Smooth bromegrass seedlings derived from individual plants were evaluated for stand :and vigor in three trials in the greenhouse and one trial in the field. The results were as follows : 1. Progenies from single plants differed significantly in seedling vigor and stand, with some superior to commercial varieties. 2. Progenies superior in one trial tended to be better in others, although exceptions occurred. 3. Top weight of seedlings was sampled in one experiment, and this measure of 'seedling vigor was correlated highly with early vigor and final plant height. 4. Seed weight was correlated positively and significantly with seedling vigor but was not associated with stand. 5. Some differences in seedling characteristics occurred when 1958 and 1959 seed lots from the same plant were compared. Seedlings originating from the seed grown in 1959 were generally superior in vigor. 6. Variation ascribed to replication was highly significant in the fleld experiment but was important in only one of three greenhouse experiments.

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The present paper describes some aspects of inducing genetic variation of polygenically controlled characters following the irradiation of two rice varieties and their hybrids. The data for the characters studied in X₂ generations were analyzed by appropriate analysis of variance. In all the cases, the mean value of the irradiated population with respect to grain size character was almost the same as that of the non-irradiated control, while the variance of the irradiated population increased. On the other hand, for endosperm quality the irradiated populations showed increase in the mean value and the variance. The results obtained in the present experiment suggest that background genotypes played an important role in the manifestation of mutated characters

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In two previous papers, the author reported about the existence of selective fertilization in Chinese cabbage and its mechanism being essentially dependent on two important factors, viz., differences among varieties with regard to the frequencies of compatible pollen grains in given population and existence of various grades of compatibility in compatible pollens (Murakami, 1964 a and b). Since the pollen compatibilities are mainly controlled by genes, genetical aspects of the compatibility systems were also studied later. All the related experiments were conducted under greenhouse conditions. Segregation studies regarding self-incompatibility in the progenies of the selfed plants were conducted during 1956 to 1960. Results for the varieties Kashin and Matsushimashin N0.2 are presented in Figs. I and 2 respectively. During 1958 to 1960, several plants in different groups were crossed in all possible combinations to study their compatibility or otherwise. Results of such studies on three groups in Kashin and two groups in Matsushimashin N0.2 are presented in Tables 1 and 2 respectively.

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A mutant line characterized by having faintly sulfur-yellowish flowers segregated from a hybrid (common x sweet) pedigree of yellow lupine was obtained in F₇ and subsequent generations of the crossing. This mutant bred true right from its start. Crossing of this line with the common one resulted in revealing simple recessiveness of the character, snggesting its origin from the common line as a recessive mutation. Its flowers are consi-dered more ornamental than those of the common line. Petals of the mutant and common flowers were dried and subjected to a test of paper-chrormatography. Xanthophyll was fcund more fully in the former than in the latter but carotene was found far less in the mutant.

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Artificial production of somatic mutations by radiations is a promising method for obtaining novelties in vegetatively propagated plants. The present authors report about their irradiation experiments carried out in various developmental stages of the bulbs which produced several somatic mutations. The alteration process of the mutants in successive seasons after irradiation was examined, and a practical technique for breeding concerned with the time of irradiation and selection was investigated. The results are summarized as follows ; ( 1 ) Irradiation effects on bulbils before flowering time were examined. By irradiation from March to April, a large change of color spreading over 2∼3 perianth segments was obtained in tho second season. By earlier irradiation from December to February, the bulbil growth was markedly inhibited, and the bulb did not flower in the second season. ( 2 ) Bulbs with entirely changed perianth were obtained in the second season after irradiation in August or in the third season after irradiation in September. ( 3 ) When the perianth was entirely changed the mutant character appeared in the next season, while when the change was partial almost no sign of mutation was observed. ( 4 ) The change of flower color was fairly common, but several different mutants could be recognized which may represent new forms not previously known in tulip. ( 5 ) Alteration process was observed in the variety Athleet (white) during seven seasons after irradiation. Entire change was obtained in the third season in various characters, and was tested by propagation. The dwarf type threw off normals in seventh season, while the majority of the others, including flower color, striped leaves and laciniated petals have maintained the mutant characten through four vegetative propagations after selection. The results mentioned above show that it is neccessary to select the entirely changed bulbs for the production of true bud mutants. These may be readily obtained if irradiation is carried out in the critical developmental stage of the bud.

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]Investigation of A-Rd linkage relationship was made in F₂ of the crosses between a test variety, Akamuro (C^BrARdRcP), and fourteen F₃ Strains from the cross, Surjamkhi (C^B₁C^B₂ARdRc^dp) × Norin No. 1 (C^BA^drdrcP). In spite of the dominant gene constitution in respect to C, A and P of the parental varieties, Surjamkhi and Norin No. 1, th e F₃ strains used here showed no anthocyanin coloration. This was proved to be due to their lack of either one or two of the three dominant genes as reported previously (Mizushima and Kondo, 1960 ; Kondo, 1961 ; Kondo and Mizushima, 1964). Their genotyes were identified as follows :

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Various morphological and cyto-histological abnormalities (as shown in Figures 1-7) were found in rice floral organs when the plants were treated with gibberellin by foliar or root application at the stage of panicle primordium differentiation with a concentration of 100∼500 pp m. Gibberellin showed a tendency to make the degenerative vascular bundle and stigma of apistil developed completely and to accelerate initiation of lateral organs in spikelet, bringing about many glumes, lodicules, stamens, pistils male or female flowerets in one spikelet which had been known as a primitive structure of gramineae spikelet

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Conception, formulas and method of the practical application of rejection ellipsis for individual selection in sugar beet breeding are presented in this paper. In summary the theoretical basis of rejection ellipsis may be said to rest on the decision of the rejection region of bi-variete frequency distribution such as of sucrose percentage and root weight, based on the information obtained from observation and by determining what statistical risk (θ) is or is not acceptable. Rejection ellipsis is applicable fcr bi-variete frequency distribution because it is possible to be drawn in the form of ellipsis in a plan and to apply the samples directly to this diagram. It may be also suitable fcr maintainance of varietal characteristics of various crops

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Since a reprint of the paper concerning the "Ein-Korn-Ramsch" method put foreword by FREISLEBEN and LElN (1943) could be secured, their method is discussed in relation to the "one-plant-one-grain method" which is one of the new methods proposed previously by the author. The rigorous proofs are mathematically given for their method. Comparing their method with the author's, the procedure of taking one seed from each of the X₁-plants is identical, but in other respects it is quite different ; and it is possible to conclude that the theoretical arguments and conculusion, the mathematical approach and the utility for application to radiation breeding of the author's method are much better than those of FREISLEBEN and LElN's method. It is very common to face two or more different kinds of desirable mutants in the practice of radiation breeding. Then, the following three cases are concerned in an X₂-population : 1) detecting at least one mutant belonging to the j-th kind of mutants, 2) detecting at least one mutant belonging to any one of all of the different kinds of mutants, and 3) obtaining at least one mutant per kind for the different kinds of mutants. In all of these cases, the "one-plant-two-grain method", the "one-plant-three -grain method" and especially the "one-plant-one-grain method" will frequently be much better, because of the smaller or smallest total of X₂-plants, and/or X₁- and X₂-plants in the aggregate. These results will be useful for breeders apart from the discussion for the "Ein-Korn-Ramsch" method

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[in Japanese]

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