Experiment I. The increase in the growth of rice plants by the addition of silicic acid (SiO₂) of 0, 0.5 1, 5, 20, 100 and 300 ppm respectively, to the cultural solution was tested. In the case of lOO ppm or less, the higher in SiO₂ concentration, the greater in the dry weight of rice plants. While little or the differences were observed among the effects of the addition of SiO₂ of 0.5, 1 ppm and non-SiO₂ on the growth of rice plants. In this test it was recognized that the addition of SiO₂ from 50 to 10O ppm was suitable for the growth of rice plants. Experiment II. The essentiality of silicon to rice plants was discussed in this experiment which was carried out in 1967. The materials used were: distilled water which was passed through the ion exchange resins (Amberlite IR-120B and IRA-410); beakers, pipets and mess cylinders made of plastics, and other materials the same with those cited in the previous reports. 7'9) Hulled rice of "Norin No. 6" were sown and grown on the bed made of plastics. After transplanting them to the pots (made of vinyl chloride) the rice plants in non-SiO₂ plot were grown in the phytotron (regulated at about 30∼33°C at daytime, but stopped to regulate at night). Sodium ions were eliminated by passing sodium silicate aqueous solution through ion excgange resin "Amberlite IR-120, " and SiO₂ (100 ppm) was added to the cultural solution in control plot. To protect the rice plants in non-SiO₂ plot from adhesion of the drops pf guttation containing silicic acid coming from the rice plants in control plot, the latter were cultured in another place (glasshouse). The results obtained are as follows: Dry weights of the harvest are shown in Table 1, Ratio of dry weights of the harvest between non-SiO₂ plot and control plot was 91% per plant, and dbout 80% per panicle. Content and percentage of silicic acid absorbed in rice plants are shown in Table 2. The percentage of silicic acid content in the rice plants in non-SiO₂ plot showed so low as one figure down from the smallest value obtained up to now. The color of chaffs of the rice plants containing 0.0025% SiO₂ was of deeper dark-brown than that of the chaffs of rice plants containing O.O6% SiO₂, and the ripened grains of the former were smaller in size than those of the latter, but they were small. Little or no difference was observed among the growth of rice plants containing 0.13∼0.20% SiO₂. There was no any great and essential difference between the growth of rice, plants containing O.2% SiO₂ and that of rice plants containing O.0025% SiO₂. From these facts, it might be concluded that silicon may not be regarded botanically as essential element to rice plants, but regarded as essential element to rice plants from agronomical viewpoint.

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1. An experiment was designed to investigate growth and yield of alfalfa grown at densities of 2500 plants/m²-A, 625 plants/m²-B, 169 plants/m²-C, and 36plants/m²-D. 2. In 1965 (the seeding year), untill the early flowering stage (the first cutting stage), dry matter yields per unit area were higher in the order A, B, C, D. After the first cutting, this order continued, though the differences between densities gradually decreased. At the second cutting, D yielded the least, there were no significant differences in yield among the other three densities. In 1966 and 1967, there were no significant differences among densities in annual total dry matter yield per unit area. 3. At each harvest except the first harvest in the seeding year, the linear relationship was found between log. dry weight per plant and log. density, and its regression coefficient was approximately 1. 4. The reduction in the number of plants was related to densities, and the percentage of surviving plant numbers to the initial densities at the final harvent of this experiment was 7% for A, 20% for B, 48% for C, and 83% for D. 5. Alfalfa swards ranging in initial density from 169 to 2500 plants per sq. meter were individual plants showing skew frequency distridution of plant weight, except in the early stage of growth in the seeding year.

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Rice plants in non-SiO₂ plot are inferior to those in SiO₂ plot in such forms as plant height, number of living leaves, number of stems, maximum width of leaf blade and length of leaf blade, number of panicles and in the size of rice grains. In the case of culm, 1 cm lower the panicle base, the rice plants in non-SiO₂ plot are also inferior in the number of vascular bundles, number and length of root hairs, speed of protoplasmic translocation in root hair, number of root hairs in which protoplasma translocate, and in the thickness of the lowest elongated internode. In the central part of the flag leaf of the harvested rice plants in non-SiO₂ plot, many mobile cells took the withered-shape and vascular bundles were smaller. In the central part of the 6th internode (from the top) of rice plants in non-SiO₂ plot, number of outer and inner vascular bundles and number of aerenchyma were smaller. From the above mentioned facts, it is recognized that silicic acid is available for the promotion of development of organs and tissues of rice plants.

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The effects of nitrogen supply under low temperature on the pod setting and fertility of the soybean plants were studied with the solution culture method. The low temperature treatment were kept at 15°C for 30 days under three different stages around flowering time. The variation in pod number under the low temperature treatments ranged widely with nitrogen (N) supply conditions. High N application during the low temperature treatments caused a remark able decrease in pod number, comparing with a 23°C condition. On the contrary, low N application during the low temperature treatments showed little decrease in pod number in the same comparison. The effects of the low temperature treatments around flowering time on the pod setting rate and fertility per cent were checked with flowers grouped, in relation to their flowering date, in four classes. High N application during the low temperature treatments considerably decreased the pod setting rate of flowers and the fertility per cent of pods in the sensitive stage, indicated l0 or 15 days before flowering till flowering, under low temperature. On the other hand, in the case of low N application, little significant direct damage was observed, under the same treatments, but some indirect damage symptoms such as the decrease in the number of flowers and flower number per node or small sized plants were remarked under the low temperature treatment in the mid - bloom stage on the main stem. The flowers escaped from the effects of low temperature, and flowers on the plants grown in the 23°C plots, showed high pod setting rate, with high N application within both nodulating and non-nodulating strains. Furthermore, the plants grown under the high N conditions had a prolongation of the flowering period and an increase in the number of flowers. These facts indicate that the high N conditions were favorable for obtaining a greater number of pods, except for the flowering stage affected by the low temperature treatments.

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The previous paper indicated that high nitrogen (N) application during the low temperature treatment caused a considerable decrease of the pod setting rate and the fertility per cent of ovules. In this paper, the unfavorable effects of high N application on low temperature treated soybeans was examined for clarifying of the relationship between the N supply conditions including level, time and period of application, and the stage of flower development with solution culture method. Flower developing plants were treated with low temperature at 15°C for 15 days and compared with the plants grown under the control condition at 24°C-day19°C-night. The flowers used in this experiment were restricted in the number per node and the time of blooming. Variance analysis of the pod setting rate, fertility per cent and the number of ovules per pod gave the significance of the interaction at the 1% level between N supply conditions and temperature conditions. N application under the 24°C/19°C condition obtained better grain yield compared with N free plot; on the contrary, N supply accompanied with the low temperature treatment showed a decreasing tendency of the pod setting rate and of the fertility per cent. The pod setting rate of the plants treated with low temperature was closed related to the time of N application. N application before or during the first five days in the low temperature treatment caused a signiftcant decrease in comparison to the N free condition and the later application showed the less damage. However no difference was observed betwen the level supplied at l00 ppm and 40 ppm N. The fertility per cent of the plants treated with low temperature was decreased by N application and, especially, all plants showed a considerable decrease in the pod setting rate which were accompanied with a significant decline. But the relation between time of N application and the degree of injury was not so clear as seen in the pod setting rate. Fertile grains which were supposed to be in a constant number of flowers per plant were calculated in each plot. N supply from before the low temperature treatment, till five days after the end of the treatment, resulted in a decrease in grain number, particularly, before the period of treatment and during the earlier period of N application, caused the greater decrease.

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[in Japanese]

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Since 1962, this study have carried out to clarify a significance of difference of the plant type as the productive structure and qualitative characteristics of assimilation system in peanut varieties under various field conditions. Four cultivated varieties typically differing the plant type, i. e., erect, Spanish type (E 1, E 2); semi prostrate or intermediate, Virginia Bunch type (SP); prostrate, Virginia Runner type (P); were used in the present experiments (tab. 1). In this paper, difference among 3 plant types and seasonal changes of the leaf amount of individuals obtained in 1962, 1964, and 1965 was described. Results and discussions are as follows: 1. In all varieties, total number of leaves per plant showed an exponential rapid increase from ca. 3 weeks after seeding till the maximum leaf amount stage, middle of August, ca. 90∼100 days after seeding. Rate of leaf production during such a period, however, differed with spacing, amount of nitrogen fertilized, and the plant type. That is, rate of leaf production was high in order of P, SP, and E. And response in leafiness for the nitrogen fertilization seemed to be characteristic of the plant type (fig. 1). 2. A positive close relationships was observed between the maximum values of total number of leaves per plant and that of branches in each of the varieties. 3. Total leaf area per plant showed the same seasonal change (fig. 2). Degree of varietal difference in the maximum value, however, became smaller than that in total number of leaves, due to both of the varietal differences in size of single foliage leaf (E>SP≒P) and in range of its seasonal variation (E>SP≒P) (figs. 3 and 4, tab. 2). Maximum values of total leaf area per plant were: E, 0.5∼1.5, SP, 0.4∼1.6, and P, 0.7∼2.0 m²/ plant, respectively. And values of L.A.I. (total leaf area/ground area/plant) were 4∼5 in E and SP, but in 1962 and 1964, 8∼9 in P. 4. Vertical distribution of dry matter weight of leaves and compactness in leafiness were also higher in P (fig. 5). Lower and denser leafy characteristics of canopy in prostrate varieties are apt to make worse the productive structure than the taller and sparse leafy varieties, E and SP (tab1e 3). 5. Very low proportion of main stem's-leaves which occupied in total leaf area of individuals, particularly, in SP and P, was observed through almost of growth period, except til1 2∼3 weeks followed the developing stage of the embryonic leaves (fig. 6). The role and contribution of main stem and its leaves for the establishment of assimilation system and dry matter production in this crop was interested. 6. Since the period of the maximum leaf amount corresponds to so-called "limiting period of effective flowering for fruit maturing" in our country, it may be suggested that the early establishment of canopy architecture and keeping of optimal leaf amount, especially in prostrate varieties, are of very important to increase dry matter production and fruit yield of peanut. 7. Based on the leaf amount and branching behavior, 3 canopy types were distinguished as follows : E : Sparse leafy type; P : Dense leafy type; SP : Intermediate leafy type. 8. It was suggested that the semi-prostrate or intermediate plant type of varieties would be the most profitable considering the productive structure among cultivated peanut varieties.

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It may be mentioned that the non-competitive condition where free space being given is required to observe correctly morphological development of peanut canopies differing plant type. Then, we will be able to avoid morphological growth distortions caused by competitive effects with the adjascent individuals in crop community. The present experiments were carried out based on the above mentions to obtain some informations on varietal difference in horizontalcanopy expansion-ability. Five Virginia type (P1, P2, P3, SP1, and SP 2) and one Spanish type (E) varieties and 2 plants per a variety were used (tab. 1). 0n May 22, two disinfected seeds were sown into the center of a wooden bottomless frame buried in land: 100 × 100cm and 50cm in depth, and before seeding, 3.2, 8.3, and 12.2g/m² of N, P₂O₅, and K₂O, respectively, and at the early blooming period, 3Og/m² of CaO were given: and then seedlings were thinned to single stand after germination. Photographs of projected area of canopies on land surface were taken half-monthly, and cutouts of their prints were weighed to calculate the coverage in per cent for the frame area, 1m². Results obtained and discussions are as follows: 1. Characteristic pattern and successive enlargement of coverage were observed in each of variety owing to difference in plant type, branching behavior and vegetative growth rapidity (figs. 1, 2 and 7). Rapidity shown by the number of days to reach both 50%- and l00%- period in coverage was high constantly in order of P1>P3>P2>E>SP 1≒SP 2 (fig. 3). Under this experimental condition, variety E showed a large canopy expansion-ability in coverage and foliage amount, but, it must be noticed an influence upon coverage by lose of erectness of lower primary branches, which makes the plant almost as procumbent like the prostrate varieties after middle growth period (fig. 3). 2. Among 3 prostrate varieties, P2 showed a characteristic sparse branching habit like "trailing type" with the slowest development of canopy and low foliage yield, and, contraly, P3 showed the largest canopy growth in the last value of coverage and foliage yield among all of varieties (figs. 3 and 7 tab. 2). 3. The maximum values of rate of rate of coverage increase which appeared in August in each of variety, were 0.15∼0.4m²/ 10 days, and during this 30 days the coverage corresponds to about 40∼55% of the last size increased by such vigourous growth (fig. 4). 4. Very high correlation (r=+0.972) between length of cotyledonary laterals and coverage was obtained (figs.5 and 6), and the importance of these laterals not only in fruiting but as the basic skeleton of stem-system and canopy expansion in this crop was recognized. 5. Horizontal and vertical distribution of vegetative and reproductive parts at harvesting time were also characteristic with the plant type of variety (figs. 8 and 9). 6. Thickness and compactness and also the expanding rapidity in coverage of canopy are of important characters particularly in choosing of the variety best adapted for covering ground, forage and green manure purposes in this crop.

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The change of angle degrees between laminae and sheaths as a result of the gravity stimulus was investigated with intact and excised leaves of rice (Oryza sativa L. ). The following data have been obtained. Lamina inclination was occurred 6 to 17 hours after placing the seed-lings at gravitational fields. The stimulation was the most effective at the angle of inverted position. Effects of IAA on lamina inclination was observed in both intact and excised leaves which were placed at vertical position. But this effect did not appear before the end of lag period which requires several hours to appear. In the excised leaves placed at horizontal position no acceleration of the inclination by IAA was observed during the lag period. From the results described here and information obtained in the previous papers it is assumed that by gravitational stimulation, first, endogenous auxin is produced in the lamina joint of leaves, second, auxin induces the biochemical progress in the lag period of lamina inclination and a reversible component to develop of the cell extension in lamina joint, thus resulting in the inclination of laminae in the intact and excised leaves.

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The influence of fertilizer on protein content of brown rice was investigated on the samples in high yield (average yield of brown rice: 694kg/10a) at farmers' field. With respect to amount of fertilized nitrogen, basal dressing and top dressing at Young panicle formation stage did not increased the protein content. However, the amount of top dressing after heading stage, both top dressings at young panicle formation stage and heading stage, and total dressing showed positive correlations with the protein content at the 1% level of probability. On the other hand, phosphorus and potassium did not affected the protein content.

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[in Japanese]

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The authors reported in previous paper that on the corn plants wilted temporarily at young stage about 6 leaves age or successively at the early stage of stem elongation about 9∼12 leaves age, the growth and fodder yield showed the tendency to increase by growing under the adequate soil moisture condition after rewatering, and that even at the stage of rapid stem elongation about 15∼18 leaves age they did so in case of a rapid drought of soil moisture. It was reported in last paper that (1) the number of roots from the nodes on which rooting occurred after rewatering increased, on the corn plants wilted successively for few days or sprayed gibberellin, (2) the rooting from the upper nodes on which it didn't take place under the normal condition was accelerated, (3) there was the regularity in the behavior of rooting on the corn plants, it was related to the closing an internodal elongation. Considering from these phenomena, it may be thought that the rooting and internodal elongation are carried away by auxin level in the neighboring nodes, and that the wiling treatment is concerned with the auxin level in the neighboring nodes. In present experiment, the auxin level in the neighboring nodes was changed artificially by using a few ways i.e. lodging, added NAA or TTP to 6th, 7th and 8th nodes and X-irradiation. Then these treatment shows the same influence as the wilting treatment on the behavior of rooting. 1. On the corn plant lodged, the lower parts of each internode which is elongating are bended and the plants pick themseves up. This phenomenon is due to undergo a change in the auxin level in the neighboring nodes, thereafter to impede the growth of internodal parenchyma in inner side of bending stem and to accelerate it in outer side. Further it is observed that the rooting from the inner side of bend is impede and the rooting from the outer side of it is accelerated and that the rooting from the upper nodes on which it doesn't take place under the normal condition is promoted, too. 2. As NAA or TTP is supplied on 6∼8th nodes, the rooting from those nodes is accelerated, thereto the rooting from the more upper nodes which it doesn't take place under the normal condition is observed, too. 3. For the investigation used drought and X-irradiation at the same time, though the development of brace roots is accelerated by drought, the number of brace roots which develop after X-irradiation decreases even if the previous treatment is drought or not. 4. These auxin variations in the neighboring nodes made the rooting and internodal elongation accelerate. It may be very interesting because it's able to consider that hydrolysis of protein is progressed under the wilted condition and then TTP or IAA increase in the corn plants. As the result of the raising of the auxin level in the neighboring nodes these morphological changes are brought on.

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This experiment was undertaken to determine the effect of sulfur dioxide on the respiration rate at the flowering stage of rape plants. The respiration rate was measured in the laboratory under the controlled temperature of l0°C, 20°C and 30°C, respectively, exposing the plants to various concentrations of SO₂, which were determined with a SO₂-analyzer of self recording system. The results obtained were as follows: 1. The respiration rate at the flowering stage of rape plants was accelarated by exposing the plants to SO₂ at the concentrations of 5, 10, 15 and 20 ppm under the condition of 30°C. At 20°C, the respiration rate was generally suppressed for five hours af ter exposing the plants to SO₂, excepting SO₂-20 ppm. At l0°C, it was depressed by the fumigation of sulfur dioxide, as seen in fig. 1, ftg. 2 and fig. 3. 2. In the relation between the concentration of sulfur dioxide and treatment hours by the gas, the respiration rate increased linearly with increasing concentration of SO₂ under the condition of 30°C. At 20°C, it was supressed for 0∼4 hours after expoing the plant to SO₂, but for 5∼8 hours, it was accelarated by the treatment of SO₂ at the concentrations of 5 and l0 ppm, without SO₂-20 ppm. At 10°C, it was always retarted by the treatment of SO₂, as seen in ftg. 4, fig. 5 and fig. 6. 3. The mean Q₁0 values at the flowering stage of rape plants showed 1.60 and 1.65, by temperature ranging from l0°C to 20°C and from 20°C to 30°C, respectively. The mean Q₁0 value was higher in the plant treated by SO₂ gas at the concentrations of 5, 10, 15 and 20 ppm, as seen in fig. 7 and table 1. From all these facts, it may be concluded that the respiration rate at the flowering stage of rape plants was affected by the concentration of sulfur dioxide, the treatment hours of SO₂ and the different air-temperature.

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The present experiments were made to clarify the characteristics of the growth of young seedling from seeds soaked and kept under 5°C over a long term (45-135 days). Young seedlings were grown under un-fertilized condition until the foods-exhausted period of seeds. Resu lts are as follows. (1) In comparison of the treated plots with the control one, the growth rate of young seedlings was slow in the early stage, which was caused by the decreased activity of the foods-decomposing enzyme (as Amylase) in seeds. On the contrary, the leaf-number was increased and this fact shows the promotion in the development of seedlings. (2) The plant hight, the length of the second and the third leaf blade were shortened. The elongation of selninal roots was also suppressed, resulting in the lowered ratio of seminal roots to crown roots in weight. Coefficients of variation in these characters were increased, as the individual difference was enlarged with the growth of young seedlings. However the increased number of roots was observed, being assumably brought about by the increase of rooting nodes accompanied with that of leaf-number. (3) The physiological activity of roots was decreased and this may be related to the growth suppression of young seedlings observed at the foods - exhausted period of seeds in case of autumn and winter sowing.

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Changes in leaf-colour are one of important indication on rice cultivation, because the leaf-colour is considered as a reflection of metabolic activity in the plant body. Some methods have been tried so far to express the leaf-colour of rice plants. However, all these methods have developed based on individual leaves and they are troublesome in measuring. Therefore, authors have tried to find out a suitable and easy method for expressing the leaf-colour in mass under field conditions., not in individual leaves, obtaining a fair success. The method and results obtained are summarized as follows: 1. For expressing the leaf-colour a standard colour plate is made by using some commercially available greenish embroidary threads. The plate has been composed of 5 grades of greenish colour and each colour on the plate is named 1 to 5, pale green to dark green, respectively, as shown in Fig. 1. 2. The standard colour plate is set, in a given field, just above the uppermost expanded leaves. Then observers stand at the distance 5∼7 meter away from that plate, turning their back on the sun, and choose the most resembling leaf-colour grade on the plate to the actual leaf-colour in mass on the field. When the leaf-colour of leaves falls intermediate between two values of the grade on the plate, it should be expressed by an intermediate value between two values. 3. So high correlation coefficients have been found between observed values of leaf-colour grade on the plate and nitrogen contents in leaf blades of upper leaves that observed values of leaf-colour may be used as an estimate of nitrogen content in leaf blades. 4. Since the method above mentioned for expressing the leaf-colour is very simple and easy, every one might be able to use it, if only the embroidery threads or similar ones were available. 5. The authors have been trying to explore a new standard colour plate, which will be developed on the basis of the three attributes of colour, i.e., Lightness, Hue and Saturation of actual leaves.

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In order to examine the growth potency of excised roots varying in length, diameter and density in the culture medium, some experiments were tried on the view point of tissue culture. The results obtained were summarized as follows: 1. The elongation of isolated roots was better in the order of the class, A.B.C and D roots whose length were 8, 16, 24, 34 and 43 mm respectively. With regard to the growth within the same class, longer excised roots gave better result in compared with shorter ones. 2. The optimum number of root for the growth in liquid medium was found to be 5∼7 when the roots were used excised to the length of 10∼20mm. 3. The optimum root diameter for the growth of isolated roots was 0.42 mm at the base of root cap. On the other hand, the roots with larger diameter gave inferior effect.

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