Summary Some anomalous modes of segregation in respect to giutinous character in pollens and in endosperms of seeds born on F₁ hybrids between rice varieties of remote origin are described. Glutinous ×non-glutinous F₁ hybrids from 72 different parental combinations among 25 varieties including 9 glutinous and 16 nonglutinlous ones were investigated. Eight of the 9 giutinous varieties used are of Japanese origin and one is of South American origin, all of these belonging to so-called Japonica group. Six of the 16 non-glutinous varieties belong also to Japonica, of which 5 are of Japanese origin and one, Sen-sho, is native to China, having been intoduced into Japan some 70 years ago. The other lO ones consist of 5 Indian, I Viet Namese, 1 Hawaiian and 3 Chinese varieties and they belong to so-called 1lrdica group (Table 1). In all of the F₁'s obtained among Japaneese varieties segregntion of glutinous character in both pollens and endosperms took place normally, i. e., the ratio non-giutinous vs. glutinous was 1 : 1 in pollens and 3 : 1 in endosperms. In some hybrids between Japanese and Indian varieties there occured a remarkable deviation from the normal ratio, presenting a significant decrease in the number of glutinous endosperm, though the segregation in their pollens was normal. In the two sets of hybrids in which other foreign varieties than Indian ones partook as a parent there was observed a significant decrease in the number of non-glutinous pollens. The segregntion ratio in endosperns was, however, normal in most of them. Sen-sho was found to behave in a complex manner.

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K123 (Ipomoea trifida (H.B.K.) G. Don.) which was collected in Mexico, is a wild species closely related to the cultivated sweet potato, I. batatas (L.) LAMK. (.NISHIYAMA 1959, NISHIYAMA, FUJISE, TERAMURA, and MIYAZAKI 1961). In th:e present work, the physiological and ecolo-gical characters of K123 were studied in comparis-on with those of I. batatas. There was observed a considerable variation in the development of stems, leaves and roots, in different clones (or 20 seedlings from the original K123) as well as under different growth conditions. Generally all clones of K123 were very similar to I. batatas, but were clearly different in some characters (Figs. 1 and 2). The flowering begins in July in a few clones, but in September in most clanes of K 123, though the number of flowers are usually limited in the natural condition. Artificial treatments such as grafting and double treatments (grafting and short-day) were g:enerally effective in promoting the date of flowering and in increasing the number of flowers, although the effect of each treatement was different by clones (Figs. 3 and 4). In order to obtain a measure of self- or crossincompatibility of the clones, germinationl of pollen grains artificially dusted on the stigma was observed. Out of 20 clones of K123, 17 were self-incom-patible, 2 incompletely self-compatible, and 1 self-cornpatible. Based on the results of crossincompatibility tests among these 20 clones, about 7 cross-incompatibility groups were identified. All the clones of K 123 were cross-compatible with 4 different cross-incompatibility groups of I. batatas, except for 2 clones which were either reciprocally or non-reciprocally incompatible with certain incompatibility groups of I. batatas (Table 1). In a preliminary observations some clones of K123 were found to be resistant to ceatain nematodes (Protylelchus pratensis and Heterodera mariolei) and also to black rot (Ceratostomella fimbriata).

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Puccifeia Menthae PERS. (a causal fungus of mint rust) which is distributed in Okayama district, infects M. arvelcsis var. piperascens (Japanese mint), and M. arvensis var. canade, vsis which is indige-nous to North America and phylogenetically near to Japanese mint, and brings about a large damage to them. Besides, the fungus also infects M. japoleica which is native of Japan, and gives it a slight injury. The mint rust, however, did not infect European arvensis and dther species of mint, not only by natural inoculation in the field but also by artificial inoculatian in the laboratory. Both tetra-ploid and triploid clones of Japanese mint were as susceptible to rust as the respective original clones of diploid Japanese mint.So it seemed to be difficult to expect a rust-resistant Japanese mint by the doubling of chromosome number, because response to rust did not change by this method. However, one tetraploid mutant was found to be extraordinarily resistant to rust and this characteristic was domi-nantly inherited. The F₁ between Japanese mint and M. japonica was as susceptible as Japanese mint, and the F₁’s between Japanese mint and other mint species which ;tre themselves immune to mint rust, suffered a slight injury or none from mint rust. That is, in the latter case, resistance of mint to rust is of complete or approximately complete dominance in heredity.

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For the establishment of the introduction plan for genetic stocks of rice in Japan, the authors compiled the informations and prepared the genealogical map of leading paddy field rice varieties in Japan. This map shows the tendency that the relationship among leading paddy field rice varieties has become closer and their gene sources have become narrower. The influence of foreign rice varieties on the parents of leading paddy field rice varieties are scarce, and none of indica varieties can be found. Reasons for these are considered to be as follows ; 1. For a leading variety in Japan it is necessary to show a high level and good balance of so many characters, that it is difficult to breed a new variety by the hybridization of minor ones. Rice breeders are inclined to cross a leading variety to a leading variety or use it at least as one of the parents. 2. Characteristics of foreign rice varietiesespecially in.dica, are different from those of the Japanese ones. Without any very serious breeding objects or very long term breeding process, indica X japonica hybridization program in Japan will not be economical. 3. The capacity for the permanent maintenance of genetic stocks of rice in each breeding organization in Japan is very low, and there is no seed center either. Up to 1954, only 17.8% of varieties introduced from tropical countries were maintained. Seed sto'rage under dry and cold conditions is recommended. 4. Since there is no information service for genetic stocks of rice in Japan, japanese rice breeders select rice varieties solely through their own efforts. These two reasons also may limit and prevent the wide utilization of genetic stocks for hybridization.

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In order to study the relationship between pollen sterility and free amino acids in the anthers of rice plants, the experiment was carried out. About 60 plants which showed various degrees of sterility caused by haploidy, triploidy, tetraploidy, translocation, asynapsis and F₁ hybrid between Indica and Japonica types, were analysed fcr free amino acids, especially for proline, hy paper chromatography. The results were compared with those from about 50 normal plants comprising various species, sub-species and varieties including wild types, Indica types and Japonica types(Tables 1, 2 and 3) . The chromatograms of the anthers from all normal plants had a very distinct yellow spot of proline, which was either lacking or very faint in the chromatograms of the sterile anthers of haploid and asynaptic rice plants. All other serni- and complete-sterile anthers in rice plants, that is, translocation, triploidy, and intersubspecific hybrid, however, gave a highly sterrile remarkable yellow spot of proline in spite of their high sterility of ahthers. From these results, the semi- or complete-sterile anthers except for haploid and asynaptic plants are not necessarily characterized by a lack of proline

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The investigation was conducted to compare the chlorophyll mutants and visib.1e, viable mutants in M₂ generation and mutations in quantibative characters in M₃ induced by X-ray, thermal neutron and diepoxybutane at the dose of nearly LD₅0 on dormant seeds of rice. Frequency of chlorophyll mutation at the seed-bed period was highest in neutron treatment, followed by the X-rayed plot and lowest in the plot of, diepoxybutane treatment. The visible and viable mutants at the heading time and matulity stage were also produced in maximum by neutron, followed by X-ray and minimum by diepoxybutane, though there appeared to be some differences in spectrum. The proportion of the frequency of viable mutation to that of chlorophyll mutation was also changed by mutagens. Although neutrons gave the highest frequency of visible and viable mutations, they also produced the highest number of low fertile strains. The reverse was true in the case of diepoxybutane. The strains derived from M₁-plant which segregated the chlorophyll mutants in M₂ seed-bed, produced much viable mutants at maturity stage as compared with strains from M₁ which did not segregate chloprophyll mutants in M₂ seed-bed. The genetic variances of the stem length and grain weight in M3 generation were increased by treatment but their mean valucs were almost the same as those of non-treated. It appeared that the variances increased both positively and negatively by treatments. The variances were also largest in neutron and smallest in diepoxybutane treatment. These results indicate that it may be a good indicator fcr finding methods to increase the mutation rates in quantitative as well as visible and viable characters to look for the factors that give high frequency of chlorophyll mutations.

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In my preceding report (SAMATA 1959 b) it was noted that the expession of MS and MD genes which modify the flower-types in cosmos is subject to the influence of temperature to a considerable degree. The present experiment was designed to determine the sensitive period to the cumulative effect of temperature of these genes. Fourteen stra:ins with known genotypes were selected as materials for this experiment. Each strain was propagated by cutting and many individuals belonging to the same clone were grown. All individuals were divided into five groups in such a way that each group was sure to include one individual of each strain. After the interval of 12 days, four of these groups were removed, one by one, into the greenhouse kept at 30°C constant temperature where they were left until flowering. By this method they were subject to high temperature treatment at different stages of flower development. One group was left out of doors all the time, and was used as the control. When the plants came into bloom, each flower type of the treated groups was compared with th.at of the control of the same clone, and the changes of flower-types between them were examined with the naked eye and by comparing the photographs taken at different periods of fiowering. By this experiment it was made clear that the changes of both ray and disk florets take place only when the plants have been placed at least l0-15 days before flowering in the room kept at 30°C. From this it may be asserted that the sensitive period to the cumulative effect of temperature of M^S or M^D genes is l0-15 days before anthesis. To ascertain this period, another experiment wascarried out in which several plants with different flower-types growing in the field were transplanted into pots at the flowering time and placed in the room kept at 30°C. After 14 days an examination of the flower-types revealed that those with M^s or M^D were changed to such types as had been expected. The third experiment was made to examine the cumulative effect of low-temperature in the case of M^D gene. Two of the three plants which prdduced the single type of flower-head during the hightemperature season were placed in a room with lO-13°C constant temperature and it was found that they change from single to double flower-type after 30 to 45 days in the room, showing that, the sensitive period to low-temperature of M^D gene is within a certain period of time after flower-initiation.

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The present studies were carried cut to make clear the varietal differences of frost resistance in barley, using two varieties, Kogenmugi and Misuzuomugi, the fcrmer being cold resistant and the latter cold susceptible. They were treated with artificial low temperature of -5°C for 6 hours in several plots at different stages of growth. The results obtained were follows : ( 1 ) The low temperature injury was severe in both varieties and the damaged plants wer6 delayed in their growth. The yield was greatly affected by a low temperature treatment given at the vigorous elongation stage to the shooting stage. ( 2 ) The low temperature injury of leaf was severe in Kogenmugi, but it was slight in Misuzuomugi. ( 3 ) Death of young ear by low temperature was frequently observed when the ear grew longer than 6 mm, while it was rare when the ear was. shorter than 5mm. Also, there was a high correlation between the death of young ear and the stenl However, varietal differences regarding height. death of young ear were not observed. ( 4 ) It was found that staining of young ear with Luyet's solution was good to discriminate whether the ear was dead or alive. The test showed that there were three cases in the death of young ear by low temperature. ( i ) Only young ear is frozen. ( ii ) Upper internodes are frozen and young ear is not. (iii) Both young ear and upper internodes are frozen.

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The records of wool production and body weight were obtained at first shearing time of yearling ewes on Corriedale sheep raised at the Department of Animal Husbandry, Hokkaido National Agricultual Experiment Station, Hokkaido the during the period from 1951 to 1957. They were analysed to determine the heritability estimates of greasy fieece weight, staple length, and body weight before and after shearing for this flock. The paternal half-sib correlation method was used with the records of 283 yealing ewes. The pa.ternal intra-sire daughter on dam regressions method was used with 206 pairs on which records were available on both the daughter and dam. Most of the yealing ewes were produced in the early stages of inbreeding. The average heritability estimates obtained from the paternal half-sib correlation method were O.33 and O.29 for body weight before and after shearing time, O.34 for greasy fieece weight and O. 39 for staple length. The average heritability estimates obtained from the paternal intra-sire daughter-on-dam regression method were O.33 and O.42 for body weight before and after shearing time, O.25 for greasy fleece weight and O.31 for the staple length. When the values iound by two estimated methods as above described were averaged for each four character the heritability estimates for the additive portion of the inheritance fcr these characters in this flock were O.33 and O.36 for body weight before and after shearing, O.30 for greasy fleece weight and O.35 for staple length

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