Authors examined the relation between the illumination by the all-night street fluorescent lamps, and its effects on the growth and yields of paddy rice. The results obtained are as follows: 1. In case of 2 luxes or less, neither the growth nor the yields were affected at all, but in case of 5 luxes, they were affected, though quite slightly, while in case of 10 luxes or more, they were affected markedly, and in case where the all-night illumimation exceeds 50 luxes, the yields were completely nil. In an extreme case of as high as 70 luxes or more, rice plants never even came int o ears. 2. The plant growth stage affected most remarkably by all night illumination was the duration from the 40th to the 20th day before the heading, which corresponds to the duration of 20 days after the differentiating stage of flag-leaf primodium. 3. The varietal differences in the delaying effect on the heading dates caused by all-night illumination are given belows. The growth and the yields of the extremely early maturing varieties for the early season cultivation (Honenwase, Reimei) were affected quite slightly. However, considerable injuries caused by night illumination were observed in those for ordinary season cultivation, i.e., the early maturing (Yamahosi, Ukonnisiki), the middle maturing (Harima, Kinmaze), and late maturing varieties (Siranui, Tokai No. 28). Among them the early maturing varieties were affected most seriously by all-night illumination. And in any cases, the varietal differences were also confirmed clearly. 4. Among varieties for ordinary season cultivation, which were greatly affected by illumination and showed the great delay in the heading, authors could discover some individuals which were affected little by all-night illumination. By examining the characteristics of their subsequent generations, it was found that they were the very strains which could bear ears and fruits even under a considerably high illumination. This phenomenon is meaningful, because the study on such an ecotype may suggest the possibility of breeding up some non-responsible varieties to all-night illumination.

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北方型 (9月播種, 5月試料採取) および南方型 (5月播種, 8月試料採取) 作物各7種の葉から抽出した脂質を, 単ーケイ酸カラムによるクロマトグラフにより phospholipid, sulfolipid, golactolipid に分別し, その脂肪酸組成をガスクロマトグラフで分析した. 作物あるいは脂質の種類のいかんを問わず, パルミチン酸, リノール酸, リノレン酸の3種の脂肪酸が, 全脂肪酸の80%以上を占めていた. 脂質の種類による差をみると, phospholipid は, sulfolipid, golactolipid にくらべてパルミチン酸含有率が高く, リノレン酸含有率が低かった. 作物の種類による差については, 南方型作物は北方型作物にくらべて (リノール酸+リノレン酸)/パルミチン酸, または不飽和酸/飽和酸の値が小さいことがみとめられた.

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前報にひきつづいて, 葉の脂質の脂肪酸組成を分析した結果, 作物の生育する温度によつて脂肪酸組成が顕著に変動することをみとめた. しかし, 少なくとも同一温度条件下で生育した場合は, 南方型作物は北方型作物にくらべて, 脂質, ことに phospholipid の(リノール酸+リノレン酸)/パルミチン酸, または不飽和酸/飽和酸の値が明らかに小さいことがみとめられた. 水稲品種間差については, 低温抵抗性の小さいインド型品種 T 136 と, 耐冷性品種染分とをくらべたところ, 30-20℃ で生育した場合は染分の方が不飽和酸/飽和酸の値が小さく, 17℃で生育した場合はほとんど差がないか, 染分の方がやや大きい傾向がみとめられた. 以上の結果から, 脂質, ことに Phospholipid の脂肪酸組成が, 温度に対する適応性の種間差になんらかの関係があるのではないかと考えられる. しかし, 品種間差のような僅少な差は, 脂質の脂肪酸組成の差異のみによつて決定されるものではないと考えられる.

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水稲, イタリアンライグラス, オーチャードグラスの葉のチトクロームオキシダーゼ活性を, 10～40℃ の温度で測定した. イタリアンライグラスおよびオーチャーグラスでは, 温度の上昇に従つて酵素活性が直線的に上昇したが, 水稲では, 20℃ 以下では温度上昇による活性増加率が小さかつた. 水稲のアスコルビン酸オキシダーゼおよびパーオキシダーゼは, 温度上昇に従つて酵素活性が直線的に上昇した. チトクロームオキシダーゼを可溶化する界面活性剤で処理すると, 上述の作物による差異はみとめられなくなつた. また, 界面活性剤処理によつて, チトクロームオキシダーゼの高温下での安定性が失われた. 以上のことから, 水稲とイタリアンライグラスまたはオーチャードグラスの間におけるチトクロームオキシダーゼの温度反応の差異は, これら作物間における脂質の性質の差異の影響を受けているものと推測した. 水稲およびトウモロコシの黄化幼植物から調製したミトコンドリアの酸化的リン酸化反応を測定した結果, 30℃以上の温度ではADP/Oの比が著しく低下し, 25℃以下でも低下する傾向があることがみとめられた.

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黄色種H-2を供試し, 日長反応におよぼす温度の影響を調べた. 1) 低温 (10～15℃) 下では, 花芽分化が促され着葉数少なく, 日長の影響は明らかでなかつた. 比較的温度の高い (20～27℃) 条件下で日長反応は明瞭となつた. また終夜照明下でも開花し, 本品種は quantitative short-day plant と言える. 2) とくに明期の低温は花芽分化を促し, 着葉数を減少させた. 12時間日長の場合, 最も低温に敏感なのは暗期直前の数時間で, 最も鈍感な時期は明期開始後3～7時間目頃であつた. 3) 暗期の低温 (10℃以下) は12時間以下の日長条件下では花芽分化を抑制し, 16時間以上の日長条件下では花芽分化を促した. 12時間日長の場合, 暗期の後期に与えた低温ほど花成抑制効果が強く, 着葉数が多くなる傾向がみられたが, 8時間日長下ではその時期的差異は明らかでなかつた.

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The efficiency and absorption of basal nitrogen (ammonium sulfate) enriched with ¹5N was studied in the paddy field in 1969 and 1970. Rice plant was transplanted at two different times, in early and late May, and was grown under the two rates of basal nitrogen, 60-70 kg/ha and 150 kg/ha. It was ascertained that the absorption of basal nitrogen by rice plant almost finished at the end of June in all the experimental plots. After that, the rice plant absorbed only soil nitrogen. The rate of plant absorption of fertilizer nitrogen was low soon after transplanting and increased gradually. The maximum rate was found in the early of June in the early-transplanted plots and in the middle of June in the late transplanted plots. According to nitrogen analysis at different growth stages, the ratios of the amounts of fertilizer nitrogen to those of total nitrogen absorbed by the plant were the highest soon after the transplanting and decreased gradually. They were higher in the plots with the high rate of basal nitrogen than those with the low rate. The recoveries of nitrogen in the plant which were calculated from the tracer were 22 per cent in 1969 and 26-27 per cent in 1970. On the other hand, the gross recoveries of nitrogen were ranged from 43 to 50 per cent in 1970. The ratios of the amounts of fertilizer nitrogen to those of total nitrogenoin the plant at maturity were about 25 per cent in the high nitrogen plots and less than 15 per cent in the low nitrogen plots. The amount of soil nitrogen absorbed by the plants was greater in the plots with basal nitrogen than in those without basal nitrogen. It was assumed that the effect of basal nitrogen contributud to the gross recovery of nitrogen in the plant which was substantially greater than the recovery calculated from the tracer.

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The fate of basal nitrogen (ammonium sulfate) enriched with ¹5N was investigated in the paddy field in 1969 and 1970. The paddy soil was relatively poor in organic matter, fine-textured and poorly drained. Rice plant was transplanted at two different times and was grown with two rates of basal nitrogen addition as previouly reported. The soil ammonium nitrogen derived from the basal fertilizer was more in the plots with the high rate of basal nitrogen than in those with the low rate. It decreased gradually and almost disappeared in every experimental, plot at the end of June. The fact above-mentioned was coincident with the results of a previous paper indicating that the absorption of basal nitrogen was finished in all the experimental plots at the end of June. The quantities of fertilizer nitrogen left in the soil after harvest ranged from 18 to 21 per cent. On the other hand, 22 to 27 per cent of the nitrogen was absorbed by rice plant. Therefore, the recovery of basal nitrogen was less than 50 per cent. According to the frequent determinations of the amounts of nitrogen absorbed by rice plant and soil ammonium nitrogen, it was assumed that ammonium formation in the soil had two maxima during the growing season -one, from the early to middle June and another, from the end of July to early in August.

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The fate of top-dressed nitrogen (ammonium sulphate) enriched with ¹5N was investigated in the paddy field. The amounts of nitrogen applied were 30 kg per hectare in 1969 and 25 kg per hectare in 1970, respectively. The earlier was the top-dressing at the growth stage of rice plant applied, the longer stayed the ammonia derived from the top-dressed fertilizer in the plowed layer. This fact is approximately consistent with the duration of absorption of top-dressed nitrogen by rice plant. After harvest only 3 to 10 per cent of top-dressed nitrogen was found in the plowed layer. Since the drainage of the paddy soil was very poor, it was assumed that almost all of the unrecovered top-dressed nitrogen was lost by denitrification. The recoveries of top-dressed nitrogen were higher for the plots applied at the young panicle formation stage than for other ones. The earlier was the top-dressing applied, the longer the duration of top-dressed nitrogen uptake by the plant. And the later was the top-dressing applied, the higher the absorption rate of nitrogen by the plant. The amounts of soil nitrogen abosrbed by the plant were greater in all the plots with top-dressing nitrogen than in those without top-dressing. Therefore, the gross recovery of nitrogen in the plant was greater than the recovery calculated from the tracer.

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さきに陸稲玄米のタンパク質含量について検討し, 水稲玄米のタンパク質含量に比較して高含量を示すことを認めた. その要因の1つとして, 灌漑の影響が考えられるので, 陸稲 : 20品種・水稲 : 20品種および水陸交配系統 : 14品種について, 畑灌および水田栽培を行なつてえられた玄米についてタンパク質含量を検討した. その結果, いずれの品種も畑灌栽培玄米は水田栽培玄米に比較して, タンパク質含量の高いことが認められた. そして畑灌栽培によるタンパク質増加割合の平均は, 陸稲玄米 : 39%・水稲玄米 : 25%および水陸交配系統 : 34%であり, 稲作における灌漑の条件が玄米のタンパク質含量に影響をおよぼすことが明らかとなつた.

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These experiments are conducted to obtain the informations on the effects of storage and drying upon cooking quality of rice. As cooking quality, water-uptake ratio and total solid content in residual cooking water are examined. [table] (1) Effect of storage on cooking quality As aging of rice progresses by storage, water-uptake ratio increases and total solid content decreases gradually. Accordingly, aged rice swells more by cooking and is less sticky in comparison with new rice. The progress of aging is faster when moisture content in rice is more and storage temperature is higher. Moreover, progress of aging depends on variety of rice and is faster in soft-texture varieties than in hard-texture varieties. (2) Effect of heating of rough rice on cooking quality In consepuence of heating in rough rice by high temperature (60°C) for 40 minutes, water-uptake ratio does not change largly but total solid content decreases apparently. Amount of decrease in total solid content depends on moisture content of rice at the start of heating and in general, the higher (especially higher than 18%) the moisture content, the greater the degree of decrease of total solid content. When rough rice is heated by high tempeeature (60°C) for 70 minutes, total solid content is not influenced in low moisture rice, but increases apparently in high moisture rice (18%), because the surface of such rice swells abnormally and disintegrates and partially mixes up in cooking water. Then adequate moist-heat treatment is available to reduce stickiness. (3) Effect of moisture content of rice on cooking quality As moisture content of rice becomes less, total solid content decreases, and decreases notably when moisture content becomes less than 12%. This effect of moisture content on total solid content is more remarkable in soft-texture varieties than in hard-texture varieties, and also has a tendency to be more distinct in rice produced under lower ripening temperature than in rice of same variety produced under higher ripening temperature.

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1. The experiment was carried out to make clear the characteristic of thickening growth of lateral roots in pea, soybean and alfalfa. These crops were selected respectively from three types showing different thickening growth pattern in main roots as stated in the previous paper. 2. Diameters, at 1 cm far from their branching points, of lateral roots which emerged along 20 cm from the base of main roots were measured by microscope at successive growing stages. 3. Trends in thickening pattern of lateral roots in each crop were as follows : A. pea Thickening of lateral roots was as little as that of the main root, and no thickening were recognized during winter time, while slightly thickened ones were found in April and May, however, even their thicker ones were not exceeding 1.5 mm in diameter (fig. 1-A, fig. 2-A). B. soybean The lateral roots emerging from base of the main root markedly thickened and their diameters reached to about 5mm, while the others that developed from the distal part between 7cm to tip of the main root did not nearly thickened (fig. 1-B, fig. 2-B and fig. 3). C. alfalfa Many thick lateral roots were found on the whole length of the main root, not only on basal but also on comparatively distal parts. Ten months after sowing, several thick lateral roots, more than 10mm in diameter, developed sporadically. More lateral thickeness is expected in both main and lateral roots at their final growing stages (fig. 1-C, fig. 2-C). 4. From these results, a close relation between the thickening growth types of the main roots and that of Iateral roots was recognized. Namely, in the little thickening type, the lateral, roots thickened also little; in the basal thickening type, the thick lateral roots concentrated at the basal part of the main root; and in the extensive thickening type, the thick lateral roots sporadically developed along the whole length of the main root.

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Flax plants (var. Saginaw No. 1) were grown in pots under conditions of combinations of various day-lengths as follows: transfer from natural day (14^h : 20^m-14^h : 40^m) to short day (8^h : 00^m) was conducted at the third week (CS₁ plot), the fourth week (CS₂ plot), and the fifth week (CS₃ plot) after germination. The control plot grown in the natural day (C plot) and also the one grown in the short day (S plot) were provided. The results obtained are summarized as follows : 1) In the case of the flax plants which were transferred from the long natural day to the short day, the effects of the short day were not recognized in both the date of anthesis and growth of the basal branches from dicotyledonal axilla, on account of the after effects of long natural day during 3∼5 weeks after germination; though the date of anthesis was delayed and basal branches of the plant became larger in the short day than in the long natural day. 2) In the case of the plants which were transferred from the long natural day to the short day at the later time during the 3∼5 weeks, the after effects of the long natural day were recognized in the growth of length of the plants, the contents of crude fibers in dry stems, the diameter of the fiber-cells and the contents of crude-cellulose, but in the case of the plants which were transferred to the short day at the earlier time during these weeks, the after effects were not recognized. These values in the short day plot became smaller than those of the long natural day, while in the case of the plants which were transferred to the short day at the earlier time, these values became just the same as those of the plants of the short day plot. 3) In the case of the plants which were transferred from the long natural day to the short day, the effects of the short day were recognized in the dry weight of the bolls, the diameter of the fiber-cells and the contents of lignin. The dry weight of the bolls and the diameter of the fiber-cells in the short day plot became smaller than those of the long natural day, while in the case of the plants which were transferred to the short day at the later time these values became smaller than those of the plants of the long natural day. The contents of lignin became larger in the plants of both the short day plot and the plots transferred from the long natural day to the short day than in the plants of the long natural day. 4) Growth in the diameter of the stems, the dry weight of the above-ground parts and the contents of α-cellulose in the flax plants which were transferred from the long natural day to the short day became smaller than those grown in the long natural day. These facts seem to depend upon the decrease of photosynthetic products owing to the transfer to the short day, because in the short day the hours of the sunshine per day were shorter than in the long natural day.

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これまでの研究では水稲根および溢泌液において3種のサイトカイニン様物質が存在していることを明らかにした. 本研究では GC 分析によつてこれらサイトカイニン様物質の同定を試みた. 4種のサイトカイニン様物質はカラムクロマトグラフィーあるいは溶媒抽出により水稲根から分離された. これらの物質は TLC の Rf 値および TMS 誘導体のガスクロマトグラムの保持時間などから, 遊離ゼアチン, ゼアチンリボシドならびにゼアチンリボチドと同定された. 他にゼアチン, および糖からなる新しい複合型サイトカイニンが認められた.

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本実験では, 水稲および甘藷などの作物の生育と老衰の過程で ABA-cytokinin 関係がどのように変化するかを調査した. その結果, 1) 水稲体各器官の ABA-cytokinin 活性をみると, 若い器官と老衰を始めた器官との間には, ABA ではあまり差異が認められないが cytokinin 活性には大きな差異が認められる. 2) 水稲の穂の切除は個体の老衰に大きな影響を及ぼすが, この穂の発育に伴う ABA-cytokinin 関係をみると, 乳熟期の穂では ABA と cytokinin とはともに高く, その後穂の発育に伴つて著しく低下している. 3) 甘藷塊茎の萠芽期において ABA-cytokinin 活性をみると, ABA 活性は収穫期の組織では高く萠芽期では低下しているのに対して, cytokinin 及び根の生長促進物質の活性は萠芽期において著しく上昇している. 以上の結果から, 作物体の内生的な ABA は内生的な cytokinin と相互に関連しながら. 個体の生育および老衰の過程において重要な役割を果たすものと考えられる.

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We reported in previous papers that the growth and fordder yield of the corn plants passed through temporary or successive wilting at early definite of growth were increased certainly, and then this increaring was considered to be due to the raising of tryptophan content in the corn plants. But it is very difficult in practice to do wilt the corn plants cultivated in field as our pleases. Then we tried to spray tryptophan 1000 ppm solution on the nine leaves age of corn plants cultivated in field instead of wilting treatment. At the same the spray treatments with indoleacetic acid (IAA) or naphthalene acetic acid (NAA) solutions were tried as compared with tryptophan spray treatment. 1. Both IAA as the nature auxin and NAA as the synthetic auxin had the same effects on the growth and root behavior of corn plants. 2. The effects of tryptophan treatment upon the primordium of roots in the neighbouring of each node were a few. On the plants with the spray of IAA or NAA 100 ppm solutions, not only increasing the number of roots in neighbouring of lower nodes but also the decrease of those in upper were significant. The effects of IAA or NAA 10 ppm spray on the corn plants were between the effects of tryptophan spray and those of IAA or NAA 100 ppm spray. 3. The rate of that the primordiums grew ub to absorptive roots was about a hundred per cent in the neighbouring of lower nodes. But in upper nodes, tryptohan spray had the greatest effect upon the increase of absorptive roots, next was IAA or NAA 100ppm spray, and then there was the least significance between IAA or NAA 10ppm spray and control. 4. The effects of tryptophan spray upon the root behavior of corn plants were just same as the effects reported in previous papers, and the assumption that tryptophan absorbed into corn plants will gradually turn into IAA and will actuate upon the growth of corn plants was reaffirmed. 5. Absorbed tryptophan must gradually have turned into IAA and had good effects on the growth of corn plants, and those effects seemed to have continued to the final stage of growth. But IAA or NAA absorbed must have had some effects upon corn plants immediately aeter the spray, and then those effects must have decreased in consequence of the lapse of time in order to be oxidized during a short term. 6. The dry matters at the harvest time were increased by spraying tryptophan. Those with IAA or NAA spray were more weighty than those of control, but were more light than with tryptophan spray. Such significant increases on the yield of corn plants appeared a few on leaves or internodes, and much on ears.

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The nicotine synthesis was examined in the big and fine root tips and in the roots varying in kind, ages and regions of roots, furthermore in the roots grown in the anaerobic and aerobic media. The results obtained were as follows. 1. Nicotine content in the roots of the class C and D whose length were 20-30 mm and 30-40 mm respectively which emerged from tobacco seedlings was higher than that in the other classes. 2. The nicotine content became higher with the increasing distance from growing tip. The root tips in the aerobic water medium produced larger quantities of nicotines than did the anaerobic one. 3. The content and synthesis of nicotine in the fine root tips of the several varieties were higher than in the big roots.

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In order to determine the effect on the nicotine synthesis, excised root tips were incubated in the media varying in concentration of nitrogen, sugar and gibberellin. The results obtained were as follows. 1. The contents of total nitrogen and total sugar in the big root tips of several varieties were much higher than those in the fine roots, while comparison of nicotine content and the ratio of nicotine-nitrogen to total-nitrogen between big roots and fine ones showed that the values in the former were lower than in the latter. 2. The amount per milligram of synthesized nicotine in the root tips was highest in the roots grown in rooting media with low nitrogen level and those grown in the elongation media with high leyel of nitrogen. 3. The sugar level in the medium seemed to give more effect than nitrogen level. Considerable amount of nicotine was decomposed in the medium of 0.5 per cent sugar level and optimum concentration of sugar for nicotine synthesis was found to be around 2 per cent. 4. With increasing gibberellin concentration from 0 ppm to 1000 ppm, the activities of nicotine synthesis decreased.

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For the purpose of finding some data on the physiological mechanism of root elongation, the influence of external and internal conditions on the respiration of root apex was studied. The results obtained were summarized as follows. 1. Oxygen uptake of roots in the buffer solution ranging from pH 4.53 to 8.30 showed a conspicuous difference. The optimum range was found at pH 7 order and the uptake decreased in the acidic side below pH 6 and basic side beyond pH 8. 2. Root apex grown under low temperature showed higher respiration than that grown under high temperature. Oxygen uptake of roots was highest in the medium of high oxygen concentration. 3. Respiratory rate of root was highest at the apex and decreased toward the base of the root. Respiration in the youog or fine roots was hihher than in the old or big ones. 4. The optimum Mol density for respirtory rate of glucose and fructose was 0.24, whereas that of sucrose 0.12. 5. Addition of malic acid and succinic acid solution to root apex increased root respiration, TCA cycle is supposed to be connected with the progress or root respiration.

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On the basis of the experimental results, Matsushima, one of the authors, has hitherto had an opinion that the light saturation point is always found on the light-curves of carbon assimilation in rice plant communities regardless of their leafiness, and he has been in opposition to Takeda et al (1955, 1956, 1957, 1957), Murata (1961), Shimizu and Tsuno (1956) and others who have reported that the light saturation point is found only in rice plant communities with a low leaf-area-index and that it goes up with an increasing leaf-area-index and it disappears in communities with a high leaf-area-ihdex and finally in an extremely leafy communities the light-curve of carbon assimilation gets near to a straight line. Using various rice plant communities differing in leafiness, the authors have re-examined the relation between the leafiness of communities and the light-curves of carbon assimilation since 1963. Different results have been obtained in the present experiments from those in the author's past experiments. The reason why the light-curves of carbon assimilation in rice plant communities are affected by their leafiness was considered to be ascribed to the changes in receiving the amount of light on each leaf in plant communities due to their different leafiness, but the authors were impossible to prove the point because of the difficulty in measuring the amount of light on each leaf in nursery beds. Therefore, using adult plant communities in paddy fields, the authors examined the relation between the leafiness of plant communities and the light-curves of carbon assimilation and further studied the above mentioned reason according to Kumura's method. The results can be summerized as follows. 1) From the investigation on the diurnal changes of the rate of carbon assimilation in rice seedling communites differing in spacing (8×8 cm, 4×4 cm, 2×2 cm and 1×1 cm) from 4 th to 12 th leaf-stage during 3 seasons, almost identical results among 3 seasons have been obtained, i. e. a light saturation point is clearly recognized in communities with a low leaf-area-index and it goes up with an increasing leaf-area-index and finally it disappears in communities with a high leaf-area-index, as can be seen in Fig. 1. 2) In the previous experiments (1), however, the amount of nitrogen absorbed per plant differs with one another in different spacing plots, and consequently the rate of carbon assimilation per unit leaf-area as well as the plant type of seedlings are also different with different spacing plots, which may affect the light-curves of carbon assimilation. In the second experiments, therefore, a plant community has been thinned out uniformly in different rates just before the measurements so that the community may be divided into 4 different leafy communities and each community may have an equal rate of carbon assimilation per unit leafarea and an equal plant type with one another, and the measurements have been conducted on each different spacing plot thus treated. The results are nearly indentical with those of previous experiments, as can be seen in Fig. 2. 3) In general, in case of the measurements of diurnal changes in the rate of carbon assimilation under natural conditions, high light intensities appear at the time when the sun altitude is high and low light intensities are liable to appear when the sun altitude is low, so the light-curves of carbon assimilation in plant communities obtained from the diurnal changes of sunlight are affected by not only the sun altitude but also the percentage of the amount of diffused light to the totoal amount of sunlight. In the third experiments, therefore measurements have been conducted under a definite sun altitude and under different light intensities obtained through different thiknesses of aventurine vinyl films which make the sun light completely diffuse. The results obtained are also nearly identical with those of Fig. [the rest omitted]

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The light saturation point is someimes found and sometimes not found on the light-curves of carbon assimilation in rice plant communities, the authors therefore have examined various factors affecting the light-curves, except the leafiness which has already been proved to be closely related to the light-curves. The following factors have further been pointed out to affect the light-curves. 1) Light incidence angle: Even if the horizontal light intensity is identical, if the sun altitude changes, the light-receiving amount on each leaf in a rice plant community changes, and, as a result of it, the light-curve of carbon assimilation changes (cf. Fig. 1). 2) Light incidence direction: In case of the rice plants being planted in rows and their leaves being unevenly distributed in a plant community, the solar direction clearly affects the light-curves, while in case of the rice plants being evenly planted and their leaves being also evenly distributed the solar direction does not affect the light-curves at all (of. Fig. 3). 3) Plant type: Even if the leaf-area-indexes in plant communities are equal with each other, the plant type in the plant cnmmunity clearly affects the light-curves of carbon assimilation, namely the light saturation point is liable to be found on the light-curves of carbon assimilation in the plant community with long and drooped leaves, while the saturation point can hardly be found on the light-curve in the plant ocmmunity with short and errect leaves (cf. Fig. 5 and 6). 4) Nitrogen content in leaves: Eyen if the leafinesses in plant communities are identical, the lower the nitrogen content in lsaves, the more liable the light saturation point to be found on the light-curves of carbon assimilation in plant communities (cf. Fig. 7). 5) Water content in leaves: The water content in leaves decreases at mid-day after heading, and moreover, it decreases the more in leaves which receives the stronger light and also it decreases the more in plants whose root-activity is the more damaged, and the rate of carbon assimilation in plant communities progressively decreases with the decreasing water content in leaves. Accordingly, the light saturation point is liable to be found on the light curves in plant communities with decayed roots (cf. Fig. 8 and 9). 6) Amount of air sent into a plant chamber: The less the amount of air sent into a plant chamber, the more liable the light saturation point to be found on the light-curves of carbon assimilation in plant communities (cf. Fig. 10). 7) Humidity in air: Under high humidity conditions the rate of carbon assimilation does not go down and consequently the light saturation point can scarcely be found, while under low humidity conditions the water content in leaves decreases and the rate of carbon assimilation decreases as well, and consequently the light saturation point is liable to be found on the light curves of carbon assimilation. 8) From the above mentioned results it has come to be clarified that the light curve of carbon assimilation is not only affected by the leafiness in plant communities, but also it is clearly affected by several factors mentioned above, and consequently, however leafy a plant community may be, the light saturation point can frequently be found on the light-curves of carbon assimilation in the plant community.

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Matsushima. one of the authors, reported in the previous paper (1957) that the more intense light intensities than 0.6 cal./cm²/min. or 350 cal./cm²/day were almost of no use for increasing the percentage of ripened grains and he made the he made the fact as an evidence of his experimental results that the light-curves of carbon assimilation even in rice plant communities show a saturation point at about 0.6 cal./cm²/min. However, after the authors ascertained that the light-curves of carbon assimilation did not always show a saturation point in rice plant communities, as shown in the previous papers (No. 102 and 103), they considered that the above-mentioned fact would be a different one under luxuriant growth conditions and under different shading treatments. Therefore, they re-examined the relation between the percentage of ripened grains and light intensity by using two different communities, i. e. one is 4.3 and the other is 7.0 in the leaf-area-index, and two different shading methods, i. e. one is the shading with white clothes and the other with lattice plates made of vinyl chloride. (The former shading method increases the pepcentage of the amount of diffused light to the total amount of sunlight, while the latter neither increases nor decreases the percentage.) The results obtained can be summerized as follows. 1) The relation between the light intensity during the ripening period and the peroentage of ripened grains (or the weight of non-winnowed 1, 000 grains) appears to show the curves with a light saturation point in a plant community having a low leaf-area-index as reported before, while it indicates the curves with no saturation point in a plant community having a high leaf-area-index. 2) Even if the light intensity is equal to each other shading method, the percentag of ripened grains (or the weight of non-winnowed 1, 000 grains) is always higher in the cloth shading method than in the lattice shading. On the basis of this fact it has been pointed out that in the shading experiments the percentage the percentage of the amount of diffused light to the total amount of sunlight should be taken into consideraton. 3) The reason why in the past experiments the more intense light intensities than 0.6 acl./cm²/min. or 350 cal./cm²/day are of no use for increasing the percentage of ripened grains may be explained as follows. In the shading experimnets conducted in the past rice plant communities used are all low in the leaf-area-index and consequently the number of grains per unit area is very small, and moreover the shading methods used are all conducted by using white cloths and percentage of the amountof diffused light is much larger in the treatments than in the natural conditions. 4) As a result of investigation on the distribution in specific gravity of imperfectly ripened grains (lighter than 1.06 specific gravity), the following facts heen clarified : The perceotage of ripened grains is much influenced by the number of imperfectly ripened grains which are lighter than 0.86 specific gravity and the caryopsis developments of which have stopped at the early ripening stage, and the occurrece of them can be ascribed to the shortage of the amount of carbon assimilation at the time at which the starch-content in culms attains its minimum.

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In the study reported herein an attempt was made to analyse the relationship between spacing and grain yield of rice plant by measuring dry matter productivity. The experiment was carried out with rice variety "Shiranui" in 1968. Six plots of spacing, i. e. 2, 10, 30, 50, 100 and 300 hills per squre meter were provided. Nine samplings (including root) were made on successive growing period and the changes of LAI and CGR were studied. The results are summarized as foollows ; 1) The constancy of final yield of dry matter at high densities was not found out. It increased slightly at higher density. 2) The grain yield was nearly constant as 530-560 g per squre meter at four densities, ranging from 10 to 100 hills per squre meter. 3) CGR increased gradually with advancement of growth stage, and reached at the maximum, and decreased gradually. But the density was higher, the maximum stage of CGR was earlier. The maximum value of CGR obtained in the experiment was 22-23 g/m²/day at all densities except the thinned plot, i. e. 2 hills per squre meter. 4) The relative equations between LAI, NAR and CGR were given as follows ; [numerical formula] where a, b, and c are constant. 5) An attempt was made to explain the constitution of grain yield by means of the relationship between LAI at the heading stage and the grain numbers per unit area, and the dry matter increment after heading.

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Generally ethylene inhibits the extention growth of plant. But we have reported that rice seedlings were elongated by application of Ethrel which id ethylene releasing agent. The experiments conducted to make clear the effect of Ethrel and ethylene on growth in rice seedlings. The results obtained were as follows ; 1. The stimulation of rice seedling elongation by Ethrel was closely related with the volume of endosperm of seeds. The elongation of seedlings was more stimulated in the seedlings with much volume of endosperm than in ones with less endosperm. 2. Untill the 2 nd leaf stage, the growth ef seedlings was stimulated by Ethrel application. After 3rd leaf stage, however, the growth was inhibited by Ethrel. It seems that promotion or inhibition of the growth of rice seedlings depended upon the growth stage which related to endosperm consumption. 3. The rice seedlings treated with Ethrel produced more ethylene than not-treated ones. Also ethylene production in seedlings was enhanced by application of methionine, as one of precursors of ethylene. Ethylene enhancement by Ethrel was more effective in dark than in light. On the other hand, ethylene production by methionine application was active in light. 4. In methionine solution rice seedlings produced more ethylene and carbondioxide than in water. The elongation was promoted in very early growth stage, especially in coleoptile, but inhibited in later stage by methionine application. In these experiments it became clear that elongation of rice seedlings by Ethrel had close relation with the volume of endosperm in seeds, and ethylene affected the elongation of seedlings. It was suggested that ethylene had the important function as stimulater of growth in rice seedlings at early growth stage.

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There are many reports about decreasing in quality of unhulled rice during temporary storage in high moisuture content. But so far as we know, no experiment has been made to investigate the relation between preservability of rice and the ethylene production in unhulled rice during temporary storage. This paper is concerned with the relation between them. The results obtained were as follows; 1. The unhulled rice which maintained high moisture content produced much ethylene during temporary storage. The ethylene production was reached maximum at 1 to 2 days after storage. 2. In the unhulled rice that was kept at high moisture content during temporary storage, the preservability decreased rapidly. 3. Ethylene application caused a difference of moisture content in unhulled rice and occurred discolour in brown rice. 4. The temperature of the unhulled rice rised at 1 to 2 days after storage in the vacuum flasks. This results support the view that the rise of temperature was caused respiratory rise owing ethylene evolution. 5. The difference of ethylene production was not clear between wounded unhulled rice and non-wounded one. 6. The difference of ethylene evolution between non-sterilized unhulled rice and sterilized one was seen at 7 to 8 days after storage. This enhancement of ethylene in non-sterilized unhulled rice seemed to be caused by microorganisms. As results, it seems that the ethylene production in unhulled rice were closely associated with the decrease of preservability of rice. Therefore, it is important that harvested rice is dried up immediately to less than 20% of moisture content for reducing ethylene production, and it is necessary that stored rice is ventilated during temporary storage for taking out ethylene from store room.

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