[in Japanese]

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This experiment was undertaken with the purpose of clarifying the expansinn of tillering attitude and the lodging resistance of rice plant caused by 2, 4-D treatment. The results obtained may be summarized as follows. Rice plant treated by 2, 4-D expressed the expansion of tillering posture under daylight, but did not show it under interception of light. 2, 4-D caused an increased content of glucoce and starch in culm, leaf sheath, and spikelets, especially in culm base indicating a promoted distribution of glucose and starch to culm with a consequent decrease in the distribution to spikelets as observed at 30 days after heading. The dry weight of culm base and breaking strength of it are also increased by 2, 4-D. These changes of culm base property were more remarkable when 2, 4-D was applied under the condition in which culm base was intercepted to light and was closedby a hemp cord not to make culm base open, but the degree of changes of culm property, caused by the artificial expansion of tillerng attitude, was less than 2, 4-D treatment except the increase of breaking strength in culm, base. From these results, we concluded that the effect of 2, 4-D in increasing culm strength and lodging resistance is not primarily due to the expansion of plant attitude but to the specific function of 2, 4-D.

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1) The influence of seedling-age… Seedlings of different age, ranging from one-leaf stage to five-leaf stage, were tested. Young seedlings with 1∼2 leaves bent upwards earlier, showing less withered leaves, and gave better setting up, which resulted in the higher rate of dry-matter increase at the early stage of growth than the seedlings with 3∼5 leaves. 2) The effect of nutrition… Increased application of phosphorus fertilizer to the nursery bed caused a more active rooting of seedlings after sown and the higher rate of increase of stem elongation and weight of dry matter than the condition without phosphorus fertilizer. An soft and weak elongate seedlings has poorly bent upwards after sown. 3) Time of sowing of seedling… Root development and top growth were very poor when sown under 10°C, an averaged temperature for 10 day period after sowing, as compared to that under 15°C. At the temperature higher than 15°C, such retardation of growth was not observed. 4) Effect of treatment of seedlings… Removal of roots from seedlings prior to their sowing resulted in a delayed growth with poor root development and many withered leaves. Seedlings sown at two-leaf stage under 15°C, an averaged temperature, gave only a few days delay of initial growth as compared to the seedlings transplanted, and it was about the same to the seedlings transplanted after removal of their roots. 5) Roots of seedlings inrush into the soil was observed one day at 15°C, 3 days at 10°C after sown, an averaged temperature. Sowing seedlings on upland field was influenced remarkably by the water contents of soil at the time of setting up. From this experimental results, authors was considered the 2 leaves stage seedlings was high stability on sowing seedlings in northern cold district.

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With an aim of knowing the effect of gibberellin on the vernalization of winter cereals, two kinds of experiment were conducted. The results obtained are summarized as follows:…… (1) Effect of gibberellin on the vernalization of immature embryos on the developing ear. Immature embryos of developing seeds of Hayaurehadaka, a winter barley variety, were vernalized. Spikes were detached 10 days after anthesis and chilled in a refrigerator at 5±3°C for 20 or 40 days with the stems immersed in water or gibberellin solution of different concentrations ranging from 1 ppm to 100 ppm. After treatment they were allowed to mature in room temperature. The seeds were stored at room temperature and then they were sown without cold treatment in the green house under long daylength (24 hrs.) It was observed that the longer the treatment, the more vernalizable they are. The gibberellin supply during the vernalization of immature embryos on the ear was effective in promoting flowering; the plants grown from the seeds treated by low tmperature and gibberellin concurrently were headed earlier and had a smaller number of leaves on main stem than the seeds treated with low temperature only. (2) Effect of gibberellin on the vernalization of germinating seeds. Cold treatment of germinating seeds has become the standard method of vernalizing cereals. The effect of gibberellin applied during the course of this standard method of vernalization, was also investigated. It was concluded that, in vernalizing varieties which possess high requirement for vernalization by chilling, the use of gibberellin was effective when the chilling was insufficent, but in the case of varieties possessing low requirement for vernalization by chilling, the effect were obscure.

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An investigation was carried out to clarify the relation between the occurrence of a white-core kernel and the ripening grade of a hull rice, using some varieties of rice with bigger grains, e.g. Hyogo-omachi, Yamadanishiki and others. The ripening grade was divided into sixteen ranks, according to specific gravity of a hull rice, ranging from 0.09 to 1.20 with an interval of 0.02. Moreover, the hull rice belonged to the respective rank of specific gravity was radiographed by the soft X-ray apparatus (SOFTEX type-EM) for the purpose of detecting a vacant space in a hull rice. The results obtained are summarized as follows: (1) The occurrence of a white-core kernel was proportionally increased with specific gravity of a hull rice and the white-core portion was born for the first time in a hull of which specific gravity was nearly from 1.08 to 1.12, being true for all the varieties tested. The frequency of occurrence of type A, one of the five types in white-core kernels, as reported previously, showed the highest positive correlation with specific gravity of a hull rice. (2) The radiographs of a hull rice revealed that a rice grain grew up with an increase of specific gravity of a hull rice, consequently diminishing a vacant space in a hull rice. It was also noticed that the dimension of a vacant space and the size of a grain, in a hull, in which a white-core kernel had to be produced were greater than those in a hull containing a non-white-core kernel. (3) On the basis of this investigation, it may be concluded that the white-core portion in a rice grain are apt to be produced when a hull rice is growing under such a favorable condition for ripening as both a hull and a grain in it are able to grow up to the size peculier to the variety with bigger rice grains.

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This experiment were carried out to analyze the effect of light intensity upon the tillering of rice plant using Mihonishiki variety by water culture in 1961. The main results obtained were as follows: Effect of light intensity on the tillering of rice plant was remarkable, but it was not always the same. It was considered that the variation of the effect was caused by the difference of the growing stages or by the time and degree of shading treatment. Therefore, it seemed difficult to determine the limit of light intensity needed for the occurrence of tillers. However, throughout every period of the tillering, a distinct difference was observed in the number of tillers between 200 calories and 300 calories of light intensity per day, so it was thought that the limit of light intensity might be about 200 calories per day in the tillering period.

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Photosynthesis is the most important factor in dry matter production. Therefore, as the first step to acquire fundamental knowledge about the photosynthesis of sweet potato, several experiments were undertaken with individual leaf. Apparent photosynthetic rates of intact leaves were measured under-natural conditions by the use of the apparatus shown in Fig. 1. As experimental materials, some varieties of sweet potato were grown in field and in Wagner's pots under different applications of fertilizer. The following results were obtained: 1) Light saturation values measured on a horizontal surface with a intact leaf and a detached leaf were about 30 k lux. Light saturation values of the population were, however, higher than that of individual leaf owing to the lowering of light intensity caused by mutual shading of leaves in the population. Maximum values of photosynthetic rates were about 20 mg CO₂/100 cm²/hr as mean value and they were not different significantly among four varieties. 2) The relation between the photosynthetic rate of leaves and nitrogen, phosphorus and potassium concentrations on dry weight basis in them was investigated with intact leaves of Norin No. 1 which include various ages except young leaves below 15 leaf position, under different manurial conditions. It was observed that potassium exerted a much larger effect on photosynthetic rates than nitrogen. Leaves which contained more. than 4 per cent potassium showed a very high photosynthetic ability even when nitrogen level was as low as 2.2 per cent. On the other hand, the photosynthetic ability was low when nitrogen ranged above 3 per cent but potassium was below 4 per cent. The young leaves below 15 days old showed, however, high ability of the photosynthesis in spite of the same level of potassium and nitrogen as older leaves (Fig. 5). There was no statistical interaction between the phosphorus per cent and photosynthetic rates in leaves.

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The difference in the short day vernalization effect as affected by the temperature during or after the short day treatment was studied. The short day vernalization effect was not marked when low temperature was given during the short day treatment. There was a trend toward an increase in this effect with the rise in that temperature up to 18°C or 22°C. Variation in the heading date of the plants treated with short day under different temperatures was smaller than that of control plants. These were also true with respect to the difference in the short day vernalization effect as affected by the temperature after the treatment. The difference in the short day vernalization effect under different temperatures showed similar trends in any variety of different winter habits. The plants were treated with short day and were given various combinations of temperatures during the darkperiod and during the photoperiod. The short day vernalization effect under the low temperature during the darkperiod or the photoperiod was not marked. This effect increased with the rise in the temperature during the darkperiod up to 14°C or 18°C or with the rise in the temperature during the photoperiod up to 18°C or 22°C. The emergence of the final leaf was hastened by about one month when the plants were sown and treated with ten short days out of doors in October, while it was hastened by only 3 days when the plants were sown in the glasshouse and treated with ten short days out of doors in December.

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(1) The authors made studies of tea tree in '59 and '60 to know some of the physiological influence caused by third-crop plucking in cold locality. The obtained results are as follows. (2) Owing to the plucking for three times a year, the tea tree was inferior to the others, without the third-crop plucking, in the following; 1) Since the third-crop plucking, the autumn bud did not grow up sufficiently, till the next spring throughout the winter. 2) The sprouting in the next spring was so delayed that tea shoots could not grow up thoroughly before the ordinary first crop season 3) The green leaf was inferior in most of the characteristics. (3) According to the above-mentioned reasons, the third-crop plucking from the middle to the last of August, is very irrational in this district.

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The influence of light intensity on the translocation of sucrose-C¹⁴ in the sweet potato plant, Ipomoea Batatus LAM., has been studied by means of Isotope tracer technique. Sucrose-C¹⁴ was introduced into a leaf and then the plants were exposed to light of different intensities (40, 000, 12, 100, and 2, 800 Lux at noon). After 12 hours the distribution of C¹⁴ throughout the plants was determined by means of radioautograph. Translocation was mainly downward from the treated leaf to root. The translocation of C¹⁴ into root increased progressively with succesively lower light intensity and 70 % of the total C¹⁴ was found in root under the lowest light intensity. The rate of C¹⁴ distribution to leaves was decreased in parallel to the lowering of light intensity.

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Flowering effects of the extracts obtained from vernalized radish seedlings were examined in this experiment, using Raphanus sativus L. var. Minowase as the test plant. The extracts were prepared as the forms of diffusate and juice. The former was obtained by the diffusion of the substances from the germinated radish seeds into the aerated water during the period of vernalization, and the latter was collected from the vernalized radish seedlings grown under the long-day condition (24 hrs. light, 20°C). At the same time, juice from non-vernalized seedlings grown under the same condition was prepared to compare its flowering effect with those of the extracts mentioned above. The extracts were successively applied with Tween 20 to the leaves of non-vernalized radish plants (sown Nov. 27, 1961) from the dicotyledonous stage to the 5th leaf stage almost every day, using a soft brush. The treated radish plants were kept in a growth cabinet conditioned with 24 hrs. light and 20°C. The bolting of the plants in both plots of diffusate and juice-V were noticed in the beginning of Feb. 1962, and finished their flowering by the end of the same month. Whereas, the flowering of the plants treated with juice-NV and Tween 20 only were much delayed until the end of March. The results of the present investigation indicate the existence of the vernalin-like substance in the extracts obtained from vernalized radish seedlings.

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1. When rice kernel is soaked in water, water penetrates to pericarp and subsequently to aleuron layer throngh germ end, and then goes into endosperm tissue through the peripheral starch-cell layer. In this process, rice kernel absorbs water, to 20∼25 percent of its dry weight in early stage of water absorption and this amount of water is considered to be absorbed physically. 2. In the kernels which absorb water rapidly, cells of peripheral starch-cell layer adjacent to aleuron layer are small, flat and irregular in shape. This shows that the filling up of starch in these cells is rather imperfect and loose. Accordingly, the rate of physical absorption may be mainly affected by the porosity in peripheral starch-cell layer of endosperm.

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In this paper, the effect of lack or air in the rooting zone of the soil on flower formation is reported. Five varieties of Nicotiana tabacum, Bright yellow (a flue-cured tobacco, highly sensitive to low temperature and short photoperiod), Hicks Broadleaf (a flue-cured tobacco which resembles Bright Yellow), Xanthi (a Oriental or Turkish tobacco, non-sensitive to both conditions), Xanthi-Ova (similar to Xanthi), Xanthi-Yaka (another strain of Xanthi) and Cavalla (a day-neutral plant of a variety of Orient type which resembles Xanthi) were used in this experiment. Two groups of seedlings which had been grown by ordinary practice were selected from each variety at 11∼12 leave s stage and were transferred from the germination bed to soil tanks in the field. One of the seedling groups was then subjected to water-logging treatment starting from the time of transplantation. In this case, the tanks were continuously watered to the level of 2 cm above the soil surface. The other groups were kept without treatment for comparison. Both treated and non-treated plants were grown by ordinary practice under the weather conditions of May to August, day-length and mean daily temperature exceeding 14 hrs. and 18°C respectively. The results were as follows: In the treated plot, each variety flowered 7 to 10 days earlier than the corresponding variety in the control. Among the varieties promotion of flowering was most conspicuous in the variety Bright Yellow and Hicks Broadleaf. Moreover, in the varieies of the treated plot the total number of leaves per plant which had already been determined at the time of flower initiation, was less by 10∼22 leaves than the control. The data from four varieties of Oriental tobacco showed that flower formation in day-neutral plants can be accelerated by water-logging treatment. As it has already been proved that these plants do not respond either to low temperature or short photoperiod, the acceleration must be directly connected with the lack of air in the soil. The data from the variety Bright Yellow which is easily accerelated by both low temperature and short photoperiod also corroborate the above assumption because the experiment was conducted in summer under adverse conditions. From this point of view, it is very probable that soil aeration is as important for flower acceleration in tabacco as temperature and day-length.

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This report deals with the results obtained in the various peanuts relative to the evaluation of calcium movement from the vegetative tissue to the fruiting organs when the nutrient treatments which differential amounts of calcium were applied to the fruiting zone, to essential amounts of calcium in the fruiting zone required for fruit filling, and to the quantitative difference of fractional calcium in above treatments. The isolated methods as reported previously, were begun on the various peanuts, and the nutrient solutions which contained the following amounts of calcium were added at weekly intervals to the fruiting zone of 2.8 kg acid-washed sand throughout the experiment: distilled water, minus Ca, 20 mg. Ca, 40 mg. Ca, and 60 mg. Ca as the complete solution. Before the pegs had penetrated the sand of the fruiting zone, 0.3 mc. of radiocalcium was applied to the rooting zone of each plant. 1. It was found that in case of runner type the immature pods including the subterranean pegs were more numbered than the aerial pegs, and that in case of bunch types the aerial pegs were more numbered than the immature pods. So far as those varieties are concerned, the unfilled fruits were formated only on the plants of Virginia type, and bunch varieties of the same type were found to have a greater tolerance against the formation of unfilled fruit than the runner ones. The rate of calcium contents in the shell and seed of Spanish varieties was somewhat greater than that of Virginia and Valencia. 2. The levels of calcium amounts of the fruiting zone where the unfilled fruits were formated, were 20 and 0 mg per 2.8 kg sand for Chiba-74 (runner type) and Tachi-Rakkasai (bunch type), respectively. In Southern Cross (bunch type of small-seed), irrespective of the amounts of calcium in this zone there were not observed the yield of unfilled fruits. In general the differences in the concentration of calcium in the fruiting zone seemed to have greatly affected calcium contents of the shell in all varieties, except in Southern Cross. On the other hand, there were no considerable differences in calcium contents in the seed of the above samples, but the contents of Chiba-74 were apparently less than the other two bunch vatieties. When the calcium deficient treatments were given in the fruiting zone, the very active translocation of Ca⁴⁵ was observed from the vegetative tissue into the shells and seeds of the above varieties, and the movement of the labeled calcium into the seed in the bunch varieties was found to be more active than in the runner one. With adequate calcium supplied in the fruiting zone, the shells and seeds of fully developed fruits contained very small amounts of labeled calcium. 3. In the shell, alcohol soluble calcium in the filled fruits of the bunch types did not show any difference in various calcium treatments of the fruiting zone, while on the other hand, that of the runner type seemed to have sensitively increased by the increasing supply of calcium in the fruiting zone. Additionally, there were high contents of calcium in the unfilled fruits, especially when they were due to the high concentration of calcium in the fruiting zone. Regardless of the various calcium levels of the fruiting zones, the shell was found to have almost the constant contents of acetic acid soluble calcium, excepting in the case of high calcium level in Southern Cross. The contents of HCl soluble calcium were increased by the increasing supply of calcium in the fruiting zone in any case, but in the minus calcium, it seemed to have the tendency that the shell having two unfilled seeds in the mature pod had lower contents of calcium than the ordinary shell. In the seed, each amount of alcohol soluble and acetic acid soluble calcium remained almost unchanged independently both of the increasing supply of calcium in the fruiting zone and of the types. [the rest omitted]

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The present writers made studies on the following matters for four years from 1956 to 1959 applying the field and pot tests in the University of Fukui (Fukui City) and Tatetsu Branch Station of Osaka Prefectural Agricultural Experimental Station (Kawachi City). We studied how the thickness of bran layer is influenced by (1) the conditions of fertilization, (2) the position of spikelet and the size of rice kernel, (3) stage in ripening process, (4) transplanting time, (5) shading of the sunlight and changing air temperature. We also measured how thick the bran layer was and studied the characteristics of its forms. Our results were a s follows: I Bran layer becomes thicker according to the different amounts of fertilizer given, namely, none, standard, or plenty; and nitrogen fertilizer proved to be most effective. The same tendency may be observed when we use base or additional fertilizer, or foliage sprays after flowering. II We noticed a considerable difference between Fukui yields and Osaka ones. Regardless of the varieties of rice or conditions of applying fertilizer, Fukui yields were always thicker. It may be conjectured that it was caused by the difference of meteorological conditions, especially that of air temperature. III A difference of the thickness of bran layer was not observed according to the position of spikelet and the width of rice grain, but the thicker grain had comparatively a thicker bran layer. IV In measuring how thick the bran layer was, we compared the materials every five days from the fifteenth day after flowering and continued our observation until the ripening time. The thickness of bran layer 15 days after flowering amounted to 80∼98 % of that of ripe one and Fukui yields grew thicker than Osaka ones. From this fact we can conjecture that the thickness of bran layer will be influenced by climatic conditions, especially air temperature during the 15 days after flowering. V One plot was transplanted at the standard time and two transplanting were caried out prior to this, while four others were done later. Every transplanting were done at a regular interval of 15 days. Then we measured thickness of bran layer and found respective significant correlations between the thickness of bran layers of the dorsal part and the average air temperatures in a day, in the daytime, and at night, and the average daily duration of sunshine for the two periods extending over 10 days and 15 days respectively after flowering. VI After shading of the sun light, and low temperature treatment we confirmed that both thse factors are harmful to the thickening of aleuron layer. VII By the morphological observation of the thickening stage of bran layers and the vascular bundles, it is possible to classify the seed formation into six types as shown in Fig. 1.

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The following facts were found concerning the secondary dormancy of the seeds. The seeds which had been kept within submerged soil became to show poor percentage germination since August, and hardly germinated in a germinator at 30°C at the time between from September to December, that is to say the secondary dormancy was induced. The secondary dormancy was overcome at the next spring. And it was observed that this process was repeated during over four years. The activity of dehydrogenase in the embryo of secondary dormant seeds was similar to non-dormant seeds, as observed with primary dormant seeds. It was elucidated that the secondary dormancy was not caused by embryo dormancy, but was due to the presence of the pericarp and epidermis. The secondary dormancy was induced experimentally by placing the seeds showing the environmental dormancy under submerged soils at germination temperature (20 to 30°C). And, it was induced more rapidly in the seeds staying in the environmental dormancy for a longer period, and at 30°C than at 20°C, and not related with Eh value of the soil. The secondary dormancy was overcome under the conditions similar to the primary dormancy. However, it was differed from the primary dormancy in the facts that the secondary dormancy was awakened more rapidly in the upland condition than in the submerged conditon at low temperature (3 to 5°C), and the freezing treatment (-5°C) was not effective in overcoming the secondary dormancy.

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We have discovered that some of the seeds lost their viability in the process of dormancy awakening. Following facts were found concerning this phenomenon. Dead seeds were found after one month from the beginning of dormancy awakening (either primary or secondary) in the storage within the soil under upland condition (70 to 80 per cent. soil moisture content of field capacity) at low temperature below 10°C (especially 10°C). Dead seeds did not differ from fresh seeds in the morphological appearance of the embryo at earlier time, but its dehydrogenase activity was missing. However, occurrence of dead seeds in the soil varied acording to the temperature and moisture content of the soil. In the storage under any moisture content of the soil at germination temperature and under submerged or air-dry condition at low temperature, dead seeds were not found. In well-drained paddy fields (submerged condition in rice season, upland condition after rice season), numbers of viable seeds decreased very rapidly during from winter to early spring. In poor-drained paddy fields (submerged condition in the whole year), numbers of viable seeds decreased very slowly because the seeds hardly died in the process of dormancy awakenig in winter. Accordingly, it was well established that longevity of seeds of barnyard grass are longer in poor-drained paddy fields than in well-drained paddy fields.

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Rice plants grown on the border of paddy fields show a strong resistance to lodging. This phenomenon may, in part, be attributed to the elasticity of plant. With this view in mind, the authors have carried out investigations on metaxylem vessel elements, in various organs of rice shoots, which may play an important role in making the plants more elastic. Observations were mainly made on rice shoots taken just before heading stage from the border as well as from the interior of the actual paddy field at Ookusamachi, Chiba City. Each organ of the shoots was macerated separately with Jeffrey's method and vessel elements (metaxylem II, according to the previous paper were examined under the ordinary microscope. It was found that there is a clear difference in the size, form and type of pitting of lateral wall of vessel elements between plants grown on the border and those grown in the interior of a field. This difference is most conspicuous in the basal elongated internodes and gradually becomes indistinct in the upper parts of the shoots, especially in the leaf blades. The morphological characteristics of vessel elements of the shoots grown on the border of a field were as follows, as compared with those of the shoots grown in the interior; vessel elements are shorter in length with larger diameters, their end walls tend to be simple transverse, and the lateral walls show a tendency of increasing alternate pitting. From evolutional point of view, it is generally believed that the morphological characteristics of vessel elements are specific for species. But our results suggest that, even if the species is the same, they are changed within some limits by ecological conditions. It is assumed that the factors controlling the water balance of plants may be most important, as suggested by Maximov and others. Our experience in actual paddy fields shows that degree of effectiveness of these factors acting on the border and in the interior of the field are likely to be different.

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