In order to make clear the process of the emergence of plumule in the direct-sowing on dry fields, elongation of plumule through soils after germination was studied. 1) The rate of emergence of plumule decreased with the increase of seeding depth of soil covering. In the case of 5 cm-seeding-depth, the more the amount of larger clods, the more the number of plumules perished under ground. 2) The growth of the plumule of 3 cm-seeding-depth plot and that of darkness was more rapid than those of 5 cm-and 7 cm-seeding-depth plots. In this case, somewhat positive correlation exists between the time of the emergence of leaves from coleoptile and the growth of the plumule. 3) The elongation of plumule was affected by temperature. In the plot of 5 cm-depth of seeding, the number of days from seeding to emergence of plumules at 30°C, 25°C and 20°C were 5∼6, 8∼9, and 11∼12 days respectively. 4) The elongation of plumule was also affected by the hardened texture of the seed bed. When the soil covering was conducted with larger clods, the degree of the inhibitive effects of soil moisture content (130∼100 per cent soil moisture content of field moisture capacity) on the emergence was decreased.

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In order to make clear the factors affecting to the accumulation of dry matter in flue-cured tobacco leaves in maturing stage, the effects of night temperature and nitrogen concentration of leaves upon the loss of dry matter from leaves due to the respiration and translocation at night were studied by means of punching method. The results obtained were as follows: (1) High temperature at night and high concentration of total nitrogen of leaves markedly affected the loss of dry matter from leaves dy respiration. At 30°C, close correlation was recognized between the loss of dry matter by respiration and total nitrogen concentration of leaves. This correlation was lowered with decrease in temperature, and at 15°C, no correlation was recognized between them. (2) When much nitrogen was supplied, increment of dry matter by translocation in upper leaves was observed. Under the low nitrogen supply, however, upper leaves lost dry matter by translocation. On the other hand, the lower leaves lost dry matter by translocation under both condition; especially this tendency was remarkable under the low nitrogen supply. (3) Negative correlation was recognized between the amounts of dry matter increment by translocation and the ratio of total carbohydrate to total nitrogen in leaves. (4) It was not able to make clear the effect of night temperature upon the loss of dry matter from leaves by translocation.

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Flue-cured tobacco seedlings were transplanted in pots of 12cm in diameter. Ten days after that, another pots were set on the pots so as to make upper roots develop, conductive tissues of which have close relation to upper leaves. After topping, the loss of dry matter from leaves by translocation was investigated in relation to leaf position on the stem, nitrogen concentration of leaves and roots conditions. Just after topping, the increase of dry matter by translocation in upper small leaves was recognized. Being fully expanded, however, upper leaves lost dry matter by translocation. When large amounts of nitrogen were supplied to upper roots, the amounts of the loss of dry matter from upper leaves by translocation markedly increased; but it decreased by cutting upper roots off. Although it had been generally recognized that lower leaves lost dry matter by translocation, high nitrogen concentration in lower leaves and increment of dry matter by translocation in these leaves were observed as the results of nitrogen supply to lower roosts. These facts, as shown above, reveal that quantitative change of leaf dry matter by translocation is influenced by nutritive condition of leaf beyond the relation with leaf position on the stem, and also influenced by metabolic activity of roots.

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The method of scab inoculation onto leaf blade, reported previously, is inconvenient to treat in the field. It will be more favorable if the scab can be inoculated onto leaf blade of the plants water-cultured after being pulled out from the field. The rerults of this study indicated that this was possible. The plants were pulled out from the field and water -cultured in the beaker. After having been inoculated, they were kept at room temperature (15∼20°C) during daytime and at 25°C in the thermostat at night. Scab infection was observed within several days. It must be mentioned that when the plants were at heading time, all the head should be removed to prevent emaciation of the treated leaves.

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This paper dealt mainly with the effects of nutritive deficiency upon the formation and physiological characteristics of lateral roots in rice plant. Thirty days old seedlings of the variety Norin No. 1 were grown in culture solutions, from which main nutritive elements such as N, P or K was remorvd respectively (Table 1). Plants were sampled 1 month later for the investigations of ecological characteristics of their primary and secondary roots. Main results were as follows: (1) Under conditions of abnormal nutrition, number of primary roots, especially of the newly emerged ones (A class root), decreased in contrast to those of more aged roots (B, C, D and E classed). The length of all roots classified was almost reversely circumstanced as compared with numbers. The root diameter increased in general (Table 2). (2) Total number of lateral roots per primary root and their density increased particularly in B and C class roots, when plants were affected by abnormal nutritions (Table 2). Lateral roots showed a tendency to appear near the tip of a primary root in those cases (Fig. 2). In addition to this experiment, the effects of nitrogen deficiency on lateral roots of the seedlings were examined. From results of this experiment, it was concluded that their lateral roots were similarly increased by the deficiency of the element (Fig. 4). Moreover, physiologically abnormal branch roots (c and t₁), showing less TTC reducing activity (Fig. 3), increased in such a case (Fig. 5).

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In this report the lateral root formation was examined in rice seedlings (Var. Norin No. 1), which were placed under abnormal conditions such as root decapitation, shoot removal and growth in dark. Changes in number, density and TTC reducing activity of lateral roots due to such abnormalities were mainly discussed. Main results were as follows: (1) During the growth of plants without any treatment mentioned above, two types of root growth were observed; the one, in which both of root elongation and lateral root formation were promoted in parallel (Fig. 3a) and the another, in which the former was retarded and the latter accerelated (Fig. 3b). In the second type of growth, root tip was without exception damaged by the unknown cause. (2) In the plant, of which root was decapitated, the lateral roots formation was always promoted (Tab. 1). (3) In both of plants, of which shoot was removed and etiolated by placing in dark, it was also observed that root elongation and lateral roots formation were accelarated (Tab. 1). (4) All lateral roots found in plants of all plats including normal and abnormal, were classified into a, b and c by the degrees of TTC reducing activity. In the abnormal plants it was generally shown that lateral roots with higher stainability decreased and those with lower ability increased (Tab. 2). All of the phenomenon mentioned above showed the same tendencies as these observed in the previous report concerning nutritive abnormality.

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In order to investigate the effect of temperature on leaf production and transformation of photosynthetic product into various organs, the studies were carried out under both controlled environmental conditions and natural field condition. Obtained results are as follows: 1) Even without clipping, under higher temperature conditions, the growth of various organs decreases gradually, plants become weaker before long, and presents the symptom of summer depression. 2) The higher the temperature, the more the flower buds are formed, and the less the portion occupied by storage organs. And the preparations to regrowth become worse. 3) Becoming worse of preparations to regrowth under higher temperature conditions seems to be a result caused by adaptation to keep the balance between production and consumption. And as a result, the plants make their non-photosynthetic parts less relatively. 4) Maximum leaf-size is found under 15°C and 20°C temperature conditions, and it is found that under higher or lower than this optimum conditions leaf-size becomes smaller. 5) Not only the interval of leaflet emrgence but also that of its death become shorter under higher temperature, longer under lower temperature, but the increasing rate of living leaf number shown by the ratio of the former and the latter reaches maximum at 20°C and 25°C, and becomes less at 15°C and 30°C in accordance with this order. 6) It is found that the number of branches and its increasing rate reach maximum under 15°C and 20°C, and under hither or lower than this optimum conditions they become less. Flower bud initiation is subject to stimulation by long day and high temperature conditions. 7) The higher the temperature, the shorter the number of days required to expand leaflet fully. 8) Judging from the above stated facts, the apparence that total leaf area of the plant under higher temperature conditions may be attributed to the following facts; (1) the size of leaflet under higher temperature conditions is smaller than that of under lower temperature, and (2) lower increasing rate of branches and higher initiating rate of flower bud under higher temperature conditions make the increasing rate of living leaf number less.

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In this paper, the effects of temperatures on the growth of petiole, stolon and root, which are non-photosynthetic-organs of Ladino clover and the correlations among organs were analyzed with the materials used in previous study that were carried out under both conditions of controlled environment and field. The results obtained are as follows. 1) The growth of petioles were better at lower temperatures (15-20°C) than at higher temperatures (25-30°C). This temperature response of petiole was about the same as that of leaflet. There were high positive correlations between the length and thickness of petiole, and also between length and thickness of petiole and length of leaflet. 2) The growth of stolons decreased as temperature rose in accordance with the reduction of weight per stolon and of branching numbers per plant. In this case, the weight reduction of stolon was caused by the shortening of each internode, as well as by the thinning of it. 3) There were high positive correlations between length or thickness of internode and petiole length, and these factors of internode and leaflet length respectively. These results suggest that the elongation of internode is accompanied with the horizontal magnification of space where to leaflets expand their area, and the thickening of internode is accompanied with the suitable growth of vessels and storage tissues to growth of leaflet. 4) The growth of roots decreased as temperatures rose. The facts that there were high positive correlation between numbers or weight of stolon per plant and root weight per plant, show that the growth of root is closely related to that of stolon.

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In this report, in order to reconstruct experimentally the process of the growth depression and to investigate them collectively, repeated cutting treatments were added at a certain intervals, and the quantitative as well as the qualitative changes in reserve organs and reserve substances in the organs which determine the following regrowth, and the changes in top regrowth at different temperature conditions were studied. 1) At 30°C, dry weight of reserve organs (stolons and roots) decreases gradually due to repeated cutting, at 25°C dry weight of reserve organs shows nearly constant value, and at 20°- 25°C dry weight of them tends to increase. 2) Under the temperature higher than 20°C, the total carbohydrate contents in reserve organs which are the substantial energy source determining the following regrowth decrease gradually. At 25° and 30°C, the crude protein contents in reserve organs which are the constitutional materials of regrowing leaves decrese gradually due to repeated cutting. 3) The highest integrated yield of three times cuttings is found at the 20°C plot, and the integrated yield decreases in the order of 25°C, 15°C, 30°C plots respectively. The ratio of the parts to be cut (leaves and petioles) to the parts not to be cut (stolons and roots) increases at higher temperature and decreases at lower temperature. The lower the temperature, the more the preparation to regrowth is promoted. 4) Investigating about the optimum temperature to growth in Ladino clover from the aspects both canges in top regrowth and changes in amounts of reserve organs and reserve substances determining the following regrowth, it was concluded that Ladino clover grew best at near 20°C.

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This experiment was carried out in order to ascertain the after-effect of short-day treatment given during the growth period of rice plant on the germination of seeds produced on the treated plants. The results obtained are summarized as follows: 1. Seeds obtained from the treated plants gave faster germination than the control seeds, especially at low temperature condition. 2. The rate of seedling growth was higher in the seeds from treated plants than control seeds under illuminated condition, while the difference was disappeared at the late late stage of seedling growth in darkness. 3. Under illuminated condition, seedlings grown from the treated plants showed a higher respones to gibberellin applied to the seedlings, giving remarkable shoot elongation, than the seedlings grown from the control seeds, white in darkness this difference in the response to gibberellin was not clear. 4. The weight of seeds from the treated plants was slightly lighter than that of control seeds. The weight of embryo, hawever, was considerably heavier than that of control seeds. Content of nitrogen, phosphorous and total sugar of seeds was higher with the seeds from the treated plants than with the control seeds. 5. The rate of respiration during the germination of seeds from treated plants were as high as double of that of control seeds. As a result of this experiment, it was comfirmed that the shrot-day treatment given during the growth period of plants appears to manifest some effect on the seed development, and concequently on the germination of seeds.

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One possible method of increasing yields of grasses would be to grow at high levels of nitrogen fertilization. However, nitrate nitrogen (NO₃-N) has at times been observed to accumulate within plants to abnormally high concentrations, with results disastrous to animals fed these plants, or to animals and humans exposed to the gaseous decomposition products. The purpose of this investigation was to determine the effects of rate of nitrogen application on the nitrate nitrogen contents in some grasses. The nitrate nitrogen contents were determined in orchardgrass (Dactylis glomerata L.), Italian ryegrass (Lolium multiflorum Lam.) and hybrid sorgo (Sorghum vulgare Pers.), grown in National Hokkaido, Shikoku and Chugoku Agricultural Experiment Stations respectively. Those grasses were fertilized with various rates of nitrogen. Bahiagrass (Paspalum notatum Flugge) and bermudagrass (Cynodon dactylon Pers.) were planted in pots and grown under 15°, 20° and 30°C temperature glass chambers in phytotron, and NO₃-N contents were determined in those grasses. The NO₃-N contents increased with increasing rates of nitrogen application in these grasses, and this tendency was shown markedly in the grasses grown in warm season than those grown in cool ones. There were two types in accumulation patterns of NO₃-N in those grasses. Orchardgrass, hybrid sorgo and bermudagrass increased in NO₃-N contents with increasing rates of nitrogen, but Italian ryegrass and bahiagrass did not increased in NO₃-N contents at lower levels of nitrogen and increased rapidly in the contents at higher levels of nitrogen. In bermudagrass and bahiagrass, application of nitrification inhibitor (N-serve) with nitrogen fertilizer did not increased in NO₃-N contents for the effective period of N-serve in this experiment.

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The inoculation method of scab onto leaf blade, reported by the author, involved the pricking as a pre-treatment and the fixation of vinyl ring containing potato agar medium on the inoculated leaf blade by cellophane tape. In this study, these pre and post-treatments were investigated for their effects on the scab infection. It was found that the damage from the scab infection appeared much faster on the pricked leaves than on the unpricked ones. The leaf age also had some effects on the scab infection; the lesion of the older leaf being larger than that of the younger one, or at least the former being equal to the latter, in each of the culms. In the experiments of leaf blade inoculation, therefor, both the uppermost leaf except the emerging leaf and the one immediately below it, or only the uppermost leaf should be used in order to eliminate the difference in the foliage lesions due to the leaf age. The size of vinyl ring also affected the scab infection. The larger the diameter of the ring, the larger the infected spots. But a number of tests showed that the best ring was the one of 5∼6 mm in diameter because of the eczematous spots from the large ring of 7 mm in diameter. The amount of agar medium, in contrast to the ring size, did not affect the spot appearance, when the rings of same diameters were used. In the field application of this method, a certain type of cellophane tape gave an injurious effect on the sticked surface. Nichiban company's "Cello-tepe" and "Scotch Sumitomo 3M company's "Scotch transparent-tape" are recommended.

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In order to find out the possibility of simplification of weeding operation on upland rice field this experiment was carried out in the following experimental design: the experimental main factor was 4 levels of the crop stage, when the competition against weed was comme ncedafter weed-free period, that were, the sowing stage (0L), the fourth leaf stage (4L), the six th (6L) and the eighth (81), and subplot factor was 2 levels of distance between the row, that were, 60cm. (hand sowing: A) and 30cm. (machine sowing: B). In addition to the levels mentioned aboved, we have such two other levels as plot completely weeded away (R) and plot only constituted of weeds (W). These were treated in Split-Plot Design with 3 replication. The results obtained were as follows. (1). Weeds (mainly Amaranthus retreflexus L.) were controlled more effectively by upland rice itself after weed-free period as the weed-free period on the field was continued longer. Also this tendency was more remarkable in narrow row distance (B) than in wide (A). The effect of row distance on weed control become more clear about the initiation srage of the internode elongation of upland rice. And it seems to be most distinguishable on 4L and 6L treatments. It is evident that this may have been induced from the light competition between weeds and uplan rice, and caucauced to the difference of "Light Intercepting Capacity" of upland rice among each treatment. (2). The crop yield in each of treatments may be arranged in such a order as B>A or 8L>R>6L>4L>0L. (3). Considering from these results, it may be conclucluded that upland rice should be sown in 30cm. row destance rather than 60cm. and raised cleanly in weed-free condition up to 4th or 6th leaf stage. It was discussed how to make the weeding pracice on the mechanized crop production simple and effective, in which we have ever had to waste the large amount of our labour and money.

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Studies on the morphogenetic effects of a cool water treatment on the spikelet formation were conducted with a special variety of paddy rice "Akaho". A cool water irrigation had been known to induce abnormal spikelets even in the common varieties and also the "Akaho" of special variety had been found by Dr. KASAHARA to have genetic characteristics to express abnormal spikelets even under usual cultivating conditions. From the results obtained in this and Dr. KASAHARA's experiments, the physiological condition in the apical meristem of spikelet in "Akaho" was considered to be very unstable genetically in regard to the morphogenetic regulation of spikelet, bringing about various abnormalities in the inception and development of organs easily by a trifling disorder of physiology in spikelet primordium. Since a cool water treatment (13-15°C) which was applied at the stage of spikelet primordium differentiation was found to promote the appearance of abnormal spikelets in "Akaho" greatly, it was considered that the physiological changes caused by a cool water treatment may be similar to those which happen when abnormality is expressed as an inherited character in "Akaho" under usual cultivating conditions. It was also found that a cool water treatment affected sex expression and promoted the female tendency, suppressing the male one. The number of stamens decreases and the development of pistilate organs becomes vigorous in the plot of treatment. The differentiation and branching of vascular bundles in the process of spikelet formation seemed to be improved by the cool water treatment, resulting in the increase of glumes in number and frequent appearance of spikelets with multi-florets or ovaries. These phenomena of modification of sex expression and promotion of vascular differentiation mentioned above, may be interesting subjects to be investigated from the aspect of the changes in level of some endogenous growth substances which are caused by a cool water treatment.

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Along the line previously reported (67, 69), the authors further studied the principles for maxmizing yield of rice and tried to demonstrate them, obtaining the following results. 1) A target number of spikelets per unit area could easily be obtained in most treatments by increasing the number of panicles, which was brought about by making the plant produce as many tillers as possible at the early growth stages. And a pretty high percentage of ripened grains could also be obtained in most treatments by decreasing the number of spikelets per panicle, controlling excessive growth and improving plant form, which were easily achieved by decreasing or stopping nitrogen supply during the critical period in which the plant form after heading is definitely predetermined. As a result, a yield of 91.9kg of brown rice per are was obtained as the maximum in the present experiment, and 8 treatments yielded more than 75kg per are. 2) A strong positive correlation was found between the number of spikelets per unit area and the amount of nitrogen absorbed by the stage of spikelet differentiation or heading time. From the correlation one can easily estimate the necessary amount of nitrogen to be supplied for producing a target number of spikelets. 3) Decreasing the nitrogen supply in the critical period, in which the plant form after heading is predetermined, made the plant proportionally decrease the amount of phosphate, potassium and silica absorbed, resulting in a decrease in the number of spikelets on the other hand, however, made the plant increase the amount of carbohydrate, resulting in favouring ripening and preventing the plant from lodging. The degree of decreasing the nitrogen supply in the critical period, therefore, must be determined by taking the number of spikelets per unit area, eventual percentage of ripened grains and the resistance of lodging of the plant into due consideration. 4) The optimum leaf-area index of the rice plant at heading stage had hitherto been reported to be about 5 to 6 under the light intnsity of near 320 cal. per day per cm², while in the present experiment it had likely proved to be about 7 to 8 for producing a maximum dry matter after heading. The leaf-area index, therefore, seems not to be constant even under a given light intensity, but to be considerably variable according to the other factors, i. e. the form and healthiness of the plant etc. 5) From the analytical investigation of high yields in the experiment it had been clarified that the percentage of the amount of carbohydrate accumulated in straw before heading to the final grain yield was always less than 20. Accordingly, the importance of the amount of carbohydrate assimilated after heading can not be overestimated for maximizing yield. For increasing the amount of carbohydrate assimilated after heading, the rice plant must be subjected to the sufficient amount of solar radiation for 25 days just after heading. For that purpose one must find out the most sunny period in the ripening season in each place from the meteorological data investigeted for many years, and must select the variety to be used and determine the planting date so that the rice plant may effectively utilize the most sunny period for carbon assimilation after heading.

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The culm tissues of paddy rice plants, cultivated in various conditions in this area, were analyzed with histological methods. After the observations on the various histological changes in those culm tissues, it was recognized that all the lodging rice plants had longer lower-internodes and thinner cortical fiber tissues than the standing ones, and the cell walls of cortical fibres of the former were thinner than the later ones, because of the feeble thickening in the middle layer of the secondary wall. It seemed, in addition, that the lower-internodes of lodging ones had greater cell length in peridermis and metaxylar vessels, but, on the contrary, shorter in cortical fibres being elongated by "sliding growth", than the standing ones. The culm tissues of paddy rice variety, cultivated in upland condition with sprinkler irrigation, represented the "xeromorphism".

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In order to know whether or not the artificial inoculation onto leaf blade can be used as measures of the scab susceptibility, several wheat varieties, which were known for their susceptibility to scab, were subjected to the leaf blade inoculation. The result, however, did not show any reliability of this method. The foliage lesion was similar in the resistant varieties as in the susceptible ones, whenever the scabs were inoculated. In both the resistant and susceptible varieties, the development of the disease was stopped within several days, without further progress of symptoms. The mycelia were found only in the diseased tissues. The result of this experiment may be explained by suggesting that the mycelia invading into leaf tissues by the nutrients from agar are incapable of utilizing the wheat cell sap; for this reason, no difference in the degree of foliage lesion could be seen in spite of the marked difference in the scab susceptibility of wheat varieties. This hypothesis will be supported by the future works.

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