食用ソラマメの生育と窒素含有量および収量に対する土壌塩類, 窒素施肥の影響をポット条件下で調査した. 塩類濃度は, 乾土当り 0.18, 0.30, 0.45, 0.60%の4水準を設け, 0.18%のものを対照区とした. 窒素施肥については, 1ポット4 kgの土壌に対して窒素成分として 0, 25, 50, 75 mg添加の4水準を設けた. 得られた結果は次の通りである. 1. 乾物重, 窒素含有量, 子実収量, 茎重, 個体当り莢数, 個体当り子実蛋白量は, 塩類濃度0.30%は促進的であったが, その他の塩類濃度では, 濃度が高まるにつれて抑制的であった. 百粒重, 子実蛋白含有率に対しては, 対照区に比べて全ての塩類濃度が抑制的に作用した. 2. 個体当り子実収量, 百粒重並びに開花前期と英形成期における乾物重については, それぞれの平均値が窒素施肥によって増加した. 3. 植物体窒素含有量, 個体当り莢数並びに子実蛋白含有量は, 窒素施肥によって増加し, 莢充実期と成熟期では 50mgの窒素施用が最も促進的であった. 4. 開花前期と莢充実期の植物体乾物重は, 最終子実収量と有意の高い正の相関が認められた. 5. 子実生産の効率は, 窒素施用量の増加にともなって高まった. これらの結果から, a) 塩類濃度 0.45%は, ソラマメの生育にとって限界濃度であり, b) 根粒菌種子接種に併用する窒素施肥は, 可給態窒素含量の低い土壌で最大収量を得るために有効であると結論された.

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Wheat were grown alone or in association with pea (Pisum sativum L.) or broad bean (Vicia faba L.) under several treatment conditions of nitrogen application, temperature and clipping in nitrogen-poor soil. The results are summarized as follows. 1. Without nitrogen fertilizer and with nitrogen 1 kg/10 a, top dry weight and nitrogen content of wheat in association with pea were the same as those grown alone on the 60th and the 70th day after sowing, but were remarkably larger on the 85th day when tops of the pea died and almost all the root nodules sloughed off (Figs. 1, 2, 3 and 4). With nitrogen 8 kg/10 a, however, they were less than those grown alone 60, 70 and 85 days after sowing. 2. Wheat grown in association with broad bean yielded smaller top dry weight and nitrogen than those grown alone till the 83rd day after planting at 10°, 15°, 20°and 25°C (Figs. 5 and 6). In the early stage of anthesis of broad bean 4 months after planting, the wheat at 15°, 20° and 25°C yielded more dry weight and nitrogen, being largest at 20°C where broad bean growth was most marked on the 53rd and 83rd day (Figs. 8 and 9). Four months after planting, acetylene reduction activity declined markedly and some of the root nodules sloughed off (Fig. 9). At 10°C, top dry weight and nitrogen content of wheat did not increase by association with broad bean. 3. Clipping the tops of broad bean plants in soil culture increased top dry weight and nitrogen content of associated wheat at 15°, 20° and 25°C. These increase were observed 30 days after clipping at 20° and 25°C and after 66 days at 15OC (Figs. 5 and 6). Broad bean grown in gravel culture containing no nitrogen fertilizer increased inorganic nitrogen in the culture solution after clipping their tops. The amount of nitrogen increased markedly at 20°C than at 10°C (Table 2). It is found from these results that the increase of nitrogen content of wheat by association with these two legumes is observed 3 to 4 months after sowing or planting and also that this increase is promoted by the favorable conditions for nodulation and nitrogen fixation, such as nitrogen-poor soil and appropriate temperature.

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Corn (Zea mays L.) was grown alone or in association with soybean (Glycine max (L.) Merill), cowpea (Vigna sinensis Endlichen) or kidney bean (Phaseolus vulgaris L.) under the Condition of small top competition for light in pots containing nitrogen-poor soil. In association with soybean, the effects of growth stage and clipping of tops of soybean and nitrogen application on the nitrogen content of associated corn were examined. The results are summarized as follows. 1. Nitrogen content of corn tops in association with soybean, cowpea or kidney bean was remarkably less than that grown alone 96 days after planting (Fig. 1). This reduction was more remarkable when associated with cowpea or late-maturing soybean than with kidney bean or early-maturing soybean. 2. Regardless of the rate of nitrogen application (0, 5, 10 and 15 kg/10 a), corn growth associated with soybean was less than that grown alone (Fig. 4). 3. Nitrogen content of corn tops was reduced by association with soybean either in the vagetative phase under long day condition or in the reproductive phase under short day condition (Fig. 5). Clipping of the tops of soybean plant increased nitrogen content of corn tops 2 months after clipping (Fig. 5 and Table 2). 4. Cropping associated with three legumes and corn increased nitrogen content of the succeeding wheat, varying with species and cultivars of the legumes (Table 1). 5. Association with soybean reduced nitrogen derived from fertilizer and soil by the corn plant on the 38th day after planting (Table 2). It is found from these results that nitrogen content of corn is reduced by association with these three legumes by their growth stages. It is suggested that this reduction is caused by competition for nitrogen in soil between legume and corn from the early stage of cultivation.

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Studies on paddy triple cropping were carried out between 1968 and 1971 at Surat A.E.C. (20°10'N., 72°20'E.) in the northern tropical area of India (Figs. 1 and 2). 1. From the results of Rabi culture (1968) by using Formosa-3 that is the earliest variety in the area on paddy triple cropping, it was proved that the bottleneck is the damage from low temperature at reductive division and flowering stages (Table 2 and Fig. 3). To solve the problem, two methods were examined ; one is to introduce earlier varieties than Formosa-3 in Rabi culture ; the other is to hasten the heading of Formosa-3 by earlier transplanting in Rabi culuture. The former is as follows; 1st cropping, customary Kharif paddy ; 2nd, Rabi paddy by introducing earlier varieties ; and 3rd, Summer paddy. (paddy triple cropping A). The latter is as follows ; lst cropping, Kharif. paddy by hastening both sowing and transplanting one month ; 2nd, Rabi paddy by hastening transplanting one month ; and 3rd, Summer paddy. (Paddy triple cropping B). 2. By earlier transplanting 3 weeks, the heading of Formosa-3 was hastened about 20 days. This suggested the possibility of one month earlier transplanting (Table 3). 3. By earlier transplanting one month, the heading of Formosa-3 was hastened about 40 days. In the end, it was proved that paddy triple cropping only by Formosa-3 is possible (Table 4). 4. On paddy triple cropping, Honenwase is better than standard variety of Formosa-3 ; because more unhulled rice yield (8, 012 kg. per ha) was gained, and the heading time was earlier a week (Table 5). 5. Compared with standard variety of Formosa-3, Cavary got increase yield of 40% in medium fertilizer, 29% in high fertilizer, and the heading was the same, so Cavary is the best variety (Fig. 4). 6. Compared with non-compost fertilizers, the application of compost from paddy straw (10t. per ha) in each cropping got unhulled rice increase yield of about 15-20% (Table 6). 7. Results of 1st (Kharif, 2nd (Rabi) and 3rd (Summer) croppings are shown in the Table 7. Table 8, which picks up marks in Table 7 shows how much unhulled rice yield was gained in each cropping on paddy triple cropping. The total unhulled rice yield of paddy triple cropping A was 18, 732 kg/ha, the items were 7, 099 kg/ha by Formosa-3 at Kharif paddy, 3, 162 kg/ha by Koshihikari at Rabi paddy, and 8, 471 kg/ha by Cavary at Summer paddy. The total unhulled rice yield of paddy triple cropping B was 20, 495 kg/ha : the items were 6, 921kg/ha by Formosa-3 at Kharif paddy, 5, 103 kg/ha by Formosa-3 at Rabi paddy, and 8, 471 kg/ha by Cavary at Summer paddy. Compared with total unhulled rice yield of paddy triple cropping A, B got increase yield of about 9%. Moreover, the transplanting and heading in the Rabi paddy of B were more stable than that of A. From the above results, the author considers that paddy triple cropping B is more profitable than A. On the growing periods of nursery bed and paddy field in each cropping on paddy triple cropping A and B, the systematic graph of cultivation was gained as Fig. 5. Notes : In Japan, one year is divided into 4 seasons of Spring, Summer, Autumn and Winter ; but in tropical area of India, into 3 seasons of Kharif (Jun.-Sept.), Rabi (Oct.-Jan.) and Summer (Feb.-May).

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The purpose of this investigation is to establish a simple method for quantitative determination of sweet substances in Stevia plant and to clarify their accumulation patterns during the growing process. The results obtained were as follows. 1. Five or six kinds of glycosides existed in the dried leaves of Stevia plant. Two of them were respectively identified as stevioside and rebaudioside A by one and two dimentional thin-layer chromatography. 2. The solvent systems composing of n-butanol : methanol : water (8 : 1 : 1 V/V) and n-butanol : ethylacetate : iso-propanol : water (35 : 100 : 65 : 30 V/V) were available for separation of stevioside and rebaudioside A from other glycosides on chromo-plate. Besides, it was confirmed that application of thin-layer chromato-scanner made it possible to determine stevioside and rebaudioside A on the developed plate, quantitatively. 3. It was observed that stevioside content and its accumulation in Stevia leaves rapidly increased during the period from vegetative to reproductive growth and the content of stevioside in leaves was markedly higher than that in stem and root. Besides, the accumulation pattern of rebaudioside A was similar to that of stevioside but its content in leaves was always lower than that of stevioside at any stages of growth.

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The effects of water stress on panicle exsertion in rice appear to differ from those in sorghum. Water deficits after floral initiation increased the time to flowering in sorghum, whereas panicle exsertion in rice was considered to be delayed by stress occurring before floral initiation. The objective of this stydy was to examine whether the effects of water deficits on phenology of flowering are really different between these two crops. Rice (Oryza sativa L.) cultivar Koshihikari and grain sorghum (Sorghum bicolor (L.) Moench) hybrid NK129 planted in a 4l (1/5000 a) pot containing sandy loam soil were grown in a vinyl house. Each pot contained either two rice plants or single sorghum plant which received daily irrigation till the start of drought treatment. Irrigation was suspended to impose 10 and 6 grildients of water stress after floral initiation in rice and sorghum respectively. Plants were rewatered after reaching a desired level of stress (Fig. 1). In sorghum, predawn leaf water potential (Ψ_L) did not change for several days after withholding water (Fig. 3). Thereafter, it declined first slowly and then rapidly. Similar trend was observed in rice, but its Ψ_L began to decrease much earlier after withholding water and the rate of decrease was greater than in sorghum. Panicle exsertion was delayed in rice due to water stress and was also delayed in sorghum with an exception in plants subjected to 19 and 24 day drought that accelerated panicle exsertion (Fig.4). The time to panicle exsertion increased linerly with decreasing Ψ_L below some threshold value (the critical Ψ_L). The critical Ψ_L differed between the crops; -0.2 MPa in rice and -1.2 MPa in sorghum (Fig. 5). Furthermore, there were considerable scatter in the data in rice : panicle exsertion was delayed by 5 to 6 days when Ψ_L remained at around -2.3 MPa. However, when delay in the time of panicle exsertion was plotted against water stress duration, most of the differences above noted were removed (Fig. 6). In other words, the identical relationship was obtained for both crops between the delay in panicle exsertion (D-D₀) and the water stress duration (T-T_C) : D-D₀=1.34(T-T_C) where D is the time to panicle exsertion in plants droughted after floral initiation, D₀ is that is plants without drought, T is the duration of drought and T_C is the duration between the initiation of drought and the time when Ψ_L declined below the critical value. It is therefore concluded that phenology of panicle exsertion in rice and sorghum is similarly affected by water deficits occuring after floral initiation.

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In order to make clear varietal difference of the amount of reserved carbohydrate at heading stage, total carbohydrate and total nitrogen contents of the same varieties used for the experiment of planting density in the second paper in this series were analyzed. Also relationships between the total carbohydrate content and plant height, culm length and ear number at heading stage were studied. The results obtained are summarized as follows : 1. Total carbohydrate content at heading stage differed with rice varieties. Varieties with shorter culm and less ears showed higher content of total carbohydrate (Table 1, Table 2). 2. Varieties with a higher plant height at vegetative stage and shorter culm length at heading stage, that is, the ratio of plant height to culm length is greater, had higher reserved carbohydrate until heading stage. This is caused by a difference between higher dry matter productivity and lower carbohydrate consumption during the period until heading stage (Fig. 1). 3. Recently improved high-yielding varieties, such as Nishihomare, Shinrei and Milyang 23 showed a greater ratio of plant height to culm length than that of old varieties. Therefore, it is considered that the ratio of plant height to culm length is one of the indices for improving a high-yielding variety (Fig. 1). 4. There was negative correlation between total carbohydrate content and total nitrogen content at heading stage. The improved high-yielding varieties showed higher contents of total carbohydrate and total nitrogen than that of low-yielding ones (Fig. 3).

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The effects of soil temperatures on rooting, and of high soil temperature on rooting and some root characteristics of sweet potato cut-sprouts (Ipomoea batatas Lam.) were investigated in a controlled environment. The results obtained are as follows : 1. In the cultivar Okinawa No. 100 the rooting of cut-sprouts occurred normally at temperatures ranging from 19°C to 37°C. The soil temperature of about 30°C gave the maximum values in the total and average length of adventitious roots and the dry weight of roots at 1 week after transplanting and the number of leaves which recovered from wilting and newly developed at 1 and 2 weeks after transplanting, respectively (Figs. 1 and 2). However, for the number of adventitious roots thc range of optimum temperatures was wider (Fig. 1). 2. Cut-sprouts of cvs. Koganesengan, Kokei No.14 and Okinawa No.100 were exposed to a soil temperature of above 40°C for 0, 1.9, 5, 8, 11 and 24 hours per day during a period of 1 week after transplanting (Table 1). Total length of adventitious roots and all roots decreased due to the high soil temperature (Tables 2 and 3). But, the extent of the decrease in the treatment for 1.9 hours per day was small due to the compensatory increase in the number of adventitious roots, although the average root length was apparently decreased (Table 2). 3. Total sugar content and respiration rate of roots conspicuously increased by the high soil temperature treatments (Table 3). In spite of the decrease in the total length and dry weight of roots, the number of leaves and transpiration rate did not decrease by the exposure to a high soil temperature for 1.9 hours per day, presumably due to the increase of the water uptake per unit root length associated with the activation of root respiration (Tables 2 and 3). 4. In the treatments with high soil temperature one week after transplanting, there was a large number of roots with few cell layers in the primary cambium and the lignification of the stele cells was accelerated (Figs. 3 and 4) and abnormal stele was observed in cv. Koganesengan (Fig. 5). From these results it can be concluded that the optimum soil temperature for the rooting and establishment of cut-sprouts of sweet potato is about 30°C, and that a temperature of 40°C prevents cut-sprouts from rooting. When the exposure to a high soil temperature (above 40°C) lasts less than 2 hours per day the suppression of cut-sprout establishment is not appreciable. From the anatomical point of view, however, it appears difficult for tuberous roots to develop when exposed to a high soil temperature even for only 2 hours per day.

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Using a culture method of excised root tip reported by KAWATA et al., the growth of seminal root tips of Japonica and Japonica-Indica hybrids were compared. Plant materials used were 20 cvs. of Japonica-Indica hybrids bred in Korea, 10 cvs. of Korean paddy rice and 10 cvs. of Japanese paddy rice. The 1 cm long root tips were excised from seminal roots and two root tips were grown in each flask containing 15 ml of the culture solution. They were grown at 27° or 3O°C in the dark for three weeks. The results obtained were as follows ; 1. Root length at 27°C varied from 10.9 to 18.0 cm in the Japonica and from 13.2 to 19.7 cm in the Japonica-Indica hybrids. At 30°C, it was from 9.1 to 19.0 cm in the former and from 16.7 to 27.3 cm in the latter (Table 1). 2. At 27° and 30°C, Japonica-Indica hybrids had more number of the primary branched roots than the Japonica (Table 2). Root dry weight was from 0.9 to 2.0 mg in the Japonica and from 3.2 to 5.7 mg in the Japonica-Indica hybrids at 27°C (Fig. 4), while it was from O.9 to 2.3 mg in the former and from 4.2 to 10.1 mg in the latter at 30°C (Fig. 5-b). 3. Excised root growth of the Japonica were better at 27°C than 30°C, while in the case of the Japonica-Indica hybrids this was reverse (Fig. 5-a, 5-b).

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ダイスの窒素(N)固定能力の品種間差異については, これまで主にアセチレン還元法により検討がなされてきた. 本実験では, ダイスのN固定の主要な代謝産物であるウレイドに注目し、植物体内で、その生育時期別変動や品種間での変異をアセチレン還元法で推定したN固定能力と対応させながら検討した. 1. 個体当たりの葉面積と根粒重は子実肥大期まで増加が認められ、以後, 急激に低下した. これに対し, 個体当たりのN固定能力は開花終期にほぼ最高となり, 天形成期までその値を維持したが, 子実肥大期には低下し始めた. 2. 茎 (葉柄を含む), 莢実のウレイド含有率は莢形成期に最高となったが, N固定能力の低下と子実の肥大にともない急激に低下した. これに対し、葉身のウレイト含有率はかなり低く, 生育時期別変動も認められなかった. 3. 個体当たりのN固定能力と有意な相関関係が認められた形質は, 茎のウレイド含有率の他に、根粒重, 地上部重などがあった. さらに, 茎中でのウレイト蓄積量を指標とした時には, より密接な相関関係が認められた.

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The number of shoot units with crown roots, which is related to the number of crown roots per stem, and the number of shoot units without crown roots, which bore close relation to the finishing time of crown roots elongation, differed among rice cultivars having the different number of leaves on the main stem. Accordingly, the number of shoot units with or without crown roots was investigated in relation to the characters of the top in the ripening stage. Examined were the number of living leaves per stem, leaf area per hill, chlorophyll content, stomatal aperture and dry weight of the top. Better characters of the top were exhibited in the rice plant having more numerous shoot units with crown roots in such experiments as cutting-off the uppermost-positioned crown roots of 2 or 3 shoot units (Exp. 2) and moulding up the lower part of stems to accelerate rooting from relatively high-positioned shoot units (Exp. 3). But, the rice plant which was transplanted at the leaf age 5.5 did not show better characters of the top than that transplanted at leaf age 8.5 (Exp. 1), although it had more numerous shoot units with crown roots than the latter. The number of shoot units without crown roots was less in the plots in which the characters of the top were better in Exps. 2 and 3, while that number was approximately equal between two plots in Exp. 1. From these results, it was proved that the characters of the top in the ripening stage were not always affected by the number of shoot units with crown roots, but they had a close relation with the number of shoot units without crown roots.

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Along the successive "shoot units" (abbreviated as SUs) on main stems of rice plants, the number and diameters of primary roots were compared with several morphological characters of the shoots. Each shoot was composed of 16 SUs, and acropetally towards the 11th SU, many characters examined tended to increase almost linearly. The characters involved here were the lengths of leaf blades, leaf sheaths and internodes, the diameters of the stem, as well as the diameters of vascular cylinder of the stem, and further the number and the diameters of primary roots, respectively. From the 12th SU upwards, on the contrary, almost all characters mentioned above, except the internode lengths, tended to decrease. These higher SUs were characterized by the remarkable elongation of their internodes. The primary roots appeared near the 12th SU showed peculiar phenomena, i.e. the abundant occurrence of dormant root primordia and the considerable decrease in their diameters. The results obtained suggest that a close growth correlation may exist among various organs of each SU, and the internodal elongation or related internal factors may change the correlation to a great extent.

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In an attempt to throw the light on pruning effects in tea cultivation, the relationship between time of pruning and changes in the respiratory rate of rootlets were investigated with a special reference to the content of storage carbohydrates in roots and the growth temperature. One year-old tea plants (Camellia sinensis (L.) O. Kuntze) grown in plastic pots in field were pruned remaining 1/2 or 1/4 of plant height (1/2 pruning or 1/4 pruning). The respiratory rate (oxygen absorption) of rootlets was measured with an electrode. The depression of respiratory rate of rootlets induced by pruning gradually grew stronger from March to July, and then gradually became weaker to November (Fig. 2). The depression was larger in 1/4 pruning plants than in 1/2 pruning plants (Figs. 1 and 2), and was larger in cvs Yabukita and Kurasawa than in cvs Fujimidori and Okumusashi (Table 1). There was no relationship between seasonal changes in the depression of respiratory rate of rootlets induced by pruning and the content of storage carbohydrates in roots (Figs. 3, 4 and 5). On the other hand, seasonal changes in the depression rate of rootlets induced by pruning and temperature at underground of 10 cm were positively related ; correlation coefficients were 0.941 for cv Yabukita and 0.892 for cv Fujimidori (both are siginificant at 1 % level) (Figs. 6 and 7). When the 1/2 pruning was done to the plants grown under two kinds of day-night temperature regimes, 25-20°C and 15-10°C respectively, the depression of respiratory rate of rootlets was larger in 25-20°C than in 15-10°C (Fig. 8 and Table 2). From these results, it was demonstrated that the depression of respiratory rate of rootlets induced by pruning was larger in summer than in other three seasons and the depression was influenced by temperature at the time when pruning was done rather than content of storage carbohydrate in roots.

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粒大が大きく異なる水稲6品種を用い, 出穂期以降照度を対照区の約75%に減少させる遮光処理と, 一次枝梗を穂軸上の着生順序にしたがって一つおきに切除し一穂粒数を半減させる枝梗切除処理を行った. これらの処理が各品種の登熟過程 (粒重増加過程) に及ぼす影響を, 特に粒大との関係を注目しつつ検討した. また本実験では, 登熟過程を一粒 (籾) 当りの粒重増加速度, 増加期間, および最終粒重の3パラメータで捉え, 解析に供した. 枝梗切除処理は, どの品種に対しても粒重増加速度を増大, 増加期間を減少させた. 増加期間の減少程度は, 非大粒品種よりもBG 1やArborio J1のような大粒品種で小さく, その結果, この処理によって最終粒重は大粒品種において有意に増大した. 遮光処理は, どの品種においても最終粒重を減少させた. 粒重の減少の原因は品種によって異っていたが, 粒大との関連は認められなかった. 一方, 粒の着生位置を考慮すると, 粒重の減少程度は大粒品種ではどの位置でも同様であったが, 非大粒品種では二次枝梗上, または下位枝梗上の粒において特に大きいことが判った. 以上の結果より, 大粒品種の登熟過程は, 上記の処理によって同化産物の穂への転流量に変動が生じた場合, 非大粒品種とは異った反応を示すことが明らかとなった. 本実験における2つの処理は, 各々異なる年次に行われたが, 各年次の対照区を比較することにより, 登熟過程の年次の違いに対する反応性が早生品種と晩生品種では異なることが判った.

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The present study was aimed to obtain basic knowledge to monitor the physiological and ecological function or state of crop communities remotely. This paper deals with the temperature distribution of crop canopies investigated with and infrared scanning therometer. The results obtained are summarized as follows : 1. The emissivity of crop canopy was estimated at approximately 1.0 with wheat, maize, soybean and sunflower according to the measurement as to their leaf blades (Table 1). 2. The range of canopy temperature was relatively small compared with diurnal change of air terperature or canopy temperature. The distribution pattern of canopy temperature was fitted to gaussian distribution very well. Standard deviation and range of each canopy temperature were estimated at 0.2∼0.8°C and 1∼3°C respectively (Figs. 3∼5). 3. Eeven if there were some structural differences within a canopy the change of distribution of canopy temperature was not significant as far as a field of view was set to a rather uniform part of such canopies (Fig. 6). 4. The temperature distribution of wheat canopy with panicles was biased from gaussian pattern because of high temperature of panicles (Fig. 7). 5. The range of temperature distribution tended to increase with increment of the dip of view. But setting a field of view fully to foliage with 10∼20° dip, canopy temperature was not affected very much by the dip (Table 2).

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