The authors investigated on the quality of seed, germination and hard seed content of milk vetch seed in relation to harvesting time for every five days in the field. 1) The germination percentage of seeds was higher in late harvested seeds than that of early harvested seeds, and also the germination tended to be quicken in late harvested seeds (Fig. 2). 2) Hard seed content in the first harvesting time (I) was 7.9 per cent and it was the lowest. At the harvesting time II, it was 17.2 per cent. At the harvesting time III, it was 18.8 per cent and was the highest. And this time contained about 30 per cent of immatured green pods and about 55 per cent of matured black pods. And at harvesting time IV and V, the hard seed content was 11.9 and 12.0 per cent respectively, and it was lower at these times than those of the immatured stages such as harvesting time II and III (Fig. 3). 3) The percentage of corrupt seeds was higher at early harvesting time. The hard seed content for viable seeds, therefore, came to show the highest at harvesting time II (Fig. 4). And this time contained about 9 per cent of matured black pods and about 63 per cent of immatured green pods (Table 1). 4) The weight of 1000 seeds increased as harvested later, but the increase was not so large in seeds harvested after harvesting time III. And the proportion of large-sized seeds was large in late harvested seeds (Table 2). Although the germination percentage was remarkably low in the seeds of less than 14-meshes, no difference of germination percentage was found in the seeds of 14-meshes or larger seeds. 5) From the experimental results mentioned above, it was generally considered that the seeds harvested and dried at immatured stage have the tendency to hardiness than that of harvested after normal maturation on the stalk.

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The author investigated the effects of fertilizers (N as sulphatate of ammonia, P as superphosphate and K as potassium chloride) upon the root habits of young plants (sown Oct. 1., about 3.5∼4 months old) of sugar beet grown in root boxes. Each of the rot boxes was divided into 3 equal sections vertically by vinyl nets, and one beet was grown in this central section. The method of application of the fertilizers in each box was classified as follows: [table] Thus, the total amount of 3 elements was applied equally per box. The washed young roots were gotten separately from each section of the box, which divided by nets, and spreaded them on the glass plate in uniform density as shown Fig. 4. As the results, first of all, the rots of suger beet grown in the box A, as compared with those in the box B, developed much more abundantly and branched more profusely. Among the boxes of C, D and E, the rots grown in soil section applied N or NP or NK branched much more profusely than those in soils applied P or K only or both of them. From these results, it was shown that when roots came in contact with the soil applied N fertilizer, the greater degree of branching were always induced, and in sections applied no fertilizers, root-branchs were limited extremely. But in this experiment, among the developments of root branchs in the soil sections applied P or K only or both of them, no remarkable differences were recognized. The investions of the further advanced rot systems should be affected by similar manner of application of fertilizers are remained in future.

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?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? P³² ?? ?? ?? ?? ?? ?? ?? ?? ?? . 1/5 ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? 29 ?? ?? ?? ?? ?? ??, ?? ?? · ?? ?? ( ?? ?? · ?? ?? ) ?? ??, ?? ?? 1 ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? . ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? . ?? ?? ?? ?? - ?? P³² ?? ?? ?? 3 ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? 1 ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ≒ ?? ?? ?? ?? ?? ?? > ?? ?? ?? ?? ?? ?? ≒ ?? ?? ?? ?? ?? ?? ?? ?? > ?? ?? ?? ?? ?? ?? P³² ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? . ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? 45° ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? . ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? 2 ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? 20∼30% ?? ?? ?? ?? P³² ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? 3 ?? ?? P³² ?? ?? ?? ?? ?? ?? ?? . ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? .

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To determine the method for discriminating the stage of yield forecast, the author examined what character of rice may be utilized as an index of the discrimination. The obtained results are as follows. 1) Close relation between the rate of moisture content of ear and grain weight on the ripening stage was found, irrespective of places, years and varieties. Therefore, the ripening process of ear can be discriminated by the former. 2) Furthermore, close relation was found between the rate of moisture content of ear and percentage of milky grains. Therefore, the former can be discriminated by the latter. It was found high correlation between grain yield and fresh weight of ear at the stage when percentage of milky grains bigins to decrease. Frome these results, the stage when percentage of milky grains became 10±3%, seems to be a suitable stag for forecasting yield.

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Four series of experiments were conducted by; (1) removing the rachis branches of "early transplanted rice" just after heading in order to equalize the number of spikelets per unit area with that of "usual transplanted rice"; (2) equalizing the number of panicles and spikelets by removing all tillers and primary rachis branches; (3) removing the upper or middle or lower rachis branch; (4) changing the amount of fertilizer and hills per area in "early" and "usual transplanted rice". In the experiment-(4), correlation between the percentage of ripened grains and the number of spikelets per area was higher than that between the percentage of ripened grains and the number of panicles per area or the number of panicles per hill or the number of spikelets per panicle. Comparing the corresponded treatments each other, "early transplanted rice" had more spikelets per area than "usual transplanted rice", but the percentage of ripened grains of the former was superior to that of the latter. Especially in the case of the similar spikelets in number, the former showed higher percentage than the latter. In the experiments-(1)·(2), the percentage of ripened grains in "early transplanted rice" was superior to that of "usual transplanted rice". Therefore naturally we consider that ripened grains of "early transplanted rice" show higher percentage than that of "usual transplanted rice", but usually "early transplanted rice" have more spikelets, so the percentage of ripened grains in the former was not always superior to that in the latter.

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The propagation of sweet potato just after its introduction into Japan was mainly carried on the plant-setting method and this method was gradually adopted with the progress of the technics of nursery bed preparation. Thus the sweet potato propagated by transplanting, and the small tuber-setting method which was being tried in dome places remained unnoticed by the majority though it seemed to be very effective. The writers had found out new method of sweet potato culture, namely, small tuber-setting cultivation with increased yield of fleshy roots preventing the setting-tuber from getting fleshy by exposing it to the light after its sprout. In this experiment the authors tried to clarify the mechanism about inhibition of setting-tuber's getting fleshy by its exposure. Main factors effecting growth in flesh of setting-tuber are temperature, light, and humidity in the ground. In this experiment, temperature and humidity were not immediate causes, but light was most effective for the refleshiness of the setting-tuber. The authors, therefore, conjecture that the cause of inhibition of setting-tuber growth is the radiation of light around it.

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Using several varieties of japonica rice, the auther observed the distribution of polysaccharides or starches near the shoot apex and the root tip under the microscope. The sections cut by paraffin method were stained chiefly by Schiff's reagent. The results are summarized as follows: 1. Normally two parts, 2-layered tunica and corpus can be recognized in the vegetative shoot apex. No polysaccharide granule can be found in the parts where the cells have much proteins and dividing activity; that is tunica, outermost layer of corpus, and leaf primordia just after differentiation. However, in later when the primordia of 1st order panicle branches cease to differntiate and shoot apex does not grow any more with only one tunica layer, small granules of polysaccharide appear even in the tunica and outermost corpus layer. In the vegetative shoot apex, cells in the 4th layer, that is the 2nd layer of corpus, begin to contain minute polysaccharide, and thereafter the cells of corpus located inwards and downwards contain gradually larger granules. It is suggested that sugars translocated from the leaves reach to the shoot apex, being consumed immediately by the active cell division without remaining any stock-polysaccharide, but that in the older cells which are relatively weak in cell division, sugars are stored as polysaccharides for a while. These polysaccharide or starch grains become larger as the cells become older and larger until the cells grow very rapidly into large ones consuming almost all starch contained there. 2. The axis is continuous from the corpus, but the differentiation of nodes and internodes are not clearly observed before the insertion of leaf-3 in which a band of starch begins to be recognized. Transitory starch grains are abanduntly stored in the nodal regions being larger as the nodes become older. At the VII node, the nodal plate grows into stellate parenchyma and the stored starch disappears, thereafter it does not store starch. Starch is also found in the internodes, but its amount is less than that in the nodal plate, especially in the central part which becomes lacuna later on. The cells in the VI-VII internode elongates so rapidly, consuming stored starch probably, that there can not be found any starch in the internode just after the completion of lacuna formation. However, the internodes gradually restore large compound starch grains soon which are dissolved and translocated to the other parts, especially to panicle, during the ripening period. 3. The base of young leaves also contain starch. The older the leaves become, the larger the starch in the size, and the largest starch can be seen in the base of 5th leaf. The starch in the 6th leaf base abruptly disappears, and this is probably due to the consumption caused by the rapid elongation of the cells. In this stage the leaf elongation almost ceases, adcompanying lacuna formation, and then the leaf-sheath restores much starch grains till they are translocated to the other parts, especially to panicle. 4. It is an interesting fact that the 6th leaf sheath, VI-VII internode, and VII node elongate very rapidly almost simultaneously accompanying tiller elongation and rooting from the VII node, and the temporarily stored starch in the above tissues disappears abruptly with their rapid elongation. 5. Root cap always contains much falling starch, but meristems of root tip scarecely have polysaccharide granules except the regions which Dr. Clowes called "Quiescent Center". In general, relatively great size of starch grains exist in the young metaxylem cells, and smaller ones in the cortex parenchyma, but in either case starch disappears with the rapid elongation of these cells, and thereafter they do not restore starch any more. But in the cases when much starches are forced to be stored in the tissues of shoot, restored starch can be seen in the cortex parenchyma in the base of each matured root. 6. [the rest omitted]

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The interrelationships among quantitative elements of the rice root system were discussed in two varieties, chiefly the relations between primary rots, root surface area and others. Number of primary roots must be the main factor which determines the whole development of the root system. The development of the root system must be ascribed to the extension of the root surface area, which may bring roots into contact with soil particles, nutritive elements and water molecules, so as to make the uptake increase. It was made clear that number of primary roots were significantly correlated with number of secondery roots, total length, total dry weights and the whole surface area of roots (Fig. 1. A∼F) (Fig. 2. A∼F). In addition, the whole surface area went hand in hand closely with number of lateral roots, total length and total dry weights of roots (Fig. 3, 4. A∼D). From these facts, the authors, were able to estimate the whole surface area from the regressions between the area and other quanta. For example, two formulae, such as log A=0.763+0.877 log W and log A=0.243+1.066 log W, were derived for the 11th and 3rd leaf stages respectively. High correlations were, moreover, ascertained between the presumable real surface area and the values calculated from those formulae, such as above mentioned and the theoretical one (A=N¹/₃×W²/₈), which was already proposed by the. author (1959) (Fig. 5, 6). Rot diameter was not always correlated with those quanta of roots mentioned above. Rot diameter was rather dependent upon the develpment of the constituting tissues, such as cortical layers and stele system (Fig. 7, A∼F). Cortical layers originate lysigeous cavities which concern with the oxygen supply from top to root and the stele system relates to the migrations of the nutrients and water absorbed. Thus root diameter must regulate the physiological activity in roots, inclusive of the whole plant. Among four varieties of which the resistabilities against soil reduction were known, the relation between the resistability and root tissue development was examined. It was in general clarified that the more resistant the variety was, the larger the development of those tissues were (Fig. 8).

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Authors investigated an influence of the surface drainage on the photosynthetic activity in rice field. The yield of rice plants was increased by the surface-drainage treatment given during a period from the end of feritile tillers formation until the soil moisture content decreased to 70%. According to the analysis of harvested materials, this yield-increase was chiefly due to the increase in ripened grains number, ratio of ripened grains to total grains in an ear, and weight of 1000 unhulled kernels. To know the reason for this, authors measured the apparent photosynthetic activiiy of rice population in field, and discussed the relation between the photosynthesis and other characters in rice plant. The total leaf area of rice plant in this drainage-plot was generally inferior to that of the constantly water-logged plot (cortrol-plot), both in the draining stage and in the subsequent irrigating stage. Connected with the total leaf area, the light transmission rate in the drainage-plot was always inclined to be higher than that of the control-plot. The water content of rice plant was lower in the drainage-plot than in the control plot, not only in the draining stage but also in the subsquent irrigating stage. Though the photosynthetic activity per unit area either of rice leaves or of the field was depressed by such draining treatment, it was promoted by the subsequent irrigation. This superiority of the photosynthetic activity in the drainage-plot lasted until the ripening stage and attributed to the yield increase. Although it has been reported by some researchers that the photosynthetic activity per unit leaf area has highly positive correlation with the water content in rice leaf blade, but in this study the correlation between them was partially disturbed because other factors caused by drainage treatment might presumably benefit the photosynthetic activity.

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The present investigation was undertaken in order to obtain some information on the mechanism of the dormancy in potato tuber. To do this, changes of phosphate composition in potato tuber upon its emergence and also in tuber slices which were subjected to various incubation treatments, were investigated. The results btained may be summarized as follows. Change in phosphate composition of sprouting potato tubers especially in the ratio of labile (readily hydrolysable) P to organic P, was larger than that in dormant tubers. As a result of incubating treatment in the solution containing inhibitor-β, the phosphate composition of the slice changed in different ways according to the kind of treatments; inhibitor-β brought about the decrease in the ratio of labile P to organic P, while the application of gibberellin or glutathione having antagonistic action to inhibitor-β, causes the increase in this ratio. It seems, therefore, to be reasonable to assume that the dormancy of potato tubers may be controlled by antagonistic actions between inhibitor-β and native gibberellin or glutathione contained in the tuber. In this case, change in respiratory system of the tuber upon sprouting may participate in the termination of dormancy of potato tuber by synthesizing energy-rich phosphate compounds.

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The volumes of plant organs and their intercellular spaces can be simply measured by means of measuring both gravity and buoyancy methods. The latter method surpasses the former one in accuracy of measurement. The buoyancy method is achieved by the following way: materials are first weighed in air (G₁), secondary weighed in the submerged condition in water (G₂), and once again weighed in water after having been infiltrated with water using an electric vacuum pump (G₃); in the case of gravity method materials are once more weighed in air (G₄), in addition to the weighing procedure of three times mentioned above. Then, the volume of the material is computed in mm³ from G₁-G₂ in the c se of buoyancy method and from G₄-G₃ in the case of gravity method. The volume of the intercellular spaces is computed in mm³ from G₃-G₂ in the buoyancy method and G₄-G₁ in the gravity method, respectively. At the measurement of leaf volume, it was confirmed that the measuring errror was less than 1%. By these methods, it is possible to measure not only in the case of turgescent organ but also wilted one. Using vacuum pump, precaution should be taken lest air should be remained in the organ. However, it was also confirmed that the measuring error owing to the above cause did not exceed 2% at 20°C. In addition, some conceivable theoretical errors caused by shrinking, deformation, infiltration of the leaf, etc. were discussed. But it was certified that they were quite negligible in this experiment.

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1). It carried out the ecological study on the main agronomical characters; e. g., yielding capacity, time of young ear differentiation, and elongation of upper stem internode, in rice plants taken by the movement of sowing time, for a research material to the planning of rice culture. 2). The numbers of elongated internodes in rice culm increase by the late croping, but in case of over-late croping these numbers decrease because of temperature in early fall. 3). The critical air-temperature of young ear differentiation in rice plant was 18°C., such as usual mentioned. However, in case of very short time exposure, the differentiation are not occurence even under this temperature. On the other hand, the elongation of internodes in a culm were possible in spite of very short time exposure, under available lowest temperature. 4). The elongation of terminal internode was clearly affected by low temperature, but the effect of low temperature to the internodes of stem lower part which being started elongation seems to be a little. 5). In the choice of rice variety forhigh yield, it should be thought the sum-temperature of them from seeding to heading; e. g., 2, 300°C in early croping, 2, 100°C in standard croping, and 1, 800°C in late croping. This problem, varietal responces to temperature, is very importance to the planning culture of rice, and to increase of effective yielding capacity in each varieties.

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The present study was undertaken to investigate, according to the previous paper, how to change the development of branching, curvatures and the shooting angles of roots in successive nodes when wheat and corn were planted under the different kinds of soil and manure. The following results were obtained: 1. The height and number of tillers were greater in compost plot and heavy fertilized plot and were inferior in clay plot. 2. The curvature and branching of rots were more developed in compost plot and sand plot but were meagerest in clay plot (Fig. 1, 2). Therefore number and length of secondary and tertiary roots were superior in compost plot and sand plot than in clay plot. 3. In compost plot the rot angles were large and elongated horizontally, but in sand plot the angles were smaller (Fig. 3, 4). From these results, it can be said that the root angle is influenced by soil conditions and there is a tendency that the root angle is larger when the plant is more grown.

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This experiment was carried on to find whether some relationship between rot hair formation and their elongation, and movement of nuclei and cytoplasmic granules in them exists or not. The living and killed root hairs were observed with the ordinary and phasic microscope. The following results were obtained. While root hairs initiated at about 1/3 of the way back from the apical ends of the short cells in epidermis, most of nuclei were located at the centre of short cells. After root hairs elongated to about 20∼30 μ, nuclei in short cells moved to the bases of root hairs and then migrated inside them. While root hairs were elongating, the nuclei inside them did not lie in a constant distance from the tip. For example, in the rot hairs measuring 150μ, the nearest and farthest points from the tip where the nuclei were found were 50μ and 125μ respectively. Furthermore, it was found that in the still elongating or already matured root hairs the nuclei continuously moved to-and-fro inside them and sometimes entered back to the hair-bearing cells. Two types of cytoplasmic granules were found in root hairs; one was 2∼4μ in diameter and the other 0.5∼1.0μ. The larger granules moved irregularly and independently of protoplasmic streaming, and strictly speaking, the movement of the small granules also did not keep pace with the protoplasmic streaming, that is, they sometimes stopped moving, and sometimes moved a short distance in the opposite direction against the streaming and followed it again. No difference was observed between the speeds of the protoplasmic streaming of the elongating and matured rot hairs. From these results it is concluded that there is no relationship between root hair formation and their elongation, and the movement of nuclei and cytoplasmic granules in root hairs.

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[in Japanese]

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