The effect of dwarf genes of rice on the sizes of embryo and embryonic organs (coleoptile and radicle), was studied in relation to the length and number of cells of these organs. Nineteen kinds of dwarf near-isogenic lines which have the genetic background of the early variety 'Shiokari' were used. In most of the dwarf lines, sizes of either embryos or embryonic organs, or both were significantly smaller than those of their recurrent parent 'Shiokari'. But, sizes of embryo and embryonic organs of the d6-, d7-, dl2-, dl8k- and d47- lines were comparatively large. Cell numbers, especially those of radicles, in the dwarf lines whose embryonic organs were small, were reduced compared with those of 'Shiokari'. Furthermore, highly positive correlations were obtained between sizes of organs and cell numbers. In contrast, in most of the dwarf lines, cell lengths of coleoptile and radicle tended to be increased compared with those of 'Shiokari'. Correlations between sizes of the organs and cell lengths were nor significant or inexistent. Application of the principal component analysis enabled to clarify the features of dwarf lines on the basis of embryo and embryonic characters. From the results obtained, it was concluded that a considerable number of dwarf genes may manifest their effect on the embryonic characters, although the degree and pattern of their expression are different depending on the kinds of dwarf genes, and that the sizes of embryonic organs depend mainly upon the number of cells which constitute the organs.

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The vulgare-spelta locus on chromosome 5A of two typical cultivars, Large White emmer and Vernal emmer, of Triticum dicoccum SCHUBL., a species of tetraploid wheat (2n=28. AABB) with keeled glumes and brittle rachis, was genetically studied by crossing them to aneuploid lines of T. aestivum (L.) THELL. ssp. vulgare MK (2n=42, AABBDD). It was found that they have the spelta gene, q Thus, for these two cultivars, a previous assumption, which had been made mainly on the basis of plant morphology, was verified. The differentiation of spike type was rationalized between these varieties and another variety, liguliforme, which had previously been found to carry the vulgare gene, Q. It turns out that the rachis brittleness, a key character to distinguish dicoccum from the rest of the cultivated tetraploids, may not be determined simply by the presence of the spelta gene, q. Besides spike type, glume-coloration pattern is found to be a major difference between the two groups.

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Photosynthetic response to air humidity and leaf characters were observed in fourteen rice varieties. In the indica type varieties the water-conduction system relative to their specific leaf weight and leaf nitrogen content was found to be more developed than in the japonica type varieties. The water-conduction system in the leaf was evaluated based on the ratio of the total cross-sectional area of xylem-vessels at the leaf blade, base to the leaf area (RVA). Higher positive correlations between the photosynthetic rates and the RVA, and specific leaf weight were detected under dry than humid air conditions. The present study suggests that RVA may be related to varietal differences in the photosynthetic rate, at least under low air humidity conditions, and that RVA can be used as an index for evaluating the development of the water supply system. The well-developed water conduction svstem of indica type varieties may have evolved as an adaptation to high temperature conditions.

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In order to study the reaction of autoteraploid rye (Secale cereale L., 2n=4x=28) to different environmental conditions, an experiment was carried out at Kyoto, Takatsuki and Grunbach. As experimental materials, a commercial tetra-rye cv. 'Tero' and four tetraploid rye populations derived from the progeny of a hybrid Secale cereale L. cv. 'Heines Hellkorn'×S, vavilovii Grossh. were used. The results of cytological examination of the materials grown at Takatsuki indicated that differences between the populations with regard to the frequency of aneuploid plants and the variation of chromosome pairing at MI were only slight and should not be important criteria for the productivity of these materials. A comparison of agronomic performance of these populations in Germany and Japan revealed highly significant differences between locations. On the contrary, no significant defferences were found between populations, which reacted differentially to the environments, i.e. they showed different levels of adaptability. Estimations of stability parameters indicated that the four selected populations performed more stably than the check cv. 'Tero'. Although the latter showed a higher average performance over all locations, the materials selected from progeny of the hybrid Secale cereale×S. vavilovii seem to offer better possibilities for further improvement of tetrarye performance over a wide range of environments.

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S 1 and S 2 are mitochondlial DNA (mt DNA) molecules found in male-sterlie S cytoplasm (cms-S) of maize but not in fertile revertants with the nucleal background of the inbred line M 825. Three male-fertile revertants were recovered from cms-S lines with the background of WF9. MtDNAs were isolated from these revertants and from cms-S lines. Agarose gel electrophoresis of undigested mtDNA revealed that both S 1 and S 2 molecules were present in the revertants. Terminally attached proteins of S 1 and S 2 from revertants were detected by proteinase K treatment. Restriction fragment analyses inclicatecl that the restriction sites of S 1 and S 2 were not altered and that each revertant had alterations in the high-molecular-weight chromosomal mtDNA.

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Defoliation treatment (clipping half of every leaf blade) was applied to rice varieties under drought and flooded conditions to determine its effect on the photosynthetic parameters, water balance, yield components and drought response of the plants. In the first experiment, photosynthetic and related leaf water parameters were measured in three upland varieties, (Moroberekan, IAC 1246 and Sensho), two lowland varieties (Bosque and IR 8) and one dwarf mutant variety (Daikoku 1). Under flooded condition, the defoliation treatment increased the photosynthetic and transpiration rates with a concomitant increase of the leaf water content and leaf diffusive conductance. The effect particularly pronounced in the tall upland varieties. When the water supply was restricted, the defoliation retarded the loss of soil moisture and accordingly the varieties maintained a high photosynthetic rate for a longer period. However, when the soil moisture tension reached a value of 40 cbar, the photosynthetic rate and leaf diffusive conductance became similar in magnitude in both the defoliated and nondefoliated plants. The decrease of photosynthetic rate by water shortag'e was the smallest in the dwarf mutant and the largest in the lowland varieties. In the second experiment, the effect of defoliation on yield components was examined in the early upland varieties (Sensho and Rikuto Norin 24), one early lowland variety (Bosque) and one dwarf mutant variety (Daikoku 1). Under flooded condition, the defoliation treatment decreased the yield components except for the tiller number of the tall varieties, resulting in a decrease of grain weight per plant in every variety. However, under drought condition, defoliation alleviated the decrease of several yield components, resulting in a lower decrease of grain weight per plant except for the dwarf mutant. It was concluded that defoliation was effective in preventing drought damage in tall varieties with large leaves. It was postulated that the lowest decrease of the photosynthetic rate under drought condition in the dwarf mutant was associated with the presence of short and thicker leaves, and that such a short-leaved plant was able to avoid drought damage.

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This study was conducted to obtain information on the causes of variation of anther-derived doubled haploid lines from a inbred cultivar of tobacco (Nicotiana tabacum). From a spontaneous doubled haploid lines of androgenetic origin of tobacco, an experimental series of doubled haploid lines was raised through anther culture or induced parthenogenesis. The field test of 38 anther-derived and 12 ovule-derived doubled lines along with 17 lines of the selfed parent revealed considerable variations among the anthel-derived lines both in quantitative and qualitative characters. On the other hand, all the ovule-derived lines, some of which were doubled by colchicine treatment while the others were doubled spontaneously, were not different from the selfed lines of the parental plant for the characters measured. No cytoplasmic effects were detected in the reciprocal crosses between anther-derived doubled haploid lines possessing variations and the parental line. These results indicate that the variations observed among doubled haploid lines of androgenetic origin were due to the mutations of nuclear genes in the course of androgenesis.

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The effect of the cutting height on the relationship between ratoon traits and the percentage of ripened grains of the uncut plant was investigated using 30 rice cultivars grown in a randomized block design with 2 replications. Variations from year to year of ratoon traits were also investigated. The plant was cut on the 10th day after heading at four different heights, i. e., at ground levcl, and at 5, 10 and 20cm above the ground. The percentage of missing hills increased as the cutting height decreased. The percentage of ratoon tillers and the ratoon height increased with the increase of the cutting height. The relationship between ratoon traits and the percentage of ripened grains of the uncut plant varied with the cutting height. Increased. cutting heights gave significantly higher values for the correlation coefficients between the percentage of ratoon tillers and the percentage of ripened grains. However, the ratoon height was not significantiy correlated with the percentage of ripened grains regardless of the cutting height. The year-to-year correlation of ratoon traits was significant and positive, although growth was different. The correlation coefficient was largel for the percentge of ratoon tillers than for the ratoon height. This suggests that the percentage of ratoon tiliers obtained by cutting at 10 or 20cm above the ground may reflect the percentage of ripened grains of the uncut plant.

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Callus tissues obtained from intact stem segments of tea seedlings, from segments stripped of epidermal layers, and only from epidermal layers (epidermis and cortex) separated from the stem were regenerated and the regeneration varied depending on the tissues. The callus from the epidermal layers formed buds more rapidly than the callus from other origins. The shoot buds developed roots on a filter-paper bridge with liquid medium and the plantlets continued to grow successfully in pots.

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Wheat cultivars generally mature later one or two weeks than barley cultivars, in the central part of Japan. It is expected that wheat cultivars as early as barley may contribute to the stabilization of wheat cultivation since they can be harvested before the rainy season as well as the promotion of double cropping. The present investigation aims to know the difference in mechanisms of earliness between wheat and barley cultivars. Two hundred ninety six wheat cultivars (or lines) and 65 barley cultivars were grown in the central part of Japan to compare the duration of the four developmental periods from sowing to initiation of stem elongation (1 st d.p.), initiation of stem elongation to heading (2 nd d.p.), heading to flowering (3 rd d.p.) and flowering to maturity (4th d.p.). The wheat cultivars used as materials were same as that of the previous report(YOSHIDA et al. 1985).

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A gene analysis to identify the genes accounting for the moderate resistance of the rice variety Shin 2 and some other varieties to the blast fungus strain Kyu 77-07A was The differential varieties, Aichi Asahi (Pi-a) and carried out in the present study. Yashiro-mochi (Pi-ta), were found to be susceptible to the strain, while Ishikari Shirol*.e (Pi-i), Kanto 51 (Pi-k), Tsuyuake (Pi-k'!b), Fukunishiki (Pi-z) and Toride I (Pi-zt) were resistant, and Shin 2 (Pi-ks) and Pi N0.4 (Pi-ta2) moderately resistant. Therefore, Kyu 77-07A was classified as one of the strains belonging to race 102. Howver, the variety Reiho with the resistance gene Pi-ta2 was susceptible to this strain. Based on the knovn facts mentioned above, the objectives 0L the present study were' to determinA- whether Pi-ks is the gene responsible for the moderate resistance of Shin 2' to Kyu 77-07A along with the reason for the different reactions to Kyu 77-07A betweerL Pi N0.4 and Reiho which both have the same resistance gene Pi-ta2. For the gene analysis, the F₂ or F₃ plants of the crosses were inoculated with Kyu 77-07A and three other fungus strains using the spraying rnethod when the plants were at the four- to five-1eaf stage. Two varieties, Mineyutaka. and Saikai 155 belonging to the Shin 2 type varieties, were used as the representative parents of the varieties susceptible to Kyu 77-07A for the crosses.

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[in Japanese]

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