Following the experiment reported in the previous paper, experiments were carried out about the effect of concentration of gibberellin (GA) and kinetin on the growth of tiller buds as well as apical buds of rice seedlings on agar medium with or without auxin (IAA), kinetin or GA. The 5th node tiller buds and apical buds were taken out from the rice seedling grown with enough space (4.5 cm × 5 cm) at seedling age 6.5 and used in the experiments. The growth of tiller buds was promoted by existence of kinetin at the concentration around 10^-7 mol, though it was inhibited at high concentration such as 10^-4 mol. As to the effect of GA, the growth of tiller buds was promoted by some kinds of concentration of GA under thc existence of kinetin; however, the growth of apical buds was promoted by GA only under the condition with IAA and without kinetin. It was observed in tiller buds and in apical buds in common that the growth was very poor when none of IAA, GA and kinetin was supplied and that the growth was not promoted by GA and kinetin when the medium lacked both of the other two growth substances. The growth of apical buds was greater than that of tiller buds in general. The rooting of bud was generally observed to be promoted by IAA in tiller buds and apical buds. However, some difference was recognized between tiller buds and apical buds as to the effect of kinetin and GA on rooting.

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The effects of oxadiazon; 5-t-butyl-3-(2, 4-dichloro-5-isopropoxyphenyl) 1, 3, 4-oxadiazoline-2-one, which represents the herbicidal action only under the light condition, on the ultrastructure of chloroplasts of barnyardgrass (Echinochloa crus-galli) was studied electronmicroscopically. When the etiolated seedlings, grown for three days in oxadiazon solution under dark condition, were exposed to light, greening and elongation of the leaves were inhibited markedly. Most of leaf tissues were considerably distorted by the action of oxadiazon. Especially disintegration of vascular bundle was remarkable. In chloroplasts of untreated leaf cells, grana was formed and starch grains were also found in some case. However, in the case of herbicide treated plants, chloroplast development was suppresscd. These chloroplast were characterized by having prolamellar bodies and circular lamella structure. However, even in cells whose nucleus and cytoplasm were distinctly affected, rupture of the chloroplast with disintegration of envelop membrane was not observed and their shape were kept their original form. It is proposed from the above mentioned results that oxadiazon influenccs in not only chloroplasts but also nucleus and cytoplasm in spite of the well known action of the substance which closely related with the light exposure.

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1. Callus tissues were induced by various concentrations of 2, 4-dichlorophenoxyacetic acid (2, 4-D) from different organs, roots, mesocotyls, internodes, nodes, coleoptiles, leaf sheaths, and epidermal cells of scutellum of Oryza sativa and roots, leaves and stems of Echinochloa crus-galli, Nicotiana tabacum, and Vicia faba. 2. Callus induction is more remarkable in some organs of young rice seedlings than old ones with lower level of 2, 4-D. 3. Different concentrations of 2, 4-D are necessary for callus induction from different organs and diverse species. Tissues and organs in rice seeds, from which callus is able to be induced, are strikingly varied by different concentrations of auxin. 4. The concentration of auxin for callus induction is dependent on a sort of auxins used; IAA, NAA, or 2, 4-D. The difference of auxin concentration for the callus induction corresponds with the difference of auxin activity of the substances used. 5. Effect of kinetin on callus induction in rice seeds is not only undistinct but also repressive. 6. Thiamine is required for growth of rice cultures but it is not essential for callus induction in rice seeds. 7. It is discussed on the effects of the cutting of seedlings on callus induction in rice. 8. The tissues from which the callus is originated in various concentrations of 2, 4-D is histologically investigated on rice seeds and segments excised from the seedlings. Anatomical studies indicated that the initiation of callus in various organs resembled to the initiation of the adventitious root, except for epidermal cells of scutellum. 9. The organ differentiation in rice callus tissues is controled with various concentrations of 2, 4-D. Namely, callus tissues without root-like structures, callus tissues with root-like structures, abnormal roots and normal roots are formed as the concentration decreases.

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穂ばらみ期の冷温によりもたらされる不稔が, イネの前歴・後歴によってどのように影響されるかを実験した。イネの前歴・後歴は, 小胞子初期の前後10日間に, 時期別に17℃で3～9日間の処理をおこなうことによってかえた。これらの前処理・後処理単独では不稔発生に及ぼす影響はほとんどないか, あるいは小さかった。しかし, 小胞子初期冷温処理(12℃3日間)と組合わせると, 不稔の発生を助長する効果が認められた。その効果は, 前処理・後処理の時期が小胞子初期に近いほど大きく, また, 後処理よりも前処理の方が大きい傾向を示した。前処理を3日間おこなった3試験区と対照区について, 小胞子冷温処理の開始直前に材料をとり, イネの窒素成分を分析したところ, 前処理によって全-Nたんぱく態-N含有率は減少し, 全水溶性含有率は増加した。その傾向は前処理が小胞子初期に近いほど大きくなった。また, 稔実歩合と全-N, たんぱく態含有率の間には有意な正の相関関係が認められた。

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1. The specific gravity of unhulled grain is mainly determined by the space left between the hull and the kernel. Consequently, the specific gravity of the unhulled grain which involved a fully developed kernel showed a high value. The unhulled grains of normal and white-belly kernels denoted a high value from 1.16 to 1.22 and those of basal-white kernels were ranged between 1.15 and 1.21 in the specific gravity. The specific gravity of unhulled grains of rusty, deformed, milky-white and partially opaque kernels distributed in lower and wider range as compared with that of unhulled grains of normal kernels. Unhulled grains of opaque kernels were ranged in the lowest specific gravity from 1.01 to 1.09. (fig. 5, 6) 2. The unhulled grains of normal, white-belly and basal-white kernels were selected by the specific gravity of 1.15 in company with those of comparatively well developed kernels among rusty, deformed and thin kernels. The unhulled grains selected by this specific gravity were appreciated as the high-grade rice and the remaining ones were recognizecl as the low-grade or trash rice. 3. The specific gravity of unhulled grain of some kernel quality was influenced by ripening condition and that of normal, white-belly or rusty kernel was heavier under well-ripened condition than under worse-ripened condition, but that of partially opaque or opaque kernel scarcely differed on both conditions. (fig. 3, 4) 4. As the moisture content of unhulled grain increase, the kernel involved in the hull expands and space between the hull and the kernel is diminished. Therefore, the specific gravity of unhulled grain became higher or lower as the moisture content increased or decreased and the variation in specific gravity-caused by moisture content was more remarkable in partially opaque and opaque kernels than in normal and rusty kernels. (table. 1, fig. 1, 2)

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An anatomical study was carried out on the tissue differentiation and growth of lemma in Japonica paddy rice, cultivars Sachikaze and Reimei. Every kind of tissues composing lemma such as outer- and inner- epidermis, hypodermis, parenchyma and vascular bundles had initiated before the lemma's rapid growth. With the beginning of lemma's rapid growth, both sides epidermes undertook such cell differentiations as uneven mitosis of epidermal cells followed by initiation of macro- and micro-hairs, and formation of tubercles in outer epidermis, and as initiation of stomata and microhairs in inner epidermis. After the rapid growth remarkable schlerization was made especially in hypodermis and outer epidermis. First sign of the differentiation of tubercles was the accumulation of a kind of substance which was not so well stained by Delafield's haematoxylin as to nucleus at the contacts of four large epidermal cells, forming a dome-like protuberance in basal portion of which some "zig-zag shaped structures" were constructed. And later the protuberance was covered by translucent membrane. Multicellular macrohairs were newly observed in the outer epidermis besides needle like trichomes and microhairs. Although both macrohairs and microhairs initiated from small epidermal cells, they differed each other on their developmental processes. Those of macrohairs were that whole small cells expanded and elongated before the enlargement of tubercles, but those of microhairs were that a portion of the small cell's wallprojected at the point of which was extremely narrowed by tubercles situated at their both sides, followred by moving the small cell's nucleus into that protuberance. It was, therefore, clarified that developmental process of tubercles was differed from those of macro- and micro- hairs, and that histogenetical center of outer epidermal cell was on the macro- or micro- hairs which were situated at the concave of both sides tubercles. Judging from that multicellular macrohairs and microhairs initiated in the beginning of lemma's rapid growth and withered in almost the same time with the end of its growth, it was suggested on the physiological functions of those hairs that they might have some relations to the rapid growth of lemma. The fact that both stomata and microhairs initiated densely at the near of vascular bundles in inner epidermis was considered that there might be some physiological correlations among them.

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Rice seeds, before and during germination, were fixed and embedded in glycol methacrylate or epoxy resin. Semithin sections (0.5 or 2 μm in thickness) were prepared and examined by light microscope after staining by several schedules. 1. Aleurone grains, lipid grains and starch grains were observed in scutellar parenchyma cells by the following histochemical procedures: PAS for starch grains, sudan black B for lipid grains, fast green for matrix protein of aleurone grains and toluidine blue for globoid inclusions. 2. Cytological changes in the scutellum and the endosperm during the first 5 days of germination were described. Aleurone grains in the scutellum enlarged and the matrix protein within them commenced to be hydrolysed 6 hr after soaking. The residual vacuoles, resulted from the hydrolysis, underwent extensive coalescence 36-48 hr after soaking. Small starch grains in the scutellar cells were observed 6 hr after soaking and disappeared during 12-24 hr. At 30 hr after soaking starch grains again appearcd in the cells and they increased in number after 36 hr and then they grew in size. Starch grains in the endosperm commenced to be digested in 1-2 cell layers near the epitherial cells of scutellum after 36 hr. These results suggest that the reappeared starch grains in the scutellum are derived from starch which was accumulated in the endosperm.

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Callus induction, subculture and shoot formation were investigated using barnyardgrass seeds. Relatively high levels of 2, 4-D (2×10^-5M or 4×10^-5M) were required for the callus induction. The callus cultures were white or yellow in color and often altered black brown under the prolonged cultivation. Hetero-geneous tissues of the cultures were remarkable in comparison with rice cultures: The higher kinetin were added to the medium, the more shoots were formed from the callus cultures. For electron microscopy the cells of callus tissues were fixed by glutaraldehyde and osmium tetroxide, and embedded in Epon 812. Thin sections were stained with uranyl acetate and lead citrate and examined with Hitachi HU-12 A microscope. Many of osmiophilic granules were seen in the proplastids. Secondary vacuoles containing cyto-membranes were often observed in the callus cells. In the green regions of cultures, amyloplasts containing the large granules of starch and chloroplasts were seen. The peripheral reticulum was indicated in immature chloroplasts. It was also confirmed that mature chloroplasts have lamellar structure and multilayered grana and chloroplast-DNA filaments are occurred in some regions of the matrix having low electron density.

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Crop plants at the 5 to 7-leaf stages possessing C₃ (barley, rice, and soybean) and C₄ (barnyard millet and maize) pathways of photosynthesis were cultured for 15 days in transparent growth chambers placed outdoors under 4 different carbon dioxide (CO₂) concentrations from 1/2 to 10 times the normal atmosphere (ca. 350 ppm) to make clear the effects of various CO₂ concentrations on growth and dry matter production. The following results were obtained: I. Increases in plant height and leaf area were promoted by high CO₂ concentrations, but the degree of promotion was relatively small. At a low concentration (160 ppm), plants often elongated and had narrow drooping leaves as compared to control plants under normal CO₃ concentration. 2. Increase in dry weight was promoted by high CO₂ concentrations and suppressed by a low concentration. This increase proceeded up to about 3 times (sometimes 10 times) the normal concentration, and this was effected mainly through the increase in net assimilation rate. The C₃- and C₄-plants responded differently to CO₂ concentrations, the latter giving less suppression at a low concentration and less promotion at high concentrations than the former. 3. Tillering in barley and rice was accelerated by high CO₂ concentratoins and withheld by a low concentration. In rice plants, observed at the 7-leaf stage, the promotion of tillering took place at the 4th node, and the appearance of tillers was made steadier at the 2nd and 3rd nodes by high CO₂ concentrations. 4. Distribution ratio of dry matter in rice and maize was in a marked contrast. In rice plant distribution to leaves was less and that to roots was increased at high CO₂ concentrations, while in maize such a tendency was not observed at all. 5. Transpiration rates (dm^-2 day^-1) were smaller at higher CO₂ concentrations. At a low concentration, the promotion of transpiration was enhanced day by day as the treatment proceeded. On fine days, the leaf temperature was about 1°C lower at a low CO₂ concentration and about 1°C higher at higher concentrations as compared to control plot, but no difference was observed on cloudy days.

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This study was done to understand the corresponded relations between plant characters and cultivation methods by using the five native millets (Setaria italica Beauv., Panicum miliaceum L., Echinochloa utilis Ohwi et Yabuno, Sorghum bicolor Moench, Eleusine coracana Gaertn.) collected in Gifu prefecture in 1974 to 1975. As the first step for this purpose, the relations between plant characters and the environmental conditions in the places where authors had investigated to find the above materials was discussed in this paper. In addition to the discriptions of the geographical distribution and natural environmental conditions of collected samples, here are results of the seed germination test which was conducted under the various temperatures (15°C, 25°C, 35°C and 45°C). 1) Distribution and natural environments: Most of Echinochloa utilis were cultivated in Hida area which situated at the high elevation (500-1, 300 m) and Sorghum bicolor were distributed at the low or middle elevation (100-600 m) Mino area. Other two crops, i.e. Setaria italica and Panicum miliaceum had been grown over all areas of Gifu prefecture. Temperature, rainfall and water holding capacity of the soil in the sampling plots were investigated to grasp the environmental conditions of the crops and obtained main values were as follows: As to mean minimum temperature at the sowing time and accumulated temperature during cultivation period, the values of the sowed areas of Echinochloa utilis were the lowest (7-10°C, 2, 720-3, 920°C) and those of Sorghum bicolor were the highest (10-14°C, 3, 540-4, 150°C) of all the samples. Total rainfall during the same period was 1, 060-1, 750 mm in Echinochloa utilis, 1, 150-1, 750 mm in Panicum miliaceum, 1, 210-1, 750 mm in Setaria italica and Sorghum bicolor. Moisture ratios at pF=3.0 to determine water holding capacity of the soil were 17-32% in Panicum miliaceum, 16-42% in Setaria italica and Sorghum bicolor, 22-60% in Echinochloa utilis, respectively. Eleucine coracana showed the similar tendency to Sorghum bicolor on the above environmental conditions though thc number of cultivation examples for this crop was only three in this survey. 2) Germination test: Germination percentage of each strain reached almost 100% and average required days for germination was mostly one day at 25°C and 35°C. In the case of Echinochloa utilis, the germination rate and average required days for germination at 15°C was 42.8-88.0% and 4.1-4.8 days but those of Sorghum bicolor was 4.0-28.0% and 5.3-6.2 days respectively. On the other case of 45°C, Sorghum bicolor showed 85.2-96.0% of germination percentage, but those of Setaria italica and Panicum miliaceum were indicated 22.8-72.0% and 32.0-62.8% respectively. As far as plant growth at 8 days after germination was concerned, maximum values of plant height of Echinochloa utilis and Panicum miliaceum were found at 35°C and those of root length were gained at 25°C. In the case of Sorghum bicolor and Setaria italica, both of maximum values on plant height and root length were obtained at 25°C. On the while, dry matter weight of Sorghum bicolor was the heaviest in 35°C but those of the rest crops were maximum in 25°C. Among the strains of Echinochloa utilis, Setaria italica and Panicum miliaceum used in this experiment, it was tended that the dry matter weight of strains in the higher elevation was the heavier than those of lower elevation at 15°C. From the above results, it was manifest that the geographical distribution of the used native millets coincided with the plant character, their temperature response at the early growth stages including germination, and also suggested that the ability of crops for cold resistance was one of the most important factors to determine the crops cultivated in the high land.

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These studies in series were devoted to clarify the characterstics of white belly rice kernel which had an opaque part at the ventral portion of its endosperm. In this experiment, the stage of initiation of white belly in the developing kernel and the relationship between occurrence of white belly and dehydration of kernel were investigated. The varieties used were Nihonkai, Kinmaze, Norin no. 8, Gohyakumangoku (Sakamai) and Sekaiichi (upland rice) of Japonica and Keikyakusen of Indica type of rice. The following results were obtained. I. Stage of initiation of white belly in fresh kernel differed with variety. In case of varieties which characterized by high occurrence and large size of white belly (external-internal white belly type), the initiation began 15-18 days after flowering when the kernel gained 89-95% of dry weight and 28-29% of moisture. The varieties featured by small white belly (external white belly type), on the other hand, initiated white belly 24-32 days after flowering when the kernel nearly attained its maximum dry weight and the moisture content of kernel decreased to 23-25%. Percentage of white belly increased with the progress of maturation and dehydration. The highest value of white belly was indicated with the attainment of maximum dry weight in case of external-internal white belly type and that of full ripe stage in case of external white belly type. 2. Initiation of white belly in dry kernel occurred earlier than that of fresh kernel. In case of external-internal white belly type, the stage of initiation was 12-15 days after flowering when the kernel had 33-34% of moisture and dry weight index value of 79-83. Whereas, in case of external white belly type, the initiation occurred 19-23 days after flowering when the kernel had 26-29% of moisture and dry weight index value of 88-92. The percentage of white belly increased with the development of kernel and reached at its highest value when the kernel just before attained maximum dry weight in case of external-internal white belly type and when the kernel attained maximum dry weight in case of external white belly type. 3. When the premature fresh kernel were dried artificially, the white belly appeared as the moisture content decreased and the moisture content at which the white belly initiated differed with the kernel age. 4. In fresh kernel, the moisture content of ventral portion was higher than that of dorsal portion, but this moisture state was reversed after the kernel was dried. This phenomenon seemed to indicate that the ventral portion of kernel had less deposition of storage matter and stronger dehydration capacity than the dorsal portion. It was also thought that this phenomenon might be related to the formation of porous tissue of white belly on the ventral portion of kernel. 5. In the premature fresh kernel of Gohyakumangoku a white core variety, the white core occurred with the progress of artificially dehydration in the same way as that of white belly, but the occurrence of white core was associated with slightly lower moisture range than that of white belly. 6. The occurrence of white belly was influenced by the condition of drying. And the dryings which resulted to the rapid dehydration of premature kernel increased the occurrence of white belly.

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ダイズ矮化病ウイルスの生育・収量に及ぼす影響を明らかにするため, 品種アダムス, ゆうづるおよびそのF₃系統13系統を供試し, 接種区および防除区における生育・収量の差異について比較, 検討した。1) 接種区における全乾物重および葉面積は, ウイルス接種約1ケ月後の7月17日において, すでに防除区に比し劣り, その差は生育とともに拡大した。2) 生育期間中の個体当乾物増加速度および葉面積は接種区が劣ったが, 純同化率は8月6日を中心に前期では防除区が, 後期では接種区がまさった。また, 接種区では比葉面積および葉身の窒素含有率が低く, 乾物率は逆に高い傾向を示し, ウイルス感染による葉の肥厚, 転流の阻害が認められた。3) 接種区における個体当平均子実重は防除区に比べ約70%減少した。また, 接種区では子実重と各生育時期における葉面積との間に有意な正の相関関係が認められ, 子実収量の系統間差異は葉面積の差によることが明らかとなった。4) 相対葉面積生長率が純同化率および比葉面積と有意な正の相関を示すことから, 接種区における葉面積の減少は, ウイルス感染による光合成率の低下と葉の肥厚に起因するものと考えられる。

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The experiment was made to determine the invisible injury to rice plants by photochemical oxidants. Rice plants were grown in two filon chambers, the one with filtered ambient air and the other with unfiltered a ambient air, for the experimental period from transplanting to harvesting at the Central Agricultural Experiment Station, Konosu, Saitama. The rice plants in the filtered ambient air chamber were compared with those in the unfiltered ambient air chaember on growth, yield and visible injury of photochemical oxidants. Both the visible injuries on leaf blade and invisible injuries such as the reduction of the growth and rate of photosynthesis were observed in the unfiltered ambient air chamber. On the otherhand, no injuries were detected in the filtered air chamber. The rice plants in the filtered ambient air chamber were more numerous in number of panicles and spikelets per hill and in percentage of ripened grains, and higher in yield than those in the unfiltered one. It may be suggested that the reduction in growth and yield of rice plants in the unfiltered chamber could be mainly due to photochemical oxidants, because of high concentration of photochemical oxidants, averaged 3.74 pphm hourly monitored in Konosu, during the experimental period from 6th of June to 15th of October.

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