The influence of a thermal factor on the soil ammonium nitrogen and its absorption by rice plants grown under the field and controlled conditions were studied. It was shown that the absorption of nitrogen by the rice plants was closely related to the accumulated effective thermal index (AETI) given by T. Hanyu and T. Uchijima (1962). The amount of nitrogen per unit area absorbed by the plants (y) grown in the field was closely related to the AETI consisting of an exponential equation (y=cd^x) for the early growth stage and linear one (y=ax+b) for the middle and late growth stages. The crossing point of these equations was the AETI of about 400. The similar equations excepting the b parameter were obtained for both low and high dosages of basal nitrogen. But the crossing point of these equation was varied by the cultural conditions, especially plant density and placement of fertilizer. Soil ammonium nitrogen decreased exponentially after transplanting. Almost all of the nitrogen disappeared at the AETI of about 400, or at the commencement of ear-primodia formation. Therefore, it was assumed that the rate of nitrogen absorption of the rice plants was the limiting factor in the exponential part. On the other hand, the rate of supply of soil ammonium nitrogen, or the rate of mineralization of soil organic nitrogen was assumed to be the limiting in the linear part.

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Field experiments were carried out in order to study the relationships between the nitrogen absorption by rice plants grown under various cultural conditions and the growth of the plants. The results obtained are as follows; 1) It was found that the rate of nitrogen absorption by the rice plants was the greatest just before the neck node differentiation stage throughout all the growth stages. The greatest rate of nitrogen absorption by the plants at this stage was positively correlated to the length of culms, the sum of lengths of lower three internodes, the sum of lengths of upper three leaf blades (excepting those of the plots of nitrogen top-dressing), and the number of spikelets per panicle (excepting those of the plots of no basal nitrogen, nitrogen top-dressing at the neck node differentiation stage and at the stage of reduction division), respectively. 2) The amount of plant nitrogen per unit area at the early stage of spikelet differentiation was positively correlated to the number of panicles per unit area. Furthermore, the amount of nitrogen in plant per unit area at the ear mergence was positively correlated to the number of spikelets per unit area. 3) It was previously shown by Matsushima et al (3, 4, 5, 6) that lodging resistance and light utilizing efficiency of rice plants were improved by the decrcase of the length of culms, the sum of the lengths of lower three internodes, the sum of the lengths of upper three leaf blades and the number of spikelets p6r panicle and by the increase of number of panicles and spikelets per unit area. In order to obtain the growth of rice plants mentioned above, the rate of nitrogen absorption by rice plants must be decreased just before neck node differentiation stage and be increased at the other growth stages. It was recognized that early transplanting and high plant density was effective means to permit the desirable rate of nitrogen absorption by rice plants and to increase the rice yield per unit area.

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The behavior or basal nitrogen and absorption of nitrogen by the rice plants in two different paddy fields, Odawara and Takadate, were compared. The results obtained are as follows; 1) The soils of both fields belonging to Gray-Brown Soil were poor ill soil oraganic matter, and were poorly drained. However, the clay contents and CEC values of the plowed layers were much greater in Takadate than in Odawara. Furthermore, the clay fraction of Takadate soil was dominated by montmorillonites. On the other hand, the amounts of nitrogen mineralized by incubation at 30°C were treater in Odawara soil than in Takadate soil. 2) The amount of soil ammonium nitrogen in both fields decreased exponentially after transplanting, and almost all of it was disappeared at the accumulated effective thermal index (AETI) of about 400. The decrease of soil ammonium nitrogen in both fields was shown as an exponential equation of AETI. Soil ammonium nitrogen derived from basal nitrogen was disappeared about the same time. 3) The amounts of nitrogen per unit area absorbed by the rice plants (y) in both fields were indicated to be closely related to the AETI (x). An exponential equation (y=cd^x) was obtained for the early growth stage, and linear one (y=ax+b), for the middle and late growth stages. The crossing point of these equations was the AETI of about 400. However, there were some differences in the parametcrs between Odawara and Takadate. It was assumed that the limiting factors were the ability of nitrogen absorption of the rice plants, for the exponential part, and the rate of mineralization of soil organic nitrogen, for the linear part. 4) The average recoveries of basal nitrogen (60-70 kg-N/ha applied) in the rice plants were 43% in Takada, and 27% in Odawara, reflecting the ammonium absorption of the plowed layers as mentioned in 1). On the other hand, the amounts of soil nitrogen absorbed by the rice plants at the ear mergence were 71 kg-N/ha in Odawara, and 44 kg-N/ha in Takadate, reflecting the amounts of nitroten mineralization by incubation. 5) The amounts of residual basal nitrogen in plowed layers were 16% in Takadate, and 19% in Odawara. Therefore, the total recoveries (the recovery of basal nitrogen in the rice plants and residual basal nitrogen in the plowed layers) were 68% in Takadate and 46% in Odawara. Since the water permeability of both fields was extremely small, it was assumed that almost all of unrecovered basal nitrogen was lost by denitrification.

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Effects of varieties (Du Puits, Moapa, Rambler), cutting frequencies (3, 4, 5 cuts per year) and fertilizer levels (0, 50, 100 kg compound fertilizer <N-6, P₂O₅-11, K₂O-11> /10a/year) on the yield and plant numbers per unit area of alfalfa swards were investigated on the alluval soil in Sapporo from 1967 to 1970. 2. Sources of variations that affected on the yield and plant numbers per unit area were varieties, cutting frequencies and interactions between the two. Fertilizer levels within a range of this experiment had no effects on the yield and plant numbers per unit area. 3. In totals for four years period, the yields of Rambler were reduced accordind as increased cutting frequencies. The yields of three-cut and four-cut treatments of Du Puits, and also Moapa, were similar, and higher than those of five-cut treatments. The rate of yield decline from four-cut treatments to five-cut treatments of Moapa was much smaller than that of Du Puits. The yields for four years period showed the ranking order: Du Puits > Moapa = Rambler under three-cut treatment, Du Puits > Moapa > Rambler under four-cut treatments, Du Puits = Moapa > Rambler under five-cut treatments. 4. Plant numbers of Rambler per unit area at the first harvest in the fourth year were reduced according as increased cutting frequencies. The three-cut and four-cut treatments of Du Puits, and also Moapa, had similar plant numbers per unit area, and more plant numbers than five-cut treatments. The rate of decline in plant numbers of Moapa from four-cut treatments to five-cut treatments was smaller than that of Du Puits. Plant numbers per unit area at the first harvest in the fourth year showed the ranking order: Du Puits = Nloapa > Rambler under three-cut and four-cut treatments, Moapa > Du Puits > Rambler under five-cut treatments. 5. There existed correlations between annual yields and plant numbers per unit area at the final harvest of that year, total yields for four years period and plant numbers per unit area at the first harvest in the fourth year. These relationships, however, did not lead to the conclusion that plant numbers per unit area were responsible for sward yields.

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1. Behaviours of dead plants in alfalfa swards grown in a series of slot-like soil containers were observed in detail and levels of carbohydrate reserves in a root of dead plants were inferred. 2. Occurrences of dead plants in swards seemed to increase when swards received too frequent cutting or no cutting. 3. Most of the dead plants in swards with cutting treatments were the plants that could never start to regrow after cuttings. There were few plants that could start to regrow and died in process of growing. 4. Percentages of carbohydrate reserves in a root of individual plants seemed to rise sharply with increasing top weights to a maximum which was constant for all higher top weights. 5. Levels of carbohydrate reserves in a root of dead plants in swards with cutting treatments, as compared with those of the alive plants in the swards, were remarkably low at cutting time. Also in swards without cutting treatments, levels of carbohydrate reserves in a root of dead plants seemed remarkably low, as compared with those of the alive plants in the swards.

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The root of Bupleurum falcatum L., Bupleuri Radix, is so important a crude drug that it is used in almost all the prescriptions of Chinese drugs, being listed in the Japanese pharmacopoeia VIII-2. The quality, however, of the crude drug produced in Japan is excellent and the production is only a little. Hence a large portion is imported from China, an increased domestic production being much required. As yet few fundamental investigations have been made on the cultivation of this plant. The seeds require a long time for germination to take place and the germination itself is unstable and irregular. This is one of the main difficulties in the practical cultivation. The present studies were undertaken with a view to elucidating this characteristics of germination and to establishing the methods of hastening of germination and of storage, being conducted during a period from 1969 to 1973. In part I, the results of experiments, carried out in 1969 and 1970, on the influence of the time elapse after seed harvest and light conditions on the germination are reported. 1. Observations of the seed germination during one year from fresh seed harvest at intervals of one month showed that there was no great difference in germination percentages between plots from fresh seed harvest (M₀) to four months after seed harvest (M₄), the highest being five months after seed harvest (M₅) (Table 1). 2. During a period of six months from M₀ to M₆, germination percentages were heightened in the presence of light, the seeds being confirmed to be a light germinator. 3. Regarding the mean necessary time (days) for germination, the plot of M₀ was the longest (30.74 days), there being no great difference in those from M₁ to M₅ (26.50-28.93 days) (Table 2). 4. The embryo size of the freshly harvested seeds (M₀) was the smallest (embryo rate, 5.10%), attaining to the largest five months after seed harvest (M₅, embryo rate, 16.69%) (Table 3). 5. From the foregoing, it has been clearly demonstraied that the characteristits of germination of Bupleurum falcatum L. is due to the after-ripening of the seeds, i.e., the embryo at the time of fresh seed harvest is yet immature and underdeveloped morphologically.

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In part II, the results of experiments, carried out in 1971 and 1972, on the method of hastening of germination with low temperature treatment and that of storage of the seeds are reported. 1. The influence of storage methods ( T, four levels) and storage period (M, ten levels) on the germination was investigated. The effect of stratification (T₃) was the most conspicuous, thc germination percentage and mean necessary time for germination of five month storage stratified in the ground (T₃M₅, 69.1%, 15.18 days) being superior to those of the control (T₀M₅, 57.4%, 25.12 days) by about ten per cent higher and ten days shorter respectively (Tables 1, 2 and 3). 2. It was observed that the stratification hastens the development of embryo, after-ripening protressing favorably as compared to the control (Table 4). 3. The influence of the period of low temperature treatment (T, 5°, five levels), the time of beginning of the low temperature treatment (D, number of days after sowing on moist filter paper in petri dishes, four levels), and time elapse after seed harvest (M, two levels) on the germination were investigated. The results with respect to the germination percentage showed that the main effect, D, T, and M and all of the interaction effects were very highly significant (Table 5a). 4. No effect of the low temperature treatment was observed on the germination percentage of the level D₀ in which it was begun just when the seeds were sown in petri dishes (Table 5c). 5. Of the four levels of factor D, the germination percentage of the level D₁₀ in which the low temperature treatment was begun ten days after sowing in petri dishes wad the highest, especially that of the plot of three-day treatment (D₁₀T₃) being the highest (66.8%) (Tables 5b and 5c). 6. In the level D₂₀ in which the treatment was begun 20 days after sowing, the germination percentage of the plots of three-and five-day treatment (T₃ and T₅) were higher than that of the control (T₀), while that of seven-day treatment (T₇) was the lowest (Table 5c). 7. In the level D₃₀ in which the treatment was begun 30 days after sowing, the germination percentage of the plot of one-day treatment was not effective, but those of more than three-day treatment (T₃, T₅, and T₇) were higher than that of the control (T₀), the longer the treatment the higher the germination percentage (Table 5c). 8. Regarding the mean necessary time for germination, that of the plot D₁₀T₃ was the shortest (22.06 days) of all the combinations of D and T.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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These experiments were carried out to throw light upon a phenomenon of the increased sterility by top-dressing of excessive nitrogen at meiotic stage (hereinafter referred to as nitrogen treatment) in rice plants from the view of functions and structural characteristics of pollens as well as proline metabolism in anthers. It was found that the nitrogen treatment increased the sterility in both superior spikelets (spikelets of the 4th, 5th and 6th position on primary branches) and inferior ones (spikelets of the 2nd and 3rd position on secondary branches) to three times as much as control. On and after trinuclear period (III period), the content of proline in anthers was decreased conspicuously with nitrogen treatment, especially in the anthers of inferior spikelets in which the sterility reached about 40 percent. Morphological observations on the development of tapetum after nitrogen treatment indicated that there were no distinctive differences in behaviors of tapetum between control and treated anthers. In the late III period of pollen development, there were a lot of pollens without deformation of the vegetative nucleus and with a higher staining ability of the nucleoli by aceto-carmine in the treated anthers. These pollens were evidently smaller in diameter than the control. This supressed development was a consequence of the reduced growth rate of pollens in III period. Additionally, the nitrogen treatment also reduced the pollen germination. These results lead to the conclusion that the increased sterility of spikelets by nitrogen treatment belongs to the male sterility which may be caused by a disturbance of the developmental pattern of pollen at III period, when being under the control of two sperm nuclei.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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Many scientists study the tuberization of potato plants from the point of view of the environments and the plant hormones. The tuberization is also recognized as the result of two separate processes, stolon formation and tuberization of the stolons. The stolons are the axillary shoots which normally arise from the underground nodes. In this paper, stolon formation was studied using the potato seedlings from which axillary shoots arose from the aerial nodes. The results were summarized as follows. 1. Three types of orientation of the axillary shoot growth in the potato seedlings were recognized:the axillary shoots grown downwards at the lower nodes, those grown horizontally at the middle nodes and those grown upwards at the upper nodes. 2. The downward growth of the axillary shoots at the cotyledonal node was a consequence of the increased upper epidermal cell number and the cell length of the axillary shoots. On the other hand, the upward growth of the axillary shoots at the 7th node was a consequence of the increased lower epidermal cell number. 3. It is suggested that the orientation of the axillary shoots was controlled by the shoot apex with some younger leaves. Whenever the excision of the shoot apex was earlier or later, the axillary shoots turned upwards to become the leafy shoots. However, the change of the orientation to upwards was accelerated by the earlier excision of the shoot apex. 4. It was recognized that the decapitation of the shoot apex caused the axillary shoots to turn upwards and show the leafy shoots. However, if IAA and IAA+KIN were applied to the cut surface, the upper-most axillary shoots grew the downward and stoloniferous shoots such as intact ones. Thus it was suggested that there was a evident relationship between the endogenous auxins in the shoot apex with some younger leaves and the growth pattern of the axillary shoot.

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1. In case of early-maturing rice variety Honen-wase, the correlation coefficients between the number of large vascular bundles in the first (highest) internode and the number of the primary branches of the panicle, the number of paddies per panicle, the weight of a panicle were γ=0.903, γ=0.877 and γ=0.850, respectively. And a fairly intimate interrelationship (γ=0.948) was noticed between the number of the primary branches and the number of paddies per panicle. 2. As the difference between the number of large vascular bundles in the first elongated internode and that in the second elongated internode showed the same tendency with the difference in the number of panicles per hill, it was regarded that the ratios of the number of large vascular bundles in the first elongated internodes to that in the second elongated intermode displayed the plant types' own characteristics; that is, the ratios of panicle-number type varieties, biased panicle-number type varieties, medium panicle-number type varieties, biased panicle-weight type varieties, and panicle-weight type varieties, stood at 1:3, 1:2.75, 1:2.5, 1:2.25, and 1:2, respectively.

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1. Viewed from the fact that several primary branches tended to gather closely with one another by making a circle on the rachis, it is possible to classify them under some primary branch groups. The ten paddy rice varieties grown in the paddy field at the Fukui Prefectural Agricultural Experiment Station could be classified under 4 to 7 primary branch troups. 2. The number of the elongated internodes showed a tendency to increase according to the increase in the total number of leaves on the main culm. The ten rice varieties mentioned above could be classified under the groups bearing 4 to 7 elongated internodes. There was a tendency that the number of the primary branch groups coincided with the number of the elongated internodes more than 0.5 cm in length. 3. The average number of paddies per piece of the primary branch showed sometimes a tendency to become less than the average number of the differentiated flowers in case of the first and second primary branch group from the bottom of a panicle. This might be ascribed to the fact that some of the differentiated flowers have degenerated. In cases of the spikelet groups ranking higher than the fourth primary branch group, it showed that the average number of the differentiated flowers was nearly close upon the average number of paddies per piece of the primary branch.

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1. The number of large vascular bundles in the first (highest) and second elongated internodes was almost invariable throughout each group of the main culms, the primary, the secondary, and the tertiary tillers. The so-called "the same rank-the same number" principle was applicable. The number of large vascular bundles in the first elongated internode varied according to the tiller tank. The number on the main culm was largest, followed in order by the primary tiller, the secondary tiller, and the tertiary tiller. The number decreased at the rate of one in order named. 2. The number of large vascular bundles in the blades of five high-ranking leaves on the main culm as well as on the tillers was almost invariable throughout the leaves of every rank. The so-called "the same rank-the same number" principle was applicable. The number of large vascular bundles in the flag leaf varied according to the tiller rank. The number on the main culm was largest, followed in order by the primary tiller, the secondary tiller, and the tertiary tiller. The number decreased at the rate of one in order named. 3. Throughout the main culm, the primary tiller, the secondary tiller, and the tertiary tiller, there was an increasing tendency in the number of large vascular bundles in the flag leaf on such culm which possessed a lot of large vascular bundles in the first and second elongated internodes.

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In the previous papers, it was suggested that the producing district of rice in Hokkaido had an effect upon the protein content of lowland brown rice. In order to confirm the effect of producing district on the chemical composition of lowland brown rice in Hokkaido, 120 samples of Norin No. 20 from 4 municipalities, 300 samples of Shiokari from 11 municipalities and 150 samples of Sorachi from 6 municipalities were collected in 1972 and investigated for the protein content (experiment 1) and 60 samples of Shiokari from 4 municipalities were further collected in 1973 and investigated for the protein, fat, ash, phosphorus, potassium, magnesium, manganese and iron content (experiment 2). The producing district had a significant effect upon the protein content of each variety in experiment 1 and 2. With respect to the average values of each variety at the producing districts, the highest was about 20% more than the lowest. As a factor of the variance of the protein content, it was presumed that the paddy field of peat soil brought about the high value because of liberating nitrogen by decomposition of the soil at the late growing period. In experiment 2, the producing district had a significant effect also upon thc chemical components except iron. The high protein district, as compared with the low protein district, was higher in ash content and phosphorus and magnesium content on dry matter basis and was lower in manganese content on dry matter basis and potassium and manganese content in ash.

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The purpose of this study is to clarify the interrelationship between the translocation of ¹⁴C-photo-synthate and ¹⁴CO₂ exposed leaf positions on the grafts of Ipomoea. Four combinations of grafts were brought about by grafting the stocks and scions of improved variety Okinawa No. 100 (I. batatas Poiret) upon the kindred wild type plant (I. trifida (H.B.K.) Don.) T-15 clone. The third or the thirtieth leaf blade counting from the top was exposed to ¹⁴CO₂ for thirty minutes in August, 1973. The sample materials were harvested in the lapse of twenty four hours after ¹⁴CO₂ exposure. (1) In case of 0-100/0-100 (scion/stock) graft, the dry matter distribution ratio to the underground organ at the time of treatment reached a maximum. In cases of 0-100/T-15 graft and T-15/0-100 graft, the ratios reduced to a medium, in case of T-15/T-15 graft, the ratios reduced to a minimum. (2) In case where the third leaf blade was exposed to ¹⁴CO₂, and where the scions used as samples were of the same types, the volume of the ¹⁴C-photosynthate translocated from the third leaf blade on the grafts of Okinawa No. 100 stock was larger than that on the grafts of T-15 stocks. The rate of ¹⁴C-photosynthate translocated to each organ varied with scion type, i.e., in case of Okinawa No. 100 scion grafts, the rate was high in the organs lower in position than the third leaf blade as well as in the underground organs. While in base of T-15 scion grafts, the rate was high in the parts of organs higher in position than third leaf blade. (3) In case where the thirtieth leaf blade was exposed to ¹⁴CO₂, the gross activity of the ¹⁴C-photosynthate translocated from the thirtieth leaf blade was almost alike in every graft, excepting T-15/T-15 grafts. The high translocation rate of ¹⁴C-photosynthate was found in the parts of stems lower in position than the treated leaf on the grafts of T-15 scion, while in the underground organs in case of grafts of Okinawa No. 100 scions. (4) From the above mentioned results, the following facts may be pointed out: 1) ¹⁴C-photosynthate translocated from the treated leaf blade to the sinks is liable to be affected remarkably by the combinations of leaf blade positions and the graft types. 2) In case of grafts of T-15 scions, ¹⁴C-photosynthate of upper leaf blade is translocated mainly upward, while those of lower leaf blade mainly downward. 3) In case of grafts of Okinawa No. 100 scions, the ¹⁴C-photosynthates are apt to be translocated to the underground organs, irrespective of the fact that either the upper leaf blade or lower one is exposed to ¹⁴CO₂.

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Changes with growth in photosynthetic ability of various organs, such as leaf blades, leaf sheaths, culms (parts without leaf sheaths) and ears of barley, wheat, oat and rye plants sown in autumn were measured during 1969-74 (table 1). Photosynthetic rates were measured under controlled conditions in assimilation chambers with artificial illumination of 0.6 ly·min^-1. Respiration rates were measured in dark chambers. In both measurements, surface temperature of each organ was kept either at 14-18°C (Nov.-Mar.) or at 18-23°C (Apr.-Jun.). All samples were collected from the fields, cut off from adjacent organs, and measured. Field study of dry matter production of six-rowed barley, wheat and oat was conducted. Due to being various photosynthetic organs other than leaf blades, a new index LAI^* was introduced, which was obtained from mutiplying LAI (leaf blade area index) by the ratio of total gross photosynthesis of a productive tiller to leaf blades. Net assimilation rate calculated by using LAI^* was named NAR^*. The main results obtained are summarized as follows; 1. Changes with growth in the ability of photosynthesis and dark respiration of leaf blade. The mean gross photosynthesis of whole leaves of a shoot was found to be high during winter in six-rowed barley, wheat and rye, but low in oat (fig. 3). After heading date, their values decreased gradually in all of the four crops. A detailed study of changes of photosynthetic rates of some leaves of wheat and rye sown in 1973, clearly showed that the life span of the leaves grown in winter was long, but the one grown in spring (at the stage of culm elongation) was half of the one in winter (fig. 4, 5). The third leaves on main stems of both crops, which developed before winter, decreased gradually their photosynthetic ability in winter. On the other hand, the fifth leaves which developed in winter showed high photosynthetic ability during long winter period. The dark respiration of leaf blades was clearly found to be of higher value during winter than spring in all four crops (fig. 3). 2. Photosynthetic ability of various organs in ripening stage (including two-rowed barley): In ripening stage, the gross photosynthesis of leaf blades per a productive tiller decreased more drastically than that of the other photosynthetic organs in all crops (fig. 7). The contribution of each organ to the total gross photosynthesis of a productive tiller was calculated on the assumption that every organ were equally illuminated. In the early ripening stage the contribution of leaf blades was high, but at the later stage decreased drastically in all crops (fig. 8). In the early ripening stage the contribution of leaf blades of two-rowed barley was low compared to the other crops, and those of ears were low in wheat and rye. In the later stage the contribution of culms of rye became higher. On the other hand, the contribution of leaf sheaths of two-rowed barley and rye were found to be higher than the other crops, through whole ripening stage (fig. 8). 3. Growth analysis of dry matter production: Both NAR and NAR^* from middle to late April were more than 3.6 times of those in winter in six-rowed barley, wheat and oat. This fact did not agree with the results of the measurements of photosynthetic ability (table 3, fig. 3). It is presumably concluded that winter cereals cannot display enough their photosynthetic ability because of injurious environment of winter in field, especially low temperature. Growth pattern of dry matter of oat was characteristically different from those of six-rowed barley and wheat (table 3, fig. 12). Both six-rowed barley and wheat kept more than four of LAI^* during the period from culm elongation stage to the early ripening stage (table 3). This clearly shows that the various organs other than leaf blades play in an important role for the production of photosynthates.

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