帯化ダイズ7系統を九州大学農学部の圃場で栽培し, 形態的特性と若干の生育特性並びに収量構成形質を調査した. 1. 帯化ダイズは, 生育初期から主茎上にしばしば2葉以上の葉を同時に出葉することが認められた. 主茎は生育とともに徐々に幅広く, 扁平となった. 帯化ダイズの主茎の葉数は普通ダイズよりかなり増大した. 2. 供試7系統における帯化ダイズの主茎の扁平度(帯化程度)には, 大きな系統内および系統間変異が認められた. また帯化ダイズにも分枝の発生がみられたが, 分枝数は普通ダイズより少なく, しかも扁平のものは少なく普通型であった. 帯化程度と分枝の多少とは, 無関係であった. 3. 今回調査した帯化ダイズには, 主茎先端の形状により, 無分岐, 2つに分岐, 3つ以上に分岐の3つの型を認めたが, 最も冬い型は無分岐型であった. 4. 帯化ダイズは着莢様相から, 次の2つの型に類別出来た. I型:莢の大部分(全莢の70%以上)が主茎先端部に密集して着生する型 - 鶏頭大豆, 錫杖(Bb1132), 錫杖(Bb1133), 刈交259. II型:莢の約半数が主茎先端部に着生するが, 中下部にも着生をみる型 - Acc.1369, Acc.1403, T173. 5. 主茎の帯化程度と収量とは関係がないようであった.

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Some experiments on transpiration and water absorption were conducted to determine the different rooting ability of millets at the time of transplanting from the viewpoint of water balance in the plant. This report also contains work on the effect of seedling quality on rooting. These experiments were done during the period from 1978 to 1981. The results obtained were as follows: 1. Transpiration rate per leaf arca was the highest in Japanese barnyard millet and the lowest in sorghum under the condition of water culture. Among the seedlings from the nursery bed filled with volcanic soil, however, Italian millet showed the highest transpiration, and the low values were seen in common millet and Japanese barnyard millet (Table 1). 2. The reason why Italian millet was subject to losing water balance in the plant at transplanting time, compared with finger millet were as follows: (1) Water content of the plant organs was lower in Italian millet and its transpiration rate was higher. This might be due to the higher stomata density per leaf area. (2) Top/Root ratio of Italian millet is extremely high and it becomes still higher by unavoidable cutting of roots at the time of transplanting. This results in a considerable decrease in water absorption by roots, although Italian millet has high water absorption rate and high level of bleeding water per root dry matter weight. This decrease in water absorption compared to a higher transpiration rate of leaves may result in losing water balance in Italian millet. On the other hand, finger millet had lower water absorption and also lower bleeding water level per root dry matter weight. But this crop had a high water content in its plant organs and a lower ratio of Top/Root. Therefore, the water balance can be kept in the plant. In the case of sorghum, ablility of water absorption and bleeding was low and the water balance in the plant may be kept with lower water contents because of its lower transpiration rate due to fewer stomata per leaf area. Japanese barnyard millet and common millet showed a similar tendency to finger millet and Italian millet, respectively (Table 2 and 3, Figs. 4-5). 3. To understand the effect of seedling quality on taking root, the rooting ability of seedlings grown at different fertilizer levels was investigated. New roots were more numerous in the seedlings of the standard fertilizer plot than the non-fertilizer application plot. The longest root was found in the seedling of the non-fertilizer plot. In the high fertilizer plot, only finger millet could produce more roots. Two weeks after transplanting, plants from the standard level plot showed greater growth, whereas common millet, Japanese barnyard millet and Italian millet displayed less growth at a higher level of fertilizer than the standard level (Table 4 and 5). From the above results, the higher Top/Root ratio is likely to cause taking root to fail at transplanting mainly due to damage of roots by pulling seedlings from the nursery bed, and the resultant decrease of water absorption by roots and loss of water balance in the plant can be seen. Therefore, especially the direct sowing type plants such as Italian millet and common millet are not suitable for transplanting. As to the effect of seeding quality on taking root, the seedings grown at the standard fertilizer levels generally showed good growth with many newly-emerged roots. But with a higher fertilizer level, all the millets except finger millet could not attain desirable growth.

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The unusually cool summer of 1980 caused the severe sterility of rice plant grown in Tohoku District (the northeastern part of Honshu), due to the low temperature at the booting stage. Although the maximum and minimum temperatures were essentially similar between Takizawa on the Pacific Ocean side and Kuroishi on the Japan Sea side (Table 1), the sunshine duration during the booting stage at Takizawa was much shorter than that at Kuroishi, due to topographical characteristics. Spikelet sterility of rice plants at the former was much higher than that at the latter, suggesting the decisive role of the sunshine duration on the microclimate of a rice canopy. A simulation model for the prediction of canopy climate (Fig 1) proposed by INouE was applied to elucidate the main causes of differences in spikelet sterility at two locations. Numerical experiment by this model were conducted during the period from July 16 to 18 in 1980. During this time the Okhotsk Sea-anticyclone spread southwestward covering the northern part of Japan and had a strong influence on the weather conditions and rice growth in this area. The results of the numerical experiments were summerized as follows: 1. Using the observed meteorological conditions (Fig. 3), the effect of solar radiation on the temperature of the air, leaf and flood water in the rice canopy was simulated by our model (Fig. 4 and 5). Although the degree of chilliness above the rice canopies defined by Σ (20-T_a) was approximately the same at both locations, the air and leaf temperatures at the height of the young panicles in the rice canopy were lower at Takizawa than those at Kuroishi. Therefore the degree of chilliness of young panicles was estimated to be about twice greater at Takizawa than at Kuroishi (Table 2). This correlation suggests that the difference in spikelet sterility was mainly due to the difference in the temperatures of young panicles in the rice canopy. 2. The simulation results indicate that irrigation with a 20 cm deep flood improves canopy climate in cool weather conditions (Fig. 6 and 7). Rice plants grown in most parts of Japan can be protected from severe sterility due to low temperature at the booting stage, if the paddy fields are irrigated with a 20 cm deep flood during the cool period at the booting stage of the rice plants. 3. The net photosynthesis at Kuroishi was estimated at about 2.5 time as large as that at Takizawa (Table 3) reflecting the difference of solar radiation. 4. The model for the prediction of canopy climate was proved to be applicable for the precise evaluation of effect or micrometeorological conditions in the rice canopy.

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秋冬季におけるチャ越冬葉の光合成速度の季節的変化, とくに冬季の低温による光合成の低下の原因について検討した. 10月から翌春3月までの光合成速度の変化を測定したところ, 11月まで上昇し, 1l月下旬に最高気温20℃, 最低気温10℃となると, 光合成速度は低下を始めた. 1月から2月初旬にかけて最低気温が0℃以下のときに, 光合成速度は最低となった. 低下時には品種間差異はみられなかったが, 低下程度ははつもみじが NN27, ZI よりも大きかった. その後, 光合成速度ほ徐々に増加したが, その回復は部分的であり, 最高速度の40-60%であった. クロロフィル量も冬季に低下したが, その低下は最低気温が0℃以下になったときにみられ, 光合成速度の低下する時期とは異っていた. このことは葉色の変化では光合成の低温阻害を確める指標とはなり得ないことを示している. つぎに, 光合成の低温阻害機構を検討するために, はつもみじとやぶきたを用いて, 冬季における光合成明反応と暗反応の変化を測定した. 可溶性タジパク質とフラクション-1 タンパク質量の変化は光合成速度の変化とは対応ぜず, またリブロース1, 5-シリン酸カルボキンラーゼ活性によっても光合成速度の低下を説明できなかった. 一方, 光強度一光合成曲線の初期勾配及び光飽和下のヒル反応速度は光合成速度と対応して変化していた. 以上の結果から, チャ越冬葉における光合成の低温阻害は光合成暗反応よりも明反応の抑制によることが示された.

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本研究は, 1. トウモロコシ・インゲンマメ間作における生産効率, 2. 収量におよぼす両作物の比率と栽植密度の効果を検討するために行われた. 作物の組み合わせは, トウモロコシのみ, 2/3トウモロコシ+1/3インゲンマメ, (2:1), 1/2トウモロコシ+1/2インゲンマメ (1:1), インゲンマメのみとし, 密度は北海道標準を100とし, 加えて150, 200%の3段階とした(第1図, 第1表). トウモロコシは, 個体当たり茎葉重, 子実重とも, 同密度では2:1, 1:1区がまさり(第2表), インゲンマメでは, 個体当たりさや収量が1:1の100, 150%区でまさっていた(第3表). その他の区は, すへて同密度の単一作物区に比べ劣っていた. 間作ではつねにトウモロコシが優勢を示し, 密度がますとさらに優勢となった(第2図). 増収効果は, 間作のときの収量をうるのに要する単一作物のときの土地面積(LER)で求められたが, 間作条件で増収となることは明白で, その密度は150%くらいまでである(第3図). また, たんぱく質の収量は, 作物収量と同一の傾向にあった.

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When rice plants of japonica type were grown on the agar medium containing ABA in darkness, the elongation of mesocotyl was strikingly simulated but that of coleoptile and seminal root was inhibited. In this experiment, the rice seeds presoaked in acetone containing ABA were used for ascertaining the direct effect of ABA on the elongation of mesocotyl and coleoptile. A japonica type variety "Koshijiwase" and an indica type variety "Peta" were uscd. After presoaking seeds in acetone containing ABA at 25°C, they were dried for two hours in a vacuum desiccator and stored for two days at room temperature. In all the experiments, each lot consisted of 60-80 plants. The results obtained were as follows: 1. In the plants grown from the presoaked seeds in acetone contatining 10^-2M or 2×10^-3M of ABA, not only the elongation of mesocotyl but also that of coleoptile was sitmulated, reaching the plateau at the soaking of 24 hours. Thus the soaking for about 48 hours may be enough to examine the effect of ABA (Fig. 1). 2. By the 48 hours soaking in ABA, the stimulation of mesocotyl elongation occurred between the concentration of 10^-3M to 2×10^-2M. The length of mesocotyl in ABA treated plants was from 3 to 16 times longer than that of control treated with pure acetone, while the coleoptile length was from 1.0 to 1.5 times longer than that of the control. Accordingly, the morphology of plumules was almost similar those from the high temperature pre-treated seed and those of indica type rice. On the other hand, elongation of seminal root was somewhat inhibited even at 10^-3M of ABA, and the inhibitory effect increased with increasing ABA concentration (Fig. 2). 3. When the seeds presoaked with acetone containing ABA were again soaked in pure acetone, the stimulatory effect of ABA on the elongation of mesocotyl and coleoptile and inhibitory effect on that of seminal root disappeared. When the seeds of high temperature pre-treated japonica rice and those of nontreated indica rice were soaked in pure acetone, whereas, no effect was detected in the elongation of either mesocotyl or coleoptile (Fig. 3). 4. Parenchymatous cell length and number in a longitudinal section of mesocotyl with about 23 mm long in each experimental lot were measured. The plumules grown from the presoaked seeds in acetone containing 2×10^-2M of ABA were almost similar to those from the high temperature pre-treated seeds, 40°C for 10 days. On the other hand, the plumules grown on agar medium containing 2×10^-6M ABA were almost similar to those from immature seeds, harvested 15 days after anthesis (Table 1). 5. Considering the similarities of plumules between those originated from seeds presoaked with 2×10^-2M ABA and those originated from seeds pre-treated with 40°C for 10 days, about 1.6 μg of ABA was estimated to be synthesized in a seedling originated from the latter, if the assumption that the mesocotyl elongation is based only on ABA is adopted (Fig. 4).

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Andigena 系統 (S. tuberosum ssp. andigena) は栽培種 (S.tuberosum ssp. tuberosum)の祖先種とされ, 現在のバレイショ栽培種の遺伝的背景を拡げる上で重要な育種材料として注目されている. そこで, 本報では農林1号, 北海61号を比較品種とし, Andigena 2 系統 (W553-4, C10193-1) の乾物生産特性および葉群構造について検討した. 1. Andigena 系統は栽培品種に比べ, 塊茎形成が約2週間遅く, 生育前半の塊茎乾物増加速度(TGR)が小さいほか, 地上部乾物重, 特に茎の割合が大きかった(第1図). 2. CGR, NAR および TGR は, 生育前半では Andigena 系統が低く推移し, 塊茎形成後の CGR は NAR(r=0.878) および TGR(r=0.882) との高い正の相関を示した(第2図). 3. 植物体が受光した光合成有効放射量当たりの乾物生産効率 (EPAR) は Andigena 系統が小さかった(第1表). 4. Andigcna 系統の塊茎は栽培種に比べ著しく小さかった. 最終塊茎収量は C10193-1 が小さいものの, W553-4 は極晩生で長期間葉面積を維持したため, 農林1号と同程度の高い値を示した(第2表). 5. Andigena 系統は栽培品種と全く異なる葉群構造を示した. 特に, W553-4 は均一な葉群構造を示し, 下位葉が大きいほか吸光係数 (K) が小さく, 受光ならびに群落内部への光の浸透が良好であった(第4, 5図).

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わずか 1cm² の供与葉から移動した花成刺激は, 非誘導條件下におかれた受容植物に開花を誘導した. しかし, 最高の開花反応をひきおこすには 5cm² より大きい面積の供与葉が必要であった. 誘導した植物より切りとった供与葉を非誘導條件下におかれた受容植物に接木する前に, サイトカイニンの N⁶-ベンジルアミノプリンで処理すると受容植物の開花反応に抑制的影響を与えた. N⁶-ベンジルアミノプリンは, 恐らく供与葉からの花成刺激の移動に干渉するものと推定された.

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The pollen fertility and the features of sterile spikelets in straighthead rice plants were Observed. The number of pollens per spikelet and the percentage of fertile pollens decreased obviously, and unequality in the size of pollens were found. As for the features of the sterile spikelets, non-flowering, unfertilization or the abortion of kernel occurred at the early ripening stage. The enlargement of some ovaries in sterile spikelets, i.e., parthenocarpylike ovaries, occurred so often. It was concluded that the sterility of straighthead plants was caused by some unknown obstacles during the growth stages of rice plants from pollen formation to the early stage of ripening.

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The ultrastructure of vascular bundles and fundamental parenchyma (parenchyma in fundamental tissue system) in the 8th leaf sheath of rice were examined with a light and an electron microscopes in reference to possible pathways for photosynthate between phloem and fundamental parenchyma. 1. In the phloem of small bundles, the sieve element-companion cell complexes located in the middle and adaxial side of phloem remained without degeneration after sheath elongation (Fig. 1). However, the degeneration of phloem in large bundles is earlier than that in small bundles, and only several sieve element-companion cell complexes that abut on xylem remained without degeneration in the second leaf sheath from the uppermost fully-expanded leaf (Fig. 5). 2. In the boundary of xylem and phloem in small and large bundles, the plasmodesmatal connections were found in each interface between sieve element-companion cell complexes and xylem parenchyma cells, and between parenchyma cells of xylem and phloem (Table 1, Fig. 1). These connections may play a role in transfer pathways to phloem for solutes absorbed from transpiration stream by xylem parenchyma cells. 3. Cell walls in phloem of large and small bundles were densely stained purple with toluidine blue O (Figs. 3 and 4) and the plasmodesmatal connections were rare in the walls between sieve element-companion cell complexs and phloem parenchyma cells (Table 1). The phloem parenchyma cells contained many mitochondria with well-developed cristae and remained without degeneration after sheath elongation (Figs. 1, 2, 6 and 7). These data support the view that sucrose moves in the apoplast between sieve element-companion cell complexes and phloem parenchyma cells. 4. Suberized lamellae occur in all walls of the mestome sheath cells of small and large bundles (Figs. 1, 7, 8 and 9). Aggregates of plasmodesmata were observed in the walls between phloem parenchyma cells and mestome sheath cells (Figs. 1 and 7), between mestome sheath cells and fundamental parenchyma cells (Figs. 8 and 9), and also between fundamental parenchyma cells (Figs. 10 and 13). Judging from these observations, it appears that sucrose moves in the symplast between phloem parenchyma cells and fundamental parenchyma cells. 5, Different types of plastids were contained in the fundamental parenchyma cells of leaf sheath. The plastids in the top of sheath were similar in structure to the chloroplast (Fig.11), whereas those in the base of sheath were the typical amyloplasts having large starch grains and a few thylakoids (Fig. 13). The plastids in the middle of sheath showed an intermediate structure of chloroplast and amyloplast (Fig. 12).

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葉緑素 b が極端に少ないイネの淡緑色変異系統, CMV-44 と MGS-859 について, 葉緑素 b を全く含まないオオムギの変異系統, Highkin No.2 (H-2) と対比しながら, 葉緑素 b の存否を調べた. 分光光度法による葉緑素 a/b 比の値は, CMV-44, MGS-859 および H-2 でそれぞれ平均37.6, 20.2および17.7であった. 抽出液の吸収スペクトルをみると, イネ, オオムギとも変異系統では葉緑素 b に基づく波長帯での吸収が明らかに低かった. 生葉の2次微分吸収スペクトルにおいて, CMV-44では葉緑素 b の存在を示す吸収が全く認められなかった. 薄層クロマトグラフ法によると, CMV-44 と H-2 では可視光および紫外光下ともに葉緑素 b の位置に全くスポットが現われなかったが, MGS-859 では葉緑素 b の位置に可視光下では黄色スポット, 紫外光下ではかすかに蛍光が認められた. 以上から, イネの CMV-44 はオオムギの H-2 と同様に遺伝的に葉緑素 b を完全に欠く突然変異系統であると結論した.

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Detop cylinder made of refuse fire extinguisher as reaction vessel for acetylene reduction assay was reversely inserted into upland field soil covered with plants. Acetylene corresponding to about 10% (v/v) and 1 ml of propane were introduced into the vessel. Then, the above gases existed in the vessel and ethylene formed from acetylene were periodically measured. The results obtained were as follows. 1. Aerial volume of the vessel inserted into field was easily calculated from the dilution ratio of the introduced propane at the beginnig of the experiment. 2. The leakage of the inner gases from the vessel was presumedly determined through the decrement of propane as guide gas. 3. The reduction of acetylene to ethylene was found to proceed linearly with same rate until the oxygen pressure in the vessel decreased to about 10%. 4. According to the above technique, the acetylene reducing activity was observed to rank in higher order of alfalfa, white clover, common vetch grasslands. 5. From this investigation, the above devised method seemed to be useful on the non-destructive determination of nitrogen fixation in upland plants and fields.

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作物体の異なる部位における同化と転流の様相を知ることは, 作物の子実生産過程を理解するうえで重要な手掛りを与える. 本報では, ポット栽培した大豆の子実肥大初期に, 異なる葉位の葉に ¹⁴CO₂ を供与し, その同化, 転流の様相を調べ, その結果から登熟期における作物体各部位間 - 特に主茎と分枝間 - のソースーシンク関係を検討した. さらに, 莢伸長期における各部位のシンク制限(摘莢処理)の影響から, 圃場条件における各部位間のソースーシンク関係を推定した. 主茎上位葉に供与した ¹⁴C は供与節の上方にも下方にも転流したが, 分枝にはほとんど転流しなかった. 主茎下位葉に供与した¹⁴C は供与節の上方に転流する割合は小さく, 供与節の下方の主茎, 分枝および根に転流した(第1, 2表). この事実は, 個体全体を大きくみた場合, 主茎上位節と主茎中位節とで1つの, 主茎下位節と分枝とでもう1つの, 計2つの大きなソースーシンク単位が形成されていることを示すものと考えた. 一方分枝葉に供与した ¹⁴C は主茎にはほとんど転流せず, また供与分枝以外の分枝にもほとんど転流しなかった. このことから分枝は, 同化産物の転流に関して, 主茎に対しては寄生的であるとともに, 分枝間においては相互に独立的であるとみなされた. 主茎上位節の摘莢は, 主として主茎中下位節の子実重を大幅に増加させたのに対し, 主茎下位節の摘莢は主茎上位節よりも分枝の子実重を増加させ, さらに分枝節の摘莢は主茎下位節の子実重を著しく増加させた(第3表). この結果は, 上述のソースーシンク単位の存在を裏付けるものと考えた. 同化効率は, 主茎上位葉で高く, 次いで分枝葉, 主茎下位葉の順であった. ¹⁴C 供与葉からの転流率は主茎上位葉と分枝葉で大きく, 主茎下位葉で小さかった(第4表). 葉(ソース)に対する莢(シンク)の比率は主茎下位節で小さいのに対し分枝では大きく, このことが両者の転流率の差の一因であると推察された(第5表). さらに, 主茎下位節では非同化部(主として茎)の割合が大きく, 同化された ¹⁴C は一時的にこの部位に貯蔵されて後に分枝や根に転流したことから, 主茎下位節は同化産物の一時貯蔵という機能を果しているものとみなされた.

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This study was planned to know how the leaf sides and leaf positions influence on the differences among cultivars in soybean. Experiment A : Differences among cultivars in stomatal density and its two components. Five and twelve cultivars were used as materials in 1979 and 1980, respectivery. Each plant was grown in a pot, in a natural-light phytotron with a temperature of 30°C during the day (06.00-18.00) and 25°C during the night. Only central leaflets in the component leaves of main stem were observed. The copies of epidermis were taken with manicure liquid from the central position between mid rib and leaf margin, in a fully expanded leaflet. Stomatal density (number of stomata per unit of surface area of epidermis, SD) is devided into two components, (1) the power of stomatal differentiation (ratio of stomatal number to epidermal cell number, PS), and (2) the epidermal cell size (surface area of an epidermal cell, EC). The relationship among SD, PS and EC is shown in the equation (1), on condition that the guard cell has very small surface area compared to the epidermal cell. Both in SD and PS, the values were a half smaller in adaxial side than in abaxial side at every leaf positsons (Table 2). Contrary to this, the values in EC did not differ so much with leaf sides (Table 2, Table 5). F values with leaf positions showed significant levels in SD, PS and EC (Table 4). But, the variabilities of SD among laef positions were smaller than those among leaf sides (Table 2). Differences among the cultivars in SD, PS and EC were also significant statistically (Table 3, Table 4). In adaxial leaf side, SD showed high positive correlation with PS, but did'nt show significant correlation with EC (Table 6). Contrary to this, SD in abaxial leaf side showed relatively high negative correlation with EC, and moreover showed lower positive correlation with PS compared to the case of adaxial side (Table 6). Experiment B : Observation on differentiation of stomata with the course of leaflet growth. Staining surface method (Table 1) was adopted for the observation, using the central leaflet of third leaf position in main stem of two cultivars as materials. It was found from the observations that the stomata began to differentiate after the epidermal cells had already differentiated moderately, and that the stomata began to differentiate somewhat earlier in abaxial leaf side than in adaxial leaf side (Fig. 1, Fig. 3). The patterns of change in EC and PS during leaflet growth were wholly differed each other (Fig. 2, Fig. 3). Between the two cultivars, the differentiation of stomata was earlier in Tokachi Hadaka than in Akiyoshi (Fig. 3). From the above results, the relation was shown that the process patterns of SD with the course of leaflet growth were differed between the two cultivars, especially in adaxial leaf side (Fig. 4).

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高性能のガス交換測定システムを作成した. 本システムはパーソナルコンピュータによる大量のデータ処理が可能で, 移動も容易であるので, 実験室内や野外における作物の生理・生態研究に役立つものと期待される. その第一段階として, イネ及びキャッサバ葉の CO₂ 吸収速度及び蒸散速度に対する風速並びに湿度の影響を調べた. 風速を毎秒0.77mから1.70mヘ高めたところ, イネ及びキャッサバの CO₂ 吸収は各々6, 7%増加し, 蒸散は70, 22%増加した. 従って水利用効率(P/T比)は風速が高まるにつれて低下した. 一方, 相対湿度を32%から83%ヘ高めたところ, イネ及びキャッサバの CO₂ 吸収は各々9, 8%増加したが, 蒸散は59, 43%減少した. この場合, 気孔コンダクタンスは蒸散速度と負の関係にあり, 水利用効率は高まった. また, 野外における気温・湿度の変化に対するシステムの追従能力を試験した結果, これらの変化に十分対応できることが分った.

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将来予想される大気の二酸化炭素(CO₂)分圧の上昇がキャッサバの生産過程に与える影響を知る一助として本研究を行った. 自然光ファイトトロンを用いて, 1/2000アールポットに土耕した材料を, 3か月(1981年)及び2か月(1982年)間350, 700μbar CO₂下で栽培し, 乾物生産を比較した. またCO₂処理3O, 55日目に葉のCO₂ - 光合成特性を測定した. 1981年は気温が28/21℃の場合700μbarCO₂により全乾物重が350μbarCO₂区の54%増加した. 1982年は33/26℃で行い, 150%の増加をみた. 地上部/地下部比は温度に拘らず高CO₂により低下した. 光合成特性は3O日目では処理間の差が小さかった. 55日目では高CO₂区の見かけの光合成速度の低下がみられ, 気孔コンダクタンスの低下と並行していた. しかしながら, 光合成と蒸散の比から求めた水利用率は常に高CO₂区の方が高かった.

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The field experiment based on the results of field surveys (1978-1979) was made to determine the effect of plant type, sowing time and planting density on growth and yield in maize-kidney bean intercropping in 1979, from a viewpoint of analysis and application of conventional intensive culture in small land. Applied planting pattern was hill space intercropping of in-row planting and the obtained results were as follows: 1. Growth: The overlapping period of growth duration of maize and kidney bean in intercropping was longer in the planting with pole type bean than with the dwarf type bean, and also it was longer in late sowing than in early sowing of beans. Maize showed a tendency of increasing plant height at high planting density after tasseling irresepective of planting patterns. Plant height of pole type bean was shorter at intercropping than single cropping and this tendency was remarkable at later sowing with high planting density (Table 2). The dwarf type tended to be taller in plant height at intercropping in later sowing, especially in high planting density, but no difference in plant height was observed at early sowing (Fig. 2) Weed prostration was remarkably surpressed at high planting density of intercropping. The weed growth was coincident with the patterns of light transmission (relative light intensity) in the plant community (Fig. 3). 2. Yield: Grain yield per plant of maize was low at higher planting density irrespective of planting patterns. This higher yield in intercropping could be obtained at the planting with dwarf type bean than the planting with pole type bean. On the other hand, yield per area was higher at high planting density of any planting patterns but this incremental rate by intercropping was small (Fig. 4, Fig. 5, Fig. 6). The intercropping bean yield was particularly low at early sowing of pole type bean and also at late sowing of dwarf type bean. 3. Evaluation of land utlization in intercropping culture by relative yield totals (RYT) showed higher effect compared with single cropping, and maximum of RYT was found at late sowing with pole type in high planting density and early sowing with dwarf type bean in low planting density (Fig. 10).

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There are many scented rice cultivars at various parts or Japan, though their small cultivated area. This study was carried out to clarify the regional differences in those characteristics using by 85 scented rice cultivars. The results are summarized as follows: Cultivars from Tohoku area and Kanto area showed early maturing and had shorter culm, longer awn, larger angle of flag leaf, less straw weight and yield. Cultivars from Kinki area and Kyushu area showed late maturing and had longer culm, more straw weight and yield. Especially, cultivars from Kinki area had the longest ear and the highest percentage of ripened grains. Cultivars from Shikoku area differed from those of other warm area, Kinki and Kyushu, in view of shorter culm and less straw weight (Table 1). Principal component analysis based on 19 characters was applied to all cultivars. The first principal component was concerned with the plant length, panicle length, awn length, spikelets/panicle, straw weight, yield and days to heading. The second component was concerned with tillering, panicles/hill, angle or flag leaf, spikelets/panicle straw weight and yield. The third component was concerned with growth rate in vegetative stage (Table 2). Cultivars were classified by the scores on the first and second principal component axis into 4 groups; i.e., types I, II, III and IV (Fig. 1). Each type was named as followes; I was long-culmed many-tillering late maturing type, II panicle weight type, III panicle number type and IV short-culmed few-tillering early maturing type. Each type was subdlvlded by the third component into 2 groups; i.e., sub type a and b. Sub type a was named as high growth rate type and b as low rate type. Each region included mostly the follwing types (Table 3 and 4); Tohoku area; IVa Kanto area; IVa Hokuriku area; IIa, IVa Kinki area; Ia, IIa, IIb Shikoku area; Ib, IIb, IIIb Kyushu area; Ia, IIa, IIb

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Konjak plants were given treatments of full sunlight, 50% and 70% shading immediately after leaflet expansion. Ultrastructure of the chloroplasts in leaflets at the top and base of blades was examined with an electron microscope at intervals of one or two weeks after treatment. 1. Leaf area increased at all light intensities for two weeks after leaflet expansion and the largest area was obtained from the plants grown at 70% shading. Green area of leaves grown at full sunlight began to decrease from 40 days after the leaflet expansion, but the leaves grown under the shade maintained the fully expanded area for three months (Fig. 1). 2. The chloroplasts just before the treatment had rudimentary grana, a small amount of plastoglobules and starch grains (Figs. 2 and 3), but two weeks after treatment the ultrastructural differences were noted in the chloroplasts developed at different light intensities. 3. The chloroplasts from plants grown at full sunlight had poorly organized grana consisting of 2-5 overlapping thylakoids, which began to separate from two weeks after leaflet expansion (Fig. 4). Most of the chloroplasts in adaxial side of palisade cells showed swelling and the grana had been destroyed at four weeks after leaflet expansion (Fig. 5), whereas those in abaxial side of palisade cells and in spongy parenchyma cells remained without conspicuous destruction (Figs. 7 and 8). In the chloroplasts from plants grown at full sunlight, the starch grains decreased but the plastoglobules continued to increase with aging (Figs. 4 and 5). 4. The chloroplasts from plants grown at both 50% and 70% shading contained well-developed grana having more than 10 overlapping thylakoids, which remained without remarkable separation for three months after leaflet expansion (Figs. 9-12). The difference was not clear in development of the inner membrane system between the chloroplasts from plants grown at 50% and 70% shading, but the chloroplasts from 50% shading contained larger amount of starch grains than those from 70% shading (Figs. 9-12). The change in chloroplast structure by shading was more distinct in leaflets at the top of blade than in those at the base (Figs. 4 and 13). According to the observation of the chloroplasts in konjak, which has been characterised as a shade plant, it is considered that the development of grana is accelerated under low light intensity and the senescence of chloroplast is delayed.

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For the last decade the high level yields, 5t-6t/ha, max. 6.5t/ha, of soybean (cv. Okushirome) have been recorded continuosly under the upland conditions converted from rice paddy fields at Saihoku Branch of the Yamagata Prefectural Agricultural Experiment Station, located in Shinjo (38°45'N, 140°18'E). In 1982 and 1983, dry matter accumulation pattern, canopy structure and light penetration for Okushirome under the converted fields at Saihoku Branch were compared with those of some cultivars (Table 2) grown under the fields of Experimental Farm of Hokkaido University (Sapporo, 43°35'N, 141°20'E). Okushirome produced the highest yields in both years, 5.3t/ha in 1982 and 4.6t/ha in 1983. It had also large LAIs (about 6), small light extinction coefficients (K:0.38 and 0.42), long leaf area duration (LAD) and high harvest indices (62% and 56%) compared with those of the cultivars grown in Sapporo (Table 3 and Fig. 5). Grain yield was closely correlated with number of pods (r = 0.886), LAD (r = 0.800) and grain filling period (r = 0.813), regardless of years, locations and cultivars. The K value was related to number of pods per maximum LAI (r = - 0.796), though not related directly to grain yield. As shown in Fig. 6, in 1982 Okushirome showed a peculiar unique plant form that the upper 3 to 4 large leaves on main stem had vertical and long (25 cm to 30 cm) petioles though stem height was very short (Table 2). In addition, leaflets of Okushirome did active solar tracking movements in both years during early morning to late afternoon, suggesting the relation to effective light penetration within the canopies (Fig. 4).

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Microclimatic environment of a growing mat rush canopy was observed during its growth period from after the tip cutting to the harvesting to analyze the process of its long stem growth in the southern part of Okayama prefecture in 1983. The results are summerized as follows: 1. The maximum air temperatures observed within a crop canopy were 28°C at the earlier stem growth stage in its lower layer and 32.5°C at the later stem growth stage in its middle layer. Both of those temperatures were higher than air temperature above the crop canopy and too high for the efficient photosynthesis of mat rush stem. Air temperature in the lower layer of a mat rush canopy became relatively low with growth of a crop canopy and it was observed that an active layer for heat transfer was established in the middle layer within a crop canopy at the later stage of stem elongation. 2. The maximum difference in atmospheric water vapour pressure between the upper and the lower layer within a crop canopy was much as 10-12 mmHg through the long stem elongation stage in the day time but the difference was decreased gradually toward the harvest time. Relative humidity within a crop canopy was higher than 90% in its lower layer in the day time and was nearly 100% in the night time though it was very low as 50-55% in its upper layer especially at around the noon. A high air temperatur with its low humidity at the upper and the middle layer and a relatively low temperature with its high humidity in the lower layer was one of the signifficant characteristics of a mat rush canopy during the stem elongation stage to harvest. 3. CO₂ concentration profile within a crop canopy at just before the harvest time, showed a remarkable horizontal transition within a day. The minimum CO₂ concentration which was measured within a crop canopy was 300 ppm in the middle layer, just below an active layer for the heat transfer, in the day time. The maximum CO₂ concentration measured was 540 ppm in the lowest layer in the night time. It was indicated that the apparent photosynthetic ability was higher in the middle layers of a canopy though there the light intensity was lower than in its upper layers and the stem part which located in those layers was photosynthetically not so active. According to the results obtained by the microclimatic observation of a mat rush canopy, several problems which should be taken into the consideration for improving the growing process of mat rush were brought out for the future studies.

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