In order to find out a clue to diagnose the activity of rice roots, some experiments were conducted concerning the relation between the morphological and physiological characteristics of the root and its nutrient-absorption. The results of experients are as follows:- 1) Sprouting of new roots was most active at the stage of most vigorus tillering, declining thereafter with the advance of growing stage of the plant. And new roots were scarcely seen after heading. 2) The highest velocity of absorption of N, P₂O₅ or K₂O, expressed as the maximum amount of each nutrient absorbed by the root in a day, was observed at about the same date at the time when root-sprouting becomes most active and the number of healthy root tips per plant becomes most abundant, while the highest velocity of absorption of FeO, MgO or SO₃ and of SiO₂ or MnO were observed 10 days and 20 days respectively after that of N, P₂O₅ or K₂O (Fig. 3). 3) Absorption of NH₄-N and P₂O₅ by excised roots was most active in new roots (Class I or I & II), than in old roots (Class III, IV), while that of MnO was rather active in older roots. 4) These facts as above seem to suggest that N, P₂O₅ or K₂O is more vigorously absorbed by new roots than by old ones. 5) New roots, especially those belonging to class I, showed a high ability for absorption of N and P₂O₅, a high content of N, P₂O₅, a high respiratory rate and a high activity of cytochrome oxidase, indicating that an active respiration through the cytochrome-cytochrome oxidase system is responsible for the active absorption of these nutrients by new roots.

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水稲根の呼吸が硫化水素や二三有機酸の処理によりいかに変化するか, それに伴い根のα-Naphthylamine酸化力, 窒素, 燐酸の吸収がいかに変化するか, また土壌の種類や土壌還元あるいは排水良否が根の呼吸に及ぼす影響を研究した. (1) 硫化水素の影響. 硫化水素によつて根の呼吸は阻害されるが, その阻害率は水稲体の窒素栄養状態によつて異なり, 多窒素状態では比較的小さく, 無窒素では大きい. 根のRQは1または1以下であるが硫化水素処理により1以上に高まり, aerobic fermentationが起つている. 根の呼吸の低下に伴いNH₄-N及び燐酸の吸収は低下し, 特に後者では根からの排出が起る. ただある呼吸量の下でどの程度のNあるいはPを吸収するかは水稲体の栄養状態で左右されるので両者間の量的な関係は明らかでない. α-NA酸化力の大小は呼吸と密接な関係を示す. 硫化水素の影響は根の生育する土壌の種類で異なり, 秋落田, 湿田土壌に生育する根は硫化水素阻害率が高い. これら不良土壌に生育する根は老化と共に急激にその呼吸が低下する特長を示し, 根の活動期間が短いと考えられる. 他方硫化水素による呼吸の低下は老根より若根で著しいので, 結局不良土壌の根は硫化水素処理によつて阻害率が大きく表われる. (2) 有機酸の影響. 酪酸処理により根の呼吸は一時増大 (20～30%) するが, やがて低下する. 蟻酸, プロピオン酸処理では直ちに低下が見られた. 根の呼吸の低下に伴いN及びPの吸収も阻害されるが, 酪酸の場合呼吸が増大し, しかもチトクローム酸化酵素活性も増大して, 正常な末端酸化酵素系による呼吸が行われているにも拘らず物質吸収は低下することが見られ, 有機酸処理によりoxidative phosphorylationが影響されていると考えられる. 尚この場合にも呼吸とα-NA酸化力とは平行的に変化することが見られた. (3) 土壌還元と排水不良. 生藁や紫雲英の多施により土壌の還元を進めると, 最高分〓期以後出穂期以後まで根の呼吸は低下する. 排水不良田に生育する根の呼吸も対照となし得べき排水良好田に於けるより低い. 以上の結果から水稲根の活力診断所上根の呼吸の大さが役に立つものと考えられ, またα-NA酸化力の比較は実用的な方法となり得るように思われる. 尚本研究は農林水産技術会議の「稲作に於ける土壌と水」に関する研究の一環をなすものである.

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Differences in qualities of starch, activities of amylase and phosphorylase, content of inorganic nutrient were investgated with plants grown on field with and without calcium silicate. The results are as follows: 1. Starch contained in the culms differs to the starch of the grains in the following points that (a) the former exerts more bluish coloration by Iodine reaction contrary to the redish coloration of the latter and also (b) the former shows larger transmittancy. 2. Transmittancy of starches in culms and panicles show high percentages, especially in the late ripening period, with the process of plant growth and in well-drained field as compared with illdrained field. 3. Amylase activities in culm bases especially at ripening time were declined in ill-drained field. These facts may be the important causes of the poor ripenihg in this field. 4. Weight of 1, 000 grains being a useful index of ripening was increased with the appilication of calcium silicate both in well-drained and ill-drained field, but when ammonium sulfates were too heavily fertilized, the effect of calcium silicate was not observed. 5. It was recognized that weight of 1, 000 grains shows a positive correlation with the percenages of silicate and phosphate contents in straws and panicles, but a negative correlation with the percentages of total nirtogen content.

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With the object of throwing more light on the mechanism of deterioration of fertility of wind-damaged rice plant, a series of experiments were conducted in which potted rice plants of various stages (during 20∼30 days before and after heading) were treated with wind (15.5m/sec. hr.), and their nutritional status after treatment were examined. The following conclusions are drawn from this study. 1) Water absorption of wind-damaged rice plant increased with the rapid increase of transpiration rate ; however, as a whole, water economy of the plant was in unbalance, and leaf-withering occured, moreover, differentiation and development of growing region and panicle came to be retar ded. 2) The occurrence of leaf-withering not only cheked the transpiration rate, but also decreased water absorption by and through root, as a result, the physiological function of root degraded the absorption of solutes, their translocation, accumulation and metabolic activity were retarded. 3) The increased leaf-withering and the reduction of capillary and constitutional water hindered carbon assimilation ability, while increased respiration rate resulted the accelerated consumption of assimilated products; this, in turn, caused further nutritional deficiency. To sum up, it is concluded that the traditional views "that the deterioration of fertility of wind-damaged rice plant is to be attributed to a direct injury by wind or storm", lacks experimental bases. On the other hand, it now seems a reality that the deterioration of fertility of wind-damaged rice plant is caused by subsequent nutritional disturbance. This is especially accountable for the fact that damages of rice plant after the Earforming stage are markedly severe.

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Rice plants, Variety Norin 37, were grown on the paddy field according to the usual culture plactices. They were covered by shading frames which have several light transmission factors at the various growing stages. Increasing of dry matter weight during the treated period and photosythetic ability was measured, and also the other physiological factors. The results obtained were as follows: 1) The increasing of dry matter weight had an intimate correlation with the light intensity in case of comparatively high light intensity throughout each stage. 2) In case of slightly shading, the photosythetic ability of a rice community developed more than normal ones at the end of 1 week after the initial shading treatments. It is due mainly to the increasing of unit photosynthetic ability, on fresh leaf weight basis. 3) The relation between the photosynthetic ability of fresh leaf weight basis and the water content in a leaf are shown at figure 9, which brings out of the fact that they have an optimum point, but this is changeable in accordance with the growing stages.

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Experiments were carried out to examine the effect of nucleic-acid on heading-retardation of rice plant grown under cool weather, applying to the soil before transplanting. The results obtained are as follows : 1) Heading-retardation produced by a treatment of 7 days' low-temperature (17°C) was diminished about 1∼3 days with nucleic-acid application at any growing stage. 2) Heading-retardation of the late-variety grown under natural cool weather was diminished about 3∼6 days with nucleic-acid application, but the same application was not effective to the medium-variety. 3) It was faintly suggested that the effect might be caused by the function of nucleic-acid itself but not by that of each component.

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1. Lodging of rice plant affected by drainage or deep water irrigation practice at different time was studied (Table 1). Soil moisture, Eh-6 of soil and NH₄-N content of the soil layer of 5∼6 cm depth are influenced by drainage (Fig. 1). Drainage or deep water irrigation produces the good or adverse effect on breaking strength of the internodes N₄ and N₃ of var. Norin No. 8, which are elongating just at that time, but scarcely affects on the internodes of var. Yuubae, which elongate after that time (Fig. 2). And index of lodging corresponds nearly with the natural lodging of rice plant in the field (Table 2). The development of lysigenous aerenchyma and the mechanical tissue of the internode N₃ is makedly affected by tratment. 2. Progressive change of the index of lodging at ripening stage was studied. Breaking strength of the lower internodes becomes small rapidly during 30 days after heading time, nevertheless moment varies in small scale. So, when the index of lodging (distance of fulcra is 5 cm) rises above 200, the plant is liable to lodge (Fig. 3).

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In the previous paper, the influences of the mode of hill arrangement on the density effect for yield and various characters of rice plants was examined, in respect to the continuous changes from the square hill arrangement with a-plant-planting per hill to the square hill arrangement with four-plant-planting per hill, through the nest arrangement of hill. In this paper interrelationships between spacing density and the mode of hill arrangement in respect to the continuous changes from the square hill arrangement to the row arrangement pass through the rectangular hill arrangement is reported. The experiment was conducted at Kashimadai Farm, Institute for Agricultural Research, Tohoku University, in 1957. Fixing the distance between rows constant and increasing the density by reducing the hill spacing in the row, yield-density relationship coincided also with the low of C-D effect as was stated in the previous papers. In regard to the relative situations among square, rectangular and row arrangement of hill in the same density, the maximum grain yield per unit area obtained at the point which the retio of row distance to hill djstance in a row is 2 : 1 or 3 : 1.

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In rice culture, the planting densities are determined by two factors, viz., the number of seedlings per hill and that of hills per unit area (spacing). This experiment was conducted to investigate competition in composition of tillers under 15 different planting densities (Table 1). Two Varieties, Norin 6 (Panicle number type) and Norin 22 (panicle weight type) were used, and hills were arranged in square. On the number of tillers analysed according to their order (Fig. 1), 3rd tillers decrease at any plot under intense effect of competition, 2 nd tillers begin to decrease at the point of 3-4 seedlings per hill in spite of increase in seedlings per hill, and it corresponds nearly with the point of which 3 rd tillers decrease to zero. 1st tillers increase at each plot and may be so to a certain densities. As to the varietal differences both in competition of inter-hills and itra-hill, we may say as follows : panicle number type is more intensely effected at lower order tillers than panicle weight type, and vice versa at higher order tillers (Table 2, 3). Simultaneously emerged tillers showed the distinctive tendency (Fig. 2), viz., with the increase of seedings per hill and of hills per tsubo, the percentage of tillers which emerged in early stages increased. From the standpoint of composition of tillers, the increased number of seedlings per hill and of hills per tsubo are desirable so far as this experiment is concerned.

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1) We had already observed the fact that the early season rice culture gave higher yield than the usual, and ascribed the reason mainly to the larger number of panicles per unit area in the former, after analysing the relation of yielding factors. 2) Rice plant grown in early season had more available tillers on the main stem, as the lower nodes bear tillers, thus enlarging the tillering zone on the stems (Fig. 1). This was true with different growing-types. 3) At both stages, when the number of available tillers was determined and when the number of tillers came to the maximum, each stalk of early season rice plant was smaller in size, but the content was quite different, the total sugars and starch percentage and the quantity per one stalk being higher than usual (Fig. 5). We supposed such fact might be attributable to the higher productivity of early season rice. 4) The result of investigation showed tolerable correlation (-) between plant height and the number of stalks per unit area among the date from many different districts in Japan (Fig. 4). The growth form ……Shorter stalks and more tillers……was generally observed in early season cultivation as well as cooler-region cultivation (Fig. 2). We have also ascertained the same phenomenon in early season, comparing between the out-door growth (lower temp.) and the glass-house growth (higher temp.) of rice plants (Fig. 3). 5) The conclusion was that the lower temperature must be favourable for tillering, rather than higher in natural circumstances, and might be beneficical for increasing the number of panicles of rice plant, thus resulting the higher yield.

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For the purpose of diagnosing nutritional status leaf analysis of rice plant, var. Norin No. 37, was carried out 1952∼54 by field experiment of N, P & K fertilizer treatments. The previous report showed that N, P & K concentrations of the particular parts of plants responded well to the N, P & K fertilizers respectively, and that the N status of the crop reflected good in the top L. B., and that the P & K status did in the 3 rd L. S. from the top leaf. This report, while confirming the above-stated results, is concluded as follows: Part VI, 1. The response of N fertilizer was detected properly in the N concentrations of the top L. B. during the vegetative growth period, and in those of the 3 rd L. B. as well. 2. The differences of the N concentrations of L. B. between N applied plots and non-N ones were remarkable under any combination of N, P & K during the vegetative growth period, and the values of N concentrations in the L. B. of non-N plots were determined to be the critical N concentration indicating N deficiency. 3. The critical N concentration of the 3 rd L. B. was also gained in the same way as in the top L. B. 4. Though in the top L. B. the P status was found, it was of little use. On thd other hand the differences of the P concentrations in the 3 rd L. S. between P applied plots and non-P ones were noticeable. The P values of the part were decided to be the critical P concentration indicating P deficiency. 5. The K status was assessed in the 3 rd L. S. and the critical K concentration was also obtained in the same manner as in the P status. 6. As the L. B. and L. S. did not always respond to the effect of fertilizer after heading stage, the part could not be used for this purpose, while the 14 th I. N. responded considerably to the effects of N & K supplies even at this stage. Therefore it seemed that this part could be used for the diagnosing of N & K status at heading time. 7. The nutritional status as to whether the rice plants are deficient in N, P & K or not on all fertilizer treatments is to be diagnosed by means of the critical N, P & K concentrations respectively during the vegetative growth period. Part VII. 1. N-P-K equilibrium, namely N, P & K composition percentage of NPK-unit, varied greatly in the parts of rice plant; L. B. had highest N and lowest P & K composition percentage, L. S. had higher P & K and lower N than those of L. B., and culms had lowest N. 2. N-P-K equilibrium of the top L. B. fluctuated according to the fertilizer treatments and the seasonal stages. As to the seasonal change of N-P-K balance, N composition percentage was highest at early tillering stage, then, as the growth progressed, it decreased, which caused K to increase (P changed little), and it reached min. value at young ear formating stage, and backed again a little at heading. 3. Effects of fertilizers were striking during early growth stage, that is, N, P & K composition percentages increased by the supplies of N, P & K fertilizers respectively, but the effects diminished after young ear formation. At heading stage N-P-K balance was nearly constant under any treatment of N, P & K; it is an interesting fact that the plants maintain constant balanced nutrient status. 4. N-P-K equilibrium in the 3 rd L. S. was greatly affected by the fertilizer treatments, and it responded the N, P & K supplies, while the L. B. did mainly in the N composition percentage. 5. In the case of N-P-K equilibrium in the 3 rd L. S., as the growth proceeded, N composition percentage decreased. On the other hand, P composition percentage increased and K composition percentage also increased except in the plots of the excess K supplied condition such as PK, K & Nil plots. 6. N-P-K balance in the 14 th I. N. of culm responded to the fertilizer treatments at heading time. 7. [the rest omitted]

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The traces for leaves and tillers were followed back along the stem by examining successive sections made across it. Their courses downward through the internode above the point of insertion of a leaf to a node are illustrated in the diagram. (Fig. 1). When the leaves were supplied with radioisotope P³² solution for a short time, it was proved, as shown in Fig. 1, and Table 1 and 2, that the quantity of P³² transferred to the other leaves and the tillers was clearly conformed to readiness of connection among their vascular strands at the node.

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The author previously made an investigation on the local characters of paddy rice using the results of variety-test conducted at each Prefectural Agr. Exp. Station all over Japan from 1931 to 1955, and here he will illustrate the local characters of the prefectural recomended varieties of all over Japan in 1955. The maximum, minimum and mean values of heading date and hervesting date of all prefectural recomended varieties of all over Japan from the North to the South are shown. And the local mean value of plant height, number of tillers and yield per "tan" of prefectural recomended varieties and then the variety test of all over Japan from the North to the South are shown. Lastly the local correlation coefficient among paddy characters was illustrated.

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Starch produced and accumulated in the straw particularly in leaf sheath and culm by the heading time is translocated into the growing dars after heading. Thus at 20∼25 days after heading starch content in the straw decreases to almost trace. In the following period starch accumulates again in the straw vainly. It is caused by the excessive production of starch by photosynthesis beyond the sufficient amount of starch required to grain development. In the control plots, amount of starch accumulated in the straw by the heading time and that accumulated again at the later stage of ripening vary with the different condition of nitrogen supply, indicating the balance between the number of spikelets and the quantity of starch produced, ie, the balance between the number of vessels and the quantity of substance to be delivered into them. Thus, in the plot B, starch production is less in relative proportion to the greatest number of spikelets formed due to high nitrogen level, and consequently the reaccumulation of starch is the least. On the contrary in plot C, being supplied with nitrogen top-dressing at the heading time, starch production is excessive in proportion to the number of spikelets and starch is stored in the straw vainly, because nitrogen supplied at the heading time has no effect in increasing the number of spikelets but is very effective in promoting photosynthetic production during the period after heading (fig. 2 and 3). The balance mentioned above determines the seed-setting percentage as well as the weight of grains (fig. 4). In the shaded plot, starch contained in the straw before heading is exhausted more rapidly than that of control plots and no further accumulation takes place. Translocation of carbohydrates from the straw to the ears is recognized not inhibited by the shading treatment. The seed-setting rate and weight of grains in the shaded plots are lower than these of the control plots. The difference in the seed-setting rate and weight of grains is caused mainly by the difference in these characters of spikelets located on the secondary rachis-branches, ie, the spikelets on the secondary rachis-branches, excluding spikelets at the top of the branches, are very changeable in these characters and are very influential in determining these characters as a whole ear (fig. 5). Content of nitrogen, phosphorus and potassium in the plant as well as the total amount per hill of these nutrients are determined with the control plot and the shaded plot in plot A. It is shown that the shading treatment inhibits remarkably not only the absorption of phosphorus but also the teanslocation of this element from the straw to the ears, whereas there is no such a change with nitrogen and potassium (fig. 7 and 8).

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1. A noticeable fact was drown out from the present experiment that the rice plants, which possess the same amount of carbohydrates and the different number of spikelets, always differ not only in the percentage of ripened grains but also in the actual number of ripened grains and in the yield of grains, and the excessive spikelets in number always act on the plant to decrease the number of ripened grains and the yield of grains on account of causing the plant to increase the number of imperfectly ripened grains which are to be eliminated in the course of threshing, husking and cleaning. From this point of view it was emphasized that the excessive growth of rice plants often brings about a rather much reduction in yield of rice-grains. 2. It was made clear that a high content of nitrogen ih rice plants at heading time, which has hitherto been considered to be more injurious than beneficial to ripening, does not damage the ripening of grains, but rather favors it, enabling rice plants to raise their photosynthetic activity. The reason why a high content of nitrogen at heading time has been considered to damage the ripening could be explained by the fact that a high content of nitrogen brings about a large number of spikelets per plant and a large number of spikelets per plant are liable to act on the plant to decrease the percentage of ripened grains. 3. The amount of carbohydrates accumulated after heading, which was proved to be most inportant in constituting the yield of rice in the present experiment, was strongly correlated with the total amount of nitrogen which is the product of the dry weight of rice plants and the nitrogen content in rice plants. And the product of the total amount of nitrogen in rice plants and the total amount of solar radiation expressed in calorie was ascertained to be highly correlated with the grain-yield. From these facts, it was pointed out that the total amount of nitrogen in rice plants at heading time would be of great importance in predicting the grain-yield of rice.

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1. 3 days after the frowering, the endosperm cells migrate towards the walls of the embryo sac against the impoverished nucellus. (Fig. 1) 4 days after the flowering, the endosperm cells undergo rapid divisions. 5 days after the flowering, these initial endosperm cells undergo further divisions. Cell divisions proceed until the whole sac becomes completely filled up with endosperm tissue. (Fig. 2) 6 days after the flowering, the endosperm cells begin to from the aleurone layer, so cell divisions already have done. (Fig. 3) 7 days after the flowering, the center line appears clearly in the middle of young kernel. Around the center line the starchy endosperm cells are spindly shape with their longer diameters parallel to the long axis of the kernel in the longitudinal section. In this form the length of kernel is nearing completion. (Fig, 4, 5) Since then the starchy endosperm cells grow up in dorso-ventral direction and become rectangular with their long diameters parallel to the minor axis of the kernel in the longitudinal section. (Fig. 6, 7, 8) In that form dorso-ventral diameter of kernel is nearing completion about 10 days after the flowering, but few layers of starchy endosperm in the neighbourhood of aleurone layer continue to grow up until about 15 days after the flowering. The growth of lateral diameter of kernel is similarly done as that of dorso-ventral diameter, and is nearing completion about 15 days after the flowering. Rice kernels begin to become translucent from the center line, and the translucent area proceed around, and that progression in the ventral part of kernel is slowly than in the dorsal part. There is high correlation between the ventral diameter and the dorso-ventral diameter. (Table 1, 2). 2. White-belly is frequently observed in grain that has large ventral part of kernel, and this shows that nutrient locomotion is insufficient to fill the well-developed ventral part. Sometimes, white-belly is found in grain that has minor ventral part ; in this case, it is recognized that the accumulation of nutrient is too poor in spite of decrease of ventral part. (Table 1, 2). 3. In the notched-belly kernel, it is observed that the atarch-cells of the notched portion of the kernel nearly stopped their growth at early atage of development, but those of the other portion continued their growth, and in milk-white grain, the starchy endosperm cells of opaque part show poor development and insufficiency of nutrient accumulation. (Fig. 11, 12, 13, 14, 15).

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In order to make clear the causes of sterility of rice flowers damaged from wind, we investgated on the pollination, pollen-germination and fertilization of the flowers exposed to the artificial strong wind generated by the wind tunnel. (1) Many sterile flowers were found after the treatment, especially among flowers bloomed on the day of the treatment. (2) The number of pollination and germination of flowers bloomed on the day of the treatment varies widely, but, on the other hand, we recognized little difference between those of untreated flowers and flowers bloomed after the day of the treatment. (3) It was found that flowers, bloomed just before or just after the beginning of the wind treatment, were unpollinated of if not, pollinated only a little, and it is considered that the fact was one of the causes of the occurrence of sterile flowers. Among flowers bloomed in the late half stage of the treatment, on the contrary, there were many pollinated extremely, and, although these show the low percentage of germination, it is considered not to be the direct cause of the sterility, because they have many germinated pollens. (4) As the causes of being unpollinated or polinated only a little, it is considered that blooming of flwors was hastened by the wind, nevertheless the dehiscence of anthers did not follow close to the blooming of flowers. We may suppose such a mechanism to be plausible from the model experiment by the artificial stimulus such as rubbing with fingers.

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1. The structure and physiology of vegetative shoot-and inflorescence apices in rice plants grown on normal and degraded paddy fields were compared cyto-histologically. 2. The volume of the vegetative shoot apex in the rice plant grown on the degraded paddy field became smaller than that on the normal paddy field from about the middle of July, and this difference in volume was caused by the number of cells which constituted it, and the mitotic activity of the vegetative shoot apex of the degraded paddy field was lower than that of the normal paddy field. 3. The number of tunica layer was fewer and the time of beginning of destruction in the stratification was earlier in the shoot apex in the rice plant grown on the degraded paddy field (Fig. 2). The apex at the transition stage also showed the fewer stratification and, as already shown by Hsu, Sharman and Esau, the apical meristem of the primary branch primordium was gradually organized to the same pattern found in the parent shoot, that was, the apex at the transition stage, initiating the secondary branch primordium which developed in the same manner as itself (Fig. 2, 4). 4. From the general observation on developmental changes of the structure of the shoot apex (Fig. 1), it should be said that the fewer stratification and the earlier destruction of it in the rice plant grown on the degraded paddy field indicate that the shoot apex of it is less vegetative physiologically than that on the normal paddy field. 5. The less vegetative condition and the lower mitotic activity of the apex in the degraded paddy field plot resulted in the earlier transition to the reproductive stage of the vegetative shoot apex, and induced not only the fewer number of vegetative organs-leaf, branch, and spikelet etc., but also the smaller morphology of them (see Table 2, 3. Fig. 3), with the lower grain yield than the normal paddy field plot consequently. 6. Development of the corpus portion was also poor in the shoot apex in the rice plant grown on the degraded paddy field, and the cells of which were of larger size, more vacuolated contents which stained relatively lightly, and the earlier formation of the central lacuna in the internode was observed. 7. The degraded paddy field used in this experiment was a ill drained paddy field, and the soil of the furrow slice of it showed little evidence of active iron compounds and in mid-summer the reduced layer of the furrow slice emited H₂S gas remarkably and the attack of Helminthosporium leaf spot occured exceedingly. 8. The apices in rice plants grown on the more typical, well drained degraded paddy field will be investigated with the same method in the near future.

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The nitrate reducing power of plant roots, i. e. nitrate respiration, has been studied in reference to oxygen transport from the top down to the roots. The results obtained are summarized as follows: (1) Attached roots of lowland plants, which are equipped with the highly developed ventilating system, are by far weak in their power of nitrate reduction, as compared with those of upland plants, whose system is feebly developed. (2) Detached roots of any species reduce nitrate very strongly. (3) These results indicate that the plant roots are, without exception, able to reduce nitrate for the purpose of liberation of free energy, as the oxygen content in a culture medium becomes too low for the roots to perform aerobic respiration, in case internal supply of oxygen is suspended. (4) Nitrate reduction may be catalyzed by nitrate reducing enzyme system, whose activity in the foots is not varied so widely with plant species. Occasional exudation of this system from a wounded part of the roots into a medium may expedite nitrate reduction in vitro, consequently giving rise to a feigned increase in the nitrate reduction by the roots.

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The authors tried to determine root types, using 280 cultivated rice varieties continuously grown in nursery. Nursery conditions favoured to make varietal defferences of root characters clearer than paddy field conditions. Three root types such as I, II and III were proposed by combining both root diameter and colour (Fig. 1). 1) From type I to III, roots became thinner and paler in colour (Tab. 1 & Fig. 8). Shoots also went hand in hand with root types, showing poorer growth in height and weight (Fig. 3 & Fig. 4). But thinner root types had larger ears in weight in contrast with culms (Fig. 5). Thicker types showed leaf tip burn earlier than thinner ones and showed also lower promotion of premature heading in nursery (Fig. 6 & Tab. 5). From these, root types suggested different abilities of physiological function. 2) Majority of varieties cultivated in temperate zone of Asia belonged to type II and III, but local varieties in Japan, "Hsien" in China and tropical ones included large numbers of type I (Fig. 2). 3) Among those varieties including type II and III which had different resistabilities against soil reduction, there were also differences of root diameter. The more resistant the variety, the larger the root diameter (Tab. 7). More resistant ones were, moreover, capable to produce larger numbers of roots and longer ones, even in solutions which were made reductive by adding hydroquinons (Tab. 8). These facts explained their resistabilities from morphological viewpoints as well as from physiological points already studied by many investigators.

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In order to know how different temperature affect the protoplasmatic streaming in pollen tube of rice plants, the rate of protoplasmic streaming (μ/sec.) was mesured under microscope from 5 minutes after setting of pollen on the germination media. 1) Changes of the streaming rate were examined with time under 20°, 30°and 38°C temperature conditions by using 7 Japanese varieties. Results are shown in Figure 1. At 30°C the initial rate of streaming was very high, but it was then slowed down. Under 20°C condition the rate was always low during the whole period of the experiment. However, when the temperature rose to 38°C, it was found that the initial rate of streaming showed the intermediate values between those of 30°C and 20°C, but it became low as the time went on. In all experiments, no varietal differences were found in the streaming rate without some exception. 2) Experiments were carried out to investigate the effect of changes in temperature (30°⇄20°C) on the rate of protoplasmic streaming. The germination beds were transfered from 30°to 20°or fro, 20°to 30°C 10 minutes after pollen setting. In the check plots it was mesured without giving temperature change. The results are given in Figure 2. According to those in the 30°→20°C plot, the rate of streaming became slow 1∼2 minutes after changing of temperature. The rate lay between those of both 20°C and 30°C check plots 4∼10 minutes after changing. In 20°→30°C plot, the streaming rate became very high immediately after changing. But the rate was lowered with time, being followed by somewhat lower rate than 20°C check plot found 8∼10 minutes after changing. These results suggest that the protoplasmic streaming is very sensitive to change of temperature.

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1) We investigated the influence of NaCl solution upon the germinating force, using unhulled rice (paddy) and hulled rice. 2) The seeds were submerged in the petri dishes with 3, 5, 7 and 15% NaCl solutions for 1 to 7 days, but the seeds were not germinated in these solutions at all. Then we examined the germination of them in the distilled water. 3) We showed the influence of NaCl upon the germinating force with the percentage of germination in the distilled water. 4) The percentage of germination in the distilled water was large in paddy and was small in hulled rice, thereby we recognized that the salt injury for germinating force was severe in hulled rice than in paddy. 5) The differences in the percentage of germination (the influence of NaCl upon the germinating force) between paddy and hulled rice were owing to the salt content of seeds, that is the salt content in paddy (husked hulled rice after treatment) was little and that of hulled rice was much.

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WEAVER, J. E. pointed out in his textbook that, "root of cultivated plants, contrary to current opinion, are not superficial but deeply seated……The old idea of roots being superficial is so commonly believed that many current textbook still speak of them as shallow." The majority of the roots of cereal crops, indeed penetrate deeper and others spread obliquely downward ; but barley roots, as he also stated in his book, often occur nearer that surface than those of oats or wheat; and if we refer to the Fig. 82, Manchuria barley of 20 days old ; though there are no descriptions about it ; yet we must perceive that, our seminal roots among the six have spread almost horizontally. Result of the observation carried out by the authors are as follows; 1 Barley plant In the observation in barley plant at the second leaf stage, two or three seminal roots out of five have penetrated almost as shallow as a depth of 2 cm., in which the seeds had been planted (Fig. 1); while wheat roots have penetrated somewhat deeper than those of barley. In the barley of fourth leaf stage, when one tiller had developed on most of the plants, three to five crown roots has spread near the surface of soil, but slightly deeper than the seminal roots. 2. Rice seedling In the rice seedling sown in nursery bed, at the fourth leaf stage, superficial roots has become in sight here and there on the soil surface. At the end of nursery period, a great number of superficial roots has spread over the surface of soil (Fig. 2). 3. Transplanted rice plant Seedling of seventh leaf stage has been transplanted in the field with a depth of 5 cm., and made hill up the earth around the stools at the 11th leaf stage, and the 13th leaf stage with a height of 3.3 cm., respectively; then about five to seven day after, several superficial roots has emerged from the soil as shown in Fig. 3. It should be noticed that the greater part of the roots in rice plants to be sure penetrate downward, but within the limits of these observations; contrary to current opinion, a part of them spread obliquely upward.

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1) No distinct border was observed between coleorhiza and scutellum at the resting stage, and coleorhiza fused with scutellum shortly above the lower part of scutellum. The border became clearly visible and fused diagonally with scutellum at the germination. 2) The border of coleorhiza of epiblast side was not clear in the resting stage, but it became distinct at the germination. 3) Rice had one empty space between seminal root and coleorhiza, while barley, wheat, oat and rye had 3 (usually) empty spaces and these spaces were detached from each other by the coleorhiza tissues. 4) From the results mentioned above and reported in the third and the fourth reports of this series, morphological features of coleorhiza were compared among rice, barley, wheat, oat and rye, and results were shown table 1.

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In the previous paper, the author reported some results concerning the correlation between growth of the primary roots and development of the leaves at the successive nodes of the main stem. In this expeliment, the author observed that correlation exists between development of the branch roots and the leaves. 1. The secondary roots began to branch regularly, with the elongation of the primary roots, from the base of the primary roots to the tip. 2. Development of the primary roots, secondary, tertiary and the fourth roots etc. proceeded at the same pace as the emergence period of the leaves. 3. When the growth of the above-ground parts was restrained and also when the growth of the roots was promoted by cutting, the development of the branch roots and emergence of the leaves showed the regularity which was recognized above. Judging from these results, we are assured that the close relationship exists in these matters. 4. We also can use the degree of development of the branch roots as a standard to distinguish old and the new roots.

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When a wheat spike infected by head blight but with a healthy culm is put in 0.5∼1.0 % eosin aqueous solution, it absorbs the eosin solution up to the portion of rachis just beneath the part to which the infected spikelets are attached. By this staining method of spikes, the author observed that the water flow in vascular bundles in the rachis was stopped at the portion of the rachis infected by head blight. According to this fact, the author classified the injuries of spikelets (or grains) on the whest spike infected by head blight into 2 groups as follows: (A) Spikelets (or grains) directly infected by head blights. (B) Spikelets (or grains) withered because function of conducting water and nutrients was lost in the rachis which was infected by head blight. And the author found that the rate of growth of head blight in rachis, especially that of downwand growth from the infected segment of rachis, showed varietal differences. For example, the downward growth from the infeced segment of rachis, showed varietal differencea. For example, the downward growth of the disease within rachis was more rapid in the case of Shinchunaga (a resistant variety) than in the case of Saitama No. 27 (a susceptible variety). From these results, the author arrived at the following conclusion : The sooner the rachis withers by infection of head blight, the more rapidly the spikelets (or grains) attached to the rachis wither. Thus, in case of a variety, such as Shinchunaga, having a rachis which withers soon after being infected by head blight, the infection to surrounding spikelets stops due to lack of moisture in the spike, since head blight requires rather high moisture for its infection and growth. On the contrary, in case of a variety Saitama No. 27, having a rachis which withers rather slowly, the disease gradually spreads from the infected segment of rachis to the unwithered lower portion, and thus, results in severe damage.

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The influences of night temperature on the water economy in some grass and legume plants were observed. The results of the experiment were as follows : 1) The cool night conditions of this experiment were favorable to the growth and yield of red clover, timothy and Italian ryegrass. Especially, red clover was susceptible to injury of a high temperature. On the other hand, ladino clover seemed to be adapted to the warm night conditions. 2) As the air temperature was going down in autumn, the cool night conditions became less favorable for the growth of all species tested. Above all, Italian ryegrass was susceptible to a low temperature. 3) The amount of water transpired through grass and legume plants was directly proportioned to the amout of water evaporated through Livingston's spherical atmometers. Namely, the march of transpiration from these plants followed the march of the evaporating power of the atmosphere, and especially that of air temperature and sunshine. 4) In general, the cooler night temperature yielded lower figures for the water requirements of red clover, timothy and Italian ryegrass than the warmer night temperature in summer. On the contrary, through ladino clover plant the water was spent efficiently under the warmer night temperature. 5) As the air temperature falled in autumn, the water utilization of all these plants became to be uneconomical. To the fall of autumn temperature red clover was the most tolerable and Italian ryegrass was the most susceptible of all except timothy.

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The soil temperature is one of significant factors affecting the growth of plants, but no study was intended to examine the effect of soil temperature in winter period upon the growth and yield of wheat varieties. In this study, two winter wheat varieties: Konosu No. 25 and Norin No. 17 were used and seeded in the containers at Dec. 1. 1957. The soil temperature treatments were performed by placing pots in two constant temperature water tanks at outdoors maintained at about 6°C. and 11°C. in winter period (Jan. 11.-Mar. 31.) respectively, but those temperatures were rised about 5°∼6°C. during Apr. 1. to May 31. (Fig. 1) The results were as follows: 1) The growth of both top and root were retarded by low soil temperature (ca. 6°C.) and the degree of retardation in growth by low soil temperature was larger in root. 2) As the development of ears were promoted by high soil temperature (ca. 11°C.), heading, flowering and ripening times were hastened about one week by high soil temperature treatment. 3) Grain yield was significantly increased in the high soil temperature plot in Norin No. 17, but in Konosu No. 25, there was little difference between each plots. 4) From the above results, we concluded that the soil temperature in winter and early spring affects markedly on the vegetative and reproductive growth of wheat plants and there is varietal differences in the degree of retardation of growth by low soil temperature. It is supposed that the susceptibility to low soil temperature of Norin No. 17 may be related to the cold and snow resistance of this variety.

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The formation of nodules was limited generally at the baseal portion of root or rootlet in leguminous crops even though growing under the different external conditions. These experiments were carried out to make clear the mechanism of the phenomenon above mentioned. 19 species, including 48 varieties, of legminous crops were used as materials just like the previous experiments (KAMATA, 1958 a). All the crops were cultured with different levels of nitrogen supply, under different conditions of shading or on field. The distance from the base of root to nodule, the number of nodules in each level on root and the dry weight of nodules per plant were measured in the progress of growing of each crop. The development of nodules were observed at the basal portion of root or rootlet in all the cases examined, with only one exception, Pisum Sativum var. Beikoku Ohosaya. The relation between the levels of both the differentiation and maturation of tissues in root and the formation of nodules was observed histologically with a serial cross-sections and longitudinal sections of the whole primary root of Glycine Max Mere var. Norin. No. 1, Pisum Sativum var. Nihon Kinusaya and Arachis Hypogaea var. Southern Cross, and the following two cases were found. Rizobium penetrated into the host tissue at the portion of primary root, in which roothairs were growing, in soybeans and peas, but no bacterium was detected under the level of secondary root appearance on the primary root in peanuts. The Glycine Max Mere var. Norin No. 1, Pisum Sativum var. Nihon Kinusaya and Arachis Hypogaea var. Southern Cross were cultured on sand under sterile condition. The primary roots of the seedlings, 12cm in length, were divided into 5 pieces (ca. 2.0∼2.5cm), and the in lateal roots 3 pieces (ca. 2.6cm). The contents of total sugar, reducing sugar and total nitrogen of the pieces obtained from equal level of roots were measured. Both the total and feducing sugar contents increased with aging of tissues, and the basal portion of root or rootlet had the highest concentration of sugars utilizable for the growth of nodule bacteria.

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In the field experiment, winter crops (naked barley, wheat, rape and common vetch) were cultivated on soils where summer ones (upland rice, sweet poteto, peanut and millet) had been cropped. In the pot experiment, the soils from each of 3 nutrient element experimental plots where those summer crops had been cultivated were used, and naked barley and common vetch were planted in those pots. 1) Better growth of wheat was recognized by following peanut than after other crops, viz. the order being as follows : Peanut>millet>upland rice>sweet poteto and naked barley, rape and common vetch yields were in similar trends, respectively. The soils where peanut or sweet poteto had been cultivated contained more aggregate than the soils that other crops had been grown, after the harvest of succeeding winter crops, however, such a fact in soil structure was not recognized. Peanut and millet gave good influences on the succeeding crops. Wheat and naked barley were remarkably influenced by the preceding crops. 2) Better growth and dry matter yield of naked barley by the pot test were found when it followed peanut or millet than other crops, and it yielded the least when it followed sweet potato. It was the same with common vetch. Residual N in these soils was effective only a little on the succeeding crops, especially in the soils where sweet poteto or upland rice had been cultivated, but generally we recognized a more remarkable effects of residual P₂O₅ and K₂O. Application of N was more effective than that of P₂O₅ or K₂O, especially on naked barley following peanut and on common vetch following sweet poteto. This pot test showed the same results as the field test, and so, pot tests may be used instead of field tests in such cases as the present ones.

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In 1953, experiments were performed as a part of the fundamental works for the purpose of setting a weeding system in field management. After perfect weeding at the time of sprouting potato plants were subjicted to 10 conditions differently controlled by weeding and cultivating in different periods in growth, and the influence of the weed volumes at the harvest time on the crop yields were examined. The weed volumes varied according to the conditions of the treatment. The yield of potato, however, seemed not to be influenced. Any correation between the weed volume and the yield were not remarked. In this experiment, the maximum weed volume was about 3 kg per. 1m² and the yield of potato was about 1500 kg per 10a.

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In order to study the water consumption of crops as the fundamental knowledge of irrigation, it is desirable to record the consumptive absorption rate automatically not in each individual plant but under community conditions. As the automatic water consumption recorders designed in the past were of automatic balance types, material plants were limited in their weight and also in number, usually only one or a small number of plants having been used. Therefore, it was hitherto impossible to record the variation of water consumption of field crops under community conditions continuously. TAMAI (1956), one of the authors, introduced the automatic water absorption recorder for field crops (Fig. 3) the design of which was based on a different principle from that of BRIGGS & SHANTZ (1915) and STEINBERG (1930). This recorder was one of the micro-automatic recorders for individual plants and could not be used for plant community. The authors newly devised another type of recorder, which is fit for the use of a group of a considerable number of plants. In the present paper, the construction of the new type recorder and some results obtained by using it will be stated. For the purpose of determining water absorption rate of crops under community conditions, many porous cups for auto-irrigation were connected with each other as shown in Fig. 1, and they were placed on the bench. Soil was piled up on the bench to bury the porous cups, then crops were planted in the soil, and the soil surface was covered with vinyl cloth. The amount of water absorbed by crops could be known by measuring the amount of lost water in the reservoir (R). Furthermore, the automatic recorder (recording flowmeter), as shown in Fig. 2, was provided between the porous cups (P) and the reservoir (R) so that the water absorption of crops could be recorded continuously by it. This recording flowmeter is composed of three main parts: (1) A lever (L) equipped with a water tank (T); (2) Electric valves (V₁, V₂) which are worked by electric magnets (M₁, M₂) ; (3) A part composed of a recording drum (D), a electric magnet (M₃) and a recording pen (R. P.). The water tank (T) is connected with the reservoir (R) and the porous cups (P), which supply water to crops, through the two valves (V₁ and V₂) respectively. Suppose a difinite amount of water in the tank is spent by the crops, the lever inclines to the left because the right side of the lever becomes light. Then a balancing ball (B. B.) rolls on the lever from the center to the left and accelerates the touching of a contact point (K₁). If the contact point touches, then the electric magnet (M₁) acts, the valve (V₁) opens, and water flows down from the reservoir (R) into the tank (T). When the amount of flowing water becomes equal to the amount of water spent by the crops, the lever inclines to the right, and the balancing ball on the lever rolls back to the center, accelerating the touch of another contact point (K₂). If the contact point (K₂) touches, the electric magnet (M₂) acts, the valve (V₂) opens, the valve (V₁) closes, and the flowing water stops. Here the water in the tank is again absorbed by the crops. Simultaneously with the action of the magnet (M₂), the electric magnet (M₃) acts and a line is drawn with the recording pen (R. P.) on the drum (D). Thus, the absorption of water, the supply of water and the recording of lines being repeated, the water absorption of crops is recorded on the drum with the density of lines. Contact points (K₃ and K₄) were especially provided to use electricity instantaneously. Though lines were drawn at each time when 50 cc of water was absorbed, the volume of water absorbed at a time is adjustable by changing the size of the balancing ball (B. B. [the rest omitted]

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Recently the irrigation of upland fields has spread in our country. Some farmers who are engaged in the irrigation wish to introduce paddy rice plants into upland fields just as they have cultivated upland rice plants in the same fields. The characteristics of water absorption of paddy rice plants when cultivated in paddy fields are known to some extent, but those are hardly known when they are cultivated in upland fields. The authors studied the water absorption characteristics of the paddy rice in upland fields with automatic recorders already reported in the previous paper. The results are as follows : 1) The water absorption by root of paddy rice plants in upland fields in early season increased proportionally to their top growth, reached a maximum in anthesis, and afterwards decreased with ripening. This tendency was almost the same as that of upland rice reported by one of the authors (TAMAI, 1950) (Fig. 1). 2) Fig. 2 shows variations of the amount of water absorption of paddy rice plants (variety YACHIKOGANE), which were planted on 17 th of April and 27 th of May, during the whole growing season. The maximum period of water absorption varied according to the date of planting, but the period always coincided with the flowering period. 3) The paddy rices planted in the early season are harvested at the time of high temperature. Fig. 2 shows that the root of the plant in the harvest time had about a half of the water absorption ability of the maximum period. 4) Fig. 3 shows the comparison of the daily variation of water absorption in both the flowering and the ripening periods of paddy rices planted in different dates. Fig. 3 was plotted from the records presented in Fig. 4 It is confirmed from Fig. 3 that the daily variation of water absorption is very remarkable in the flowering period but becomes small in the ripening period to some extent. Fig. 5 also shows the same tendency as Fig. 3 The daily variation of water absorption of these paddy rices harvested in a hot season is still remarkable in the ripening period (just before harvesting). While, the daily variation of the same variety. harvested in autumn (bottom in Fig. 3) nearly disappears in the ripening period. 3) and 4) show the fact that the root of paddy rice plants grown in the early season and harvested in summer has a high ability of water absorption as compared with that of the same plant harvested in autumn. These results arouse our attention to the control of watering of paddy rices in the ripening period when they are cultivated in upland fields. 5) Table 1 shows water requirement and its original figures which are obtained under upland irrigation conditions. The water requirement has figures amounting to 300. The figures in the right column represent the amount of water which is needed to produce 1 liter of unhulled rice. It is said from these figures that the amount of water needed by paddy rice plants cultivated in upland fields is about 700 times of the volume of rice to be produced. These values seem to be near to the values obtained under paddy field conditions, but this point must be ascertained in future.

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The crumbling action caused by a slight cultivation helps erosion control. Its effect is very remarkable in Hokkaido, where we have a heavy precipitation in a short time. Further, this effect depends upon the time cultivation is performed. It is effective for reducing erosion to cultivate after the first excessive rain-fall. But cultivating tends to reduce the effect when it is done to much. However, the erosion in the contour ridge is heavier than in the up and down hill when it is left after the ridge is fallen. It is necessary for keeping the effect of contour lister that we repair fallen ridge by cultivation as soon as they are fallen.

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The present paper reports the results obtained from our observation of growing process of lower spikelets of var. Yukiwarimugi cultivated at upland field, both when nitrogen fertilizer is and is not top-dressed and from our examination of the change in physiological functions in case of top-dressing of the fertilizer. 1) In a group of dressing plots, flag-leaf at the heading time shows remarkable increase both in their fresh weight and dry weight; the chlorophyll contents also increase. And in that case osmotic pressure of flag-leaf sheath is comparatively high, and amount of bleeding sap examined at pedunde indreass. 2) So far as non-top-dressing plots are concerned, Qo₂ value of spikelets at the lower part of the ear is lower than that of spikelets at the middle part of the ear; whereas in top-dressing plots Qo₂ value is higher with the lower spikelets. The similar tendency is seen in flag-leaves. 3) The activity of dehydrogenase, in non-top-dressing plots, is degenerate in lower spikelets than in spikelets in the middle part of the ear, whereas in top-dressing plots, their activity in the former is promotive. The results of T. T. C. reaction indicates the similar tendency. 4) The activity of ascorbic-acid-oxidase is lower with the lower spikelets than with spikelets at the middle part of the ear. 5) After the flag-leaf has been fully opened, nitrogen and carbohydrate content in the flag-leaf, in spikelets at the middle and the lower parts of the ear, the top-internode and in the flag-leaf node, are higher with the top-dressing plots than the non-top-dressing plots. 6) The ratio of sugar content in those parts of the ear and the top-internode mentioned in 5) to sugar content in a flag-leaf, is smaller in the top-dressing plots than the other, especially in the group of spikelets in the lower part of the ear. In other words, in the top-dressing plots, the sugar concentration gradient between the lower part of an ear and the flag-leaf increases. 7) The C/N ratio of the spikelets, in the top-dressing plots, is seen to be lower than in the non-top-dressing plots. This is presumably because the enzyme activity and respiration being promoted by top-dressing, and thus the carbohydrates being actively utilized. This seems to make the gradient in sugar concentration larger, and probably promote the translocation of carbohydrate from flag-leaf to ear. Judging from the above results, physiological activity in the lower spikelets is promoted by the top-dressing and thus accelerates the growing of the spikelets that is apt to degenerate. It is consequently presumed that this fact enables the normal ripening of spikelets, in other words ensure the efficienty translocation from the flag-leaf to the lower parts of the ear.

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We studied on the inflence of shading treatments upon the NH₄-N absorption of the wheat plant grown by nutrient solution. The results were summarized as follows; 1. By the shading treatment in which the plants were covered with a wooden plate or a sheat of white victoria lawn, the absorption of NH₄-N was decreased. 2. By the diminution of the time of full daylight, the absorption was retarded, too. 3. Those tendencies were in proportion to various degrees of shading. 4. After the shading treatment had been stopped, the effect of it was still observed to some degree.

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Recently so called "Kareure" phenomenon of barley plants in which the plants mature too early and die, has been rather widely observed on fields in warm and dry region of western Japan. An extremely marked symptom appears in ears. This phenomenon has been observed to occur seriously in years with dry and warm maturity season, and on soils deficient in potassium, and sometimes in magnesium etc. The writers studied the phenomenon and recognized a degeneration in the roots of "Kareure" plants. The degeneration was as follows;- After heading, especially in milky maturity stage, the root which had grown quite normal up to that time showed discoloration in the root stele which was due to the filling with yellowish brown substances in the pareachyma and vessels. In a few cases, the similar degeneration was also observed in internodes of stems near the ground. The degeneration was proved to be controlled almost by an application of potassium and magnesium which is deficient in the soil.

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From the results of the experiments, it may be concluded that the radiosensitivity of barley plant to gamma-ray is less than that of wheat plant under the same condition of treatment. It may be also presumed that the functional damages of those sample crops can be divided into two staged, i. e. the primary and the secondary.

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The influence of the "residual solution" by wheat vernalization upon the earing of wheat was examined. 1. Some substances are supposed to diffuse into the surrounding medium (water) from the seeds during the course of vernalization, and this diffution seems to compose one of the causes of vernalization. 2. The diffusing substances are considered not to be characterized as a hormones. No positive effects of hastening the earing of the plants can be recognized.

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To ascertain the phenomena of devernalization in wheat and barley, reported before by PURVIS etc. in detail with Petkus winter rye, a simple experiment was carried out in our laboratory. The treated seeds as showh in table 1 were sown in 1/50, 000 tan pot in a glass house on March 1. With careful managements during their growing periods, number of tillers per plant, number of leaves on main culm and date of heading were noted. The results were compiled in tables 2∼6. From these data we concluded that both vernalized seeds of highest winter type wheat and medium winter type barley during 3 weeks at 0°C were completely devernalized by high temperature treatment at 22°C during 3 weeks with restricted water-supply.

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Repeated spraying of gebberellin solution promoted the initiation of spikelet primordia in cold requiring wheats under the condition of high temperature which was unfavorable for the progress of vernalization. It proves that gibberellin can replace the vernalization by low temperature. In such cases, the primordium differentiation in shoot apex was stimulated by the chemical before the initiation of spikes. There were, moreover, some indications that the spikelet production in a young ear might be enhanced. No discernible elongation of internodes was seen before spikelet initiation in all gibberellin-treated plants.

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The seed of milk vetch which is green-manure and forage legume of the most importance in Japan, contains the hard seed of about 20 % in their seed lots. Although it is known that the hard seed content is influenced by the environmental factors such as drying condition during the seed storage, weather, soil condition and nutrient element, but it is not clear why some are of hardness and others are not in the seeds produced on the same plant. The authers have investigated on the hard seed content of milk vetch hand harvested in relation to its blooming time and maturing period, growing the plant in pots in green house and out-doors. The number of days for the maturing of milk vetch seeds produced in early blooming pods is larger than that in late blooming pods in the same plant (Table 1 & Fig. 1). It was found that the hard seed content of milk vetch is higher in green house plot than that of out-doors plot, though its differences among individuals are existing (Table 2 & Fig. 4). In the seeds produced in early blooming and maturing pods, the germination speed is rapid and the hard seed content, a portion of seeds remained hard at the end of the test period from 11 th October, 1957 to 10 th February, 1958 at room temperature, is higher than that of late blooming and maturing pods. This tendency is remarkable in the seeds of green house plot than that of out-doors plot, that is, in out-doors plot the hard seed content of the earliest blooming and maturing seeds is about 28 % and that of the latest blooming and maturing seeds is about 8 %, while in green house plot the hard seed content is about 50 % and about 6 % in the seeds of the earliest and the latest blooming and maturing ones respectively (Table 2 & Figs. 2, 3 & 4). The number of pods and seeds per head in green house plot is large in the early blooming and maturing head, and decreases accordingly to the lateness of the blooming and maturing time, but in out-doors plot the number of pods and seeds per head is large at the maturing time III and IV than II, and then decreases accordingly to the lateness (Figs. 5 & 6). No difference is found in the weight of 1000 seeds in both green house and out-doors plot in earlier blooming and maturing seeds, but the weight decreases gradually in later blooming and maturing seeds (Fig. 7). From the experimental result mentioned above, although the hard seed of milk vetch is influenced by the environmental factors such as temperature and drying condition during and after the maturing of seeds, it is found that the hard seed content of milk vetch is influenced by the time of blooming and maturing as well as the number of pods and seeds and the weight of 1000 seeds.

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The root samples were taken by Monolith method from plots to which fertilizer was applied in row and broadcast. The root distribution influenced by the method of fertilizer placement varied according to the kind of crops (Fig. 1). On the top and root growth of immature soybean, there was no distinct tendency between two fertilizer placements. In common vetch, the top and root growth was better in row application. In red clover, it was better in broadcast application. The most part of the roots distributed in 6 cm depth from the surface of the soil in immature soybean and red clover, and 15 cm in common vetch (Fig. 2). The root of immature soybean penetrated into the subsoil about 60 cm deep, but that of others did about 40 cm deep. In general the tap roots penetrated deeper in broadcast application (Table 1).

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Tobacco seedlings were grown under various combined conditions of different nitrogenous fertilizers and spraying of sucrose solution to obtain the seedlings containing various levels of nitrogen and sugars. Then these seedlings of each plot were transplnated to the field under the conditions of standard nitrogenous and non-nitrogenous fertilizers, and studied on the relations of their nutritious conditions in the seed-bed period and growth after transplanting. As the results, it was recognized that the amounts of nitrogen maintained in the seedlings correlated significantly with absorption of nitrogen and growth on the field after transplanting through a function as a starter. Consequently, to obtain such a good seedling that shows good appearance in growth after transplanting, it was suggested that the supply of nitrogenous fertilizer to the seedlings in the seed-bed period should be considered and also existence of sufficient soluble nitrogen in the field available to seedlings at the time of transplanting should be assured.

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Development of adventitious roots in tobacco grown on pots and fields was investigated as follows: 1) Adventitious roots of tobacco appeared on stem about 20 days after soil dressing and spread conspicuously during the stage from budding to flowering. 2) Comparisons among 3 varieties differing in budding time revealed that development of adventitious roots had a close connection with the time of budding, namely, the development was the earliest in the early budding type of tobacco and the latest in the late one. 3) Topping accerelated the development of adventitious roots. 4) From the facts mentioned above, it seems to be very important for cultivation practice to promote the growth of tap roots and to accelate early growth of tobacco to hasten the development of adventitious roots.

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Several varieties of tobacco plant were grown on water-logged soil and their developmental responses were compared with those of plants on soil whose underground water-level was 90 cm below the soile surface. From this experiment, it was concluded that plants grown on water-logged soil bore a smaller number of leaves and their flowering time was obviously accerelated. Thereupon, the auther conducted the following experiment in the greenhouse. Seedlings of various ages whose leaf numbers were 8, 10, 12 respectively, were transferred from the same seed bed to pots. The pots were subjected to water-logging treatment starting either at the time of transplantation or 10 days after. The remaining pots were kept without treatment. The results were as follows: In the seedlings with more than ten leaves, regardless of the time of treatment, the total leaf number per plant decreased and the flowering time was accerelated as in the previous experiment. In the seedling with 8 leaves, on the other hand, the flowering time was obviously retarded and their leaves showed frenching like symptoms of disease. From this experiment, it may be said that the change in flowering time due to water-logging seems to differ according to the growth stage of seedlings at the time of treatment.

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The authors measured photosynthetic rate of tea plants grown in field, with an apparatus modified from that reported in part 1. After training, the rate of carbon assimilation (c. a.) decreased and midday rest was observed distinctly. Before plucking when tea shoots developed 4 leaves or more, the rate of c. a. reached its summit. At sprouting time or after training, 0.5 cal/cm²/min. was the light saturation point, and when the light intensity exceed 0.6∼0.8 cal, the rate of c. a. somewhat decreased. But before plucking time, up to 1.0 cal light intensity, the rate of c. a. increased with light, and excepting the period of midday rest, both the depression with light and the changes by temperature of c.a. were not observed.

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In order to obtain the relationship between the root thickening and some characters of sweet potatoes, 30 varieties and lines were grown and harvested at early and late time. Some results of this experiment were given in figure 1, 2, 3 and 4. By the figure 1, We can say that the higher the ratio of the early and late harvesting potato yields, the better tuber thickening we can have. As the result of the above relationship, positive correlation between early tuber thickening and marketable tuber number, and negative correlation between early tuber thickening and T/R ratio are seen in figure 2 and 3. Then also negative correlation is seen between early tuber thickening and degrees of dry-matter accumulation in Fig. 4.

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While many studies concerning the changes in the components of sweet potatoes during storage have been investigated, the detailed distributions in the varied region of seed tuber are little understood. In the present paper, with a desire to obtain some further information on the physiological nature of seed tuber during the storage period, particular attention was paid to the variations of carbohydrate and nitrogen contents at the apex, center and tail both in the pith and cortex of seed tuber, using the variety "Gokokuimo" as material. The experimental results obtained are summarized as follows : 1. At the early stage of storage, the reducing sugar contents rose at the apex and center both in the pith and cortex, while those at the tail fell particularly in the pith. Moreover, the non-reducing sugar contents increased at all of the parts of tuber, and the starch contents declined at every part except the tail in the pith. 2. Being accompanied with the stage advanced, the reducing and non-reducing sugar contents were rich only at the tail in the pith, but poor at the other parts of tuber. And at the same time the starch contents were comparatively abundant at the apex and center, while those at the tail decreased both in the pith and cortex. 3. At the later stage of storage period, the reducing sugar consents declined at the apex, but they were considerably high at the center and tail both in the pith and cortex. Moreover, the non-reducing sugar contents were high at the apex and center, while those at the tail were low. On the other hand, the starch contents showed a striking contrast to the tendencies of non-reducing sugar contents in the pith and cortex. 4. Concerning nitrogen compounds, the soluble-N contents were generally high at the early and later stage, on the contrary the protein-N contents were abundant in the middle stage at all of the parts of tuber.

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1. Mean air temperature in levee of paddy field growing soybean was lower than in upland, while mean soil temperature was higher slightly and relative humidity was higher fairly. And the diurnal ranges of air temperature, soil temperature and relative humidity in the levee were all smaller than in upland. (Fig. 2) 2. It was found the growth of soybean cultured in levee was smaller but stronger, and the yield was more stable, as compated with that in upland. This stability of yield of soybean cultured in levee was due to the higher percentage of fertile flowers and the less degree of sterility or abortive grains by injurious insects than these of upland soybean. 3. Both the growth and yield of soybean cultured in low levee (about 5 inches) were inferior to that of higher levee (about 8 or 11 inches). The fact is likely caused by the excessive soil moisture, the limitation in root development (Fig. 3) and the increase of shade by the rice plant growth.

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