日本作物学会紀事
Online ISSN : 1349-0990
Print ISSN : 0011-1848
ISSN-L : 0011-1848
43 巻, 3 号
選択された号の論文の16件中1~16を表示しています
  • 松葉 捷也
    1974 年 43 巻 3 号 p. 325-334
    発行日: 1974年
    公開日: 2008/02/14
    ジャーナル フリー
    In order to make clear the morphological nature of the 'compound 2-flowered' spikelet [Plate 1-1, 2] in Oryza sativa L., the present investigations were carried out from two aspects as follows; 1) Gross morphological ones of the acropetal orders of each bract (glume and lemma) on its own spikelet axis and those of the disposed direction of each bract relative to the primary (or secondary) rachis in the inflorescence. 2) Anatomical ones of the vascular courses of the 'compound 2-flowered' spikelet with two ovaries. As a result of the first investigation, a concept was composed, which is to be called 'isobract'. This concept is defined as a 'set' of the bracts among which each acropetal order is equal on spikelet axis and each disposed direction is equal or bisymmetric relative to primary (or secondary) rachis. For example, in Plate 1-8, there are five isobracts; (rg1, I), (rg2, II), (eg1, III), (eg2, IV), and (1, V) respectively. The palea (p) and the bract VI aren't isobract because of the fact that the former is the bracteole on floret akis. Hence it is considered that the development of the bract VI is caused by the prolification of spikelet primodium and not by the reversion of phylogenetically degenerated bract. As regards this problem, other authers' interpretations arc discussed, particularly those of Parodi (1941) and Schweickerdt et al (1956). In the other side, it became clear from the second investigation that two main vascular bundles of floret axis exist in the stalk of the 'compound 2-flowered' spikelet. One diverges from mother vascular bundle at the axil of the bract V and the other does in the same manner at the axil of the bract VI [Plate 2, vfa and vfa']. The mode of the vascular courses, where each main vascular bundle of floret axis diverges from that of spikelet one (mother vascular bundle), is plainly the same as that of the normal spikelet. These results demonstrate that the stalk of the deformed spikelet consists of three axes; one spikelet axis and two floret ones, the letters independently arise at each axil of the bract V and VI, and have grown together in each dorsal side. Therefore the 'compound 2-flowered' spikelet with two ovaries truly had two florets which has compounded ontogenetically. The hypothesis and Model II (Matuba, 1971) mentioned in previous report are thus confirmed.
  • 松葉 捷也
    1974 年 43 巻 3 号 p. 335-344
    発行日: 1974年
    公開日: 2008/02/14
    ジャーナル フリー
    In the present report, firstly the vascular courses were investigated in both materials, the compound 2-flowered spikelet with one ovary and the double-ovaried spikelet. The one is caused by gibberellin treatment in var. 'Vialone nano' and the another is the typical spikelet of the double-kerneled rice. Secondary the breadthes of the main vascular bundles were compared each to each among three kinds of spikelet in 'Vialone nano'; the compound 2-flowered spikelet with one ovary, another one with two ovaries and the normal spikelet, and also the breadthes of the main vascular bundles of the double-ovaried spikelet were compared with those of the normal spikelet of 'Vialone nano'. The results are as follows. As regards the vascular courses, the, compound 2-flowered spikelet with one ovary is got different in quality from another one with two ovaries. But between both the main vascular bundles of floret axis, the lower one, which diverges from the main vascular bundle of spikelet axis at the axil of the first lemma, is ordinarily smaller than the upper one, which does in like manner at the axil of the second lemma and always connects with the dorsal vascular bundle of the ovary. Likewise as regards the vascular courses except that of pistil, there is no difference between the double-ovaried spikelet and the normal spikelet, and also between each the compound 2-flowered spikelet, which is caused by gibberellin treatment in the double-kerneled rice and 'Vialone nano'. The conclusions to be reached from these results and the previous informations (Matuba, 1973 and 1974) are as follows: 1) The compound 2-flowered spikelet with one ovary too has two florets, the lower one is male or non-sexual at the axil of the first lemma and the upper one is bisexual at the axil of the second lemma. 2) The double-ovaried spikelet has only one floret at the axil of the lemma in spite of the external appearance of multi-ovaries. 3) The number of ovaries is not always correspond to that of florets. In other words, there are two developmental mechanisms under multi-ovaried phenomena. These conclusions are. supported by the measurements of the breadthes of both the main vascular bundles, that of spikelet axis and that of floret one, and are in good accord with the foreknowledges deduced from a hypothesis (Matuba, 1971) shown previously. The hypothesis is thus confirmed.
  • 中野 寛, 前田 英三
    1974 年 43 巻 3 号 p. 345-353
    発行日: 1974年
    公開日: 2008/02/14
    ジャーナル フリー
    The histological structure of compact and friable callus derived from rice seeds was observed. It was ascertained that the development of rice callus is of characteristic as follows. The development of the compact callus is composed of five phases. Phase 1: A clump of meristematic cells is formed. Phase 2: The clump differentiates into inner parenchyma and peripheral meristem. Phase 3: Sub-surface meristem appears along the inside of the peripheral meristem, and then parenchyma originated from the sub-surface meristem occurs far inward. Phase 4: The peripheral meristem turns into peripheral parenchyma. Phase 5: The cells of the sub-surface meristem vacuolate. A mass of the compact callus grows through the clump of meristematic cells occurring on the various positions of the callus. The development of the friable callus is composed of two phases. Phase 1: A clump intermixed with meristematic cells and parenchymatous cells is formed. Phase 2: The clump differentiates into inner parenchyma and peripheral meristem. The clump is either formed by the outgrowth of the sub-surface meristem in the compact callus or by the fragmentation of the peripheral meristem in the friable callus. Tracheary elements associated with cambial cells were observed scatteringly or as a mass in the compact callus, while few tracheary elements were observed in the friable callus. The peripheral region of the compact callus in phases 4 and 5 showed many structures resembling to root primordium. Therefore, the development of the compact callus would be considered as the early process of organization of the adventitious root.
  • 川田 信一郎, 副島 増夫
    1974 年 43 巻 3 号 p. 354-374
    発行日: 1974年
    公開日: 2008/02/14
    ジャーナル フリー
    As designated previously, shoots of rice plants consist of "shoot units", each with an apical leaf basal bud and upper and lower roots zones. And roots of upper shoot units concentrate near the soil surface and produce a net with many branched roots. These are usually called superficial roots. Up to the present, it has been believed that after such superficial root formation during the period from the young panicle formation stage to the heading, rice plants complete the formation of the root system. But as the result of an investigation of the superficial root formation by the authors, it is found that the superficial root formation continues until the full-ripe stage of rice plants. As it is well known, the developmental process of rice plants from the young panicle formation stage to the full-ripe stage is divided into the following stages: the differentiating stage of rachis branch, the spikelet differentiation stage, the reduction division stage, the pollen formation stage, the heading stage, the flowering stage (the fertilization stage), the milk-ripe stage, the dough-ripe stage, the yellow-ripe stage and the full-ripe stage. In the rice cultivar "Mubo-aikoku" grown in wagner pots, it has been clarified that the superficial root system according to progress of such stages is formed as follows : Elongation of primary roots initiated from the ninth shoot unit comes to a stop at the spikelet differentiation stage (Fig. 1). Thick secondary lateral roots and thick tertiary roots appear in the same shoot unit during the period from the spikelet differentiation stage to the flowering stage (Fig. 6 and 7). And fourth, fifth and sixth lateral roots emerge in the milk-ripe stage to elongate until the dough-ripe stage (Fig. 6 and 7). Primary roots initiated in the tenth shoot appear in the spikelet differentiation stage and the elongation ceases at the flowering stage (Fig. 1). Elongation of secondary lateral roots takes place in the milk-ripe stage and tertiary lateral roots begin to emerge at the pollen formation stage. Fourth lateral roots appear in the milk-ripe stage and cease to elongate in the yellow-ripe stage. fifth and Sixth lateral roots emerge in the tenth shoot unit at the yellow-ripe stage and elongate the full-ripe stage (Fig. 6 and 7). In the, eleventh shoot unit, growth of primary roots in length ceases in the dough-ripe stage (Fig. 1 and 3). And secondary lateral roots start to emerge in the reduction division stage. Tertiary lateral roots appear in the flowering stage and fourth lateral roots emerge in the dough-ripe stage. These continue to elongate until the full-ripe stage (Fig. 6 and 7). As to upper primary roots of the twelfth shoot unit, these roots become visible in the reduction division stage and elongate to the dough-ripe stage (Fig. 1). Secondary lateral roots appearing i1] the reduction division stage continue to grow until the full-ripe stage and tertiary lateral roots emerge in the full-heading stage, stopping elonga-tion in the yellow-ripe stage (Fig. 1 and 7). Fourth lateral roots come into sight in the yellow-ripe stage and continue to elongate until the full-ripe stage (Fig. 6 and 7). The superficial roots of all of upper shoot units, in general, show such features as : (1) the period of elongation of thick secondary roots are longer than that of thin secondary roots (Fig. 6), (2) tertiary lateral roots are found in lower primary roots of upper shoot units and fourth, fifth and sixth lateral roots are found in upper primary roots of upper shoot units (Fig. 5 and 6), (3) in tertiary, fourth, fifth and sixth lateral roots of upper primary roots of upper shoot units, two kinds of branched roots are respectively formed, one being thicker in diameter than the other (Fig. [the rest omitted]
  • 池田 勝彦
    1974 年 43 巻 3 号 p. 375-381
    発行日: 1974年
    公開日: 2008/02/14
    ジャーナル フリー
  • 岸 洋
    1974 年 43 巻 3 号 p. 382-388
    発行日: 1974年
    公開日: 2008/02/14
    ジャーナル フリー
    Under the six times harvest in a year, the yearly and seasonal changes of their compositions, orchardgrass, tall fescue and kentucky bluegrass with clover, were compared respectively. The yearly change of the yield of grass component corresponded with the tiller density. The tiller density of orchardgrass had a tendency to decrease year after year, but that of tall fescue and kentucky bluegrass to be maintained. It owes to the different growing characters of grass species. One of the characters was the growing vitality of their upper parts during summer and autumn, and the other was the tillering capability during late autumn to early spring of next year. Tall fescue has a strong growing vitality of its upper parts in summer and autumn, and gets an advantage in competition with clover. As a result, the tiller density of tall fescue in next spring became increased than that of the spring of first year. The tiller density of orchardgrass and kentucky bluegrass with weak growing vitality in summer and autumn were strongly suppressed by competition with clover. Kentucky bluegrass recovered the tiller density during late autumn to early spring of next year than that at the spring of first year, but orchardgrass could not.
  • 川原 治之助, 長南 信雄, 松田 智明
    1974 年 43 巻 3 号 p. 389-401
    発行日: 1974年
    公開日: 2008/02/14
    ジャーナル フリー
    In rice plants, large traces of the panicle or each leaf run down through two internodes and turn into diffuse bundles in the second lower node (figs. l, 2 and 3). The diffuse bundles take oblique course surrounding the swelling elliptical leaf traces, and join with them only at the basal points of the node (○ mark in fig. 2). It may be supposed that assimilates from a leaf go down through the phloem of swelling leaf traces, and rise up through the diffuse bundles via the 〇 mark points by the metabolic activity of their numerous phloem parenchyma (figs. 7 and 10). In the xylem of swelling leaf traces, tracheids, and xylem parenchyma containing xylem transfer cells (figs. 17, 18, 19, 20, 21 and 22), display a mosaic structure (figs, 14, 16, 17 and 18). But, no phloem transfer cell has been found in the vegetative nodes. When the cell wall ingrowth of xylem transfer cells is formed in a vegetative node, the leaf of this node is developing out, and the second upper leaf primordium, about I mm long, begins to elongate, whose leaf traces do not function as conducting tissues yet. In the swelling leaf traces, solutes of transpiration stream are absorbed by the xylem parenchyma, and are raised to the upper internode by two pathways as follows. A part of the solutes moves horizontally into the phloem of the swelling leaf traces, and travels with assimilates. The other part moves horizontally across the bundle sheath and parenchyma bridges lying between the swelling leaf traces and the diffuse bundles (figs. 7, 23 and 24), and travels by the diffuse bundles. This supposition was able to be verified by the distribution in the node of barium absorbed the roots (fig. 25).
  • 佐藤 庚
    1974 年 43 巻 3 号 p. 402-409
    発行日: 1974年
    公開日: 2008/02/14
    ジャーナル フリー
    Rice plants (CV. Norin-17) of vegetative stage (8.2 leaf-stage) were grown in five glass houses the temperature of them were differentially controlled under two photoperiods using natural light; long day (14-h light) and short day (9-h light). The day-night temperatures used were 35-30, 30-25, 25-20, 20-15, and 15-10°C. The plants of each house were sampled when they expanded five new leaves on main-stem (at 13.2 leaf-stage) to compare growth and chemical composition. As the day-temperature was maintained during light period and the night-temperature during dark period, the daily mean-temperature of each plot under long day was respectively 1°C higher than the corresponding plot under short day. 1) It took progressively longer time to reach a definite leaf-stage as the temperature decreased with slower leaf appearance rate. Plant height was highest at 25-20°C, being decreased at higher or lower temperatures. In general, tiller number increased as temperature decreased, although with a somewhat increase at 35-30°C and decrease at 15-10°C under short day. Both plant height and tiller number were greater under long day than under short day. 2) Dry weight of whole plant became greater as temperature decreased except that at 15-10°C under short day. The distribution of dry matter at leaf-blade was higher at higher temperatures, whereas at lower temperatures the roots weight became relatively greater. The dry matter percentage of leaf-blade and specific leaf weight (SLW) increased as temperature decreased, and there was found a minus correlation (r=-0.832**) between SLW and net assimilation rate (NAR). 3) The values of RGR (relative growth rate), RLGR (relative leaf area growth rate) and NAR were higher under long day than under short day. Under long day they were highest at 25-20°C or 30-25°C with a little decrease at 35-30°C and sharp decreases at lower temperatures, while under short day they showed a tendency to increase as temperature increased, except at 35-30°C where NAR decreased a little. Intimate correlations were found between RGR and RLGR, RGR and NAR with the correlation coefficients of 0.996*** and 0.924***, respectively. RLGR was strongly correlated with mean leaf appearance rate (r=0.982***). 4) Nitrogen concentration of shoots changed little by temperature treatments, but was higher under short day than under long day. Other elements, in general, decreased their concentrations at intermediate temperatures. The concentrations of total elements estimated tended to decrease with decrease of temperature. The total amounts of elements accumulated in the shoots paralleled dry matter accumulation. However, at higher temperatures Si, K, Ca + Mg, Mn, Fe, P, and S accumulated relatively more as com-pared with the accumulation of dry matter, and N and S accumulated relatively more at lower temperatures. K/N ratio increased but Mn/Fe ratio decreased with increase of temperature. 5) At leaf-blades, N concentration increased with decrease of temperature and under short day. At other organs the similar tendencies were found under short day, but under long day the concentrations were lower at intermediate temperatures. Non-protein soluble-N also increased with decrease of temperature at all plant parts, although with a little high value at 35-30°. TAC (total sugar + crude starch) concentration tended to increase with decrease of temperature. It was noticed that the dead leaf at low temperature had rather high nitrogen and TAC concentrations. C/N ratio (C:TAC, N: total-N) of whole plant increased under long day and with decrease of temperature.
  • 佐藤 庚
    1974 年 43 巻 3 号 p. 410-415
    発行日: 1974年
    公開日: 2008/02/14
    ジャーナル フリー
    The effects of air- and soil-temperature, regulated separately, upon transIocation and distribution of 14C photosynthate in rice plant were studied. Norin-17 which is a japonica variety adapted to Tohoku district was used at its vegetative growth stage. Higher air-temperature increased the percentage of <14>C assimilates translocated fronl (the fed) leaf-blades, but the effect was not so evident. Relatively more assimilates were translocated and recovered at unexpanded young leaves at higher air-temperatures, but at lower air-temperatures they were distributed more at leaf-sheath, stem and roots, parts of them being stored there as sugars and starch. In general, high soil-temperature showed a tendency to stimulate the distribution of 14C in roots. It was concluded that higher T/R and LB/TOP ratios generally induced under higher air-temperatures were related to faster translocation and greater distribution of assimilates at unexpanded yollng leaves which behaved as a strong "sink" under these conditions.
  • 佐藤 庚
    1974 年 43 巻 3 号 p. 416-424
    発行日: 1974年
    公開日: 2008/02/14
    ジャーナル フリー
    Two kinds of experiments (A- and B-plots) were carried out using a single clone of orchardgrass to trace the effects of photoperiod and temperature before or after cutting on the subsequent regrowth processes. A-plot: The plants were grown for two weeks at four growth chambers (day-night temperatures; 30-25, 24-19, 17-12, and 9-9°C) and were cut at the end of the treatment, then were moved to outdoors in May and to glasshouse in October under natural day-light. The former is called spring experiment (LD) and the latter fall experiment (SD). B-plot: All the plants having been grown outdoors were cut and moved to the above four growth chambers to trace regrowth at different temperatures. It also consisted of LD- and SD-experiments, both being begun in June and October, respectively. 1) The plants under LD of both A- and B-plots all headed at the cutting date, whereas no heading occurred under SD. This difference in development between LD and SD may have induced fegrowth difference in various ways. 2) In A-plot, the growth at cutting date was best at 24-19°(LD) and 17-12°(SD), respectively. Under LD, early regrowth in leaf area was greatest at 17-12°, smallest at 30-25°, while under SD it was smallest at 9-9°and no significant difference existed among the rest three temperatures. The subsequent regrowth for three weeks was 17-12 > 24-19 > 9-9 > 30-25°under LD and 17-12 > 24-19 > 30-25 > 9-9°under SD in order. These ranks coincided with those of leaf area formation which was regulated by tiller number. Under LD, strong correlations were found between early leaf regrowth and nitrogen or TAC or both contents in stubble and roots at cutting time, but no significant correlation was found under SD. 3) In B-plot, early regrowth was greater at higher temperatures, but later regrowth became greater at lower temperatures and greatest at 17-12°then at 24-19°. 4) RGR from one week to three weeks after cutting had a keen correlation with NAR (r=0.935***) and an weaker correlation with RLGR (r=0.751***) during the same period. 5) The fact that the best regrowth was obtained at 17-12°followed by 24-19°in both plots under both day-lengths with abundant accumulation of nitrogen and TAC in cut herbage. stubble and roots may indicate these temperature range (mean temperature of 15°or a little higher) be optimum for forage production.
  • 長南 信雄, 川原 治之助, 松田 智明
    1974 年 43 巻 3 号 p. 425-432
    発行日: 1974年
    公開日: 2008/02/14
    ジャーナル フリー
    In the leaf blades, sheaths and internodes of rice plants, the large and small vascular bundles are arranged longitudinally. When the longitudinal vascular bundles of the leaf blades are traced backward into the culm, the large vascular bundles extend downward through the leaf sheath and two internodes. The small vascular bundles, which are located in the middle between large vascular bundles of leaf blade, extend downward through the leaf sheath and one internode, and the other small vascular bundles end blindly at the base of leaf blade. In the leaf blades and sheaths, the longitudinal vascular bundles are laterally interconnected by the transverse veins. The transverse veins have the most simple composition of the vascular element, that is, a sieve tube, a vessel, and only two files of vascular parenchyma cells. In the leaf blades at lower levels of shoot, the small vascular bundle is surrounded by a single layer of parenchymatous sheath cells with dense chloroplasts. However, in the leaf blades at higher levels of shoot, the small vascular bundle is surrounded by two layers of sheath cells. The outer layer is consisted of parenchymatous sheath cells with small numbers of chloroplasts, and the inner layer is consisted of mestome sheath cells with thickened walls. The mestome sheath of the large vascular bundle is more developed than that of the small vascular bundle. The vascular bundles of the leaf sheaths and internodes have more companion cells and larger sieve tubes and vessels than those of the leaf blades. On this histological observations, the functional significance of the vascular bundles in rice plants is discussed.
  • 篠原 俊清, 山本 義忠, 北野 沖, 福田 三千夫
    1974 年 43 巻 3 号 p. 433-438
    発行日: 1974年
    公開日: 2008/02/14
    ジャーナル フリー
  • 井上 和雄, 山本 良三
    1974 年 43 巻 3 号 p. 439-444
    発行日: 1974年
    公開日: 2008/02/14
    ジャーナル フリー
    テンサイ種球中には生長阻害物質が含まれており, 発芽時において発芽および実生の生長を阻害するが, 種球を水で洗うことによって容易にその生長阻害物質を除くことができる. しかしその生長阻害物質については多くの報告があるけれども, それぞれの意見は一致していない. そこで本研究は実生の根の生長を阻害する物質を明らかにするために行なわれた. 1) テンサイ種球の水抽出液は根の生長を阻害し根端を黒変させた. この抽出液ははい軸に対して生長阻害を示さなかったが, 希釈した時にはかえってはい軸の生長を促進させた. 2) 水抽出液からエタノール-氷酢酸-水(8:2:5v/v)を展開剤としたぺーパークロマトグラフィーにより阻害物質を分離した. 根の生長の阻害効果はRF 0.47からRF 0.95の部分でみられ, 最も著しい部分は RF 0.47からRF 0.55であった. またはい軸の生長促進効果は RF 0.55からRF 0.73の部分でみられ, 最も著しい部分は RF 0.55からRF 0.62であった. RF 0.47からRF 0.55の部分からの水溶出液をアセトンで可溶部と沈殿部に分け, 阻害効果のある沈殿部から無色透明の斜方状の結品を得た. この結品は酸性塩であることが確認され, その赤外線吸収スペクトルがシュウ酸一ナトリウムのそれと一致した. したがってテンサイ種球中の主要な阻害物質はこれまでシュウ酸塩として存在していると報告されていたが, その塩はシュウ酸一ナトリウムであることが明らかにされた. シュウ酸一ナトリウムは水抽出液中に根の生長を阻害するのに充分量存在しており, その阻害は水抽出液と同様に根を黒変させる. しかしはい軸の促進効果はもっていなかった. 3) ぺーパークロマトダラムから阻害効果をもつ他の部分に種々のフェノール化合物の存在が確認されたが量的に主要な生長阻害物質ではないと考えられる.
  • 武岡 洋治, 清水 正治
    1974 年 43 巻 3 号 p. 445-452
    発行日: 1974年
    公開日: 2008/02/14
    ジャーナル フリー
    This experiment was carried out to make clear whether the apical meristems in the proliferated spikelet primordia of the mutant strain induced by X-ray irradiation were different or not in size and organization with those of normal ones at the differentiation stage of stamen primordia, and whether, the vascularization of "spikelet-like organ" was the same or not as normal spikelets. The apical meristems of young proliferated spikelets, differentiating glumes or spikelet-like organ(s) successively, indicated larger values both in height and bottom dianmeter, especially in height, than those of normal ones, and the ratio of height to diameter (H/D ratio), therefore, were larger in the proliferated spikelets than in normal ones. The structure of the apical meristems in the proliferated spikelets had considerably definite organization composed of initial cell(s), rib meristem and peripheral meristem, though the smaller apical meristems (diameter: below 50 μ, H/D ratio: below 0.5) had one layer of tunica and indefinitely organized corpus. These shoot apices had a tendency to elongate remarkably, differentiating some organ primordia at the subapical region of them. The differentiation and connection of provascular bundles in the spikelet-like organ was confirmed to be the same as the normal spikelets histogenetically. Judging from the facts that the proliferated spikelets have larger and more protuberant apical meristems and successively differentiate spikelet(s) or glumes, it is evident that the shoot apices of the proliferated spikelets have prominent mitotic activity, especially in corpus, and continue the vegetative growth which differentiate branches or leafy organs, retarding the transition into the reproductive stage. The phenomenon which one or more spikelet primordia are differentiated in a spikelet is considered to indicate that the apical meristem of the proliferated spikelet has regained the morphogenetic character of previously passed developmental stage, and a rejuvenation or a kind of de-differentiation has occurred in the shoot apex of it. If we can make progress the physiological and genetical studies on the development of these proliferated spikelets, we might be able to contribute to clarify the mechanism of morphogenesis of normal spikelets, especially that of the transition from vegetative growth into the reproductive one, sporogenesis in rice plant.
  • 福山 正隆, 武田 友四郎, 前田 均
    1974 年 43 巻 3 号 p. 453-461
    発行日: 1974年
    公開日: 2008/02/14
    ジャーナル フリー
    In this study, three experiments were conducted to make clear whether or not the expansion of leaf area is closely related to photorespiration in C3-plant, and the effect of oxygen concentration on the growth of C4-plant. Materials used were two row barley (Hordeum vulgare) in C3-plant, and vasey gass (Paspalum urvillei) and sorghum (Sorghum vulgare) in C4-plant. Exp. I. Seedlings of vasey grass and sorghum were grown for 5 days in specially devised growth chamber which is equipped with water culture facilities, under 2.5% O2-0.03% CO2 and 210% O2-0.03% CO2, and light intensity of 45 Klx at 25°C leaf temperature under a regime of 10 hr light and 14 hr darkness. Exp. II. Seedlings of two row barley were cultured under 2.5, 5, 10 and 21% O2(control) at 20°C leaf temperature. And other experimental procedures were followed to Exp. I. Exp. III. Seedlings of two row barley were grown under 21% O2 in light and 2.5% O2 in darkness (treatment A), and the reverse condition (treatment B). The experimental results obtained are summarized as follows: 1. No major differences in dry rnatter production (ΔW and RGR) and NAR were found between the plants grown under 2.5% O2 and 21% O2 in both vasey grass and sorghum. These results corresponded roughly to the phenomenon that C4-plant lacks an apparent enhancement of CO2 uptake by low oxygen concentration below normal air. Expansion of leaf area (ΔLeaf area, RLGR), however, decreased at low oxygen concentration in both species, especially in sorghum, as well as C3-plants. 2. In Exp. II, the greatest NAR of two row barley was found at 2.5% O2, but NAR at 10% O2 was still greater than one at 21% O2. It is suggested that the photorespiration is tolerably suppressed even at 10% O2. On the other hand, RLGR rand ΔLeaf area decreased at 2.5% O2 and 5% O2, but at 10% O2 they did not decrease as compared with control. It call be deduced that at O2 concentration below 10%, expansion of leaf area is influenced and above 10%, it is independent to oxygen concentration. 3. In Exp. III, ΔW and RGR increased extemely in treatment B as compared with treatment A. On the other hand, no major differences in ΔLeaf area and RLGR were found between both treatments. 4. As for the question of whether or not expansion of leaf area is closely related to photorespiration in C3-plant, the answer may be given as follows. In wheat, rice plant (preceeding report5)) and two row barley (Exp. II.), suppression of photorespiration and expansion of leaf area occurred together under low concentration (2.5% O2). Whereas, even in C4-plants possessing no apparent photorespiration, expansion of leaf area was reduced under low oxygen concentration (2.5% O2). Furthermore, in two row barley in Exp. II, photorespiration was considerably suppressed even at 10% O2, but expansion of leaf area did not decrease at this concentration. In addition to these results, as seen in Exp. III, there were no major differences in the effect of low oxygen concentration on expansion of leaf area under between light and darkness. From the results mentioned above, it can be concluded that there exists no direct causal-relationship between photorespiration and expansion of leaf area in C3-plant.
  • 原田 二郎, 中山 治彦
    1974 年 43 巻 3 号 p. 462-464
    発行日: 1974年
    公開日: 2008/02/14
    ジャーナル フリー
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