日本作物学会紀事
Online ISSN : 1349-0990
Print ISSN : 0011-1848
ISSN-L : 0011-1848
33 巻, 4 号
選択された号の論文の37件中1~37を表示しています
  • 北條 良夫, 小田 桂三郎
    1965 年33 巻4 号 p. 285-288
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    Plants of Sekitorisai-No. 1 (brittle culm variety) and Haganamugi (stiff culm variety) were subjected to shading treatment at four different stages, ie. culm elongation stage, heading stage, milk stage, and paste stage. Effects of shading on culm growth was examined from the stand point of chemical composition of culm. Generally, it was observed that soluble nitrogen content was increased whereas content of cellulose and silica was decreased by shading. These changes can account for the lowering of culm strength caused by shading. Potassium was related slightly to the osmotic value of tissue juice, but it was not recognized to be directly related to the culm strength. The ratio of potassium to silica seems to express a physiological property of culm; the higher the ratio, the lower was the bending moment of culm.
  • 北條 良夫, 小田 桂三郎
    1965 年33 巻4 号 p. 289-292
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    Relation between the development of nodes and that of bending moment in nodes was researched. The bending moment in nodes was exceedingly larger than that in internodes. In the basal nodes, the bending moment showed the most large value, and in upper nodes it showed lower value. Cross section of nodes was considered as an ellipse, so we measured the long diameter and minor diameter. On the other hand, nodes were constituted by the culm and leaf sheath, so we measured the length of longitudinal direction of nodes including the leaf sheath. Consequently, those values became larger with the development of culms. The growth of culms reached to the maximum at the heading stage and afterward it declined. It was considered that the breaking of nodes in Haganemugi (stiff culm variety) related to shriveling of tissue in nodes and decline of bending moment in nodes. The ratio of bending moment in nodes to in internodes indicated the degree of stiffness of culms.
  • 北條 良夫, 小田 桂三郎
    1965 年33 巻4 号 p. 293-296
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    The effects of growth substances on development and bending moment of nodes were researched by tissues culture method using 6-rowed barley (Haganemugi, stiff culm variety, and Sekitorisai. No. 1, brittle culm variety). In this experiment, we used the following growth substances: α-naphthalene acetic acid, kinetin, and gibberellin. Morever, we used the water extracts of total plant or culms. The growth rate in the length of longitudinal direction of nodes was especially higher in Sekitorisai-No. 1 than in Haganemugi. On the other hand, in Haganemugi, the high growth rates in nodes length of the longitudinal direction of culm axis in the first and fifth nodes were observed. The nodes in Haganemugi have been same little growth rates. It was considered that the most effective substances were α-naphthalene acetic acid and kinetin, and gibberellin, the extract of total plant and that of culms were next to them.
  • 北條 良夫, 小田 桂三郎
    1965 年33 巻4 号 p. 297-300
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    The negative geotropism of nodes in 6-rowed barley (2 varieties were used : Haganemugi, stiff culm variety, and Sekitorisai-No. 1, brittle bulm variety) were studied in relation to the stimulus and temperatures. Generally, the reaction of negative geotropism was larger in Sekitorisai-No. 1, and more apparently in the basal node than in upper nodes. Stimulus was larger and temperature was higher, the reaction became larger. But in Haganemugi, the reaction was different in each node, so it was considered that the physiological states in each node were different in the variety. The negative geotropism of nodes continued untill the late growth stage, and especially so in the upper nodes. The reaction was disappeared by the treatment of α-naphthalene acetic acid in nodes. From the auto-recording diagram of the reaction, it was pointed out that the reaction began soon after the beginning of stimulus and a half of reaction finished in 36 hours after the beginning of reaction.
  • 稲田 勝美
    1965 年33 巻4 号 p. 301-308
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    For the purpose of estimating the deepness of green color and chlorophyll content per leaf area in intact leaves of crop plants, a type of chlorophyllo-meter was constructed, basing on the principle of a difference attenuance which corresponds the difference between the attenuance at 670 mμ attributable to chlorophyll contained in leaves and that at 750 mμ showing the basic absorption. From the photoelectric characters of chlorophyllo-meter, it was suggested that the reading (-log T) of the meter might be directly proportional to the quantity of chlorophyll present within the light path, provided that the leaf tissue is homogeneous and the chlorophyll content is less than a certain limit. The experimental results may clear the following points: (1) High correlations exist between the order of reading and that of deepness of green color judged by naked eye in rice leaves, particularly in case where the reading difference was greater than 10 per cent (Table 1). (2) Relation between the reading and chlorophyll content per leaf area was studied in several crop plants including rice, wheat, Italian rye grass and sweet potato. As the result, very high positive correlations were obtained within respective plant kind when the leaf parts determined were relatively homogeneous exclusive of the midrib or veins (Figs. 5 and 8B), while some lowering in the correlation was noticed when the midrib was placed in the center of light path in graminaceous plants (Figs. 2, 3, 4, 6, 7 and 8A). (3) Regression coefficient of chlorophyll content per leaf area to the reading differs widely according to the kind of plants. There was not, however, much difference in coefficient among the plants which are included in the same family (Fig. 9). It was concluded that the chlorophyllo-meter may be used for determining the deepness of green color and estimating the chlorophyll content per area in intact plant leaves.
  • 稲田 勝美
    1965 年33 巻4 号 p. 309-314
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    セイロンにおける水稲の生理病ブロンヂングについて, 発生程度の異なる3カ所の水田を用い, 数種の処理が本病の発生, 水稲の生育ならびに収量に及ぼす影響を明らかにすると共に, 罹病葉における呼吸系の変化について研究を行い, つぎの結果を得た. 1. ブロンヂングの発生程度は, ゴム林に接した砂質水田(sandy area I)では大であったが, 有機質を多く含む水田(boggy area)および道路に近い砂質水田(sandy area II)では小であった. 2. 石灰施用によって, boggy areaでは本病が発生が抑制され生育ならびに収量が増加した. しかし, sandy area Iでは罹病抑制の効果がいちじるしかったが, 生育が遅延し収量が低下した. 3. 堆肥施用や有機質土壌の客土は本病の発生を抑制し, 収量を増加させた. その効果はboggy areaよりもsandy area I, IIで大であった. 4. 本病が早期に発生すると生育, 収量構成要素ともに罹病がいちじるしいほど低下したが, 発生時期がおそい場合にはおもに収量や登熟が低下する傾向が認められた. 5. 罹病葉では呼吸がいちじるしく高まり, 呼吸増加と罹病程度との間に密接な関係があった. 6. 罹病植物の葉身は健全植物にくらべてDNPによる呼吸の促進率が低く, azideによる呼吸阻害率が減少し, チトクロームオキシダーゼ活性が低下した. しかし, パーオキシダーゼ活性がいちじるしく高かった. この結果から, 罹病葉ではエネルギー生産効率の低い呼吸系が発達すると考えられた.
  • 稲田 勝美
    1965 年33 巻4 号 p. 315-323
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    ブロンヂング発生の原因を明らかにするために, 圃場試験, ポット土耕ならびに水耕試験を行いつぎの結果を得た. 1. 土壌の酸化還元電位(Eh6)の低下が本病の発生を誘起する要因の一つであることが認められた. ただし発生期間中のEhレベルは激発土壌では相対的に高く, 発生し難い土壌では低い傾向があった. 2. 本病の発生は単に土壌の低pHとは関係がないが, pH約6.5以下で発生することが明らかになった. 3. 土壌中の可溶性鉄含量は本病の発生と関係かなかったが, 水耕液に過剰の二価鉄を加えるとpH 6.5以下で本病に似た症状が現われた. 4. 土壌または水耕液中に高い濃度の硫化物ことに硫化水素と過剰の二価鉄が共存すると本病酷似の症状が現われた. 5. 罹病葉身では鉄含量がいちじるしく高く, 罹病程度と鉄含量の間に密接な関係が認められた. また, 発生田の植物体には極端にマンガンが少なかった. 6. 以上の結果から, 一つの可能なブロンヂングの発生原因をつぎのように推定した. すなわち, 硫化物, 二価鉄およびほかの有害物質が土壌中に集積して根の生埋的活性を阻害し, その結果, 鉄の過剰吸収と植物体への過剰蓄積をおこすとともに, 他方ではマンガン, 加里, 珪酸などの養分吸収を阻害して代謝の撹乱をひきおこし遂にブロンヂングを発生させる.
  • 菅 洋, 山田 登
    1965 年33 巻4 号 p. 324-329
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    麦類の春化誘導反応における核酸の役割を明らかにする目的で二つの実験を行った. 1. 核酸ピリミジン塩基ウラシルの代謝阻害物質である. 2-チオウラシルの高秋播性小麦の低温春化感応に及ぼす影響をしらべたところ, 2-チオウラシルは小麦の低温春化感応をいちじるしく阻害した. この阻害はウラシルによりかなりの程度まで, また, ヌクレオチドのウリジン燐酸やシチジン燐酸の前駆物質であるオロチン酸により完全に回復する. しかし, チミンでは回復は不十分であった. 2. 胚培養法を用い, 秋播性大麦の花成誘導に及ぼす, DNA, RNAの効果を非誘起状件下で調べたところ, 実験終了時までコントロール区は栄養状態でとどまったが, 核酸を加えたものの中で, とくにRNA 1および10ppm 区で出穂個体が多くみられ, 核酸が春化感応の代替作用を有することが認められた.
  • 菅 洋, 山田 登
    1965 年33 巻4 号 p. 330-334
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    すでに水稲において分けつ発生がオーキシン・アンチオーキシンと関係があり, NAAにより分けつがおさえられ, TIBAにより増加することを明らかにしたが, 小麦においてもこれらの関係を調査し, とくにTIBAによる分けつ増加の機構をしらべた結果, つぎの点が明らかとなった. 1. 小麦においてもオーキシン(NAA, IAA, p-CPAなど)は分けつ発生をおさえ, アンチオーキシン(TIBA)は分けつ発生を促進する. 2. アンチオーキシンによる小麦の分けつ増加にはつぎの機構が関係していることがわかった. (1) 出葉のテンポすなわち出葉速度が早くなる. (2) 主稈葉と分けつ葉の間の出葉に関する秩序性が乱されるようで, 分けつの葉はそれに対応する主稈葉の出葉より早く出現することがみられた. (3) 処理区では, 同じ環境条件におかれた対照区でみられない高次分けつが発生する.
  • 田中 市郎, 野島 数馬, 上村 幸正
    1965 年33 巻4 号 p. 335-343
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    水稲の直播栽培における灌漑法の効果を明らかにするため, 早期灌漑, 晩期灌漑, 間断灌漑の3種の灌漑法と窒素の施肥量および耕深を組合せた圃場試験と灌漑に伴なう水の運動と土壌窒素との関係を解析する室内実験とを行なつた. 得られた結果は次の如くである. 1) 一般に水稲の養分吸収は灌漑法および窒素の施肥量によつて影響されるが, 耕深による影響は僅かであつた. 即ち, 早期灌漑区に比して晩期灌漑区の窒素, カリ, マンガンの吸収量は高いが, 燐酸および珪酸の吸収量は低い. また間断灌漑区の窒素, 燐酸, カリ. 珪酸の吸収量はいずれも早期灌漑区より低いが, マンガン吸収のみは逆に著しく高い. また窒素の施肥量の増加に伴つて乾物重が増すので, 各種の無機成分の吸収量は高くなる. 2) 水稲の収量は灌漑法および窒素の施肥量によつて影響されるが, 耕深による差は僅かである. 一般に窒素の施肥量の少い場合間断灌漑区の収量は早期灌漑より著しく低いが, 窒素の施肥量が多くなると両者の差はなくなる. また全重と窒素の施肥量との間には各灌漑法を通じて一次の回帰式がよく適合すること, また玄米重と窒素の施肥量との間には早期および晩期灌漑では二次の回帰式が, 間断灌漑では一次の回帰式が適合した. 3) 灌漑や降雨に伴なう地下水位の変動と透水が土壌の無機態窒素に及ぼす影響を明らかにするためincubation testを行なつた. その結果土壌からの無機態窒素の損失は次のような条件下でおこることを明らかにした. i) 地下水位が-10cmまたはそれより高い場合, ii) 地下水位が周期的に変動し, 土壌が酸化状態と還元状態を繰返した場合, iii) 硝酸態の窒素が湛水および湿潤状態の土壌に施用された場合, iv) 畑状態の土壌が多量の灌漑水や降雨を受けた場合等にみられた. なお畑状態の下ではNH3-N肥料を与えるよりNO3-N肥料を与えたときに土壌の無機態窒素量の著しい増加がみられる場合があつた. 4) 本試験の結果から水稲の収量に対する灌漑の効果は主として灌漑や降雨によつて土壌の無機態窒素量が変化し, それに伴つて稲体の窒素吸収が変化するためにもたらされることを明らかにした.
  • 戸田 正行
    1965 年33 巻4 号 p. 344-350
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    Some experiments on the artificial induction of injury, same to the one found at the region of Shigarami, were conducted by the author using a refrigerator. The results of the experiments were as follows: 1) The same type of the injury caused by the chilling at the region of Shigarami could be induced by treating wheat variety Norin No. 27 at the heading stage with a low temperature of 1-2°C. for 4 hours. 2) Only the ears at the heading stage among various stages were found to receive the greatest injury by the treatment. And the ears at a stage few days earlier orlater than the heading stage received no injury. 3) The threshold temperature by which the injury arises was somewhat different according to wheat varieties, physiological conditions of plant, and air moisture in the refrigerator. Under a certain condition, the occurrence of the injury required a low temperature 0°C.
  • 戸田 正行
    1965 年33 巻4 号 p. 351-356
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    The abnormal pollens which have empty cytoplasm were never observed somewhat before the heading stage of Norin No. 39 at the region of Shigarami in 1957, but were remarkably observed after the heading stage. Cytological studies on the injured ears produced by artificial induction were performed in 1962. 1) The abnormality of pollen similar to that in injured ears at the region of Shigarami was found out also in the injured ears induced by the artificial low temperature. 2) Types of the abnormal pollen could be mainly classified into two kinds, immature pollen and degenerated pollen. The immature pollen tended to arise, when the injurious low temperature was relatively severe. 3) The anthers in the injured florets contained the abnormal pollen generally in proportion of more than 50 %. 4) It seemed that the pollen abnormality is caused by gradual physiological processes acompanied with a decrease in the function of the anther, and neither from direct and quick actions of low temperature at the heading stage, nor from chromosomal aberrations at the PMC stage, and nor from abnormal swelling of the tapetum. 5) It was thought to be difficult to express the sensitive stage to low temperature with the cytological stage of pollen, but to be better to express it with the anther stage. The development of ovary in the injured glume stopped suddenly after the flowering stage, although it was normally performed until just before the flowering stage. All the injured glumes were re-opened in a few days after the flowering stage. And it was clear by the observation in use of the microscope that the injured grains were not fertilized. The injured grains induced by the refrigerator was nonfertilized ones similar to those induced by the natural conditions at the region of Shigarami.
  • 戸田 正行
    1965 年33 巻4 号 p. 357-361
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    A comparison was performed between the theoretical values expressing the degree of the injury calculated from the experimental results and the observed values of that of wheat plants which suffered the chilling injury at the region of Shigarami. 1) The theoretical values were calculated from two numerical data the degree of the injury per every heading date obtained from the artificial low temperature treatment and also from the investigated results of heading status in the fields. 2) It was found that the theoretical values and the observed values agreed considerably, when the two values were applied to the experiments on the seeding period at the region of Shigarami. 3) This fact is thought to indicate that the quantitative estimation of the injury by the chilling may be possible.
  • 戸田 正行
    1965 年33 巻4 号 p. 362-365
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    It has been pointed out that the sterile type caused by the chilling is universally found out in such provinces as San-in, Tokai-kinki, and Kanto, which have predominantly acidic soil.
  • 安永 隆, 大森 芳子
    1965 年33 巻4 号 p. 366-370
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    Optimum condition for measuring apparent viscosity of wheat flour suspention in lactic acid with McMichael type viscometer were reexamined to evaluate gluten quality with smaller amount of samples and more simple procedures than those used today. The procedure proposed on the base of this examination proved to be available for detecting and estimating those characteristics in dough, expressed as low resistance/extensibility on extensigram, which are seen very frequently on Japanese domestic wheat.
  • 田島 公一
    1965 年33 巻4 号 p. 371-374
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    作物の高温障害に関する基礎的研究として, 牧草および水稲の生育および呼吸に対する高温の影響をしらべた. 夏期高温時に播種したイタリアンライグラスの生育は地温を低下することにより, ある程度促進されるのがみとめられた. 地上部と地下部の呼吸に対する温度の影響をしらべたところ, 水稲葉身では実験範囲(20℃~44℃)の内では温度の上昇にしたがって呼吸も増加したが, イタリアンライグラス, オーチャードグラス, チモシーの葉身では32℃以上では温度上昇に対する呼吸増加率が低下した. 一方根の呼吸は水稲では32℃以上で呼吸増加率が低下し, イタリアンライグラス, オーチャードグラスでは26℃以上で呼吸増加率が低下するのがみとめられ, 地上部にくらべて根は高温障害に対して弱いようであった. つぎにこれら高温による呼吸活性の低下の原因を明らかにするため, 呼吸基質としてのグルコース, あるいは原形質の主要な構成成分である脂質に作用すると考えられるクロロフォルムの影響と高温の影響との関係をしらべ, 高温による呼吸活性の低下は, 呼吸基質の消耗以外にも原因があることを推定した.
  • 田島 公一
    1965 年33 巻4 号 p. 375-378
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    前報に報告した高温による呼吸活性の低下の機構を明らかにするため, チトクローム C オキシダーゼ活性の変化についてしらべた結果, 呼吸活性が低下するような温度条件下では, チトクローム C オキシダーゼ活性も低下するのがみとめられ, 呼吸活性の低下には酵素活性の低下が関係していることが推定された. また高温により低下したチトクローム C オキシダーゼ活性は燐脂質(大豆レシチン)の添加により回復するのがみとめられ, 高温の影響は酵素蛋白自体よりも, 酵素活性発現に必要な脂質に対して作用していると推定された.
  • 清水 正治
    1965 年33 巻4 号 p. 379-387
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    The morghogenetic effects of gibberellin on rice plants were studied, providing several plots according to the time of gibberellin application. Gibberellin was applied at the concentration of 100 ppm and 500 ppm as foliar spray or soil treatment. Available results are as followings. 1) When gibberellin is applied at the stage of early vegetative growth, the number of tillers is increased and the leaf blade, leaf sheath and internode which are under the rapid elongation stages at that time, show marked elongation. 2) In the case of application at the stage of late vegetative growth, the date of young panicle differentiation is hastened distinctly, while the number of leaves is increased on the other hand. 3) When gibberellin is applied at the stage of young panicle differentiation, branches, especially the secondary ones and pedicels of the panicle show striking increments in number and consequently the number of spikelets is increased conspicuously, while the ratio of unfertilized spikelets grows larger than that of the control. 4) The date of heading is slightly promoted by the application at the just before heading time due to a rapid elongation of the upper internodes. 5) More cells and mitotic figures are observed in shoot apices and internodes of the treated plants than in those of the control. 6) Various abnormalities as shown in photograph No. 4 are caused by gibberellin application. From the results above mentioned followings are considered. The effect of gibberellin is not specific to the growth or differentiation of organs and tissues, but varies according to the physiological state of them at the moment of application. Referring to the growth of cell, the effect of gibberellin appears not only in cell elongation but also in cell multiplication and accelerates the meristematic activity. From the fact that branches and spikelets of the panicle treated show marked increases in number, gibberellin is thought to have some effect to advance the differentiation of vascular bundles in the panicle. Phenomena of the frequent appearance of bract leaf and well development of the primary branch at the first bract, suggest that gibberellin may have some physiological act in revelation and development of degenerate organs or tissues, though sometimes induces morphogenetic disorders.
  • 長南 信雄
    1965 年33 巻4 号 p. 388-393
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    The mesophyll structure of leaves inserted at different levels of the main shoot of wheat plants were observed. In the leaves of wheat plant, most of the mesophyll cells, the arm-palisade cells, have several lateral protuberances developed at right angles to the leaf surface. The number of protuberances in a mesophyll cell increase from the lower to the upper leaves. The average cell length is longer in the upper leaves than that in the lower, and there are positive linear relationships between the number of protuberances and the cell length as far as the leaves in the same levels are concerned. The ratio of the protuberance length to the cell width is higher in the upper leaves. The diameter of protuberance is shorter in the upper leaves. In the leaves at lower levels, the protuberance diameter decreases from the base to the top of leaf portions, on the other hand, such a obvious relation is not seen in the upper leaves. The ratio of the cell surface to the cell volume is raised as the number of protuberances increase, and the number of cells per unit leaf area is increased from the lower to the upper leaves. Therefore, the total cell surface per unit leaf area is greater in the upper leaves, comparing with that in the lower leaves. Generalizing from the observations in this study, it may be concluded that the upper leaves have a relatively more strongly developed arm-palisade tissue than the lower leaves.
  • 中條 博良
    1965 年33 巻4 号 p. 394-398
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    To make clear the varietal difference in critical daylength of short day vernalization response of barley, sixteen naked varieties and seventeen covered varieties of barley were treated for three weeks under 8, 11, 14, and 20 hour daylength. Almost all the varieties showed the pronounced short day vernalization effect under 8 hour daylength. Under 11 and 14 hour daylength, however, there was difference in short day vernalization effect among the varieties. The varieties were classified into three grades, i. e. A, B, and C on their short day vernalization response under S, 11, and 14 hour daylength compared with that under 20 hour daylength. The trend of short day vernalization response of the varieties under 11 of 14 hour daylength which depended on their critical daylength was not parallel with that under 8 hour daylength. The schematic curve of short day vernalization response under different daylength was discussed.
  • 姫田 正美, 泉 清一
    1965 年33 巻4 号 p. 399-402
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    The experiment was performed to find out the effect of irregular disposition of drill-seeded rice plants upon yield in direct sowing culture. Row of 1 m length was divided into ten equal sections (10 cm row) and number of plants in them was varied. Co-efficient of variation (cv) of number of plants in 10 cm row was used as the index of irregular disposition and five plots of cv 0 %, 30 %, 60 %, 100 %, and 150 %, were established. 1. The more irregular disposition of plants was, the more decrease in grain weight (per unit area) was. It's degree was more remarkable in Fujiminori (early maturing and panicle type variety) than in Manryo (medium maturing and medium tiller type variety). 2. Decrease of grain weight was caused by that of number of panicles (per unit area). In Fujiminori, number of panicles decreased according as irregularity in disposition of plants increased. grain weight per panicle being remained unchanged. Therefore grain weight decreased in proportion to increase in irregularity of plant disposition. In Manryo, however, grain weight per panicle increased though number of panicles decreased. Accordingly decrease of grain weight compared with the plot of cv 0 % was not observed in plots of cv 30∼100 %. 3. In Fujiminori, decrease of grain weight with irregular disposition of plants was more marked in the case of low seeding density than in that of high one. In Manryo, however, the difference of the effect of irregular disposition on grain weight caused by different spacing densities was not clear.
  • 長瀬 嘉迪, 竹村 昭平
    1965 年33 巻4 号 p. 403-408
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    The relations among planting time, plant population and irrigation in corn culture were investigated in order to appraise the practicability of irrigation in an early and a late season culture, in 1962. The results may be summarized as follows: (1) Weight of stover per are was decreased strikingly in late planting and increased with dense population and by irrigation. The effect of irrigation which appeared on the length of internode was larger in high population from early growing period. (2) The interval between tasseling and silking time and the percentage of barren plants were decreased by irrigation and were increased by late planting, and increased strikingly with increasing plant population in late planting. The irrigation lessened remarkably their increase by late planting and high population. (3) The number of kernels per m2 was increased by irrigation and was decreased by late planting. In early planting, the number of kernels per m2 increased as increasing plant population in both irrigated and non-irrigated plots. But in late planting, the number of kernels per m2 decreased with increasing population in the case of non-irrigation and increased with population rise in the case of irrigation. The irrigation lessened the decrease by late planting. The reason of different effects of dense population between irrigation and non-irrigation was considered as follows. Irrigation decreases the percent of barren plants and sustains the increasing of number of ears per are by high population and in addition lessens strikingly the decrease of number of kernels per ear by high population throuth the increase of length of ear and the decrease of variation of ear size. (4) Weight of 1, 000 kernels was increased by irrigation and was decreased by late planting and decreased with increasing plant population. The quality of grain was deteriorated by late planting, and was scarcely practical value except the case of low population level in irrigated plots. (5) The yields of grain showed similar tendency to kernel numbers per m2. The yields of grain were increased remarkably by irrigation and were decreased notably by late planting. In early planting, the yields of grain increased with population rise in both irrigated and non-irrigated plots, however, in late planting, decreased with increasing plant population in the case of non-irrigation, but increased with population rise to the population of 833 plants per are in the case of irrigation. On the yields of grain, the interactions of irrigation × plating time (0.1 % level) and irrigation × plant population in late planting (1 % level) were significant. (6) By the above results, it was made clear that 1) high grain yields of corn in early season culture are obtained by irrigation and higher plant population, and 2) late season culture of corn (planting early in July) is unvaluable in the case of non-irrigation but considerable high yields and relative good quality of grain are obtained in the cese of irrigation at low population level.
  • 渡辺 和之, 児玉 敏夫
    1965 年33 巻4 号 p. 409-413
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    Experiments were made to probe the effects which the soils of different bulk densities would have on the conditions of crop plants in their early growth stage. 1) The authers, using a kind of crop plants, examined the effects which the soils of different bulk densities would have on their conditions observed in their early stage of growth. As a result, it was known that the effects in question are different according to the kind of crop plants. As a matter of fact, the growth of such kinds as soybean, buckwheat, Japanese radish, Chinese cabbage, cucumber and pumpkin was hampered considerably, whereas no remarkable growth-inhibiting effects were observed in the case of sorghum, upland rice and paddy rice under the high bulk density of soil. It was also observed that the growth of the roots of crop plants in its early stage was liable to be affected by the soil of high bulk density much more than that of the upper parts of such plants. 2) The germinating capacities of various types of crop plant seeds in water were compared with one another to probe the effects the controlled supply of oxygen would have on such capacities at the germinating time. The result was that those crop plants which had attained good germinating and growing conditions even under the controlled supply of oxygen were mostly those which were not easily affected by the relatively high bulk density of soil (in this case, correlation coefficient γ= + 0.62). 3) The effects which the soils of different structures would have on the early-stage growth of crop plants were examined by the use of the soils which were aggregated under the effect of soil conditioners, together with their original soils. Those crop plants whose growth conditions were considerably improved by the aggregated soil were Japanese radish and buckwheat, and no such effect was observed in the case of paddy rice and barnyard millet. 4) In studying the effects which the soils of different bulk densities and under different aerating conditions would have on the early-stage growth of crop plants, it was found that the effects in question were different on the kind of the crop plants used. That is, the growth of sweet potato plant and soybean was liable to be affected adversely when soil aeration was not good. In the case of corn, the growth was affected more by the soil strength than by the soil aerating conditions. As for upland rice, its growth was less affected by such soil physical conditions than three other crop plants.
  • 渡辺 和之, 児玉 敏夫
    1965 年33 巻4 号 p. 414-417
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    Using upland rice, soybean, sweet potato, soiling corn and cucumber as specimens, the authors studied the effects of the soils of different bulk densities and moisture contents (in this experiment, brown-colored volcanic ash soil was used) would have on the growth and yield of crop plants. The result was that the effects of the varying soil physical conditions due to the difference in its bulk density and moisture content were different depending on the kind of the crop plants used. But in all the kinds, conditions were largely influenced by the magnitude of the soil air capacity. In fact, the yield was lowered when the capacity in question was extremely small (or when the soil bulk density or moisture content was relatively high). In this case, the rate of decrease in the yield differed according to the kind of crop plants-the rate was high in the case of sweet potato plants (weight of tuberous roots), cucumber plants (number of fruits) and soybean plants (weight of grains), and was relatively low in the case of upland rice (weight of grains) and soiling corn (weight of parts protruding above the ground). In the authors' experiment, the yield of crop plants increased with the rise of the soil air capacity. When this capacity rose beyond a certain level, however, the moisture content of the soil decreased correspondingly, and as a result, the yield was lowered. This phenomenon was especially evident in the case of upland rice, and was least noticeable in soiling corn. Thus, the soil air capacity favorably affecting the yield of crop plants differed according to their kinds. The influence of the soil air capacity at various levels on the total weight of crop plants was, generally speaking, similar to such influence on their yield. In the case of sweet potato plants, however, the soil air capacity required for the growth of their upper parts was different from that required for the growth of their tuberous roots. That is to say, the soil air capacity, when decreased, had less unfavorable effects on the growth of the upper parts than on the growth of the tuberous roots. This goes to show that the effects of diffects of different soil air capacities differ from one part of the crop plant to another.
  • 渡辺 和之, 児玉 敏夫
    1965 年33 巻4 号 p. 418-422
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    The authors clarified the relationship between the type of soil and various soil-managing methods (control of soil bulk density, moisture content, height of ridges and amount of fertilizers), on one hand, and the soil air capacity and the soil air composition, on the other, and studied the effects these factors would have on the growth and yield of the sweet potato plant. 1) The soil air capacity was found to decrease when the soil bulk density became higher or when the soil moisture content became larger. Also, the capacity in question was larger where the height of ridges was larger, than where the height in question was smaller. In terms of the type of soil, the capacity was smaller in the alluvial soil and larger in the volcanic ash soil. As for the change in the soil air capacity after tilling, the capacity decreased considerably in the alluvial soil with the lapse of time, while it decreased very slowly in the sandy soil. The air capacity of the volcanic ash soil was affected also by the soil-managing methods to a greater extent than that of the sandy soil. 2) In the brown-colored volcanic ash soil, the composition of air contained in it is closely related with its air capacity. The O2 concentration in the air in question was lowered when the soil air capacity became smaller, and the CO2 concentration in it increased under the same condition. But the effect was different depending on the type of soil a significant correlationship was observed between the soil air capacity and the CO2 concentration in the soil air in the case of the alluvia soil and the volcanic ash soil, but no such correlationship was noticed in the case of the sandy soil and the aggregated alluvial soil. 3) With regard to the relationship between the soil air capacity and the composition of soil air, on one hand, and the growth and yield of the sweet potato plant, on the other, the growth of the upper parts of the plants was male active when the CO2 concentration in the soil air was increased, whereas the growth of the tuberous roots was checked under the same condition, and as a result, the weight of the tuberous roots was reduced. All this goes to show that the soil air capacity needed to assure the growth of the upper parts of the plant is different from that required for the growth of the tuberous roots, and that therefore the different soil air capacities have their respective influences on the distribution of the substances produced through photosynthesis among the upper and underground parts of the plant.
  • 川田 信一郎, 芝山 秀次郎
    1965 年33 巻4 号 p. 423-431
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    In rice plants the lateral root originates in the pericyclic cells of the crown root opposite to a protophloem and between two protoxylems. Before the initiation of such root primordium the nuclei in a group of pericyclic cells gather in a certain zone (Fig. 3B, "R") and the density of the protoplasm around it becomes higher (Fig. 3). Similar phenomenon is also found in the adjacent endodermal cells (Fig. 4 and 5). After that, this group of the pericyclic cells undergoes anticlinal division (Fig. 6) followed by periclinal division (Fig. 7-10). The same phenomenon is also observed in the cells of the endodermis (Fig. 12 and 13). In this stage, the cells derived from such division in the endodermis are divided into two sets, one forms "Tasche" and the second forms the epidermis of the basal part of the lateral root primordium (Fig. 12, 13 and 17.20). In the crown roots of rice plants two kinds of lateral roots are recognized, one is thicker in diameter than the other. The thick one is different from the thin one in, the number of cell layers in the cortex, and the organization in the stele. Both primodia in the early stage are much alike anatomically, but at a certain stage of development they are markedly different in thickness (Fig. 17-20). This difference is mainly contributed to the periclinal division which takes place in the endodermis of one more than the other.
  • 福井 重郎, 小島 睦男, 渡辺 巌
    1965 年33 巻4 号 p. 432-436
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    The studies were carried out in an attempt to make contribution to the establishment of principles regarding seed production of soybean plants, by elucidating the photosynthetic properties. Measurement of photosynthesis was performed with intact leaves under artificial light. The following results were obtained. Under saturating light condition, photosynthetic activity of soybean leaves increased slowly and reached maximum value at about 60∼120 minutes after insertion in chamber. Apparent photosynthesis and respiration were measured with seedlings at various temperatures ranging from 5 to 40°C. Within the range from 15 to 30°C, temperature little affected the apparent photosynthetic rate, though slight depression was obsered above 26°C up to 30°C. While outside the range from 15 to 30°C, temperature depressed the activity the more severely the more it diverged the range. The optimum temperature of true photosynthesis was found at about 26°C.
  • 小島 睦男, 福井 重郎, 渡辺 巌
    1965 年33 巻4 号 p. 437-442
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    Using the intact leaves of non-nodulated soybean variety, T 201, the effect of three nutrient elements supply on the photosynthetic rate of leaves was investigated. And then, using the mature intact leaves of soybean variety, Norin No. 2, the apparent photosynthetic rate was continuously measured for 24 hours under constant temperature, light intensity, using the out door air as CO2 source. The following results were obtained. 1. Soybean plants were supplied with different amount levels of nitrogen, phosphorus and potassium, respectively. It was found that nitrogen gave limiting influence to photosynthesis and the photosynthetic rate was promoted with increasing nitrogen content in leaves. While the rate of photosynthesis was scarcely affected by phosphorus, potassium and water content. In most case, respiratory rate showed a close correlation with photosynthetic rate. 2. The photosynthetic rate of leaves attained to the highest value at the time of completion of leaf expansion. The highest value continued for about one week, and afterward activity declined gradually. 3. The diurnal fluctuation in the photosynthesis of leaves showed a close relationship with CO2 concentration in air. But, even when kept under constant temperature, light intensity and CO2 concentration, it was observed that there existed the endogenous rhythm of photosynthetic rate which declined at night and recovered in the morning.
  • 浦野 啓司, 滝沢 康孝
    1965 年33 巻4 号 p. 443-449
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    Four corn varieties, each representing early, medium and late maturity were sown respectively at various times from April 30 to August 5, and their fresh weight was investigated in 1959 and 1960 at the kikyogahara Branch of Nagano Agricultural Experiment Station. The results obtained were as follows: 1. Fresh weight of early maturing variety planted somewhat late is comparatively heavier than that planted at the other dates. While, fresh weight of late maturing variety planted earlier is heavier than that planted at the other dates. Increase in culm length shows a tendency similar to that of fresh weight throughout the growth period. In this respect, medium maturing variety shows the intermediate tendency between those of early and late maturing varieties. 2. Days from emergence to tassel differentiation are less in the cases of later planting. The time of tassel differentiation of early maturing variety is earlier than those of later maturing ones. The tassel of early variety initiates before the lowest internode begins to elongate. The duration of the lowest internode elongation is constant among varieties, if they are seeded at the same time. 3. Days from emergence to tassel differentiation or to the time of the lowest node elongation are affected by mean temperature and are scarcely affected by day length during the course of plant growth. 4. The fresh weight at the time of young tassel formation is varied according to planting time and also to varieties. 5. Fresh weight of plants during the time from the lowest ioternode elongation to tasselling is affected by temperature in the case of early maturing variety, while those of the medium and late maturing variety are affected by day length as well as by temperature. Extreme late maturing varieties are affected mainly by photoperiod. The earlier the tassel differentiation begins the less fresh weight is. 6. In early maturing variety, the degree of elongation of the lower internodes is remarkable when planted somewhat late. When planted extremely late, the elongation of the upper internode is inhibited by low temperatre and the number of nodes decreases. The elongetion rates of upper internode ate affected ramarkably by low temperature in the case of late maturing varieties planted rate, while the elongation of lower internode is promoted in the preceeding warm condition. Therefore in later maturing variety, the culm length of earlier planted one is longer than that of later planted one.
  • 浦野 啓司, 坂口 進
    1965 年33 巻4 号 p. 450-453
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    Early and late maturing varieties of corn plants were planted during the period from April 30 to July 6. The following conclusions were drawn out from this experiment. The grain yield of early maturing variety planted somewhat late is comparatively more than that planted at the other times of the season. On the other hand, grain yield of late maturing variety planted earlier is more than that of late planted ones. In the case of early maturing variety, dry matter weight per plant is less in the earlier planted one than those in somewhat late planted ones throughout the growth period. In the case of late maturing variety, during the early stage of growth period, accumulation of dry matter in early planted one is more than those in the later planted ones. During the time from early stage of growth period to silking, increase in dry matter weight of early planted one shows the tendency almost similar to that in the later planted ones. After silking, increase in dry matter weight of early planted one is accelerated more than that in the later planted ones. Increase in nitrogen and carbohydrate content seemes to be similar to that in dry matter weight throughout the growth period. Early maturing variety is insensitive to day length. Therefor, once the plant has accomplished its basic vegetative growth, tassel primordium differentiates even under long day regime. Assimilated carbohydrates are accumulated in grains under ideal condition throughout the ripening period in early as well as in middle planted ones, however, vegetative growth of the former is less strong than that of the latter, because the former plant has grown under lower temperature than the others during the course of vegetative growth. In consequence, amount of carbohydrate accumulated in grains is less in early planting. Plant growth and yield of early maturing variety planted late are less than those planted at the other time of season due to the same reason as the case of late maturing varieties planted late. On the other hand, late maturing variety is sensitive to day length. Tassel primordium does not differentiate untill day length become shorter, so amount of vegetative growth is more than that of early maturing variety. In late planting, however shorter day length restricts vegetative growth and lower temperature during ripening period degresses photosynthesis and accumulation of cabohydrate in grains, and these bring decrease in yield finally. Grain yield is better when seeds are planted earlier.
  • 長田 明夫, 村田 吉男
    1965 年33 巻4 号 p. 454-459
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    The varietal differences of photosynthetic activity among rice varieties and their relationship to dry-matter-production were studied with twelve varieties at seedling and maximum tillering stages, the results being as follows: (1) Relatively stable varietal difference was found with varieties tested through young and adult plants grown under different cultivating conditions. It was also observed that early maturing varieties tended to have higher activities than late maturing ones. (2) Photosynthetic activities of varieties at the former growth stage were determined by protein-nitrogen content on unit leaf area. (3) When leaf area was not too big or solar radiation was abundant, relative growth rates of varieties were determined by photosynthetic rate on unit leaf area through net assimilation rate.
  • 長田 明夫, 村田 吉男
    1965 年33 巻4 号 p. 460-466
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    In ripening period, rate of photosynthesis per unit leaf area, respiratory activity, leaf area, dry-matter-production, grain yield and yield components of six rice varieties grown under different nitrogen levels were determined in reference to adaptability for heavy manuring. Results obtained are as follows: (1) Under high nitrogen level, the rate of photosynthesis was greater in varieties more suitable for heavy manuring than in less suitable ones. On the other hand, the rate of increase in respiration and leaf area were greater in less ones. (2) When solar radiation was scarce promotion of dry-matter-increase during ripening period by increasing supply of nitrogen was higher in suitable varieties. (3) Further, as the more general characters of rice varieties : When solar radiation was not scarce, varietal difference in dry-matter-increase and panicle weight were governed mainly by photosynthetic activity. (4) It was seen through all the varieties tested that the percentage of ripened grains was determined chiefiy by the ratio of photosynthetic rate on unit leaf area to the product of leaf area and the number of total spikelets both on unit field area.
  • 玖村 敦彦, 浪花 勲
    1965 年33 巻4 号 p. 467-472
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    Soybean plants, var Shirohara-Sai No. 1 were cultivated under field condition, and the various, characters related to photosynthesis and respiration were observed at about two weeks intervals. The results obtained are as follows; (1) Total area of green leaves increases upto the begining of ripening and then decreases because of senescence. (2) Photosynthetic activity (photosynthetic rate per unit area of leaf) of individual leaves of main stem increases with the development of the leaves and after attaining a maximum value, declines with progress of senescence. These processes proceed successively from lower leaves to upper leaves. However, in several upper leaves, senescence occurs simultaneously with advancement of maturation irrespective of the time of formation. The maximum value of photosynthetic activity of each leaf rises with the rise of the position of leaf on the main stem. (3) Photosynthetic activity of the leaves of main stem is higher than that of the leaves of branches. (4) Total photosynthetic capacity of leaves (sum of photosynthetic rate of individual leaves on plant) increases with growth upto the begining of ripening and then decreases. (5) Green pods have somewhat photosynthetic capacity but is small compared to that of the leaves. (6) Green part of stem has photosynthetic capacity, too, but of lower rate than that of pods. (7) Respiratory activity (respiration rate per unit weight of tissue) is highest in leaf, lowest in stem and intermediate in root. Respiratory activity of young pods is very high, but with progress of ripening it declines rapidly. (8) At the first half of the growth period, respiratory capacity (total amount of respiration of each part of plant) is largest in leaves and is relatively small in other parts. At the second half of the growth, both pods and leaves are predominant in respiratory capacity.
  • 玖村 敦彦
    1965 年33 巻4 号 p. 473-481
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    The influence of light intensity on photosynthetic rate of soybean plant population was studied with reference to light receiving aspect of the assimilation system. In this investigation, light condition was limited to the case where the intensity varies only by the change in weather condition. The case where horizontal light intensity varies with the variation in the angle of incidence, was eliminated to simplify the analysis of the problem. Light-photosynthesis relation was observed with the population as well as with single leaves. Light receiving aspect of the assimilation system was investigated by measuring the light intensity on the surface of the individual leaves under various light conditions. Then the photosynthetic response of the population to light intensity was analyzed on the basis of light-photosynthesis relation of single leaves and the light receiving pattern of the whole assimilation system. The results obtained are as follows; (1) The photosynthetic rate of single leaf increases rapidly with the increase in light intensity upto 15 Klx and then more slowly upto 25 Klx. Above this the photosynthetic rate is almost constant or rises only slightly. (2) Also in the photosynthesis of the population, light saturation was observed in general. (3) Under the condition in which the population is not so luxuriant and the spatial arrangement of the leaves is simple, light saturation is brought about by the saturation of individual leaves of whole assimilation system. Under full luxuriant condition, however, light saturation of population photosynthesis is not based on the saturation of individual leaves but on the mode of light receiving in the assimilation system, that is, any increase in the intensity of incident light beyond a certain limit will result only in a corresponding increase in the illumination of the already saturated upper leaves, while the unsaturated lower leaves remain practically unaffected.
  • 伊藤 浩司
    1965 年33 巻4 号 p. 482-486
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    The method of measuring the photosynthesis with detached leaves of sugar beet plant was investigated, and some fundamental problems on measurement of photosynthesis were also examined. The results are summarized as follows. (1) The photosynthesis of leaf blade was not affected by cutting the petiole under the condition of air temperature ranging from 18°C to 28°C and of normal air humidity. (2) In order to maintain the photosynthetic ability of detached leaf as high as before excision, it was necessary to supply water to leaf blade from the cut end of petiole. And it was effective in maintenance of photosynthetic ability for a longer period, to keep the inside of the leaf chamber in high humidity and moderate temperature. (3) The leaf temperature under light intensity of about 40 Klx could be kept at the same level as the air temperature in the leaf chamber, by the placement of a water filter of adequate thickness between the light sourse and chamber. (4) There was a linear relationship between relative photosynthetic intensity and mean CO2 concentration in the leaf chamber. This relationship was represented by the following formula; P=0.482·C-44.5, where P=relative photosynthetic intensity (P=100 at C=300ppm), and C=CO2 concentration in the chamber. (5) The diurnal variation in photosynthetic ability was hardly detected.
  • 伊藤 浩司
    1965 年33 巻4 号 p. 487-491
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    The abilities and some characters in photosynthesis and respiration of single leaf of sugar beet plant were studied with leaves of different positions. The intensity of photosynthesis was measured under a condition of almost constant CO2 concentration of about 300 ppm. The results are summarized as follows. (1) Total photosynthetic and respiratory abilities of top parts of a plant increase at a little lower rate than that of the increment of total leaf area and total dry weight, respectively. (2) Photosynthetic ability per unit leaf area is highest in leaves of middle position, and is lower in leaves of upper and lower positions. On the other hand, respiratory ability per unit leaf dry weight is highest in leaves of upper position, and is lowest in leaves of lower position. As for the photosynthetic ability per leaf, the leaves of middle position have the highest photosynthetic ability because of their large leaf area as well as their high photosynthetic ability per unit leaf area. The respiratory ability in the leaves of middle position is higher than that of any other leaves because of their heavier dry weight. (3) The temperature coefficient (Q10) of respiration is about 1.8 at the temperature ranging from 20°C to 35°C. This value is a little smaller at the temperature ranging from 10°C to 20°C. (4) Photosynthesis is hardly affected by temperature ranging from 10°C to 35°C, which is an ordinary temperature condition in culture field of sugar beet plant. (5) Light response curve of photosynthesis is saturation curve, having a saturation point at the light intensity of about 30 Klx. (6) These characters of leaves mentioned in (3), (4), and (5), are not appreciably different from leaves of different positions and of different growth stages of plant during about five months after sowing.
  • 伊藤 浩司
    1965 年33 巻4 号 p. 492-498
    発行日: 1965/06/15
    公開日: 2008/02/14
    ジャーナル フリー
    The effect of light on the photosynthesis in the community of sugar beet plants was studied from the view point of intensity of light received by the individual leaves of the community. The results obtained are as follows. (1) Light response curves of photosynthesis in community obtained by calculation on the basis of light intensity on the surface of individual leaves and light response curves of photosynthesis of individual leaves, showed the same tendency as those obtained by direct measurement on photosynthesis of community. (2) These light response curves are light saturation curves, having a saturation point at the horizontal light intensity of ca. 40 Klx. The similar fact is seen in the communities of different leaf area indices (LAI) ranging from 0.9 to 5.6. Light receiving coefficient (ρ) under the incident horizontal light intensity where the photosynthesis shows saturation phenomenon, is lower than 1, and the higher the LAI of community, the lower the ρ. (3) When the horizontal light intensity of incident light becomes higher, some leaves in community receive more and more intense light. However, there remain some leaves on which light intensity does not increase, regardless of the increment of incident light intensity. Even though horizontal light inetnsity gets higher than 30 or 40 Klx, the area of leaves that receive light intensity below the saturation point, does not decrease, and their mean light intensity does not increases either. Consequently photosynthetic rates of these leaves remain at low level. On the other hand, accompanying with the increase of incident light intensity, the photo synthetic intensity of another leaves will become higher untill light intensity of these leaves reaches at saturation point of single leaves. These circumstances cause the light saturation phenomenon in photosynthesis in community. (4) The percentage of leaves whose photosynthetic intensity remains at low level, increases as the LAI of community becomes higher, resulting in the lower ρ in the community of larger LAI.
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