To clarify the rice plant growth cultured in the ill-drained paddy field in the Hokuriku district, the authors investigated the relation between yield and several conditions differing in spacings, methods of nitrogen fertilizer dressing, and water managements, with special reference to the growth analysis during the ripening stage. The results obtained may be summarized as follows. 1. Such cultural conditions as thick planting, double row planting, split application of nitrogen fertilizer, midsummer-drainage were effective in increasing yield. 2. Number of both panicles and spikelets, leaf area and top dry weight per unit field area at heading time, had not close relation with yield. 3. Three curves were drawn through the levels of light extinction coefficent in the figure illustrating the relation between NAR and nitrogen content in the leaf-blade during the ripening stage. 4. Such properties as optimum leaf area, high nitrogen content and good arrangement of leaves during the ripening stage increased both NAR and RGR, and resulted in increasing yield.

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[in Japanese]

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When studied on silicified tissue of plant by histochemical method, Grob's phenol method was used as the most popular technique. But this method did not caused by chemical reaction of silicate, silicified tissues of leaf in rice plant was not cleared enough. In this studies we separated pure silicified tissues from leaf spodogramm by adding dilute hydrogen chloride. Results are summarized as follow: 1. Figure 1 to figure 6 shows the silicate accumulating process as the growth of leaf blade. In these figures we found the dumbbell form cell was most rapidly silicified and other epidermis cells were also beginning to silicified gradually. But when the leaf blade emerges from the leaf sheath of under leaf, these cells have been silicified almost completely. 2. Silicified motor cells of matured leaf are shown in figure 7, 8, 13 and 14. Situation of motor cells in leaf blade tissue are shown in figure 9, 10 and 11. According to these figures, motor cell's square shape in figure 7 is the same as bottom line of motor cell in figure 12 (C). 3. Leaf sheath also was silicified completely as figure 15 to figure 17. Leaf sheath node was partially silicified as form as net showing in figure 18.

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The differentiation and subsequent growth of seminal roots in the developing wheat embryo were investigated. At the 11th day after anthesis the primary seminal root was differentiated in the central portion of the embryo, when the coleoptile had already been initiated and the 1st foliage leaf was on the point of differentiation. At the 17th day, 2 days after the 2nd foliage leaf initiation, the 1st pair of seminal roots were initiated from the sides of the hypocotyl in a plane parallel to the face of the scutellum. At the 26th day, 2∼3 days after the 3rd foliage leaf initiation, the 2nd pair of seminal roots were initiated immediately above the 1st pair and in the same plane. On few cases the differentiation of the 6th seminal root from the middle point between the bases of the 2nd pair rootlets was observed at the 34th day. Most of the embryos, however, ceased their activity before the initiation of the 6th seminal root could be detected. The 3rd pair of seminal roots, whether their emergence occur after germination or otherwise, did not differentiate during the ripening stage of embryo. Based on these results the already recognized steps of embryo development were revised by including the developmental processes of seminal roots.

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Dry matter production was analysed in terms of the leaf area index (LAI) and the total chlorophyll amount of herbage per unit area of land, in the sward of Ladino clover (Trifolium repens L. race giganteum), and an attempt was made to replace the LAI by the total chlorophyll amount (chlorophyll index, g/m² of land, abbreviated here to CI). It has been pointed out by some workers that the chlorophyll content of higher plant would not be usually limiting photosynthesis and the use of the total chlorophyll amount would not eliminate the complexities associated with leaf display. The CI, however, may account for the probable photosynthesis in petiole or leaf sheath and the differences in light transmissibility among leaves. Besides, it may also decrease errors and save manhours in separating the mixed pasture samples and measuring the leaf area of the herbage with small and slender leaves in field experiments. At several days' intervals over a period of seven weeks from defoliation, measurements were taken of the dry matter yield, the leaf area, the chlorophyll content, the CI (chlorophyll in petiole and stolon was also taken into account), and the relative light intensity penetrating to the ground level. The vertical distributions of leaf area, chlorophyll amount and relative light intensity in the sward were also measured at every 5 cm from the ground level by the stratifying clip method, on the 30th and 51st day of regrowth. The mean chlorophyll content per dry matter weight increased with the regrowth in leaflet, hardly changed in petiole, and decreased in stolon, over the period. The LAI reached to the maximal value of 4.7 on 26 days after cutting, and thereafter it showed an approximately constant value of 4.5, while the total dry matter yield increased throughout the period, and the CI similarly increased even after the LAI attained a plateau (Table 1). The CI correlated significantly to the LAI, the total dry matter yield (TDM, g/m²) and the logarithmic relative light intensity, over the whole period of regrowth. The correlationships, however, did not become so close among these measurements after the maximal LAI was once attained, except the case between CI-TDM (Table 2). The daily dry matter increase per unit value of CI (E_c, g/g/day) was calculated from the equation (2) in this text similarly to the calculation of the net assimilation rate from the equation (1), after Watson, and the E_c declined with the increase in CI (Fig. 3). The growth rate (g/m²/day) attained the maximum at the CI value between 1.2-2.3 g/m² of land, and this value was regarded as "the optimal CI" of the sward, corresponding to the optimal LAI (Fig. 3). The vertical distribution of relative light intensity (logarithmic value, log_e I/I₀) showed highly significant correlations to the leaf area of herbage (F) above the light-measured level and to the chlorophyll amount (Ch1) of the herbage (Fig. 2). The relation of I/I₀ to the Ch1 can be expressed as the equation (4) in the text, where a constant K_c corresponds to the coefficient of light extinction by a chlorophyll layer in the sward. The value of K_c was determined to be 1.21 per chlorophyll g/m² of land on the 30th day of the regrowth.

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Three series of experiments were conducted in a hope of elucidating which leaves of ladino clover are most active in assimilation and contributing most to the matter production, in what speed the assimilated substances move in the plant, in which parts they are accumulated, and what is the relationship between the leaf order and the direction of the translocation of the assimilates. 1) The whole plants were treated for 41/2 hours with ¹⁴CO₂, immediately followed by 10 sec. of boiling water treatment, and the radioautographs were taken. ¹⁴C activity in every leaf of the plant was fairly high, but the younger the leaves, the higher was the activity, showing the difference in assimilating ability. ¹⁴C was seen at the end of treatment already translocated in the roots. Strong accumulation was found at nodules and root tips (Fig. 2-A). After 4 days, it was seen largely accumulated at the growing points, lateral buds and roots, while the three or four youngest leaves kept high activity of ¹⁴C, the rest showing decreasing activity from that of immediately after the treatment (Fig. 2-B), (Table 1). This is considered to be due to the consumption by respiration and the translocation to other parts of the plant. 2) Single leaves (Leaf No. 5 from growing point) of 5 plants were treated for 2 hours. Even upon the completion of treatment ¹⁴C was distributed widely in the plant, though in slight amount. In the roots and growing points, it was seen rather highly concentrated. After a day, it was, distributed all over the plant, fairly intensely at the growing points, lateral buds and roots, and especially intensely in root tips and nodules (Fig. 4-B). After 5 days a large accumulation was seen in the newly-opened leaves on the main stem and the leaves on the lateral buds which were observed as developing at the time of treatment (Fig. 4-C). This accumulation remained the same on 15th day and 47th day, the leaves newly-developed after treatment having but a weak activity of ¹⁴C. Similar fact was shown in the roots. After 1-5 days, the accumulation was strong at root tips. On 15 th and 47 th day the old parts which are identified to be the root tips at the time of treatment retained the strongest accumulation, while the newly-developed parts had only a small amount of ¹⁴C (Fig. 4-D∼E). These facts lead us to the consideration that the assimilates are consumed for the composition of the structure of the growing parts, and its retranslocation from there does not appear too much. 3) The newest leaf immediately after opening (Leaf No. 1) was treated with ¹⁴CO₂. The assimilation was seen vigorous, and the translocation active. The accumulation was observed in the roots, growing points and lateral buds. Further some translocation was seen into the old leaves (Fig. 5-A). All this shows that in ladino clover the newly-opened leaf acts not as an accepter but a supplier of photosynthetic products. The leaves numbered 4-8 were active in assimilation and in supplying the assimilates into all parts of the plant, just like Leaf No. 1 (Fig. 5-B∼C). In Leaf No. 11, the ability of assimilation was smaller and the translocation was mainly basipetal and ¹⁴C was translocated not so much into the growing points on the main stem as into the lateral buds and roots in the plant base (Fig. 5-D∼E).

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Following the previous report (LXX), the authors futher examined the combined effects of air-temperatures and water-temperatures at different growth stages on the growth and morphological characteristics of rice plants by using the same method as in the previous report (LXX), and obtained the following results. (1) The increase in the number of tillers during each treated stage is little affected by air-temperature, but much by water-temperature. The maximum increase in the number of tillers is found at 31°C at Stage I (rooting stage), at 36°C at Stage II (tillering stage), at 16°C and 36°C at Stage III (panicle initiation stage), respectively. (cf. Table 2) (2) The increase in plant height at Stage I is not influenced by air-temperature, but only by water-temperature, and its effectiveness for increasing the plant height is found as the following order, i.e., 31°C>36°C>21°C>16°C. At Stage II and III both air-temperature and water-temperature have serious effects on increasing the plant height, and the order of their effectiveness for increasing it is also found as follows, i. e., 31°C>36°C>21°C>16°C. At Stage IV both air-temperatureand water-temperature still affect the increase of plant height, but in this case the effectiveness of air-temperature is a little stronger than that of water-temperature. (cf. Table 2) (3) The plant age in leaves is much more effectively increased by water-temperature than by air-temperature, and the plant age is markedly increased by high water-temperatures such as 31°C and 36°C, while it is little increased by low water-temperatures such as 16°C and 21°C. (cf. Table 2) (4) The total number of leaves on the main stem is little affected by air-temperature, but much affected by water-temperature. In particular it is most severely affected by the water-temperature at Stage II (tillering stage), and it is likely to be the more increased by the higher temperatures so far as the experiment is concerned. (cf. Table 2) (5) The number of days required by the plant from the transplanting time to heading time is little affected by air-temperature, but much affected by water-temperature in the early growth period (Stage I and II), and it is also remarkably affected by both air-temperature and water-temperature in the middle growth period (Stage III and IV), but it is affected only by air-temperature in the late growth period (Stage V). In any growth period a temperature of 31°C (in air as well as in water) is most effective in hastening the heading time, while a temperature of 16°C is most effective in delaying it, so far as the present experiment is concerned. (cf. Table 2) (6) Cnmbined effects of air-temperatures and water-temperatures at different stages of growth on the length of main culms, panicle length and the length of each leaf-blade, leaf-sheath and inter-node from the uppermost one to the downward 5th one have been examined. As a result, it has been clarified that the air-temperature or water-tempeture at particular stage has a conspicuous effect on lengthening a particular leaf-blade, leaf-sheath and inter-node and also the length of main culms as well as that of panicles. In other words, close relationships have been found between morphological characteristics and temperature (air or water) at particular growth stages. These relationships will be effectively used on diagnosing the defect in the rice cultivation by a morphological examination of the hills of rice. (cf. Table 2) (7) The present results, together with those given in the previous report (LXX), have been suggested to play a significant role in improving rice cultivation as well as in forecasting the yield of rice.

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With a view to making clear the difference in yield-determining process between transplanted rice plants and directly sown ones, the authors carried out nitrogen top-dressing experiments on directly sown plants in 1962 and '63 along the same line as in the previous experiments (LI) in which transplanted plants were dealt, obtaining the following results. 1. The most effective time for top-dressing to increase the magnitude of each yield-component was found as follows: (1) The number of panicles per unit area is most effectively increased at the most active tillering stage, (2) the number of spikelets per panicle is at the neck-node differentiation stage, (3) the percentage of ripened grains is at the full heading stage and (4) the weight of 1, 000 grains is just before the reduction division stage. 2. On directly sown rice plants the number of degenerated spikelets was much less than that on transplanted ones, so the nitrogen top-dressing just before the reduction division stage was hardly effective for decreasing the number of degenerated spikelets. (On transplanted plants the nitrogen top-dressing at this time is quite effective for decreasing the number of degenerated spikelets.) The reason why the number of degenerated spikelets on directly sown plants was much less than that on transplanted could be ascribed to the fact that the number of differentiated spikelets was much less on account of much more number of panicles per unit area being produced on directly sown plants than that on transplanted ones, respectively. 3. There was no top-dressing method which consistently gave either the highest yield or the lowest yield under all conditions, which suggested that the best top-dressing method varies with the cultural conditions and seasons. The four components of yield have their individual best time for top-dressing a time when each component is most easily increased, while the yield which is a product of these four components has no one definite top-dressing time at which it is most easily increased. 4. Examining the results, the authors reached the following conclusion which was the same as that obtained from the previous experiments on transplanted plants. The most suitable method of top-dressing differs with conditions under which the plants grow. Under conditions which produce plants with a high percentage of ripened grains and a small number of spikelets, a top-dressing which makes the plants increase its number of spikelets is suitable, while under conditions which produce the reverse effect, a top-dressing which makes the plants increase its percentage of ripened grains is suitable. Accordingly, it is necessary for the growers to adopt the most suitable method of top-dressing by examining the rice plants in their own paddy fields. However, in case of the percentage of ripened grains and the number of spikelets per unit area being both moderate in magnitude or both components being well balanced (and such cases seem to be common), the methods of top-dressings which increase the number of spikelets per unit area as well as the percentage of ripened grains (such as Treatment No. 7 and 10) would be the most suitable.

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Some characteristics of IAA-oxidizing enzyme existing in dark-grown wheat seedlings were studied, and the results obtained were summarized as follows: After demonstrating the existence of IAA-oxidizing action in dark-grown wheat seedlings, the crude- and dialyzed homogenates were prepared from root, coleoptile and plumule. Then, their IAA-oxidizing and guaiacol-peroxidizing activities were determined and compared with each other. The dialysed enzyme preparation from wheat seedlings showed a considerably high IAA-oxidizing activity. Descending order of this enzyme activity was root, coleoptile and plumule, and pH 4.5, 5.0, and 5.5 were the optimum pH value in root, coleoptile and plumule respectively. Similar results were obtained in the activity of peroxidase from the same source. There was, however, a eminent difference between the crude and dialysed enzyme preparation in the mode of action that the crude enzyme preparation is lacking in IAA-oxidizing activity in spite of its high peroxidase activity. It may be, therefore, concluded that the lack of IAA-oxidizing activity of the crude preparation is due to the existence of some dialysable, heat-stable inhibitors in the preparation. In order to clarify the caracteristics of IAA-oxidizing enzyme furthermore, the authers have undertaken some experiments and obtained the following results. IAA-oxidizing activity of the dialysed preparation was inactivated by heat-treatment as the exactly same as the activity of peroxidase in the same preparation, and IAA-oxidizing activity of the crude preparation was considerably promoted by addition of both Mn⁺⁺ and DCP, while the activity of the dialysed preparation was inhibited by added Mn⁺⁺ and was promoted by added DCP. In the mode of inhibitory action of some enzyme inhibitors added, there were considerable differences between IAA-oxidation and guaiacol-peroxidation. A comparatively low concentration, 10^-5M of H₂O₂, showed a little promotion of IAA-oxidizing activity in the dialysed preperation, but the activity was greatly inhibited by a much higher concentration, 10^-4M of H₂O₂, and catalase showed little effect on the activity of the same preparation. From the above-mentioned results, it may be concluded that IAA-oxidizing enzyme existing in dark-grown wheat seedlings is a peroxidase and there are some differences between IAA-oxidation and guaiacol-peroxidation in the reaction mechanism. Furthermore, from the results concerning the effects of catalase and H₂O₂, it is suggested that IAA may be oxidized by wheat seedling peroxidase through the same reaction mechanism as the scheme presented by YAMAZAKI and SOUZU (1958). ADDENDUM: Since this manuscript went to press, we have noticed that the inhibitory effect of Mn⁺⁺ on IAA-oxidizing activity in the dialysed enzyme preparation may be due to the chelating effect of citrate in McIlvaine's (phosphate-citric acid) buffer used, and that this phenomenon has been already described in the following papers. Kenten, R. H. 1955. The oxidation of indolyl-3-acetic acid by waxpod bean root sap and peroxidase systems. Biochem. J. 59 : 110-121. Stutz, R. E. 1957. The indole-3-acetic acid oxidase of Lupinus albus L. Plant Physiol. 32 : 31-39.

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In 1963, wheat production in south-western part of Japan heavyly suffered from extraordinarily long rain from heading time to ripening stage. Then, by the comparison between wheat quality produced in 1962 and 1963, the authors intended to make clear what changes on the quality of wheat grain and flour had been occured by the extraordinarily long rain. Followings are main results obtained. 1. In 1963, litter weight and 1000 grains weight decreased, but ash and protein of grain increased strikingly. 2. Flour yield in 1963 remained as same as in 1962, but milling score, semolina yield and fragileness of semolina were deteriorated. 3. Ash content of low grade flour highly increased, but that of high grade flour (60% flour) remained as same as in 1962. Flour colour was deteriorated. 4. In farinograph test, water absorption and stability of dough increased a little, and weakness of dough, highly increased. As the result, Valorimeter Value diminished. 5. In extensograph test, damage of dough was most clearly detected. Area under the curve, resistance to extension, and R/E value were extremely deteriorated. 6. Maximum viscosity of amylogram decreased remarkably. 7. In these results, we recognized the varietal difference too.

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Rice seedlings, which were growing normally under suitable condition at the seedling space 5cm × 3cm, were given suddenly unfavourable condition as shading (plots A and B) or transplanting (plot C). Afterwards, the growth of each tillering bud was followed and compared with control (plot D) at each seedling age. Shading or transplanting was made at the 4th seedling age, that is when the leaf blade of the 4th leaf had just completely emerged out the leaf sheath of the 3rd leaf. According to the previous paper and observation in this study, the primordia of the 5th and 6th tillers have already been formed though as a mere "swelling", and the 4th or lower ones have developed into buds with one or more leaf primordia at this seedling age. Shading treatment was carried out by means of a layer of yoshizu (marshreed screen) to the light intensity of about 10% of natural sunlight for 2 days (plot A) or 4 days (plot B). The increment of dry weight per plant was very slight under shading or during rooting period. After removal of bad condition the dry weight increased, although it was finnally inferior to the control (fig. 1). The growth of the 2nd and 3rd tillering buds of treated plants were inferior to the control not only at the end of treatments but also after recovery of growth (for instance at the 7th age), especially those of transplanted plants were inhibited completely. In the 4th, 5th and 6th tillering buds, the growth were inferior to the control immediately after the treatment (at the 5th age), afterwards, however, grew more rapidly and became superior to the control. The differentiation of new leaf primordia, in addition, proceeded almost normally. In the case of shaded plants, it is supposed that the difference in growth response between the lower (the 2nd and 3rd) buds and the upper (the 4th, 5th and 6th) ones may not be due to the stage of these buds when were treated, but be due, on the one hand, to the delay of growth of the upper buds in control plants, and the other hand, to the sufficient supply of nutrient substances from main stem to the upper buds in treated plants. Concering the fact that these lower tillering buds failed to grow in transplaned plants, it is assumed to be due to a competition for nutrient substances between these buds and roots developing on the same node. As mentioned above, during the period of treatment, the 5th tillering bud was in the stage developing into bud from "swelling". The 4th tillering bud has one leaf (prophyll) primodium at the 4th age, and at the 5th age it has 3 leaf primodia. This tillering bud, therefore, was also in important stage developing with particular rapidity. Nevertheless, both of these buds ultimately carried out excellent growth rather than suffered inhibiting effect, though the lower buds were suffered ultimate supression. This is interesting fact from the viewpoint of dormancy and development of tillers. The mechanism is to be investigated.

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Several kinds of microorganisms were found on the surface or in the tissues and cells of rice roots sampled in the paddy fields of Yamagata Prefecture. A kind of these microorganisms was sphere in shape like sporangium about 20μ in diameter, in which very small granules were compacted. This microorganism, which was presumed to be aerobic, was observed only on the apical parts of root hairs, but not on other epidermal surface, i. e. it had more intimate relation with root hairs than other epidermal cells. It is assumed from this observation that root hairs have better ability to oxidize the rhizosphere than that of other epidermal cells. Furthermore, the authors isolated some Fusarium spp., yeast and bacteria from rice roots.

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It was assumed in the previous paper that root hairs have better ability to oxidize the rhizosphere than that of other epidermal cells in rice roots. The present experiment was carried on to detect the oxidizing power of root hairs by observing oxidation of Fe⁺⁺ to Fe⁺⁺⁺ in agar culture containing ferrous sulfate. The following results were obtained. Two kinds of epidermal cells, i. e. haired short cells and hairless long cells, had the same oxdizing power in the region where the papillae first made their appearance in the epidermis about 5mm from the root tip. When root hairs elongated to more than 20μ in length, root hairs and hair-bearing cells had better ability to oxidize the rhizosphere as compared with hairless cells. Furthermore, the oxidizing power in fully-developed root hairs existed for long time, even after it was extinct in hair-bearing cells and hairless cells. These results were further ascertained by the distribution of peroxidase and hydrogen peroxide in the epidermis using the histochemical test.

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