The color reaction of rice grains with phenol can be clearly and quantitatively determied by the present method in which both the colorations of grain surface and phenol solution are measured after soaking grains in diluted phenol solution for 3 to 5 days. This method is more effective to clarify the phenol reaction of the cultivars with colored hull and brown rice, as compared to the ordinary method in which only the coloration of grain surface is observed. The phenol oxidation system is localized only in grains, but not in rachis, branches, leaves, nodes and internodes. Hull and brown rice separated from the grain showed different reaction with phenol each other. F₃ hybrid seeds of the cross between wild (positive phenol reaction) and cultivated (negative phenol reaction) rice segregated into four combinations of hull and brown rice regarding their color reaction with phenol, i.e, both positive, positive and negative, negative and positive, and both negative, respectively. Therefore, when testing the phenol reaction, hull and brown rice should be examined separately. Phenolase activity test suggested that the rice cultivars showing negative reaction with phenol are unable to be further hydroxylated into aromatic ring of phenol due to a lack of hydroxylating enzyme and/or a shortage of electron donors.

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The relationship between ratoon ability and lodging resistance was investigated with 21 paddy cultivars grown in a randomized block design with 2 replications. Plant characters concerned with lodging such as internode weight, stem base weight, breaking strength of culm and lodging index were noted at 5 successive 10 days intervals starting on the day of heading. Internode weight, stem base weight and breaking strength increased during the first 10-days period following heading then declined during the next 10- or 20-days period, but reached again the levels at heading or beyond on 40 days following heading. Lodging index increased during the 30-days period following heading, and then declined down. The rice plant was also cut at 5cm above the ground at 5 different growth stages, i.e the day of heading, and 10, 20, 30 and 40 days after heading. Some characters of the ratoon crops were surveyed at the ripening stage. Percentage of ratoon tillers showed the same change as internode weight, stem base weight and breaking strength. Changes of the percentage of ratoon tillers and the ratoon height showed a similar tendency in cuttings during the period from 10 days after heading to 40 days. Traits of the ratoon did not show any clear relationship to breaking strength. However, there were significant and negative correlations between traits of the ratoon and lodging index in cuttings on 20, 30 and 40 days following heading. It was suggested from these correlations that ratoon ability might be used as a test indicator of lodging resistance. The contribution rate of leaf sheath to breaking strength ranged approximately from 15% to 40% in the later period of ripening, and it was depended on cultivars and growth stages.

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By using ten characters concerning the inflorescences, principal component analysis and cluster analysis were applied to the 34 taro strains, which were collected from Nepal, Thailand. Malaysia. Indonesia, China and Japan. The strains were grown wild except two cultivated strains of Nepal and Japan. From the result of the principal component analysis, the total contribution of the first and second principal components was 81.6%. The first principal component was considered to be a shape factor and the second a size factor. In the first and second component plane, all strains were divided into five groups, namely, Thailander, Malaysian, Nepalese, Chinese and Okinawas'. Japanese strains were included into three groups: (1) Thailander-those of Ishigaki and Iriomote Islands, (2) Chinese-those of Kyushu and Honshu, and (3) Okinawas'-those of Okinawa Main Island. Yoron and Tanegashima Islands. Therefore, the geographical variation in taro was shown distinctly. The results of the cluster analysis were similar to those of the principal component analysis. Observation on chromosomes revealed that two strains from Nepal, one from China, and all from Kyushu and Honshu of Japan were triploids (2 n=42) and the others were diploids (2 n=28). There was no triploid with comparatively small scores of the first principal component. Thus, geographical classification of taro based on the multivariate analyses may be more useful than based on a few characters of the inflorescence.

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This study was conducted to find appropriate methods for storing pollen of Iris ensata. The longevity of pollen stored in organic solvents and dry air was examined as well as the fertility by pollen stored for 12 months. Storing in acetone for 12 months at -20°C and storing in dry air with CaC12 at -20°C after pre-soaking in acetone provided viability as high as that of fresh pollen. The longevity of dry pollen with C_aCl₂ was 3 months for 25°C and 6 months for O°C. However, pollen stored for 12 months at -20°C retained viability almost equal to that of fresh one. Pollen stored in acetone and dry air for 12 months at -20°C produced fertility as high as fresh one.

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The growth inhibiting effect of hydroxy-L-proline (Hyp) on rice seedlings and the selection technique for a resistant mutant in M₂ seedlings were studied. Retardation of seedling growth was detected in the culture at concentrations above 5×l0-5 M Hyp and increased with the increase in both Hyp concentration and the soaking time prior to addition of Hyp. In M₂ generation, the seedlings following gamma-ray irradiation and treatment with sodium azide, ethylene imine (EI) and ethyl methanesulfonate were cultured in the presence of 2×10-4 M Hyp. Twenty-seven resistant seedlings were selected. EI was the most effective mutagen for inducing Hyp resistant variants in rice. Following 0.2% and 0.4% EI treatments for 2hr, the frequencies of resistant seedlings were 2.5×l0-4 and 1.6×l0-3 on an M₂ seedling basis, or about a tenth of that of chlorophyll mutations in both cases. Of the progenies of selected seedlings, 24 progenies were confirmed to be resistant to Hyp at M₃ and established as rcsistant mutant strains.

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The simplified triple test cross analysis of Jinks. Perkins and Breese (1969) and of Jinks and Virk (1977) was used to study some components of genetic variation of 13 malting quality characters. The Fl and F₂ populations of the 48 crosses including reciprocals between the two extreme testers and 12 inbred parents, together with their parents, were investigated for plumpness, thousand corn weight, total nitrogen, falling-time, glucose, falling-time index, malting loss, filtration rate, cold water extract, hot water extract, adjusted extract, permanently soluble nitrogen and modification index. No reciprocal differences were found in any of the characters except the falling-time index of the F₁ The two characters, falling-time and falling-time index, were mainly controlled by additive gene effects with some epistatic and/or dominance effects. Epistasis and dominance components of variation were, in general, minor components, and their manifestation changed with the generation; there appeared to exist genotype-environment interactions. All other characters showed no distinguished results in this respect except that parental and/or progeny differences were detected in most characters. There seemed to be no insuperable genetic barriers to the improvement of malting quality characters under study.

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A cultivar of bread wheat, Canthatch was compared with resynthesized hexaploid wheat strains derived from the reconstituted tetraploid (AABB) components of Canthatch and each of several varieties of Aegilops squarrosa L. with regard to the spike, internodes and culm length, and their intra-plant variability. A significant difference among strains was obtained except in the first and second internode lengths. Intra-plant variability was significant for the lower internode lengths. Variation of D genomes were remarkable in the lower internode length. Canthatch was longer in the characters measured except in the spike length than the resynthesized of var. typica. The var. strangulata-resynthe-sized was not so clearly different from Canthatch. Canthatch showed moderate intra-plant variability. Discriminant factors (characters) of some differential D genomes were clarified by canonical discriminant analysis. Variation of D genomes were well characterized by spike length, culm length and lower internode length.

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Factors influencing embryogenesis were investigated on the hypocotyl calluses of a cultivar (Shinko-Yaenari) of Solanum melongena L. When actively growing calluses were conditioned by NAA, occurred embryogenesis which was observed by the appearance of green spots (GS). 1. A wide range of the concentratlon of NAA (4-20mg/l) in the medlum was effectlve for GS formatlon whlle 7-9mg/l was the optimal. 2. Duration of the callus culture with high NAA medium gave influences to the yield of embryoids; longer duration increased the percentage of the GS forming calluses, while shorter duration enhanced the GS number per callus. 3. Calluses on the 2mg/l NAA medium kept the callus growth for more than 19 passages (14 months). When the callus was conditioned by the high NAA medium, embryoids were formed. Calluses transferred to NAA-free medium induced organogenesis. The organogenetic ability decreased at the early passages and was lost finally but the embryogenetic ability was kept for a longer period. Plants embryogenetically regenerated from early passages were diploids except one plant, but those from later passages contained many polyploids. 4. The embryogenesis was also influenced by the condition of explants; long explant pieces taken from non-elongated hypocotyls yielded many GS.

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Occurrence of notched grain in rice is considered to be due to unbalance between the length of glume-clipped caryopsis or the potential length of caryopsis (Tl) and the length of non-treated caryopsis or the capacity of floral glumes (Cl) as demonstrated by the author's previous works (TAKEDA 1982 and others). In the present experiment, selection response of notched grain percentage and Tl/Cl ratio and their mutual correlated response have been investigated using hybrid populations derived from crosses between a strain L-45 and other varieties. L-45 is a unique strain which has high degree of unbalance between Tl and Cl, and develops notched grains with high frequency. In the first experiment, L-45 was crossed with a Japanese cultivar Akiminori. A total of 839 F₂ plants, together with parental varieties and F₁ plants were grown in the field and investigated for notched grain percentage in 1974. For the statistical analyses, arcsine transformation was applied for notched grain percentage in all the experiments.

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The crossability was investigated in the interspecific cross, B.oleracea×B.campestris, in order to breed mono-genomic hybrids and following progenies in genus Brassica. Among 31 cross combinations examined, pollen gennination index(Table 2, 0≤P.G.I.≤4) ranged from 0.7 to 3.8 with mean value of 2.4. Insufficient pollen germination and pollen tube glrowth was recognized in many crosses. It is pointed out that the interspecific barrier would operate in pre-zygotic process for fertilization. Number of hybrid embryos obtained per pod varied from 0 to 9.5 with mean value of l.2 (Fig.1). Most of them developed to the torpedo stage abot', t 0.4mm long. No hybrid seed was obtained in any cross combination (Table 5). Secondary interspecific barrier was ascertained to turn up in post-zygotic process of embryo development.

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Near isogenic lines of rice, Oryza sativa L., with or wrthout a gene Pi-zt for resistance to Pyricularia oryzae CAV., have been developed through backcrossings and selfings. The heterozygosity with respect to Pi-zt has been maintained during 15 generations from F₁ through BC4F₁0 in a cross between the Malaysian cultivar Morak Sepilai and the Japanese cultivar Fujisaka 5 in which Fujisaka 5 was used as the recurrent parent through successive four backcrosses. During these generations plants were tested for resistance to a Ken 53-33 strain of the blast fungus with a wide spectrum for virulence to Japanese cultivars, and heterozygotes were selected to transmit a Pi-zt gene from Morak Sepilai to the genetic background of Fujisaka 5 (Table l). Homozygous resistant (Pi-zt/Pi-zt) plants and homozygous susceptible (+/+) plants were obtained in the BC4F₁1 and their progenies showed the similar agronomic characteristics under the favorable conditions free from blast disease (Table 3). They had a Pi-i gene for resistance in common that was transmitted from Fujisaka 5 (Table 4).

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