The velocity of glycolysis of available substances to rooting on the chilled seedling in dark and low temperature of 5°C preseuted intervarietal differences among rice varieties. One of the varieties investigated showed a very high speed of glycolysis, especially of the phosphorolysis of starch, and was able to develop new roots, while, the others showed slow glycolysis. The intervarietal difference seemed to be partly due to the specialization of phosphorylase activity, which should appear again in microsporocytes under low temperature and control the starch formation receiving g-l-p from tapetal cells.

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1. Transloation of P³² through the stems of rice plants artificially broken down at the heading time of the plant was reduced in proportion to severiy of the treatment. 2. When the stem was cut around the outer wall, the translocation was similarly suppressed in proportion to the extent of cutting. Therefore, the main factor of impeding translocation in broken-down stems may be considered to be the destruction of the stem wall. 3. When some of the stems of a plant were broken down, the translocation in those stems was hindered, while that in the stems untouched was not interfered. Therefore, the compensational translocation seemed not to exist. 4. The translocation in the stems which had once been broken and rose up afterwards by apogeotropism was observed to be nearly equal to that immediately after the treatment, and so natural rising-up of the stems seemed to have no effects on recovery of translocation. 5. Recovery in translocation in the broken stem when artificially raised up was found to be not so remarkable, though not negligible. To postpone helping up the broken down stems may generally be conductive to larger damages.

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Winter rye was grown on an experimental paddy field and in spring, before transplanting rice, it was ploughed into the soil at the rate of 246-600 kan per tan. To the control plot, ordinary compost manure was applied at the rate of 300 kan per tan instead of rye plants. The field was leaky, its subsoil being "Awasuna", a kind of sand. The resluts were as follows : In the years of warmer seasons, the growth of the rice plant on the rye plots was slower than that on the compost plots, while no signifcant differences in yield were found between them. In the cooler years (1053 and 54), however, the heading times on the rye plots were conversely 8-9 days earlier than those on the control ones, and the yields fronm the formers were 98-149 % heavier than those from the latters. The correlation between the temperatuer during the growth period and the increment of yield due to the rye application was very high (1, 946). According to the result of an experiment performed in 1954, it was elucidated that the difference in water temperature between the rye plot and the cotrol compost plot was not large during daytimes, while at night, it was higher in the rye plot, the irrigation water requirement being reduced in the rye plot to almost a half of that in the control plot. In this year, the yield of the rye plot increased by 325 % of that of the control. The main reason for such favorable effects of rye application on rice crops in cooler seasoned years may be that the rye plant ploughed in the soil should have controlled the water percolation to some extents and kept consequently the water temperature fall at night within a narrower range than that in the ordinary field supplied with ordinary compost manures.

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Deteriorated paddy fields of a peculiar type popularly known as Nieda exist widely in the districts of Kujukuri Coast, Chiba Prefecture, where abnormal retardation in the rice plant growth usually takes place early in mid-summer. The results of the authors investigations of the phenomena are as follows : 1) The surface of Nieda was covered by a sort of viscid mud, and water percolation was so poor that there were proved various products of soil reduction such as ferrous compounds, hydrogen sulfide and organic acids generally injurious to the plant accumulating and gradually being concentrated around the roots. 2) A symptom like Akagare was frequently observed on the rice plants grown in Nieda. True Akagare, however, is generally known as a symptom of potassium deficiency. As the plant cultured with Nieda soil was proved to have absorbed potassium normally, the symptom above mentioned should not directly be ascribed to potassium lack. 3) According to the results of the author's studies, the injury was supposed to be attributable to disturbance of normal aerobic respiration induced by absorption of ferrous compounds under the peculiar soil conditions, because the plants in Nieda were found to accumulate in their bodies abnormally large amounts of ferrous compounds. It was demonstrated, in fact, that Nieda soils could be improved very remakably by removing the viscid mud from their sufaces by means of supplying MgCl₂ or by admixing with red-colored hill soils.

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水稲の光合成と光との関係については最近いくつかの報告があるが, いずれも切断葉または孤立した個体について得られた結果である. 圃場に集団をなして栽培されている水稲では, 個体間に複雑な干渉と競合とが行われており, 従って光合成と光との関係もおのずから異なるものと考えられる. 光合成と水稲の生産性との関連を明らかにし, 実際栽培に役立つ知見を得るためには, このような群落体としての水稲の光合成の実態を明らかにすることが必要である. この見地から著者等は先ず1954年に群落内の個々の葉の光合成と光との関係を求め, さらに1955年には群落内の個体群を対象として両者の関係を追求し, さきに切断葉について得られた基本的な法則が群落内ではいかに具現されるかを明らかにした.

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In connection with researches of physiology and ecology of crop plants, methods especially effectual for instantaneous and successive analysis of gases exchanged by growing plants have long been wanted by many investigators. Most of the devices hitherto known are more or less inaccurate and tedious though designed ingeniously, and not satisfactory for general uses in such researches. In the present report a negative type "Infraed gas analyser" newly devised by the authors is described. A schematic outline of the instrument together with its working principle is represented in Fig. 1. Infrared radiation send from a light source, of which the energy distribution is shown in the figure a, enters into the absorption cell, and is partially absorbed at λ_x, λ_y and λ_z by H₂O, CO₂ and other gases contained in sample air in the cell, respectively. Its distiibution of energy after absorption is changed as shown in the figure b. Then, the ray enters into the negative filter, consisting of two chambers, one containing 100% CO₂ gas and the other N₂ gas. The part of the ray passing through the former is strongly absorbed at the region, λ_x, its energy distribution being changed so as shown in the figure d, while the part passing through N₂ gas in the latter chamber is not absorbed here at all, its distribution of energy being unaltered as shown in the figure c, which is almost similar in shape as the figure b. Each of the two parts of the ray falls finally on each junction D₁ and D₂, respectively, of the thermal detector, a thermopyle of differential type. The potential difference betwen the two junctions thus measured corresponds to the difference between the amount of energy absortion by 100% CO₂ gas and that by the sample air; that is, to the shaded portion in the figure d. The larger the concentration of CO₂ gas in the sample air, the smaller becomes the difference measured, no other gases than CO₂ interfering with the measurement. The sample air is sucked by a pump alternately through either of the three ways, one for a blank test and the others for two replicated measurements of the air from the assimilation chamber, being turned from one to another by a gas switch which is operated electromagnetically and synchronized with the automatic allocation of the marking pen of a triple-ways recording voltmeter. Several examples of results obtained by the apparatus concerning the diurnal changes in photosinthetic activity of rice plants growning isolated in pots and of those growing in a community are presented.

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In this experiment, the effects of Diffusate which is assumed to contain flower promoting substance was investigated. The substauce was slowly diffused out from vernalized rye-seeds into deionized sterilized water at a cold dark room avoiding contamination of microorganism. Washed air was continuously supplied into water for four weeks until Diffusate was collected. The heading of spring rye plants when treated with Diffusate was found about two weeks earlier than that of the control plants. Spring rye was used as a tester of Diffusate-efficiency in this case. Winter rye grains were intersected at the center and were divided into two parts i. e. embryo +endosperm (part A) and endosperm (part B). Then Diffusates were collected from both A and B, and were named D-A and D-B. Three kinds of method were taken for applying D-A or D-B; (1) soaking the seed in the substance, (2) contacting a piece of cotton wet with it to the coleoptile-tip and (3) injecting it into the stems of winter rye seedlings. As shown in Fig.4, both D-A and D-B accelerated the heading of winter rye, and D-A strongly accelerateds the stem growth in lengths.

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The potato crops in Japan were divided into following eight types according to the growing season

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Effects of temperature upon the germination of the pollen of autumn buckwheat, a common race of it grown in Iwate Prefecture, were investigated. Fresh stigmas were pollinated artificially, and after 5, 10, 30, 60 and 120 minutes, they were fixed and stained in lactic blue. Pollen grains which had germinated and developed long pollen-tubes, the contents, however remaining in the grains were graded as A; pollens, the whole contents of which had passed into the pollen tubes leaving vacant grain bodies, were graded as C; ant those which reached half-way between A and C were graded as B. Germinating pollen grains of A and B grades appeared when the stigmas were kept at 15 to 42°C., but at lower temperatures, C-grade pollens increased in number as time went by, amounting to 65.1 % of the total number. Under the temperatures higher than 42°C, C-grade germination was not observed. In general, at lower tempertures the growth of pollen-tube was slow but continuous, while at higher temperatures it was rapid at the beginning, and stopped soon afterwards leaving germination incomplete. In buckwheat plants, pollen germination was observed to take place at 18 to 30°C., its optimum being about 20°C.

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The species investigated were as follows: Sesamum alatum, S. angolense, S. angustifolium, S. capense, S. prostratum, and S. radiatum. The reed germination rate and germination energy of these species were generally low, and the terms required for germination were longer than that of the cultivated species Onishi-shirogoma (S. indicum). But we could obtain high germination rates by either of those two treatments, namely, wounding their seedcoats or alternating the germination temperature (30°C-8 hours and 20°C-16 hours, alternatively). S. alatum, S. angolense, S. capense, and S. radiatum showed more remarkalbe branching habit than the cultivated species (S. indicum). S. prostratum was found to have a creeping habit. S. angustifolium came into full bloom about one month later than the other species, and maturing was also late. The foliar glands of those wild species were larger and more numerous than those of the cultivated species (S. indicum). Capsules of S. prostratum were difficult to dehisce at maturing time. According to Index Kewensis, S. alatatum is identical with S. capense. We express our hearty thanks for the kindness of those who sent us the sesame seeds for this experiment.

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For the purpose of improving the rice crop on ill-drained lands distributed over Chiba Prefecture, experimental studies were made by the authors on the effects of Baido practice, a method of cultivation to earth up growing rice plant hills. The soil concerned being ill-drained and especially rich in humus, there took place usually severe decomposition of components promoted by the sudden rise in soil temperature in late July, and it became so reductive, as to retard the plant growth. remarkably. The results obtained were as follows: 1) In the experimental plot where Baido practice was applied, both the plant height and tiller increased, and the leaf color became deeper than those in the control plot of ordinary tilling. 2) The Eh value of soil was foud to rise considerably after the operation and to be kept higher than that of the control plot for about a month. 3) NH₃-N was produced in the soil about 10 days after the operation, and the K₂O content in it became higher, while Mn₂O₃ was less than in the control. 4) The grain weight, number of grains per panicle and number of panicles per plant were generally higher in the Baibo plot, giving decidedly better yields than in the control. But, the promotion was only a little when the operation had been long delayed after transplanting, probably because the late operation injured the plant roots. 5) Absorption of inorganic matters (Mn₂O₃, MgO, K₂O, CaO, etc.) by the plant was accelerated by earthing-up, among which that of K₂O was affected most remarkably, while the amount of total nitrogen in both the plots scarcely differed, the fact being possibly due to strong synthesis of protein by aerobic respiration of the roots. 6) From the results above mentioned it may be concluded that Baido practice is a useful technique especially for ill-drained fields, if it be worked timely. The oxidation layer in the soil may thus be retained, and in consequence the aerobic respiration in the root may be favoured.

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This study was planned to make clear whether the promotive effect of low temperature on the flower bud initiation in tobacco plants is exerted more in diurnal dark period or in light period. The material used was Bright Yellow, a Virginian variety, which had been grown in an air-conditioned glass-house under various photoperiod. The detailed design of experiment is given in Table 1. The results may be summarized as follows: 1) By the 1st experiment, wherein 12hours' light and dark period were alternated at either high (25°C) or low(13°C) temperatures, it was observed that the plant maintained constantly at the temperature initiated first the flower buds, while next was that grown under the low temperature for the light period and last was that under the high temperature for the dark period. No marked difference in response was recognized between the plant under the costant high temperature and that under the high temperature only for the light period. 2) Exposures to different lengths of illumination from 8 to 14 hours at constant high or low temperatures were given in the second experiment. It was proved that under the low temperature developmental response was accelerated regardless the day-length, while under the high temperature it was decidedly retarded under 12 or more hours' illumination, though not so much under 8 hours' illumination. 3) An experiment of various combinations of the length of photoperiods and the height of temperature was also performed. The result was that, the plant development was promot d by the low temperature for dark period regardless the day length just as by the constant low temperature. And the plot maintained at the high temperature during 8 hours' illumination and at the low temperature for dark period reached its flowering stage as rapidly as those which were subjected to the low temperature for light period or as that subjected to constant low temperature. On the other hand, the imilar plots illuminated however for periods longer than 8 hours showed retardation of bud formation. 4) The above results may suggest the fact that the promotive effect of low temperature upon flower initiation in tobacco plants is remarkable at a light period than at a dark period.

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As a fundamental study of controlling measures of Alopeculus aequalis, an annoying weed in wheat and barley cultivation on drained paddy fields, certain factors which would have closer relations to its germination and emergece, were examined. The results are as follows : 1. The optimum soil moisture for emergence of Alopeculus was found to be about 80 % of the water capacity (Fig. 1), being higher than that for wheat. The optimum, minimum and maximum air temperatures for emergence were about 15°, 5° and 23°C, respectively(Figs. 4 and 5). The depth of soil through which the weed can emerge differed according to soil moisture. Generally speaking, the limit of it was about 4cm. which is very shallow as compared with that for wheat. It may be natural that frequency of emergence should be closely related with the density of distribution of viable seeds within the top layer of soil. The population of viable seeds decreased from day to day after the field was drained in autumn (Fig. 6). 2. Emergence of this weed in paddy fields occur most vividly in autumn after they have been drained, and also in spring. Its population may be decreased by means of late autumn tillage 3. In wheat and barley cultivation on drained paddy fields, later seeding should be a very effective measure of controlling that weed.

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Experimental studies were conducted through four years, from 1951 to 1954, at Tohoku Agr. Exp. Sta., Morioka Prefecture, on the influence of crops of 16 kinds on soil erosion on an experimental field with a slope of 10° and a slope length of 36 feet. 1. The soil loss in the plot without cover crops was 12, 872kg per Tan through four years. The cover-cropped plots was lower in erosion intensity, and there was observed a high correlation between the soil loss and the density of crop plant canopies. 2. Among the crop kinds studied, red clover was the highest in the soil conserving efficacy, while rape was the lowest, the order being as follows. red clover (in the second year) > sweet potato > turnip > soybean > cabbage > potato > sawa-millet > upland rice > oats > red clover (in the first year) > green cut corn > buckwheat > radish > corn > wheat > rape. 3. If we should consider the allowable soil loss 3 to 4 tons per acre per year, cropping continuously in furrows along the slope lines on a hill, which is usual manner of cropping practice in the majority of Tohoku District, would evidently be not favourable for soil conservation.

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1. Three types of special vascular bundles were found in the rice coleoptile. The author has named them as short bundle, cortical bundle and separated bundle, respectively. 2. The separated bundle was found to diverge from the ordinary coleoptile bundle, but both the short and cortical bundles to be differentiated ad nouva from the cortical parenchyma near the coleoptilar node. 3. No morphological difberences were found between the cortical and the separated bundles, and their lengths were both a little shorter than that of the ordinary bundle. 4. All those special bundles were differentiated during the period of most rapid development of the embryo, but they were distinguishable with each other from the beginning of their appearance. 5. Frequency of appearance of the bundles was different from each other. As the coleoptile nervation increased, there differentiated first the short bundle, next the cortical bundle, and then the separated bundle. So the intensity of function of each bundle should be supposed to be increased in the similar order. 6. As seen from the variation in coleoptile nervation responding to environmental conditions, the appearance of the special vascular bundle in the coleoptile will be supposed to show control-action of coleoptile against the change of internal conditions of the embryo during its development.

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In his previous reports, the author demonstrated that for rice plants it is very desirable to maintain many green leaves at the ripening period for producing a good yield and quality of the grain, and that abundant starch is found remaining in the culms of harvested plants in such a case. In the present study, he tried further to elucidate the relation between the quality of the grain and the amount of starch in the culm. In the experiment, the leaf-blades were cut off from the plant or the panicle-branches were thinned at the heading time, for the purpose of changing artificially the relativity between assimilatory abilty and storing capacity of assimilated substances. By cutting off the all leaf-blades at the heading time, the fruiting percentage and the weight of the kernel were both lowered remarkably, and the grains harvested became very poor in quality. By thinning the panicle-branches, the effect was reverse. In the culm of the plant deprived of the leaf blades, starch diminished rapidly. and vanished completely within two weeks after the treatment, while in that the panicle branches of which were thinned, there remained abundant starch, the fact-indicating want of spaces in tue kernel tissues to receive and store the substance. Compound starch grains were seen in the pericarp tissues on the next day of flowering, they developed in size, and after two weeks they disappeared. In the endosperm tissues, compoud grains were similarly observed on the fourtn day after flowering, and then increased rapidly in volume. It was very interesting to note that the number of single grains constructing a compound starch gain was larger in the endosperm than in the vegetative tissues including the pericarp.

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The pH values of the cytoplasm of definite tissues in the plant, especially susceptible to soil acidity, were observed to decrease decidedly when it was cultured with solutions adjusted at pH 4. It was found however, that the method might be improved in various ways more simple and efficacious.

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Further studies were made on the ventilating system in various plants in relation to the ventilating pressure, the results being summarized as follows: 1) A highly developed ventilating system was observed in various lowland plants, wherever they might be grown, They exhibited a lower ventilating pressure, varying almost in accordance with the metabolic activity of their roots. 2) On the contrary. feebly developed ventilating systems were observed in upland plants, as far as they were growing under dry conditions. They could accomodate themselves to over-moist haditats, by means of reconstructing the ventilating system likely enough to make it possible for their roots to receive considerable amounts of oxygen from their tops. Considerable degrees of reformaticn in the ventilating system and renewal of the root system were observed when they met with over-moist conditions. 3) Referring to the POISEUILLE's and FICK's laws, a theoretical explanation of the relation between the significance of the ventilating pressure and the gaseous diffusion from the top to the root was presented. Explanation of figures The dotted portions in all the figures refer to the intercellular spaces containing much air or the tissue having those spaces. The abbreviations are as follows : Ca, cavity; co, cortex or hypodermis; en, endodermis; ep, epidermis; ha, hair; ly, lysigenic space; pi, pith; rh, root hair; rv, reinforced vascular bundle; sv, separated vascular bundle; sz, sizogenic space; va, vascular bundle. Rice plant (common to the lowland and upland rice pldnts). Fig. 1. Internode of the peduncle. Fig. 2. The 1st internode (the uppermost). Fig. 3. The 2nd internode. Fig. 4. The 3rd internode. Fig. 5. The 4th internode (the lowest elongated one). Fig. 6. Not elongated internode in the 5th order. Such an internode is a component of the so-called tillering portion, totaling about 12 internodes in succession. Barn-yard grass and other grasses. Fig. 7. Internode of the peduncle. Fig. 8. The 2nd internode. Fig. 9. The 4th internode. Fig. 10. The 6th internode (the lowest elongated one). Fig. 11. The stem of Ranunculus sceleratus. Fig. 12. The stem of Veronica Anagallis. Corn plant growing on upland (12 leaf-stage). Fig. 13. Middle portion of the 4th green leaf-sheath. Fig. 14. The 4th node to which the 4th green leaf-sheath is attached. Fig. 15. The 6th internode. Fig. 16. Root zone with a crown root. Fig. 17. Basal portion of a crown root. Fig. 18. Middle portion of the crown root. Corn plant kept flooded (12 leaf-stage). Fig. 19. Middle portion of the 4th green leaf-sheath. Fig. 20. The 4th node to which the 4th green leaf-sheath is attached. Fig. 21. The 6th internode. Fig. 22. Root zone with a crown root. Fig. 23. Basal portion of a crown root. Fig. 24. Middle portion of the crown root.

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The pH value of the sample shifts from the original value, as the amount of water added to the material at homogenization is increased or as the time elapses after the process. Either to keep the fresh material refregerated till homogenization, or to saturate the homogenized juice with toluol are good measures for preventing changes in the pH value. Anyhow, the pH-measurement should be made under a definite concentration of the juice and within a definite period after homogenization.

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The relation of the rachilla-length in rice plant (variety "Aichi-Asahi") and the funiculus-length in Vicia sativa L . var. normalis M., to germination was investigated. The funiculus-length in Vicia was measured after soaking the sample pod in hot water (at 80∼90°C) for several to fifteen seconds. Then the seeds, detached previously from the pod, were tested of their germination in a PETRI-dish in the laboratory, observation being continued for about one year. Germination tests of rice seeds were made only in a week in an electric thermostat at 26-28°C with LIEBENBERG's germinators, after measurement of rachilla-length. The results are as follows : (Fig. 1∼3) 1) In rice, the rachilla of a terminal caryopsis on each rachis was longest being about 13mm. in length, followed by those of the others in an order: 6th, 5th, 4th, 3rd and 2nd from the apex, the length of the last one being only about 2mm. 2) 2nd caryopsis which had shortest rachilla germinated earliest and the terminal one did latest. Thus, the order in germination speed agreed with the order in rachilla length. 3) In Vicia, the funiculus lengths were irregular. But the germination order was similar to that in rice, the seeds with shorter funicula were earlier in germination than that with longer ones. In the authors previous reports it was mentioned that a positive correlation was found between the thickness of outer-integument and the length of funiculus in the ovary in Vicia. They supposed in the present studies that funiculus-length had some relation to hardening of legume seeds.

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1) The authors divided the whole period from differention of flag leaf primordia to heading into 21 stages, as seen in the previous paper. (Vol. 23;24, 1955) 2) It has been made clear, that the first bract primordia can always be found as a vestige on the neck-node of an adult panicle, the second bract on the base of the second branch, and the third on that of the third branch in first order. Sometimes the first bract changes into a flag leaf, and one can easily recognize such a case by observing an imperfect neck-node and a well developed or a degenerated first branch inside the sheath of the flag leaf on an adult plant. 3) All vestiges on adult panicles can be classified into four kinds-bracts, spikelets, branches in first and second order. But the vestige on the base of the top branch which can be seen on every panicle has been proved to be a compound vestige of a bract and a growing point. 4) Investigating successive cross-sections of young panicles, the authors have found the large bundles in the axes of panicles were divided into each branch one by one. 5) The lowest branch on the axis always differentiates first, but it starts last to grow, that is to say, the order of differentiation among branches is quite contrary to that of growth among them. The same is true with secondary branches, while the order in differentiation of spikelets is in accordance with that of their growth. 6) Duration of each differentiation stage on an individual stem has been made clear, as seen in Table 1. (The weather in 1953 was rather bad, and that in '54 was nearly normal.) 7) By tracing up the developmental process on all culms of three hills every other day, the authors have succeded, for the first time, in ascertaning on a whole field, when the beginning, the middle and the late periods of every developmental stage occur respectively, and how long the duration of each stage is. An instance of it can be seen in Fig. 1. 8) After examining the methods of identifying each stage without microscopical investigations, the authors have found the following methods to be recommendable: (a) Age-index of the plant, which is represented by the perce ntage of the number of leaves which emerged on a main stem by a given time to the finally attainable number of leaves of the stem, showed good fits for identifying the stage. (The finally atainable number of leaves on the main stem of a definite variety keeps constant every year under a definite culture condition.) And the relation between the-indexes and the developmental stages is given in the Table 1. (b) Length of the young panicle can be utilized to a considerable extent in knowing each stage : stage VII.... 0, 4∼0, 5 cm., VIII.... 0, 5∼0, 9 mm., IX∼X.... 0, 8∼1, 3 mm., XI.... 1, 5∼3, 0 mm., XII.... 3, 5∼15, 0 mm., XIII.... 1, 5∼5, 0 cm., XV-XVI.... 10∼17 cm., XVIII.... nearly full length, XIX.... full length. (c) Distance between the blade-ear of the flag leaf and that of the second leaf can be utilized conveniently to identify the stage of the reduction division of pollen-mother-cells which is the most critical period for rice plants in growth. The prosperous period of the reduction division occurs generally at a time when the blade-ear of the flag leaf begins to appear out of the second leaf-sheath. (d) The length of the spikelet increases with the developmental stage of the panicle, attaining the full length at the end of extine-formation stage (XIX). The first or the second meiotic division can generany be seen in spikelets grown half as large as full length. (e) The numbere of days prior to heading which has hitherto been employed can also be used only under normal weather.

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Photosynthesis in rice plants grown on a field was studied using Norin 37 variety in 1955. Apparent rates were measured by comparing the CO₂ content in normal air with that in the air stream from a blower passing through a plant chamber which covered four plants under it. CO₂ analyzer with a slight modification of that described by CHAPMAN and LOOMIS (1953) was used. The results obtained were as follows: 1) Diurnal clranges in the rate of photosynthesis showed a tropzoid and a saturation point was observed on fine days during the period from tillering to booting stages. With the progress of plant growth, however, the saturation point disappeared and there occured a complete parallel relation between the photosynthetic curves and light intensities, up to the time of heading. 2) Changes in light intensity and the rate of photosynthesis associated with growth stages were shown in fig. 3. The saturation point which was comparatively low during the tillering stage, ascended gradually with the progress of growth, and disappeared completely at the atage just before heading. The results seemed to indicate that the plant under field conditions had different demand for light intensities for the maximum photosynthetic activity at different growth stages. 3) The seasonal changes in the rate of photosynthesis are presented in fig. 5. The first maximum point appeared immediately before the stage when the young panicles begin to differentiate. During the subsequent elongating stage the rate gradually decreased and again reached the 2nd maximum point at the boot ing stage, followed by reduction that continued until the time immediately after hegding. At the earlier milk stage, or when the carbohydrates began to be translocated to ears from the culm and the leaf sheath, the rate was recovered.

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Barley (variety Sekitori Sai-No. 1) and wheat (variety Norin No. 50) were grown on a diluvial clay loam soil in every season during 5 years, 1949-53, and the relations of the irrigation period and the growth and yield of the crops were studied, the results being as follows: 1. Though the grain yields were bound more materially affected by the amount of precipitation irrigation, either in the middle of March or in April was effective to increase them. Winter irrigation tended to reduce the yields. The increase in grain yields due to irrigation was generally more conspicuous in wheat than in barley. The barley yield in the irrigated plots showed decided increases only in dryer years, 1949 and 1952 being such cases, while that of wheat increased almost every year of the experiment giving increments of ten to twenty percent of the yield from the unirrigated plots in dry years. 2. The increase in grain yield by spring irrigation was ascribed to those in fruitful tiller percentage, in culm-length and in grain weight per 1000 kernels. 3. The reasons why winter irrigation did not favoured the yield, even reducing it in some cases, might be explained as follows: a) Both the crops concerned do not require much water in the early and middle stages of their growth. b) In winter, the soil moisture does not decrease so much as in spring. c) Frost and ice crust formation, promoted by irrigation, and besides the soil temperature fall due to their thawing, may retard the plant growth. such adverse effects of winter irrigation upon barley crops may probably be due to shallowness of root zones and high susceptibility to water lodging of soil of the plant as compared with wheat. 4. It may be duely concluded that irrigation of wheat or barley should be practised most favourably in spring.

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Yamasaki, one of the authors, has once reported that wheats are less resistant to the toxic action of chlorate than spring ones, and he attributed the phenomenon to the difference in the contents of reducing substances such as glucose, aldehydes etc. in plant tissues. The present authors studied the interrelations among the content of vitamin C, one of the reducing substances in plant tissues, intensity of winter nature and chlorate resistance of varieties in wheat. Experiments were made with shoots germinated in Petri-dishes with pure water, employing 6 varieties varying in winter nature intensity. The relations of the vitamin C content to the winter nature were found as follows : 1) In the experiments conducted in winter, the higher the intensity of winter nature of the variety was, the more vitamin C was proved, under natural condition as well as in the dark. 2) In spring or summer, however, there was no correlations between these two characters. 3) When the temperature either or both in the daytime or at night was low, the results similar to those in the winter experiments were obtained, that is, a significantly high positive correlation wad represented (cf. Table 1, 2). From these facts and other results, the followings should be extracted : In order that the above-noted correlation between these two characters is presented, low temperatures are necessary. The light condition or the difference in temperature between the daytime and the night has no effect on such relation. The resistance to the toxic action of chlorate of the same varieties was tested simultaneously. A high negative correlation was recognized between the resistance and the winter nature intensity, regardless of temperature in the daytime or at night. (cf. Table 3). Considering of the results of the vitamin C determinations and the chlorate resistance tests, the negative correlation is recognized between the chlorate resistance and the vitamin C content, except when the temperatures both in the daytime and at night are high, under which condition the chlorate resistance seems to be affected by some uncertain factors other than vitamin C.

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The intensity of the toxicity symptoms due to salinization was found significantly greater in the plants under anaerobic conditions than under aerobic conditions when the plant was grown at the level of a sline concentration critical for its growth, while at higher levels, the difference was not so remarkable. The similar relation was indicated by the reduction in the root and top growth, in hydration ratio or in the leaf number. Sodium accumulation in leaf blades was lower under anaerobic conditions, the fact being particularly distinct at the critical concentration. Other elements decreased generally in the plants treated by saline solution under aerobic conditions, while under anaerobic conditions such relation was not evident. On polder fields, wheat crops, when it was alternated with rice, gave extremely small yields compared with that of upland culture of the same crop, and the length and width of leaf and size of stoma on top leaves of the plant in the former case were remarkably reduced, while the number of stomata increased. The porosity of the upper layer soil on the fields after rice cropping was distinctly smaller than that on the other fields. So far as the present experiment is concerned, it might be suspected that the toxicity symptoms of salinization should be intensified by anaerobic conditions around the roots.

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Experimental researches were performed on the growth and yields of kidney bean plants as affected by the treatment of pinching-off one or two of the three leaflets of every leaf at its very young stage. 1) The growth in the stem length was retarded, while the numbers of leaves and flowers were increased by the treatment. 2) The leaflets left on the treated leaves developed generally larger than those of the corresponding positions on the untouched control plants. While the areal ratio among the three leaflets on every normal leaf was nearly 1 : 1:, the ratio between the two leaflets left on every treated leaf was still found to be 1 : 1, not disturbed by the treatment, though they developed respectively larger in their absolute areas. The central leaflet however proved itself somewhat peculiar in areal growth, differing from the side leaflets. 3) There were obseved a tendency that pinching one of the leaflets of every leaf favoured the yield, while to pinch two of them reduced the yield.

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At each of several seed farms located at various hight of elevation of 80 to 1350 meters on the foot of Mt. Fuji and on the side of Mt. Yatsugatake, soybean seeds of two varieties were raised and their productive predispositions were examined. The results of studies for three years, 1951 to 1953, were as follows : 1. The size of the seed produced varied according to the farm within each variety. The differences were proved, however, due chiefly to the difference in the edaphitic conditions rather than in the climatic conditions among those farms. 2. The higher the farms were located, the earlier the plants bloomed and matured, and the less were the amounts of fat contained in the seeds produced. No cumulative nature in such effects were noticed. 3. Growth of the plants raised from larger seeds was generally better than that from smaller ones in the same variety in earlier stages. But as the growth proceeded, the differences diminished gradually and became very little on harvest. 4. Differences in the progeny growth and yielding ability of the seeds due to the differences in the elevation, where they were raised, were small when they were selected for an equal size. The seeds produced on barren soils or at localities where plant diseases prevailed showed lower productivity regardless the size 5. It was concluded that to adopt localities as free as possible from plant diseases or noxious insects should be indispensable for producing superior seeds of soybean, and that, out of those seeds, larger sized ones within every variety should be selected for planting to expect more abundant yields.

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As a fundamental investigation of controlling Alopeculus aequalis, one of the dominant weeds in wheat and barley cultivation on paddy fields, the seasonal variation in the distribution of the seeds in the soil of the field was studied. The results are as follows: 1. Dormancy of the seeds buried after their ripening in spring disappeared almost completely until the middle of or late in September. The longevity of buried seeds was found comparatively ahort; about a year in well-drained fields, and about 2 years in poor-drained fields (Table 3). 2. The density of viable seed populations top in soils decreased from day to day after the field had been drained in autumn, and process of the decrease varied wideiy with the depth of soii layer, and also with tillage practised or not (Table 4). 3. The vertical distribution of viable seed populations in top soils changed remarkably as the time elapsed after drainage of the field. Moreover, the distribution varied with the methods of tillage prior to transplating of rice plants, and with the autumun tillage (Fig. 2). 4. Based on these relations, a schema showing seasonal distribution cycle of the seeds in the soil was illustrated (Fig. 3).

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Rice plants, the variety Norin No. 29, were grown in pots under various environmental conditions and several aspects concerning their carbohydrate accumulation were observed. The results may be summerized as follows: At higher levels of N nutrition, the amount of carbohydrates accumulated in the plant at its maturation period was found larger and the proportion of the amount of accumulation during the later period of growth to the total for the whole period was high, in comparison to that in the plant grown at lower levels of N. In the latter cases, the rate of carbohydrate accumulation was found to be accelarated by supplying N. in the ripening period, in contrast with the former cases where the plants had previously been grown at higher levels of N, the acceleration being less distinct. The plants grown at lower levels of P nutrition accumulated smaller amount of carbohydrate than that by the plants grown at higher P levels, but the rate of accumulation in the former plants was accelarated by application of P in its ripening period. The plants grown under low intensity of light (shaded by cloth) showed many characteristics similar to those in the plants grown with high levels of N nutrition, and the dry weight of the plant and the absolute amount of accumulated carbohydrates in it were found to be smaller than those in the plant grown under a natural light condition. At the period of maturation, it was found that about 90-95 % of accumulated carbohydrates were distributed in the panicles, while only a small part of them was distributed in the vegetative organs under the ordinary condition. Under the condition where the photosynthetic activitities of leaves were extremely vigorous, a large amnunt of surplus carbohydrates, being unable to move into the panicles because of exceeding the receiving capacity of the part for storage of the substance remained in the vegetative organs, particularly in the culms.

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In 2nd report authors have discussed that the rice plant cultured in pot, i. e. in the isolated conditions, have got different demands for light in order to have its maximum photosynthetic capacity according with its different growing stage, and this differences of demands for light was due to the differences in conditions of receiving the light, which was influenced by the mutual shading rate of leaves within the individual plant. It is quite clear that the ecological conditions of the pot-cultured plant is remarkably different from that of the plant in community. In general, the rice plants are cultured in community conditions at the paddy field, therefore, in order to approach the practical problems of the rice cultivation, the studies of photosynthesis of rice plants must be done in community conditions. In this paper authors have tried to clear the relationships between the spacing of plants and the demands for light by the plants. The effect of light intensity on the photosynthetic rate of plant, which was cultured in community conditions in different spacing, was measured by the "Infrared gas analyser" described in the previous paper. The results obtained were as follows: 1. In community conditions, at the early stage of growfh the demands for light by the rice plant for its maximum photosynthetic rate are comparatively low, and the saturation point lies under about 50 K Lux, and then the demands for light by the plant increases gradually according with the growing stage, after middle stage of growth about full tiller stage) the light satutation phenomenon is extinguished, and the transition from light-saturation to -unsaturation is influenced by the spacing of the plants. The thicker the spacing of the plants, the earlier the extinction of the light-saturation phenomenon. After the extinction of light-saturation phenomenon, the relationships of photosynthesis to light intensity becomes linear gradually, and this is due to the differences in conditions of receiving the light, which is greatly influenced by the mutual shade among the plants. 2. Changes in photosynthetic rate of rice plant in community are remarkably influenced by the growing stage and also by the spacing of the plants. In the thin spacing (36 × 36 cm) and intermediate spacing (24 × 24 cm), the maximum photosynthetic rate is observed at the stage when the most active tillering takes place, then it decreases gradually untill the booting stage, and after heading time it decreases remarkably. On the other hand, the thick spacing (12 × 12 cm) shows its maximuin photosynthetic rate from full tiller stage to booting stage, and after heading time it decreases gradually. The differences of the changes in photosynthetic rate duing to the spacing of the plants may be seemed to be due to the differences of the interrelationships between the top-growth and the uptake abilities of fertilizer duing to the differences in conditions of receiving the light, which is greatly influenced by the spacing of the plants.

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