crop and breeding science have been collected in order to publish a book to analyze various characters of the paddy rice cultivar "Koshihikari". These literatures have been referred to items of chapters and paragraphs of the book and outlines of informations have been analyzed. Now, "Koshihikari" is considered as a main breeding objective and used in many cultivation technique studies in central and southern area of Japan, and also popular abroad. The literatures increased passing through 3 steps for 38 years after the cultivar registration of "Koshihikari" in 1956. From a viewpoint of good eating quality, "Koshihikari" was used in eating taste studies and as a breeding material, the easy lodging susceptibility promoted cultivation technique studies. "Koshihikari" still greatly influenced various new technique development studies. Another plan is also considered to utilize the collected literature information as a data base.

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[in Japanese]

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[in Japanese]

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Large vascular bundles in peduncle and lower elongated internode, and their relations to primary rachis branches of the spike were investigated in a total of 10 rice cultivars belonging to Indica, Hsien (Indica with Chinese origin), Javanica, and lowland and upland types of Japonica. Numbers of vasculer bundles in peduncle markedly varied among the above ecotypes; cvs of Indica and Hsien showed higher numbers from 17 to 25, and consequently the ratios of vasculer bundles to rachis branches (Vb/Rb ratio) were higher than 1.6. On the other hand, cvs of Japonica bore fewer vascular bundles from 10 to 13 and the Vb/Rb ratios showed the range from 0.9 to 1.2. These distinct variations in Vb/Rb ratio were mainly due to the difference in numbers of vascular bundles in peduncle but not in those of lower internode or of basal parts of flag-leaf sheaths. It was discussed with the relation of the differences in Vb/Rb ratios among ecotypes and translocation effeciency of photosynthetic product or the rate of senescence.

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In order to clarify the inheritance of numbers of large vascular bundles in peduncle (Vb). primary rachis branches (Rb), and the ratio of Vb to Rb (V/R ratio), F_2 and F_3 progenies derived from the cross of Indica and Japonica (Milyang 23×Akihikari) were investigated. An F_2 population of Indica Japonica hybrid showed continuous variation in all traits, this suggesting that these traits were controlled by some major genes or polygenes. The narrow-sense heritabilities for Vb, Rb and V/R ratio were 0.593, 0.530 and 0.367, respectively, all of which seemed to be relatively high heritability among the quantitative traits in cultivated rice. Heritabilities of broad-sense in Vb, Rb, and V/R ratio were also estimated from the variance analysis of 10 cultivars of different ecotypes of Asian rice. High heritabilities as to be 0.784, 0.887 and 0.922, respectively, were obtained.

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The yield components of 37 demonstration farms in Fukui pref. were investigated by multivariate analysis. The demonstration farms were classified into the southern and the northern parts of Fukui pref. bordering Kitakoyama in Takefu. This classification was coincided with soil texture in Fukui pref. Then, from the results of principal component analysis of yield components in Koshihikari in the southern part the yield mainly depended on ripening, on the otherhand, in the northern part it mainly depended on the grain number per head.

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[in Japanese]

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The suspension culture medium of rice (cv. Koshihikari) was investigated. Koshihikari's calli proliferated well in DKN liquid medium that contained R2 inorganic salts (KNO_3 and (NH_4)_2SO_4 concentration were diluted to 1/5), B5 vitamins, 5mM aspartic acid, 5mM glutamine and 30g/l sucrose with 1mg/l 2, 4-D.

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The effective plant regeneration from calli of rice, cv. Koshihikari, was investigated. The embryogenic calli formation from suspended calli was observed on DKN medium containing 30g/l sorbitol, 2g/l casamino acids, 0.4mg/l 2, 4-D, 0.1mg/l Kinetin, 0.5mg/l ABA and 10g/l agarose for 14 days culture. These embryogenic calli would be efficiently regenerated in plants on DKN medium containing 2g/l casamino acids, 0.2mg/l IAA, 0.5mg/l BAP and 10g/l agarose after 28 days culture.

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