The grain with ventral swelling (GVS) is regarded as one of the damaged grains in malting barley and it lowers the quality of grain. For the breeding of GVS-resistant lines, we investigated the environmental factors causing GVS occurrence for nine years from 1989 to 1997 using four barley cultivars. GVS occurred frequently in four years; 1990, 1994, 1996 and 1997, when the frequency was significantly different (P<0.01) among four cultivars (Table 1). A positive correlation was found between the percentage of GVS and the number of days with precipitation over 25 mm during a period of 15 days before maturity (Fig. 2, Table 2), and GVS occurred frequently in years with more than one day of the critical level of precipitation. In the test of covering the barley's spikes with paraffin paperbags to prevent rain during its maturity in 1998, the rainfall from 8 to 6 days before maturity caused GVS occurrence, but that from 4 to 2 days before maturity did not (Table 3). These results indicated that GVS occurrence was caused by successive rainfall and once GVS occurred on the spikes, it did not increase further. Thus, it was suggested that GVS resistance could be selected by applying successive artificial rainfall from the middle of the ripening stage of the early maturing cultivars to the ripening date of the late maturing cultivars.

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The parents and progenies of the cross between Haruyutaka and Katepwa were used to investigate the relationships between highmolecular-weight glutenin (HMWG) subunits and bread-making quality. The HMWG compositions of Haruyutaka and Katepwa were 1, 17+18, 2+12 and 2, 7+9, 5+10, respectively. Glu-A1 and Glu-B1 subunits did not show any significant effects on any of the bread-making quality indices. The Glu-D1 subunits did not show any significant differences with the amount of flour protein, Farinograph development time or weakness. However, the Glu-D1 5+10 subunit gave greater values of SDS-sedimentation volume (P<0.01), breaking force (P<0.001) and specific loaf volume (P<0.01) than the 2+12 subunit. On the other hand, lines with the Glu-D1 2+12 subunit gave greater breaking deformation (P<0.001) than those with the Glu-D1 5+10 subunit. The specific loaf volume correlated significantly with the breaking force (r=0.716, P<0.001) and the breaking deformation (r=-0.703, P<0.001). The lines giving both higher breaking force and smaller breaking deformation tended to have a high specific loaf volume. Haruyutaka gave values equivalent to lines with the Glu-D1 2+12 subunit in breaking deformation, but the breaking force was similar to that of lines with 5+10 subunit. It could give a good estimation of bread-making quality of Haruyutaka in Japanese cultivars. The protein component besides HMWG may be associated with bread-making quality of Haruyutaka.

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This study was conducted to clarify the varietal differences in the occurence of coarse grain texture due to the high-temperature stress given during the ripening period, using 96 old and new varieties developed all over Japan. By the early-season culture, the plants were exposed to a higher temperature for 40 days after heading (ripening period) than in the normal-season culture. The percentage of highquality grain and 1000 kernel weight was lower in the early-season culture than in the normal-season culture. White-bucked rice and/or milky-white rice mainly caused the deterioration of grain quality. Most varieties developed recently in Hokuriku region showed less deterioration of grain quality caused by the high temperature during the ripening period. These facts suggest that, in the Hokuriku region, rice breeding has been conducted in a high temperature condition after heading resulting in the selection of varieties with high tolerance to the high temperature after heading. In particular, Koshihikari, Koshijiwase, Fukuhikari, Fukuhonami and Yukinosei were highly tolerant varieties. These varieties are all relatives of Koshihikari. Both types with high and low tolerance types to the high-temperature stress in grain quality are included in the old and new varieties developed in the regions except for the Hokuriku region. Consequently, it was suggested that tolerance to the high-temperature stress after heading is genetically controlled and it is very important to select the cross combination, particularly for the development of the varieties to be cultivated in the early-season culture.

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Using recombinant inbred lines (RILs) derived from two intervarietal crosses in soybean Heihe 5xAkisengoku and Heihe 5×No.29, where parental varieties differed in photoperiod sensitivity, we investigated the inheritance of days to the first flowering (DTFF), using an RFLP locus, GmN93, as a linkage marker. The distribution of DTFF in F₆ differed among the genotypes for GmN93, suggesting that a major gene is linked to this marker. Ten-day-old plants of randomly selected 14 F_{6: 7} RILs derived from these two crosses were transplanted five times at 45-day intervals from Dec. 18 to June 16. Change of DTFF with the delay of transplanting date was investigated at 28°C under natural day length. Three parameters, which corresponded to photoperiodic sensitivity, basic vegetative growth and critical optimum photoperiod, were estimated for each of the RILs investigated. It was suggested that flowering time of the RILs were determined mainly by the photoperiod sensitivity, although the basic vegetative growth was positively correlated with DTFF. The critical optimum photoperiod was not correlated with DTFF.

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An inheritance study on the three phenotypes of glossiness, including glossy (g), non-glossy (G) and true-glossy (tg), was conducted using seven varieties (3 true-glossy, 3 glossy, 1 non-glossy), and 23 F₁ and F₂ between the above varieties with different phenotypes. The phenotypes of F₁ were g in the combination of (tg×g), G in (tg×G) and G in (g×G), respectively. In the F₂ of (tg×g), (tg×G) and (g×G) where segregations were observed in glossiness, the expected ratios of (tg: g=3: 1), (tg: G=3: 1) and (g: G=3: 1) were well fitted. These results suggest that tg, g and G would be multiple alleles located in a glossy locus. Although the symbols gl and Gl were proposed for g and G by Tarumoto (1980), the symbols gl¹, gl² and gl⁺ are newly proposed to denote the multiple alleles for g, tg and G in the glossy locus, respectively.

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