To clarify the role of recumbence habit in the occurrence of intervarietal competition, the present experiments were carried out with the two vaneties of wheat "Shmchunaga" and "Norin N0.22"which were grown separately and in a mixture in water-culture (c.f. Fig. 1). The fonner showed erect type and the latter prostrate one in the young stage of growth. It was found by the preliminary experiments hat the erect variety was superior in the root development throughout the vegetative growth stage to the prostrate variety, as shown in Table 2, the trend agreeing well with that obtained previously with barley in Report I.

View full abstract

The present experiments were perfortned to ascertain to what extent the temperature during colchicihe treatment affects the frequency of occurrence of polyploid plants. The materials used were radish (Raphanus sativus L.), buckwheat (Fagapyrulee esculetum MOENCH.) and adzuki bean (Phaseolus angularis W.F. WIGHT). The several kinds of colchidine treatment were ado.pted as follows t (1) soaking seeds in colchicine solution, (2) dropping colchicine solution on young buds, (3) dropping colchicine agar agar solution on young buds, (4) mounting colchicine lanoline emulsion to young buds, and (5) soaking seedlings in colchicine solution. Each treatment was carried out at lower (5-7'C) intermediate (15-20'C) and higher (25-30'C) temperature respectively, resulting in that the lower the temperature during colchicine treatment is, the higher the frequency of occurrence of polyploid plants, regardless of the kinds of colchicine treatment. This fact may be due to that, at lower temperature, the poisonous effect of colchicine. is almost negligible, but at higher temperature as soon as colchicine penetrates into cells and becomes effective for chromosome doubling, the cells begin to be killed from suffering the toxic action of colchicine, sa that, induction of 4x cells is hardly successful. The resistance to the toxic action of KCI0₃ showed that induced 4x radish is more susceptible to the toxicant th, an original 2x radish. It may be possible to use this test for distinguishing induced polyploid plants from original diploid ones.

View full abstract

In Timothy, Phleum pratense L., some experiments on the bulk emasculation by hot water method were made. 7 temperature classes (41'53'C) and 10 time classes (2-40 minutes) were used in combinations. In view of the destruction of the function of pollen as well as the higher percentage of seed set, the treatments 43'C-15 or 20 minutes and by 45 ?? -10 or 15 minutes were found best for practical use. 41'C-30 or 40 minutes may also be useful. The germination of seeds thus obtained was good, no remarkable difference being observed among different conrbinations in treatments.

View full abstract

One of the important problems in the breeding of polyploid plants is the early identification of chromosome doubling plants induced by the colchicine treatment. In this paper the authers report the study of the "Leaf smear method" which applied to the investigation of Solanum plants. and find this method will be effective in the study of tea plants. The o;tline of the autllors investigation is follows :(1) Materials : The suitable specimen will be find in the parenchymatous layer of the Ist spreding leaf, on the young leaf bud. (2) Microscopic management : Fix the specimen about 5-10 minutes in the HCI solution (1:10)and wash in water. Smear it slightly on the slide glass, stain it with aceto-carmine solution or aceto-orcein solution (1-2%), put the cover glass on it, and crush the specimen carefully with the finger by holding it down under the coverglass, then we probably find the suitable cells which present the mitotic metaphase chromosome behavior.

View full abstract

1. Crossing 20 flowers of V-icia sativa L. with the pollen of V. tetrasperleea MOENCH., 1 pod containing 3 seeds was obtained. The F₁ seeds were smaller than the mother seeds, and the number of days necessary for germination was larger compared with that of the parents. 2. The growth of Fl plants in young stage was poor, but they became gradually more vigourous later. 3. In Fl the type of branching, the colours of stems and leaflets were intermediate betweeh the parents, the leaflets being broader conipared with the parents. The tendrils were long resembling those of the father plant. The hairs at the border of leaflets were shorter and thicker in Vicia sativa L., Ionger and thinner in V. tetrasperleea MOENcH., and in F₁ they were longer and thicker. The number of compound leaves grown from a node was smaller resembling that of V. tetrasperleea MOENCH. The colours of standards and wings of F₁ flowers were rather rose resembling those of V. sativa L., though were more or less tinged with violet. In general appearance, however, the F1 plants quite resemble the mother plant, showing a matroclinous tendence of inheritance. 4. The chromosome number in V. sativa L, is n=6, and in V. tetrasperma MOENCH. n=7, so that the diploid number of F₁ is 13. In F₁ the chromosome conjugation at lst metaphase of PMC showed most frequently 1111+511, while other types of conjugation being observed. At ana- and telophases the lagging chrornosomes and chromosome bridges were frequently found. In the tetrad stage a small amount of pentads and hexads was observed. 5, In F₁ the % of good pollen grains were 50-63, and the seed fertility was quite good like those of the parents.

View full abstract

In regards to the glume color of rice, six colors are noted : a) normal or colorless ; b) yellow to gold ; c) grey to black ; d) brorn ; e) red to purple ; f) olive. The present report deals with genes responsible for the glume colors oth. er than red, purple, tawny (a kind of brown) and olive. Some varieties, especially those which belong to " Indica ", have yellow pigment in the cell wall of the glume. These glumes are a pale yellow at first but change to yellowish brown or gold on ripening. The authors are concerned with two types of this coloration ; one is self colored and is called "ripening gold ", and the other "dark furrows " in which only the inter-veins are colored. According to previous workers such as Parnell et al "gold " is single donrinant over colorless and " furrow " is the result of the existence of a supressor, acting on "gold ". The authors made similar cross experiments, coming however to a quite different conclusion., namely ; i) " gold " is single recessive (gene symbol rg) to colorless without exception, ii) "furrow " is due to a dominant gene F, and iii) the coexistence of F and its supressor I or the deficiency of F give birth to colorless.

View full abstract

Seedlings of 11 species of Agropyron. 5 species of Eiymus and 18 species of Bromus were tested with Puccinia graminis PERS. f. sp. Tritici 11. and 2 biotypes (races) of Puccinia triticilea ERIKS. (Puccinia rubigo-vera WlNT. f. sp. Tritici). The experimental results are summarized as foilows : (1) Among species of Agropyron. Agropyrole Griffithsii and A. repens were susceptible, Agrapyron Scribn;eri and A.trachycaululee were resistant to moderately resistant, and Agropyron Kamoji, A. ciliare, A.elo, cgatulee. A.iletermedium, A. cristatum, A.rirarium and A. Smithii var. molle were highly resistant or inunune to Puccinia gramileis f. sp.Tritici 11.

View full abstract

It is well known that in Zinnia elegans the frequency of fiower heads exhibiting doubleness in a population decreases fast in a few years, when seeds are taken continuously in open-pollinated condition. The object of the present study was to investigate the cause of the phenomenon above mentioned. from the genetic standpoint. The flower heads of Zinnia are highly variable in respect to the number of petalous and tubular florets in a 1lead. In 1950, a reciprocal cross was carried out in the variety Pumila scarlet between completely double, No. 4-5, and completely single, No. 4-1. The flower types of the parents are presented in Fig. l. As Fig. 2 shows, eleven types were recognized in 1950 and 1951. The F1 hybrids between completely double (B type) and completely single (A type) showed the so-called E type, in which the basal part of the head consists of 2-3 Iayers of petalous florets, while the tubular fiorets occupy the remaining part, except for the top which has a few petalous florets. Between the reciprocally produced F₁ hybrids no difference was observed. Those flower types were so easily affected by seasonal factors that one could easily distinguish between the summer and the autumn-heads of the F₁ generation (see Fig. 3). According to the flower types shown in Fig. 2, 208 plants of the F₂ generation were classified. From the results shown in Ta, b. 1, it may be concluded that the difference between the A- and the B- type is governed by three Mendelian genes. Thus, the complete double type would be recovered in the F₂ population at the ratio of ohe per sixty four. Moreover, the completely double type yields only a few seeds. The completely single type and the approximating subtypes reproduce powerfully in comparison with the completely double type and its subtypes, because they have many tubular florets, and thus, give many seeds per plant. If the pollination by insects were at random, a general degeneration of an open-pollinated Zinnia population would inevitably take place. The role of F₁ hybrids between the completely double or approximately double types and completely or apploximately single types affecting the genotypic constitution of successive generation was discussed.

View full abstract

1. In this investigation external characters and maturation division in PMC's of autotetraploid rye produced by means of colchicine method were studied. 2. Autotetraploid rye was produced by means of injection method employing 0.1 and 0.05 % aqueous solution of colchicine, and the latter case was proved to be more available. 3. The tetraploids were inferior in length of stem and percentage of seed fertility to the diploid (Table 1). 4. The kernels of autotetraploids were much larger than those of diploids. 1000 kennels of tetraploids and those of diploidsw eight 49. 6 gr. and 34. 5 gr. respectively, in other words, the kernel weight of tetraploids is 43.77 % larger than that of diploids. 5. In most cases, the number of somatic chromosomes of autotetraploids was 28, while in very rare cases 27 was observed. 4 members (two pairs) of those 28 chromosomes have each a satellite at one end. 6. The 28 chromosomes correspond to twice the somatic chromosome number of original diploid rye. Further, in meiosis of PMC's of tetraploids 14II were observed. 7. At metaphase in heterotypic division of PMC's of tetraploids, 0 - 8 univalents and consequently 10-14 brvalents were sometlmes observed (Table 2). These univalents may have been produced from some bivalents dividing earlier than the others. 8. Tetravalent chromosomes which is characteristic of tetraploid plants were observed in rarecases, but no trivalent was observed. 9. There is a marked incompatibility between autotetraploid rye and original diploid of it.

View full abstract

1. The genetic portion of the variance in birth weight of Corriedale Breed in the Takikawa Sheep Breeding Station is estimated 32 percent, the portion of variance arising from differences in tangible environment is 26 per cent, while 42 per cent arises from intangible environment or accidents of development. 2.The sex difference in birth weight is real but camparatively unimportant among the other causes of differences in birth weight. 3. The effect of the litter size on birth weight is comparatively large and f.he heritability of the litter size is 34 per cent. Hence, the differences of litter size are caused mostly by differences in the environrnent such as " Flushing " 4. The yearly difference in birth weight is not found.

View full abstract

In the present paper the authors dealt with the results of experiments on the varietal differences in the susceptibility of rice plants using 1004 varieties. The susceptibility to the present disease was expressed by calculating from the formulas (table I and 2) based on the number of spots and their area per a unit area of leaf. The results were also compared with those obtained from the ordinary method by measuring only tlle nuniber of spots per a unit length of leaf. These two results did not completely coincide. The most resistant and susceptible varieties are as follows : resistant : rice plants from Hainan Island ; No. 217 ; Chiu Tzu Chiu, susceptible : Sakigak:e No.126 ; Kairyo Mochi No.1; Bozu No. 6 ; Naka No. 3.

View full abstract