前報において,摘心による生長部(sink)の除去が,葉のタンパク分解および葉からのチッソの流出をともに抑制する事実を明らかにしたが,このことは,葉の全タンパグ質のターンオーバーが,sinkの大きさによって規制されているという可能性を示している. そこで本実験では,大豆の各本葉について,葉面の1/3,1/2,2/3を段階的に除去し, sink(生長部)とsource(成熟葉)の比率を異にする材料を用いて,sinkの相対的な大きさと,葉のタンバク質のターンオーバーの関係を調査した. 各摘葉区の植物にまず24時間¹⁵Nをパルス供与し,葉のタンパクおよび全チッソ部分にとりこまれた¹⁵Nの,その後の変化を8日間追跡調査して次の結果をえた. 成熟葉では,摘葉の程度が増加するにしたがい,葉のタンパク分解速度も増大した. 言いかえれば,一定葉量に対してsinkが相対的に増大すると,葉のタンバク分解は急速となる. したがってsinkの大きさは,葉のタンパクのターンオーバーをかなり規制するものと思われる. また摘葉処理は,その程度に応じて,葉からのチッソの転流速度をも増加せしめた. sinkとしての生長部分には,いったん成熟葉その他の器官にとりこまれた¹⁵Nが,再分布の過程を通じて配分され,かなりの量に達したが,処理区間に大きな差は認められなかった. なお摘葉処理の2次的影響として,各摘葉区の葉のタンパク態チッソ含量が著しく増加したが, このことは,摘葉区の成熟葉において,タンパクの分解のみならず,合成も増加したことを示すもので,大豆の葉のチッソ代謝機能を考えるうえで,注目すべきことのように思われる.

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稲属5種12系統を用いて自然日長区および短日処理100区を設け,80日齢と85日齢に達した時,11.0,11.5,12.0,12.5および13.0時間明期の短日処理を開始した. 処理期間中に種々の程度の自然日長条件を挿入した. これにより苗齢・日長・短日条件累積効果の組合せ結果に関して調査を行った. 反応に従ってまず8群に分類された. 同一系統内である明期にのみ感応が認められる進行現象が10例,ある明期にのみ感応が認められなくなる退行現象が6例みられた. 前者は11.0明期にのみ,後者は13.0明期にのみ認められた. 両者の発現にある程度の種特異性が認められ,前報の結果を考え合せると,これらの現象は稲属に安定した形質とみなし得るものと思われる. 苗齢効果がかなり確認され,またある明期において特異的に"明確化"または"鈍化"する現象がみられた.

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本研究はグレインソルガムH-726について,発育の様相と植物体各部の発育の相互関係を明らかにしようとして行った. ガラス室内のワグネルポットに1977年7月21日に播種して,出穂期は各葉出葉期ごとに,出穂後は1週間ごとに7週間後まで採集した. 出葉の間隔は止葉出葉前はおよそ3日,止葉出葉期から出穂期(9月7日)までは7日ほどであった. 結果は次のとおりである. 1. 幼穂は11葉出葉期にすでに分化しており,出穂期に全長の86%まで伸長していたが,花柄は36%しか伸長していなかった. しかし花柄は出穂期以後急速に伸長して止葉葉鞘から抽出し,両者は同時に最高値に達した. 穂,花柄の長さおよび草丈は出穂後2週間で最高値になった. 2. 上位葉の葉鞘,葉身の長さと葉身幅は出穂後1週間で最高値になった. また葉身の長さと幅は各葉とも同時に最高値になった. 同一葉では葉鞘は葉身よりおくれて伸長しはじめ,下位の葉ではおよそ1葉期おくれて最高値になったが,上位の葉では葉鞘の生長速度が早くなり葉身と同時に最高値になった. 3. 最高値に達するのに上位葉は下位葉より長時間を要した. また生育の初期より後期の方が同時に伸長しつづけている葉数が多かった. 4. 節間の伸長は葉身や葉鞘よりおくれて始まり,上位のものは出穂後2週間で最高値に達した. 5. 節間の伸長が始まると間もなく節間部に根が分化し,節間の長さが最高値になると節間の基部から伸長を始めるという相互関係のあることが明らかになった. 本実験では伸長した根は第7節部までで,第8節部の根は原基のままでとどまった.

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供試した10品種の中で6品種は光周期に不感応で,2品種は弱い感光性があり,2品種は強く反応した. これらの10品種はすべて西アフリカの主要な作期および二期作において使用されている. 強感光性品種を二期作において早く植えると,日長が長くなることによる過剰生長から回避できる. 西アフリカにおいては,感光性品種も非感光性品種も両作期において長日による遅延なしに作付可能である. 二期作における一般的な開花遅延はむしろ低温に起因するようにみえる.

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For a reasonable understanding of the difference of weed ecological distribution caused by soil moisture conditions in non-cultivated paddy fields, a growth analysis experiment was carried out on several Gramineous summer species under three different soil moisture levels. Soil moisture treatments were started at the early growth stage of plants with five to seven leaves, by means of keeping the soil submerged under water, wet, and dry conditions. The wet and dry conditions of the soil were controlled by means of constant capillary tention method. Results obtained are as follows: 1. It was found that each of the species in this experiment exhibited a tendency to flourish better in an optimum soil moisture, required for their growth. They were grouped under three categories according to their growth response to the different soil moisture conditions. Some species showed the tendency of declining relative growth rate (RGR) as the soil moisture decreased (type-I), whereas some other species showed the highest RGR under wet conditions (type-II) and the remaining species scarcely reduced the RGR even under drought conditions (type-III). 2. Change in the two growth parameters, the net assimilation rate (NAR) and the leaf-area ratio (LAR), depending on soil moisture conditions were different for each of the three types. LAR of the species in type-III and NAR of the species in type-II were more affected by soil moisture conditions in these two types, whereas type-I species were little affected by soil moisture conditions in both the parameters. 3. Comparing the growth response to soil moisture of C₃ with C₄ plants, the results showed that C₄ species had a tendcncy of higher RGR and LAR under relatively dry conditions, while C₃ species grew better under relatively wet conditions. 4. Results showed that the ecological distribution of the weeds in non-cultivated paddy fields, as for their growth response was concerned, seemed to be attributed to the soil moisture.

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Using the new color chart which was developed based on the colorimetrical characteristics of actual leaves in rice plants, the authors investigated the usefulness of the leaf color diagnosis and the possibility estimating the number of spikelets per squarc meter by leaf color. Following results were obtained: 1. The newly developed color chart was easier to judge the leaf color grade (greenness) than the chart which was made of embroidery thread, because the new one had greater size in greenish parts (4 × 8 cm) and the equally plotted scale with reference to the lightness as compared with the old chart. 2. Observation values of leaf color highly correlated with the nitrogen content (%) in leaf blade of rice plants, and the percentage of the length of leaf sheaths stained by iodide solution to the whole length of them, which represented the degree of starch accumulation in these organs, showed highly negativc correlation to the nitrogen content (%) in leaf blade. Moreover, the ratio of thc observed values of leaf color to the percentage of stained length of leaf sheath showed higher correlation to the nitrogen content in leaf blade, compared with the case applying the two characteristics, the leaf color or the percentage of stained length of leaf sheath, individually. 3. High correlation existed between the number of spikelets per square meter and the product of the observed values of leaf color and the number of tillers at the stage of leaf number index, about 90. Accordingly, it was confirmed that the number of spikelets per square meter was able to be estimated based on the observed values of leaf color and the number of tillers per square meter. 4. The results mentioned above (in Tanashi) were also recognized in the experiments carried on at Fukuoka, Miyagi, Shiga and Toyama prefectural agricultural experlment station.

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グレインソルガムH-726について,短期間の水分不足をうけた植物の生育収量が優れ,蛋白含量も多くなるのは植物体内のオーキシン含量が増加したためではないか,また生育期間に何回も土壌乾燥が繰返された場合の影響はどうか,について明らかにするため,1978年と1979年に名大農学部附属農場で実験を行った. 結果は次のとおりである. 1. 生育の初期における1回の短期間の土壌乾燥や茎の伸長期における1回の一時萎凋で,生育収量が無処理区より優れ蛋白含量も多かったが,このような植物の水分不足を生育期間中に何回か繰返すと,反対の結果が得られ生育収量が減じた. 2. 生長ホルモンの葉面散布で根は,原基のままとどまるものも伸艮するものも無処理区より数が増加した. これに反し植物にX線を照射してオーキシンの一部を分解した場合には根数が減少した. 3. 生育初期における1回の短期間の土壌乾燥と茎の伸長期の一時萎凋がオーキシンの葉面散布とほぼ同様の影響を与えたので,短期間の土壌乾燥で植物体のオーキシンレベルが高まり,植物の生育を促がしたのも原因のひとつと思われる. 4. 本実験では植物体で生成されるオーキシンであるIAAと合成されたNAAとは同じ反応を示した. 5. 前報で水耕液の窒素濃度が低い17.5PPmより高い44PPmの場合に最高の穀実収量が得られた. それゆえ,穀実収量が増大するのはただ単にホルモンレベルがあがっただけではなく,土壌水の窒素濃度が乾燥期間に高まることも原因していると考えられる.

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In order to determine the abscisic acid relationships in the resistance of the rice plants to ozone, endogeneous abscisic acid content in varieties with different sensitibity to ozone was examined. 1. The cultivars differed in their visible injury to ozone fumigation. Nipponbare and Jinheung were more sensitive than Tongil, Milyang No. 23 and Te-tep. 2. Endogeneous abscisic acid content in the resistant variety (Tongil) was higher than in the sensitive one (Nipponbare). 3. Visible injury caused by ozone fumigation was decreased by application of abscisic acid. 4. Abscisic acid content in rice cultivars was found to increase differently depending on varieties response to ozone fumigation (0.3 ppm for 3 hours). The increase of abscisic acid content caused by ozone fumigation was higher in Nipponbare than in Tongil, although the endogeneous level of abscisic acid was higher in Tongil than Nipponbare.

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馬鈴薯塊茎を収穫後約5か月間,3℃暗所に貯蔵し,その頂芽部より採取した円筒状組織をCEPAで処理し,7日間,29℃の暗黒下で通気状態のもとにおいた. その結果,CEPA処理は萌芽を抑制し,その抑制の程度はCEPAの濃度に比例した. CEPA1.0mg区では,処理7日後でも萌芽がみられなかった. 一方,処理によって組織のエチレン放出量は短時間内に急増し,24時間後にピークに達し,その後も高レベルを保った. この放出量のピーク時に組織の遊離オーキシン活性の低下がみられたが,これはCEPA由来のエチレンによるもので,これが萌芽の伸長抑制の一因と考えられる. 他方,カイネチンで前処理するとその後のCEPA処理による萌芽の抑制とオーキシン活性の低下はみられなかった. この事実は,サイトカイニジは遊離オーキシン活性の維持を介して萌芽の伸長に作用しているものと解される.

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Using the 5 varieties grown on the field with sufficient nitrogen fertilizer as the basal dressing, we investigated the effect of nitrogen topdressing and foliar application of urea at full heading time on the translocation of nitrogen from the leaves and culms to the ears and the protein content of brown rice. 1. The amount of dry matter production increased 40% by topdressing and 36% by foliar application compared with non-topdressing on the average of 5 varieties. Most of the dry matter produced after full heading time was used for the increase of ear weight and a part of it was used for the increase of culm weight. The weight of leaves and leaf sheaths at harvest time was less than that of full heading time due to the translocation of dry matter, but the weight decrease of leaves and leaf sheaths, especially the former, was suppressed by topdressing of nitrogen and foliar application of urea. 2. The recovery rates of nitrogen applied at full heading time were 53∼73% on the topdressing plots and 74∼84% on the foliar application plots. The recovery rates of nitrogen on the foliar application plots were higher than those of the topdressing plots. 3. The distribution ratio of nitrogen to ears was about 50% of the nitrogen recovered on the topdressing plots and about 60% of the nitrogen recovered on the foliar application plots. 4. On the non-topdressing plots, 31∼38% of the nitrogen contained in the ears at harvest time was translocated from the leaf blades and 6∼10% from the leaf sheaths, and the nitrogen amount absorbed from the soil was 34∼49%. The translocation of nitrogen from the culms to the ears was little. On the topdressing plots, 9∼17% of the nitrogen of the ears at harvest time was translocated from the leaf blades and little or nothing from the leaf sheaths or the culms, and the nitrogen absorbed from the soil was 68∼76%. On the foliar application plots, the translocation of nitrogen from the other organs and the soil to the ears showed almost the same tendency as the topdressing plots. 5. The protein content of brown rice increased 23% by nitrogen topdressing and 48% by foliar application of urea at full heading tinle on the average of 5 varieties compared with the non-topdressing plots. The foliar application of urea was more effective than the nitrogen topdressing on the increase of protein of brown rice when the same amount of nitrogen was applied.

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The structure and distribution of globoids in protein bodies have been examined with light microscope as well as electron microscope. The size and frequency of globoids in aleurone and scutellar tissues, and total phosphorus content in embryos and endosperms indicated that the seeds could be divided into two distinct types. In the first type, a largc proportion of phosphorus was confined to the aleurone layer, although the scutellum as well as the aleurone layer were rich in phosphorus. In the second type, both the amount and the content of phosphorus in the scutellum were more as compared to the aleurone layer. The former type was found in the seeds of barley, oat, orchardgrass, rice, rye and wheat, and the latter was present in the seeds of barnyard millet, common millet, finger millet, Italian millet, Job's tear, maize, pearl millet and sorghum.

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腹白米を最も生じやすい米粒の発育時期を明らかにするために,登熟各期の稲体に暗黒処理と強風処理を行なった. 暗黒処理は暗室にポットを搬入し,4日間行なった. 強風処理は,風洞を用いて風速10 m/sの風を2時間穂部にあてて行なった. 出穂後25日目の材料には風速5,15m/sも併用した. 1. 出穂後16-20日目,20-24日目,24-28日目,28-32日目の暗黒処理は腹白米の発現を高め,とくに出穂後20-24日目の処理ではこの割合が著しく,無処理区の3.8倍であった. 出穂後20日目の米粒(上部枝梗強勢粒)はその乾物重が80%(最大乾物重に対する割合)に到達した発育時期であった. 2. 暗黒処理は,処理期間中の粒重増加量を低下させた. この低下割合は出穂後20-24日目の処理で最も大きかった. 3. 出穂後25日目,30日目の強風処理は腹白米の発現を高め,とくに出穂後30日目の処理では顕著であり,無処理区の3.8倍であった. 出穂後30日目の米粒(上部枝梗強勢粒)は25%の含水率を示した. 4. 強風処理後5日間の米粒含水率の低下量は,無処理区に比較して大きかった. この低下量は出穂後25日目,30日目の処理で非常に大きかった. 5. 強風処理は籾殻から,水分の放出を促進した. この放出割合は籾殻の含水率が38%以下になると,著しく増大した. 6. 風速を変え強風処理を行なった. 腹白米の発現率は風速が増すとともに高まった. また,処理後5日目の米粒および籾殻の含水率は,風速が増すほど低かった.

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Diurnal variations in CO₂ exchange of rape plants were observed over 2-4 successive day at about two-week's intervals from their early growth to full maturity. The measurement of CO₂ exchange was conducted using an assimilation chamber in which conditions were regulated as similar as possible to those of the outside. Principal environmental factors, i.e., total solar radiation, diffused solar radiation, air temperature, soil temperature, air humidity and CO₂ concentration of air were recorded simultaneously writh CO₂ exchange. From the data obtained, dependence of the CO₂ exchange rate on the environmental factors was examined. In addition, the after-effects of low night temperature on daytime photosynthesis, the existence of which had been suggested by the result of field observations, were examined under controlled conditions. The results obtained are summarized as follows: 1. The photosynthetic rate depended primarily on total solar radiation throughout daytime on all the days when observations were conducted. 2. Based on the mode of correspondence between the photosynthetic rate and total solar radiation at each time of a day, patterns for diurnal variations in photosynthesis were grouped into the following two types. Type A: In this type, photosynthetic rates in the morning were nearly equal to those in the afternoon provided they were compared at equivalent solar radiation levels. Type B: In this type, photosynthetic rates in the morning were lower than those in the afternoon even compared at equivalent solar radiation levels. 3. The pattern of Type A was observed on cloudy days, or on fine days whose preccding night was not so cold or warm. The pattern of Type B was observed on fine days preceded by a very cold night. 4. Type B predominated in winter while Type A prevailed in other seasons. 5. The dark respiration rate at night varied mainly with air temperature at each stage of growth. 6. It was confirmed in the experiment under controlled conditions that the photosythetic rate in the daytime was affected by the air temperature of the preceding night. Night temperatures below a certain limit brought about depression of photosynthesis during the succeeding daytime. The lower the night temperature, the lager the extent of depression and the longer time required to recover from the depression.

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Differences between locations in potato root system were studied with four varieties. Climatic conditions in two locations were almost same, though soil types were different: Soil of Sapporo and Shimamatsu were alluvial clay loam and volcanic ash sandy loam, respectively. Root dry weight of surface soil (depth to 30 cm), leaf area and tuber dry weight were measured biweekly during the growing season. Growth rate, duration of increase, maximum value and duration of root DW and LAI were calculated from quadratic regression curves fitted to raw data. Maximum values in root DW and LAI were greater in Sapporo than in Shimamatsu. Two values showed highly significant correlation (r=0.951). Diffcrences were also found in morphological characteristics of root and shoot. Root diameter, stem diameter and stem length were significantly greater in Sapporo. Number of root per stem, however, were greater in Shimamatsu. Differences in maximum root dry weight between locations were based on root growth rate in early varieties, and on root growth rate and duration of root increase in late varieties. On the other hand, differences in maximum LAI were attributable not to growth rate but to duration of leaf increase which was longer than duration of root increase. Greater maximum root dry weight in Sapporo delayed leaf senescence, and root dry weight duration during tuber bulking period was coerrelated with leaf area duration. Greater root dry weight duration and leaf area duration in Sapporo did not increase tuber bulking rate, but prolonged duration of tuber bulking and increased tuber yield. If root system increases rapidly or longer, then leaf growth also continues longer, thus leaf senescence might be delayed. It should result in long maintenance of tuber bulking and increase of tuber yield.

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