In a crown root of rice plants (fig. 24), protophloem elements (PP) were the first of all vascular elements to show maturation usually at about 1 mm from the apex, and secondary wall layer starts covering protoxylem elements (PX) at a distance of 4-5 mm region from the apex. At about 7-8 mm from the apex, nuclei and cytoplasm in the protoxylem elements have degenerated and successively the secondary thickening ends. A first lateral primordium (I) of the crown root seems to originate in pericyclic cells between two protoxylems in which nuclei are degenerating and secondary thickening is going on. While covering by secondary wall in early metaxylem elements (MXI), anticlinal divisions of the first lateral root primordium (II) in the pericyclic cells begin to take place. Before and after periclinal division of the pericyclic cells of the first lateral root primordium, a certain grains (fig. 17 and 18, G) gather near the end wall as well as along protoplasmic membrane of metaphloem elements (fig. 24, MP) and a rounded shape of nucleolus in the metaphloem has changed to a chestnut-in-burs like shape (fig, 19) and the nucleolus is found near the sieve plate of the mature metaphloem as an extruded nucleolus. At a half-way penetration of the cortex (fig. 24, IV), secondary thickening of the early metaxylem completes and maturation of the metaphloem takes place. Before the first lateral root emerges on the surface of crown roots (V), late metaxylem elements (MXII) begin to be covered by secondary wall and all vascular elements except the late metaxylem have matured. A certain causal relation between the first lateral root primordium formation and the development of the vascular element, especially the protoxylem, may be estimated generally in any roots of rice plants.

View full abstract

The experiment was undertaken to elucidate after-effects of SO₂-treatment for long period on photosynthesis and dark respiration in the rice plant after it was released from the treatment. The measurement of photosynthesis and dark respiration was made 24 hours after the gas had been removed. Treatment with SO₂ was for 90 hours at the tillering stage and 66 hours at the maximum number of tillers stage. The concentrations of SO₂ to which the plant was exposed were 0, 1.2, 4.0 and 10 ppm at the latter stage, and 0, 0.271, 0.719 and 1.415 at the former stage. Under the condition in a single leaf, apparent photosynthesis and dark respiration at 1st, 3 rd and 6 th days after SO₂ had been removed were measured, respectively. Treatment with SO₂ was for 80 hours at the maximum number of tillers stage. The results obtained were as follows: 1. Apparent photosynthesis of the rice plant exposed to SO₂ for long period, as compared with the control, showed a considerable decrease 24 hours after the plant had been released from fumigation with the gas at both the tillering and maximum number of tillers stages, this being true to any concentratrations of the gas. 2. Gross photosynthesis of the rice plant was gradually decreased with an increase in the concentration of the gas and the difference between the control and treated plants in apparent and gross photosynthesis was enlarged with an increase in the light intensity. 3. Light compensation point of the rice plant moved towards a higher light intensity in accordance with the concentraion of the gas. 4. Under the condition in a single leaf, the light-curve of carbon assimilation in the rice plant treated with SO₂ for 80 hours showed always lower values than that of the control (SO₂-Oppm) at 1st, 3 rd and 6 th days after SO₂ was removed, respectively. As increasing in the SO₂ concentrations, apparent photosynthesis decreased proportionally. 5. From the above-mentioned facts it was demonstrated that the decrease of dry matter production in the rice plant exposed to the gas for long period might be resulted not only from a decrease of photosynthesis and an increase of dark respiration during SO₂-treatment, but also from a decrease of photosynthesis after the gas had been removed. In this case, however, the after-effect of the gas treatment on dark respiration was not so large as that on photosyntheis.

View full abstract

[in Japanese]

View full abstract

The number of days before heading has hitherto been used to express developmental stages of rice plants, and it is known that the number of days before heading can also been used practically in case of a definite variety grown in a definite area. However, in fact, the number of days before heading is strongly affected by many factors such as varieties, time of seeding or transplanting, cultural conditions and so on. On the other hand, the number of leaves on the main culm is also affected by the factors mentioned above. Therefore, the authors have tried to clarify the relation between the leaf number index, which is possible to express the developmental stages of young panicles of rice plants, and the number of days before heading at various stages, and the following results have beed obtained. 1. The relation between the leaf number index (LNI) and the number of days before heading (DBH) is variable with varieties, time of seeding or transplanting and cultural conditions etc. For instance, the number of days before heading corresponding to a given developmental stage (a given LNI) is larger in late varieties than in early ones, in the case of an identical seeding time. Likewise, DBH is larger in early seeding time than in late one, in case of an identical variety being used. These facts suggests that the variation in the number of days before heading corresponding to a given leaf number index might be mainly governed by the number of days from seeding to heading (DSH). 2. The number of days before heading is divided by the number of days from seeding to heading and is multiplied by 100, and then its relation to the leaf number index has been examined, so that the time difference in the number of days before heading caused by various factors may be eliminated. As a result of it, relation between leaf number index and DBH/DSH ratio shows always a definite tendency irrespective of variation caused by varieties and other factors. Accordingly, the values of DBH/DSH have been proved to be effectively used for estimating each developmental stage of young panicles in rice.

View full abstract

As stated in previous papers, the nitrogen top-dressing at full heading stage maintained high photosynthetic activity of leaves after heading and contributed to the increase in percentage of ripened grains, in the weight of 1000 grains and in yield. At the same time, it was known that protein content in brown rice fed by nitrogen top-dressing at full heading stage was raised by 20-30 % in comparison with that of control. The authors tried to make it clear that whether nitrogen top-dressing at full heading stage would have another effects besides the effects mentioned above. For instance, the question, does the top-dressing at full heading stage increase the root activity and the lodging resistance. or improve the qualities of rice grains?, was set in this experiment. To achieve this purpose, a different amount of nitrogen was individually applied at full heading stage in the form of ammonium sulphate, and the following results were obtained: 1. By nitrogen top-dressing at full heading stage, the percentage of ripened grains, the yield and the amount of dry matter accumulated after heading were increased as the dose rate of nitrogen was raised in the range of 3-9 g/m². 2. By the same treatment, an activity of α-NA oxidation and O₂ consumption by root was increased, and the rice plants were maintained freshly untill maturity. Consequently, the breaking strength at culm base and the lodging resistance became larger than those of control. 3. As to the quality of rice kernels, the following results were obtained by the same top-dressing ; a) the nitrogen content in brown rice was increased by 11-25 %, b) the number of kernels thicker than 2.0 mm was increased, and c) the percentage of perfect kernel was raised up, and the percentages of white belly (and core) rice and of milky white rice kernels was lowered, respectively, especially, characters described in this item were conspicuous in the plot where nitrogen was restricted during the period from 70 to 90 in leaf number index. 4. Effecfs of nitrogen top-dressing at full heading stage on nitrogen content in brown rice was more amplified in the case of upland conditions after heading and calcium basal dressing.

View full abstract

There are many papers that the translocation is controlled to an appreciable extent by the mutual interaction among systems, i.e., source, conducting, and, sinks, then, it is presumed that each system is influenced by the other systems through the translocation. But, these interactions have been very slightly studied from the quantitative angle. Isolated sweet potato leaves have the advantage that photosynthates are translocated to the principal sinks, i.e., tuberous roots. Using the simplified system described above, the dry matter production and the translocation of ¹⁴C-photosynthates have been investigated. The results obtained were summarized as follows: 1. The leaf area of the isolated leaves increased in the early vegetation period, and did not wither during the period of 10 weeks. In spite of extensive leaf area, its photosynthetic rate continued to be relatively highter than that of the intact plants during the same period. The starch contents in the leaves did not increase with growing, being higher those in the intact plants. However, the former seemed not to differ greatly from the latter in contents of N, P, and, K in leaves. 2. The formation of tuberous roots was observed even in the isolated sweet potato leaves. From the standpoints of varietal characteristics, the isolated plants showed to be similar to the intact ones in enlargement of tuberous roots. No distinct differences were found between the isolated and the intact plants about the starch contents and the dry matter distribution ratios in the tuberous roots. 3. The amounts of ¹⁴C-photosynthates in the leaves, after exposure to ¹⁴CO₂ for 1 hour, remarkably decreased during the subsequent period of 24 hours, and then decreased slightly during the period from 24 hours to 5 weeks. About 20% of ¹⁴C-photosynthates were assumed to move from the leaves to others within 30 minutes after exposure to ¹⁴CO₂. 4. The specific activities of ¹⁴C-photosynthates in the tuberous roots increased at higher rate than those of the other organs with passage of time up to 24 hours after the treatment. ¹⁴C-photosynthates were primarily translocated towards the tuberous roots in a short time. 5. The specific activities of ¹⁴C-photosynthates in the stems·axillary buds were observed to be high throughout the experimental period. The translocation to the stems·axillary buds continued for long time under the conditions mentioned above. 6. More than 50% of ¹⁴C-photosynthates were disappeared from the plant during the period of 24 hours after exposure to ¹⁴CO₂, possibly due to respiratory consumption. 7. From the autoradiographic observation, it was assumed that the translocation to the tuberous roots was directly related with the development of vascular bundles and the diffusion from them into the storage parenchyma.

View full abstract

The protein content of brown rice of dwarf lowland variety was investigated on 12 samples each grown in 1968 and 1969 (experiment 1). Further, the protein content of brown rice and the nitrogen content of each part of rice plant at heading and full ripe stages were investigated on 14 samples grown in 1969 (experiment 2). There was considerable variation in protein content of the same variety in experiment 1 and 2. The low kernel-weight variety in the samples showed a tendency of high protein content. With respect to the same cultural condition, the protein content was negatively correlated with thousand-kernel-weight on 1968 sample (experiment 1) and 1969 sample (experiment 2). In experiment 2, the protein content of brown rice was positively correlated with the nitrogen content of ear and leaf sheath+culm at heading stage. On the other hand. the thousand-kernel-weight was negatively correlated with the nitrogen content of ear at heading stage.

View full abstract

The protein content of lowland and lowland-upland hybrid brown rice was investigated on the non-glutinous and glutinous types by upland polyethylene film mulching culture. The upland mulching culture gave higher protein content in lowland brown rice as compared with the lowland culture. The average increasing index, i.e., (upland mulching culture/lowland culture) × 100, of the non-glutinous and glutinous types was 120.6 % and 122.6 %. The upland mulching culture also gave higher protein content in lowland and lowland-upland hybrid brown rice as compared with the upland culture on the same manuring condition. The average increasing index, i.e., (upland mulching culture/upland culture) × 100, is as follows : a) lowland brown rice : non-glutinous type 106.0 % and glutinous type 107.6 %. b) lowland-upland hybrid brown rice : non-glutinous type 106.9 % and glutinous type 107.2 %. Regarding the protein content of the lowland brown rice by the upland mulching and upland cultures, it was shown that Hokkaido district variety was higher than Tohoku district variety.

View full abstract

[in Japanese]

View full abstract

To clarlify the role of main stem against the establishment of canopy or the productive structure of dry matter of peanut individuals of two cultivated varieties differing plant type, Chiba shoryu, Spanish type (E) and Chiba handachi, Virginia Bunch type (SP); two treatments, continuous defoliation and excision of main stem apex, were done at the various growth stages under the greenhouse condition. In the peanut plant showing weak or no apical dominance of main stem in early growth stage, branch formation was disturbed in large degree in variety SP, much branched type, than variety E, fewer branched type, by the inhibitory treatments of main stem growth such as the removal of apex or continuous defoliation at the beginning of the development of individual "stem-system". General responses in the vegetative and reproductive growth in the treated plants, especially, the total and each organ's dry matter production and yield of matured fruits, may be shown as the summarized scheme (fig.5). As already reported by the author (1970), the occupying ratio of main stem's leaves in the individual assimilation system at the stage of maximum leaf quantity is very small, compared with that in the early growth stage when the main stem's leaves largely contribute to the growth as the major assimilative organ of the plant. However, with the further progress of canopy growth, the growth of main stem is disturbed by the rapid increasing of lateral branches and their leaves. And the main stem gradually loses the role and becomes "parasitic" due to the fall of its contribution to the individual growth, formation of ineffective flowers in some varieties, and promotion of self-shading. In such a sense, it may be suggested that the main stem of the plant of Virginia type varieties contribute for longer period to the individual dry matter production through the establishment of "stem-system" than the one of Spanish or Valencia type varieties.

View full abstract

Following 2 experiments were undertaken to re-investigate in detail the varietal difference of the number of main stem leaves on the day of first flowering (MAEDA, 1968), using 6 varieties (see, note of fig. 1) differing the plant type, of which seeds have been storaged under low moisture in room temperature during 10 months after harvest. Experiment I. Varietal difference of the leaf emergence on the main stem during the pre-flowering period (48 days after seeding) under controlled condition (day : 14 hours, 27°C, 18∼20 klx; night: 10 hours, 22°C). Leaf emergence (full expansion of 4 leaflets) of 10 plants from 50 plants (10pl. × 5 replications) per a variety, in density of 6 × 7.5 cm per a plant, were observed every day. Experiment II. Morphological differentiation of the leaf primordia in the matured embryo of the selected newly shelled seeds of the same materials in Exp. I. The 1st and 2nd leaf primordia (plumule) were observed with dormant seeds, and the primordia of upper order of leaves were observed with 20- and 40-hours-incubated seeds placed on the moistend vermiculite at 30°C in dark, to avoid breakage of primordia of cured seeds which are too fragile to dissect under microscope. The embryos of incubated materials were cut-off and at once fixed in 80% alcohol solution. Results obtained and considerations are as follows : 1. A clear turning point of leaf emergence rate on the main stem was observed about 2 weeks after seeding in each of all varieties, and the number of leaves at the turning point was about 4 in large-seeded varieties (SP1, SP2, and P 1) and a small-seeded variety E 1, and about 3 in the other small-seeded varieties (E2 and P2) (fig. 1). Accordingly, varietal difference in the number of main stem leaves on the characteristics in leaf emergence of 2 varieties, P 2 and E 2. 2. Higher rate of leaf emergence (LER) shown by the regression coefficient until turning point after the 1st and 2nd leaf had unfolded, declined after turning point in every varieties. Thus, a difference in the behavior of LER before and after turning point between the peanut and the soybean which shows acceleration of LER after turning point (5th or 6th foliage leaf emergence period, OIZUMI, 1962), was noted. In the peanut which shows weak or no apical dominance, this fact may be explainable by the presence of competitive inhibition upon the leaf emergence on the main stem by vigourous growth of the primordia of cotyledonary laterals had developed in the embryo and would follow after the main stem's growth when seed germination occurred. 3. Close relationship between the occurrence of turning point of leaf emergence rate and the number or degree of morphological differentiation of embryonic leaves was suggested. Then, from the anatomical and microscopic observations of plumules and upper order-leaves' primordia, it was clarlified that 5 primordia (the 1st∼5th leaf primordia) with the developed leaflets and the lowery developed 6th primordium were observed in large-seeded varieties, SP1, SP2, and P1. However, 4 well developed and 1 or 2 lowery developed ones were observed in 2 small-seeded varieties, E 2 and P 2. And variety E 1 showed the intermediate tendency in the degree of development of leaf primordia (fig. 2, A∼D and table 1). The gap of the degree of differentiation of leaf primordia recognizable between the 4th and 5th primordia (or between 3rd and 4th) in each variety differing the seed size, appeared to be a reason of occurrence of the turning point of leaf emergence rate and, at the same time, of the varietal difference of the progress of leaf emergence on the main stem in the peanut. 4. And also it may be said that the verietal difference of LER during the pre-flowering period obtained in this experiment is a reason of the varietal difference in the number of main stem leaves on the day of first flowering reported by the author. [the rest omitted]

View full abstract

For the purpose of finding the role of roots on the aerial parts, tobacco plant of about ten varieties were water cultured. Respiratory rate and morphology of roots were investigated with reference to leaf weight. The results obtained were as follows. 1. A close positive correlation between leaf weight and root activity expressed by means of respiratory rate of whole roots was found to exist at the maximum growing stage. 2. The positive correlation between leaf weight and root number was indicated by both of the fine and thick roots at the maximum growing stage, the coefficient in the former, however, was higher than in the latter. At the flowering stage, the correlation between leaf weight and thick root number was insignificant. 3. Close relationship between the weight of leaves and roots was observed at the maximum growing stage. In this case, the correlation between the weight of leaves and fine roots was larger than that of thick ones. At the flowering stage, there could be found a significant relationship between the weight of leaves and those of the thick and fine roots. At the maturing stage, however, the correlation existed only between the weight of leaves and thick roots. From the results obtained, it can be concluded that the correlation between leaf weight and the physoilogical and morphological characteristics of tobacco roots is highest at the maximum growing stage.

View full abstract

During the growth of seminal root, the dividing character of root apex is converted into the elongating one and the protein synthetic character into the cell wall synthetic one, when supply of nitrogen and phosphorous from endosperm to seminal root ceases. The changes in the characters of root apex effected the morphogenetic processes of the root, that is, the decrease in number of cortical layers in main root axis due to the fall of the dividing activity in epidermis-cortex initial cells, and the decrease in cell number of central cylinder, especially of phloem elements in the lateral root axis. The lateral roots are divided into the following three types according to size of root diameter and presence of an inner-cortical sclerenchymatous tissue as well as of a central metaxylem vessel. S type (Photo. 3) : Lack of an inner-cortical sclerenchymatous tissue and of a central meta-xylem vessel, degenerative tendency of phloem elements, 50∼60μ in root diameter. L type (Photo. 1) : The same structure and tissue orientation as seminal root fundamentally, 120∼140μ in root diameter. T type (Photo. 2) : The same structure and tissue orientation as L type except lack of an inner cortical sclerenchymatous tissue, 80∼110μ in root diameter. It was observed that laterals of S type were dominantly distribute dover all parts, especially over the parts formed by utilizing nitrogen and phosphorous derived from the cortical disintegration of aged root region, but laterals of L and T type were detectable only in the parts formed by utilization of the same from endosperm. All these laterals were active in the absorption of NH₄-nitrogen and phosphorous.

View full abstract

1. Three varieties of alfalfa (Moapa, Rhizoma and Williamsburg-chosen because of differences in their characteristics) were grown at densities of 2500 plants/m², 625 plants/m² and 25 plants/m², to clarify the relation between stand density and yield of alfalfa swards. 2. In dry matter yield per unit area for three year period, all varieties showed the ranking order: 2500 plants/m² plot=625 plants/m² plot > 25 plants/m² plot. The difference in yield between 25 plants/m² plot and the other two plots was attributed to difference in yield of the first harvest in the first harvesting year. There were no significant differences among densities in annual yield in the second harvesting year and in yield of the first harvest in the third harvesting year. 3. As for varieties, the yield for three year period approximately showed the ranking order: Williamsburg > Rhizoma > Moapa. Although very small in variance compared with that of main effect, the interactions between variety and density suggested the possibilities that the ranking order of varieties was altered according to densities. 4. Plant numbers per square meter at the final harvest of this experiment were 94, 79, 15 plants/m² for Moapa, 103, 83, 18 plants/m² for Rhizoma and 130, 99, 18 plants/m² for Williamsburg, in the order of 2500, 625 and 25 plants/m² plots. It was suggested from the decreasing trend of plant numbers of Rhizoma that the surviving rate of a variety was affected by cutting regime. 5. Individual stem weight was inclined to become heavier as density decreased. Although the differences in stem weight between 2500 plants/m² plot and 625 plants/m² plot gradually disappeared as cutting schedule proceeded, the differences between 25 plants/m² plot and the other two plots were observed even at the final harvest of this experiment. 6. Yield of alfalfa swards was maintained satisfactorily even at the density of approximately 15 plants per square meter.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

Paddy rice was cultivated on several types of soil, and the relation between the taste and physicochemical properties of rice grains were studied. the results are summarized as follows. Peat soil and severely lodged plants grown on diluvial soil produced rice grains low in starch content and also those grains were low in alkali resistance. Owing to these characters of rice grains the gelatinization upon cooking was depressed and resulted in inferior taste of boiled rice. These properties of rice grains are considered to be resulted by the over-luxuriant growth caused by excess nitrogen in later stage of the growth of the rice plants as reported in the previous paper. Alluvial and tertiary soil on the contrary produced rice grains with high starch content and high alkali resistance and cooked rice showed good palatability. The lodged plants on diluvial soil produced rice grains high in total nitrogen and proteins, and the latter might have induced the collapse of outer layer and promoted the depression of softening of inner layer at cooking. The rice grains prduced on peat soil was next to the lodged rice grown on diluvial soil in the amount of globulin and had cosiderable amounts of other proteins. Owing to these characters, the rice grains grown on the peat soil showed depression of the amounts of dissolved materials and swelling at cooking under higher temperature and ultimately became inferior in softness. The rice grains prduced on alluvial soil was poor in their nitrogen content and the amounts of dissolved materials at low cooking temperature was high and both the high amounts of dissolved materials and good swelling at high cooking temperature resulted in the high softnese of the cooked rice. The rice grains on tertiary soil was high in proteins other than globulin and proved to be gelatinized easily in cooking at high temperature. As to the effect of nitrogen, the cases of lodged plants and rice grown on peat soil, the proteins especially globulin in rice grains appeared ot depress the amounts of dissolved materials and swelling. Globulin might do so more severely at higher temperature. The rice grains produced on volcano ash soil was deficient in phosphate especially in rice bran, and both starch content and alkali resistance were low, the depression of dissolved material and swelling in cooking were found to occur ultimately resulting to the considerably inferior in taste. In these rice grains, the mal-effects of proteins at cooking as stated above was probably negligible because of the low content of total nitrogen and globulin. The main factors of rice grains produced on different types of soils to be cooked soft, sticky and palatable are considered to be the content and alkali resistance of starch, and high content of proteins especially that of globulin might promote the inferiority of boiled rice. Amylose contents had little influence in these cases.

View full abstract

To investigate the proper environmental condition for the healthy growth of rice seedlings, 24 treatment plots were set up in this experiment, combining 6 different temperature conditions (2 different air temp. ×3 different soil temp.) with 4 different soil moisture levels. The effects of temperature and soil moisture on the growth and characteristics of rice seedlings were examined at the age of 6.5 in leaf-number. The seedlings harvested at the age mentioned above were transplanted and grown under a low temperature condition, and the rooting ability was examined 10 days after the transplanting. The following are the results obtained in this experiment: (1) The leaf-emergence rate was mainly influenced by the temperature, and was hardly affected by the soil moisture as far as a relatively low temperature (16∼21°C) was concerned. However, the effect of soil moisture was gradually appeared as the temperature was raised up. (2) The plant height, the dry weight, the nitrogen content and the carbohydrate content in rice seedling were more strongly influenced by the temperature than the soil moisture. (3) On the other hand, the number of roots and water content in the seedling were more influenced by the soil moisture than the temperature, and were increased with the raise of soil moisture. (4) The number of tillers was apparently influenced by both soil temperature and soil moisture. The optimum soil moisture which produced the maximum number of tillers at each temperature condition was different, i.e. the soil moisture of 100% was the optimum at 21°C/air×16°C/soil and at 21°C/air×21°C/soil, and 80% was the optimum at 21°C/air×26°C/soil, 31°C/air×26°C/soil, 31°C/air×31°C/soil and 31°C/air×36°C/soil. (5) The following conditions combined soil temperature with soil moisture, i.e. 16°C/soil×60%/soil and 21∼36°C/soil×40%/soil were respectively suitable for the vigorous rooting under the low temperature condition. (6) In the nursery period, the combinations of 26°C or 31°C in soil temperature and 80% in soil moisture caused the poor rooting under the low temperature condition. It was pointed out from the results mentioned above that the proper soil moisture management as well as temperature management is quite necessary for raising of healthy seedlings. Therefore, the importance of the soil moisture management, especially in the high temperature condition, should be emphasized.

View full abstract

It became clear that the successive elongation in seminal root and the development of laterals depended upon the nitrogen and phosphorous derived from the cortical disintegration in aged root parts, after supply of the same from endosperm to seminal root had ceased. This result indicates that the seminal root axis on and after 4th day was composed of two parts, the one formed by utilization of nitrogen and phosphorous from endosperm and the other from aged root regions. Two types of lateral roots in growth pattern emerged from these parts respectively. The first type emerging from the former regions had an increasing protein synthetic pattern during the growth. On the other hand, the second type gave a pattern increasing cell wall substance synthesis during the growth. While the synthetic character in nitrogen and phosphorous metabolism was converted into catabolic one on each parts in root axis, begining with the rooting of laterals, the increase of lacunae formation synchronized with them. In these parts about 50 to 60 % of the nitrogen and phosphorous contained in root cylinder was translocated to younger root parts during cortical disintegration. For this reason, the cortex of rice root seems to be regarded as the reserve tissue of nitrogen and phosphorous compounds.

View full abstract