In the present study, upland cotton, variety "Kanno No. 1" was grown in pot culture. Making a distinction between the two stages of growth, namely before and after the first flowering, plants were grown in the glass house and/or in the outdoor and their growth was investigated. Accordingly, as an experimental method, nine treatments were provided as follows: (1) Plants were grown in the glass house continuously. (2) Plants were grown in the glass house until the first flowering, and after that time they were moved to the outdoor. (3) Plants were grown in the outdoor until the first flowering, and after that time they were moved to the glass house. (4) Plants were grown in the outdoor continuously. (5) Plants were sown on June 6, one month later than the other plots, and were grown outdoors continuously. (6)∼(9) Plants were treated as in (1), (2), (3), and (4) respectively, except such a treatment as that squares (flower buds) were cut off sucessively until the time of first square emergence in the plot of late sowing which showed retarded flowering. The elongation of main stem, the increase in number of main stem nodes, the development of branches, and the increase in dry weight of plant were investigated in these nine plots. Considering from these investgations, the glass house condition was better for the cotton growth than the outdoor condition, and at the same time the late sowing was better for the cotton growth than the control except for the increase in number of main stem nodes. The plants grown in the glass house from the sowing or after the first flowering had a period of interruption for about two weeks of boll setting. Therefore, in the behaviour of boll opening observed every week, the plants grown in the glass house from the sowing the first flowering showed two peaks in the frequency of boll opening through ripening period, while the plants grown outdoors from the sowing or after the first flowering showed one peak in the frequency of boll opening for the same period. Considering the influence of temperature on the yield of seed cotton, the investigations in relation to the yield of seed cotton before the interruption of bolls opening frequency which was brought by the interruption of boll setting frequency above described, were carried out in this experiment. In both of the number of bolls and the weight of seed cotton per plant, the plants grown in the glass house before the first flowering were superior to the one grown in the outdoor before the first flowering, while after the first flowering the plants grown in the outdoor were superior to the one grown in the glass house; and as far as the earliness of the first flowering concerned, the later the first flowering the better the result. In the weight of seed cotton per boll, the number of seeds per boll, and the lint percentage, the plants grown in the outdoor from sowing to maturity were superior to the one grown in the glass house before and/or after the first flowering; and as far as the earliness of the first flowering concerned, the earlier the first flowering the better the result. In the average seed weight, the plants grownin the glass house from sowing to maturity were superior to thc one grown in the outdoor before and/or after the first flowering; and as far as the earliness of first flowering concerned, the later the first flowering the better the result. In the present study, it is found that the vegetative growth becomes active and the number of bolls per plant increases in rather high temperature, but after the first flowering the setting and developmnt, of boll are better in rather low temperature.

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In order to find out the differences of water content between the soft and the hard-textured rice kernels in their ripening process, the present writers compared the rice grains harvested at Fukui and that harvested at Osaka. The former is regarded as soft-textured kernel and the latter as hard one. Experiments were performed on the farm attached to the University of Fukui (Makinoshima-Cho, Fukui City) as representing soft-textured rice producing area and on the field of the Osaka Prefectural Agricultural Experimental Station (Konoikeshinden, Kawachi City, Osaka Prefecture) as representing the other type area. Two varieties, Norin No. I and Yutakasenbon, were used for each of the soft and the hard rice. They were grown under the standard cultivation method for two years 1956-1957. Followings are the results obtained: (1) The water content (percentage and weight of water in one grain) of the soft-textured rice kernel was found generally lower than that of the hard one. (2) The dry matter content (percentage and weight of dry matter in one grain) of the former, on the contrary, was generally higher than that of the latter. (3) It may be said that the differences in the water contents, both percentage and weight in one grain, between those two kinds of rice kernels are determined by the difference of the meteorological factors especially average daily duration of sunshine and air temperature between Fukui and Osaka. From the above results it may be concluded that water content is not the characteristic factor for the soft-textured rice kernel.

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Silicified tissues of rice culm were ascertained by following technique; the spodgrammes of internode, culm-node and leaf sheath-node were made, and then they were dissolved by heated dilute hydrogen chloride. As silicified tissue is insoluble, the silicified tissue in epidermis of internode, epidermis at the bottom of internode, inner parts of culm-node, node-plate and node-plate abutting on the culm could be observed under microscope as shown in Fig. 1-8. The culm differs from leaf blade in that the culm contains silicate in various tissues, while leaf blade contains was found silicate only in epidermis. Silicate content in internode was found closely related with growth stages and cultural conditions as summarized below: 1) Seasonal changes of silicate content in each internode indicate that percentages of silicate content at harvesting time are in higher level than that at heading time. 2) Relation with cultural conditions; a) As compared with ill-drained field, rice culm in well-drained field contained more silicate, especially in upper internodes (N₁∼N₃). b) In plot with heavy application of nitrogen, amount of silicate content in upper internodes was less. c) Silicate content in lower internode was high in plot with silicate calcium application.

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Studies have been carried out intending to clarify content and distribution ratio of phosphate and potassium in internode of rice plant at heading and harvesting time. Results are summarized as follows; 1) In the plants grown under well-drainage condition, translocation of phosphate to ear was promoted. 2) Phosphate and potassium have an opposite charactor to each other in the distribution of them in parts of rice plant, that is, phosphate is very less in top internode and abundant in panicle while potassium is abundant in top internode and less in panicle at the time of maturity. 3) An existence of potassium oxalate within tissue of the top internode was proved by crystallizing it from the extract of top internode of rice plant. 4) It may be concluded from these results that high content of potassium in top internode and high content of phosphate in panicle have positive correlations with photosynthesis, translocation and ripening process resulting in the yield increase.

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Studies were made to get information concerning the influences of cutting on nodule formation in Ladino clover. Particular attention was given to the inactivation on active nodule and reactivation on inactive nodule in treated host plants. The results are summarized as follows: (1) The increase in nodule number and in nodule weight accompanied with growing of host plants was inhibited by leaves clipping treatments. In this cases, the total duration of an inhibitive period was proportionately increased with an increase of clipping volumes. (2) The active nodules (red pigmented) were inactivated to the inactive nodules (green pigmented) by leaves clipping treatments, by the following method: The lacked region in leghemoglobin, bacteroid-shape bacteria and starch was formed on base in the bacteroid tissue of active nodules. These lacked regions continuously enlarged from base to top of bacteroid tissue accompanied with progress in the senescence. (3) The inactive nodules (green pigmented) produced by clipping treatments were again activated to active nodules (red pigmented) during a regeneration periods of host plants in the following ways. The coexistence region with leghemoglobin, bacteroid-shape bacteria and starch was formed on base of bacteroid tissue of inactive nodules, and it successively enlarged uperward of bacteroid tissue. The completion of recovery of inactive nodules was detected after 5-6 days of the coexistence region formation. (4) When the host plants were removed for a periods of 2-4 days into the dark condition, the active nodules were inactivated. In this experimental condition, the application of 10 % sucrose solution to the leaves of host plants prevented the inactivation of active nodules. And, when all the leaves and leaf stalks except one leaf stalk per plant were cut off, the active nodules were inactivated. In this condition, (the absorption of 10 % sucrose solution with the leaf stalk remaining prevented the inactivation of active nodules. These results suggested that the leaves clipping on host plants bring down the carbohydrate concentration in host plants which helps inducing inactivation of active nodules.

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A high rate of salt accumulation in rice plants is usually observed when these plants were heavily injured by salinity. Accordingly the mechanism of salt absorption and accumulation in such rice plants injured by a high salt concentration could not be considered similarly to that of rice plants growing under normal nutritional conditions. Actually, very little is known about the absorption mechanism of sodium chloride by rice plants under the condition of presence of excess salt in the cultures. The present study was undertaken to obtain some approach to the solution of this side of the problem, using Oryza sativa L. variety Eiko as material. Rice plants were cultured in the nutrient solution for 21 days, then these young seedlings were used for the absorption test in the solution containing O. 1 Mol of sodium chloride. Amounts of chloride ion and phosphorus ion absorbed were measured for comparison, as the latter is considered to be absorbed in close conjunction with metabolic processes. The exprimental results obtained may be summarized as follows: (1) Metabolic inhibitors (DNP, KCN, NaN₃) showed some tendencies to promote the absorption of chloride ion, while they suppressed the absorption of phosphorus ion. (2) The absorption of phosphorus ion was clearly depressed by subjection to low temperature (5C). but very little effect of low temperature on the absorption of chloride ion was recognized. (3) The root system of the intact rice plant which was killed previously by immersing into boiling water, showed no capacity to absorb phosphorus ion, while the amount of chloride ion absorbed was higher than that by the healthy rot system. (4) These results suggest that the absorption and accumulation of chloride ion by rice plants does not take place metabolically. (5) When the roots of rice plants were transferred from a nutrient solution containing excess sodium chloride (0.1, 0.2, 0.3, Mol) to deionized water, no exudation of chloride ion from the root cell into this water was recognized.

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(1) 種子を20℃で48時間吸水せしめ鳩胸程度に催芽せしめてのち直ちに風乾する(催芽・乾燥処理)か, あるいは催芽せしめた種子を5～10℃の低温下に10～20日間放置しておいたのち, これを風乾する(催芽・低温処埋・乾燥)と, 無処理種子に比して発芽が顕著に促進される. 発芽速度は催芽・低温処理・乾燥>催芽・乾燥>無処理種子の順に明らかに三つの段階を示す. しかもその発芽の促進は水中発芽よりも0.25M, あるいは0.45Mの蔗糖液を発芽床とせる場合に拡大される. (2) 催芽・低温処理・乾燥の処理を行う際に水の代りにジベレリン溶液(1～10ppm)を利用すると, 水を用いた場合に比して発芽, 発根ともに著しく促進される. これらの処理を行わないで, 普通乾燥種子を水中で発芽せしめた場合とジベレリジ溶液内で発芽せしめた場合とを比較すれば, ジベレリンによる発芽の促進は極めて僅かである. しかし催芽および低温処理期間中にジベレリンを供給すると, その発芽促進効果が顕著に発現する. (3) ジベレリンのみでなく, thiamine(ヴイタミン B₁)を同様にして供給するとやはり発芽を促進する効果が見られ, これらの単独処理よりジベレリン+B₁の方がさらにやや効果が大きい. しかしB₁の発芽促進効果は発芽時の温度によつて異なるようで, 比較的低温下ではB₁の効果があるが, 高温下では効果が見られない. (4) 上記以外の植物ホルモン物質についても若干検討したが, ジベレリンに優るものはなかった.

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水稲の生育を人為的に制御しうる物質を探索する目的を以て, Indole-3-acetic acid, coumarin, maleic hydrazideなど多数の物質を供試して, 一連の研究を行ないつつあるが, そのうち naphthaleneacetic acid (NAA)および2, 3, 5-triiodobenzoic acid (TIBA)についてえられた結果の若干を報告する. (1) NAAの水溶液を水稲体に散布すると, NAAの濃度100～1000 ppmにおいて草丈と分けつの顕著な抑制が起る. この抑制は散布当時に生育しつつある部分に強く現われるが, 散布期以後, 新らたに生育する部分に対してはほとんど影響がなく. したがつて日数の経過とともに生育の抑制は漸次回復する. とくに多肥条件下ではその回復が早い. 有効分けつ終止期にNAAを散布すると無効分けつの発生を抑え, 有効茎歩合を高めることができる. 茎葉が過繁茂状態になる場合にはNAAの利用によつてそれを防止することができるのではないかと考えられる. (2) TIBAは以前から一種のanti-auxinであるとされている物質であるが, その水溶液(100～1,000 ppm)を葉面に散布することによつて, 水稲の分けつの生成を顕著に増加せしめることができた. TIBA 5,000 ppmでは薬害を生じ, 細長い異常葉を発生するが, 1,000 ppm以下の濃度ではなんらの薬害を認めず, 草丈が若干抑制されるだけである. 分けつの増加のし方は, 対照無処理区で分けつが急増している間には処理との差がないが, 対照区で分けつ増加がゆるくなつても処理区ではさらにそのまま増加がつづくという状態である. すなわち分けつ発生の規則性は乱されてないが, その増加のテンポが低下しないと見られる. (3) 以上の結果は水稲の分けつ発生がauxinあるいはanti-auxinによつて支配されていることを示唆する. (4) NAAおよびTIBAともに比較的高濃度においてその作用が発現することは, これら物質が水稲体内に侵入しにくいことを示していると考えられる.

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It has previously ken shown by the writer that a weak dehiscing power of anther is the most critical factor governing the sterility under several such environmental factors as high temperature, short day length, low phosphate level accompanied with high nitrogen application, acid soil, diseases, and so on. Accordingly it may be considered that amount of carbohydrates accumulated in the flowers should play important role to the incidence of sterility. In this experiment, amount of starch in the filament was microscopically estimated by the iodine method, employing florets just before flowering. Experimental materials were planted at two widely separated date in the spring, April 25 and May 25, and the resultant sterilizing percentages were 11.8 and 65.6 per cent respectively. Results are summarized as follows. 1. Irrespective of difference of planting date, there were not any starch reactions in the vascular bundle and its surrounding parenchyma cell of the connective and in the joint tissue lying between filament and connective (Fig. 2 and 3). 2. Starch reaction which has not yet been observed in the connective was noticed first at the top of filament, adjacent to near the base of the connective (Fig. 4 and 5). This reaction gradually increased, reaching a maximum level at a point about 70 p distant from the joint tissue and then is maintained at this level at the remaining lower parts of the filament. 3. Intensity of the reaction at the maximum level, relating the quantity of carbohydrates migrated into a flower, decreased with delay in sowing (Fig. 6 and 7). It appears likely that this decrease is attributed mainly to the rise in temperature. As sterilizing percentage has been proved to increase with late sowing, it is a matter of course that the reaction has a negative close correlation with it. 4. In the sterile plants starch reaction was blue in color showing the existence of amylose. On the other hand, in the fertile it is purpul red indicating amylopectin. Amylopectin is originated by branching from amylose molecule under the existence of "Q" enzyme. Consequently, it is considered that the activity of enzyme is lowered to some extent in the steril plants. 5. In view of these points, it can be said that poor starch migration into the filament from the vegetative organ at anthesis and falling of enzyme activity caused the failure of normal dehiscence of anther and subsequent male sterility in barley.

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In direct seeding culture of paddy rice on upland field condition, germinating processes as influenced by the seeding depth, hardness of covering soil and hardness of bed soil layer were examined morphologically. Under all conditions, the rate of germination were more than about 95 %, but the rate of emergence of seedling at 30 days after seeding decreased with the increase of seeding depth. In case of 5 and 7 cm depth of seeding, the number of perished seedlings under ground were increased remarkably. Plant height of deep seeded plots were more than those of shallow seeded plots. Dry weight of seedlings of deep seeded plots exceeded those of the shallow ones under soft soil conditions, but the relation was reversed under hard soil cover conditions. Age of seedlings decreased with the increase of seeding depth. The first tiller was shooted out from the third node of main stem in 1-5 cm plots, while in the case of 7 cm plots it came out from the fourth node. In this experiment it was observed that the length of mesocotyl increased with the depth, reaching its maximum at 5 cm depth but decreased again at deeper seeding. The process of elongation of the underground internodes in 5 and 7 cm plots are illustrated in Fig. 2. In the perished seedlings the internode elongation did not occur at all, and root formation in the nodes were also lacked. Coleoptile also elongated in proportion to the seeding depth as shown in Fig. 3. The first foliage leaf became the longest one in 3 cm plots, but in 5 and 7 cm plots their length were shorter than their coleoptile. The second leaf, therefore, appeared above the ground after penetrated through the cover soil layer in these cases. While, those of the perished seedlings were unrolled, twisted, and could not appear above the ground. The elongation of the internodes and coleoptile, the ability of rooting and the power of the foliage leaves to penetrate through the soil layer were considered to be the determining factors for the emergence of good and healthy seedling in direct seeding culture of rice on upland field where the deep seeding is necessary. And that, these factors showed remarkable variation in the same condition examined and also in the same variety. Therefore, it is suggested that the attention should be paid to these factors in the breeding of varieties suitable for the direct seeding culture on upland field.

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The effect of temperature on the growth of sugar beet at different stages of growth has been studied. The sugar beet plants of variety GW 359, grown in Wagner pots under natural condition, were subjected to temperature treatments in which the plants were grown under the temperature of 15°C, 20°C and 30°C for 30 days. One group was exposed to similar temperature conditions in its early stage of growth, one in its middle stage and the other one in its later stage (Fig. 1). Plants were harvested at the end of treatments for determination of dry matter production, leaf area, leaf numbers and total-sugar concentration. Results obtained are as follows. 1 Throughout all the growth stages, the total dry matter increase of whole plant is highest under 20°C At the early stage, the increase of total dry weight is more in the plants which have been exposed to 30°C than those exposed to 15°C. But this becomes reverse at the middle and at the later stages. Dry weight of tap root increases most under 20°C, then under 15°C and least under 30°C. As regards the top of plants, it is found that the dry matter increase of the petiole is generally retarded under 15°C (Table 1). 2 The total leaf area always becomes maximum under 20°C, then under 30°C and least under 15°C. From the other results on leaf number and leaf area per one leaf blade, it is clarified that as the beneficial effect of high temperature on leaf expansion of one leaf blade is very little in comparison with its harmful effect on leaf number increase, the total leaf area is less under 30°C than under 20°C and that the less total leaf area under 15°C is due to the harmful effect of low temperature both on leaf expansion and on leaf number increase (Table. 2, Fig. 2). In the early stage, a positive correlation between the leaf area and total dry matter increase is seen. But no such correlation is seen between them at the middle stage and at the later stage (Table 1, Table 2). These phenomenon can be explained by the following assumption: As the plant grows, the non-photosynthesizing organ begins to occupy more and more portion of the whole plant and as the results, the dry mattes production becomes more and more influenced by respiration rather than by photosynthesis. 3 The ratio of dry matter increase of tap root to top is generally higher under low temperature with an exception of middle stage at which this ratio becomes highest under 20°C (Fig. 3). 4 The lower the temperature, the higher the total sugar concentration of leaf blade, petiole and tap root. As regards the total-sugar concentration of tap root, it is found that its difference is little among three plots at early stage, but it becomes remarkable at the later stage. This different effect of temperature with different stage is also true with the dry matter increase ratio of tap root to top, as described above. These facts suggest that sugar beet possesses self reguratory mechanism for modifing the effect of temperature on sugar accumulation in tap root (Fig. 4). 5 At the early and at the middle stages, the beneficial effect of the temperature of 15°C on total-sugar concentration in tap root is so little that sugar produced under 15°C is actually less than that produced under 20°C, which is the beneficial temperature for dry matter increase of tap root. In the later stage, however, the total-sugar content in tap rot becomes more under 15°C than under 20°C, as the beneficial effect of the temperature of 15°C on sugar concentration is more in comparison with the beneficial effect of temerature of 20°C on dry matter increase. Under the temperature of 30°C, the sugar content of the tap root is always least due to the harmful effect of high temperature on sugar concentration and dry matter increase of the tap root (Fig. 5).

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In many papers hitherto reported, it was concluded logically that the roots synthesize and supply the shoot with certain substances necessary for continued metabolism of protein. The authers' experiments showed that the roots played an important role in RNA and nitrogen metabolism of the shoot. The object of these experiments was to clarify the relation between protein and RNA metabolism in the plant and the influence of the roots on the RNA synthesis in the shoot. Results obtained are as follows 1) When rice plants were grown under various conditions such as different light intensity and nutrient supply, it was seen that the changes of protein content were accompanied by the changes of RNA level, i.e. strong light or excessive nutrients resulted in the increase of the RNA and the protein level. Accordingly, it was confirmed that there was high correlation beween protein and RNA contents. From this fact it seems logical to assume that protein metabolism is controlled by RNA in both the organs, shoot and roots. 2) When the roots were removed from the shoot, the RNA content of shoot went down to 65 % in comparison with the control. If, however the shoot formed roots, the RNA contents tended to increase, and the protein content showed the same tendency as that of RNA. 3) As regards the relationship between roots and shoot, it was observed that elongation of the newly developing leaf was largely retarded by the removal of the roots, (rice plant). 4) The changes of RNA, acid soluble-P and nitrogen compounds which occur in the rooting process of cuttings were investigated on Commelina communis. Before rooting, the RNA content decreased and simultaneously .the acid soluble-P content increased. After rooting, however, the RNA regained the original value and the acid soluble-P decreased. Here again, the protein content behaved in the same way as RNA. 5) If the leaf is provided with a growing root system, the incorporation of ³²P into RNA in the case of foliar application of ³²P proceeds more rapidly as compared with the leaf with no roots (tobacco, soybean and rice plant).

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The present studies reported in this paper were made in an effort to make clear the basic facts of dry matter production in sweet potato under field conditions. Sweet potato, variety Norin No. 1, was grown on a feild at 1961 with different fertility levels, planting dates and planting densities. Dry matter increasing was measured at intervals of 3 weeks over all growing course. Maximum rate of dry matter increase per unit field area showed 120 g/m² field/week which existed at middle stage of growth. Maximum values of net assimilation rate and leaf area index were 55 g/m² leaf area/week and 4.3 m²/m² field, respectively. Optimum leaf area index of sweet potato on field for the dry matter production was 3.2 on solar radiation 380 g.cal/cm²/day at middle growing stage, from July 17 to Sept. 18. When leaf area index became all excess, it had an unfavourable effect on the dry matter production due to lack of light intensity in community, moreover, stems weight/leaves weight ratio tend to increase. Increasing of this ratio was considered to be disadvantage for the net assimilation rate owing to rising the respiratory consumption in non-productive parts. Table 1. Total dry weight and tuberous rots weight at harvesting time. [table] Note. 1). Harvesting time…Early planting: Oct. 10. Late planting: Oct. 31. 2). Abbreviation……P: poor soil. F: fertile soil. D: dense planting. T: thin planting. 3). T is same as in Fig. 9.

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開田土壌に発生する赤枯病について, 愛知県三方原の酸性燐酸欠乏土壌で鉢試験を行なった. 葉身の褐変の発生は分けつ初期の土壌がまだ酸化状態の時に始ったが, 土壌の還元が進行する条件下で発生が増大し, その逆の場合に発生が少なくなった. アルミニウムの土壌への添加は本病発生の促進と同時に葉身を暗紫色に変色した. 地上部の窒素, 炭水化物代謝と発生との関係は, 前報I, II型赤枯病の場合と異っていたが, 呼吸および呼吸酵素の変化と発生との関係ならびに抵抗力の品種間差は同じであった. 本病の発生している土壌の滲透水で水耕すると葉身に褐変が発生し, 更に滲透水から抽出した物質を普通に水耕している水稲の水耕液に加えると褐変するのがみとめられた. したがって本病の原因には土壌の酸化還元と直接関係ない何等かの未知物質が関与している疑いが大きい.

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1) In order to obtain some fundamental informations for determination of planting space of potato, the responses for theee elements, planting space, amounts of fertilizer and number of stem per tuber were investigated by using two varieties on the cultivated volcanic ash soils. 2) As the stem length was shortened by decreasing planting space, no lodging was observed. 3) In the case of dense planting or of numerization of stem number per tuber, number of stolons and number of tubers became numerous and percentage of tuber bearing stolons and mean weight of one tuber were decreased. But, the reverse relationships were obtained in the case of corse planting or of diminution of stem number. 4) The nitrogen content of leaves of main stem at the maximum top weight period was lowered and the phosphorus content was slightly heightened by the reduction of planting space in Irish Cobbler. But these tendencies were not observed for Norin No. 1. 5) The distribution rate to underground part of dry matter was increased in case of the low amount of each element in the leaves at the early growing stage. High minus correlation between nitrogen content and distribution rate was observed throughout the growing season and very high minus correlation between potassium content and distribution rate was observed at the flowering stage. But such correlation value for phosphorus at the flowering stage was low. 6) The ut'most top dry weight and tuber yields per unit area accompanied with the decrease of plant spacing were estimated by the A. J. Reestman's method. In the case of the most dense planting, the top dry weight approached to the limit, but the tuber yields were observed to be increased even when the planting space was enormously dense and the amount of fertilizer was higher. 7) The ideal planting space was thought to be obtained by using 7, 100 hills per 10 ares.

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The experiments were conducted in order to find out the effects of daily alternating temperature and photoperiod on the progress of vernalization, that is defind as the process leading to ripeness-to-flower, in the growing plant of wheat, Norin No. 64, medium cold requiring variety. The relation beween the progress of vernalization in plant as manifested by the vernalization test, and the turn-over of morphogenetic ability in shot apex, revealed by the excised stem tip culture, were also determined. From the results of these eyperiments, following inferences may be drawn; 1), The rate of vernalization depends on temperature and not on photoperiod. The vernalization in growing plant may complete within one month even under as high a mean temperature as 19°C. These facts may be explained by the information contained in the following paragraphs, 2) and 3). 2). The daily lower temperature at night apparently controls the rate of vernalization, while higher temperature during daytime has little effect on the rate. The fact that the daily day temperature above 30°C permits the rapid vernalization, when the daily night temperature is below 10°C, suggests the devernalization in the plants grown under field conditon to be improbable. 3). Althogh low temperature promotes the onset of vernalization, it is not a requisite for its completion. The turn-over of morphogenetic ability in shoot apex occurs in the earlier cold-requiring phase of vernalization.

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