The effects of nitrogen supply (1N, 2N) at heading on the pattern of accumulation of dry matter and nitrogen in the caryopses at different positions on panicle were investigated to clarify the positional differences of caryopsis growth. The photosynthetic activities and the nitrogen contents of leaf blades were also taken into account. Caryopsis position on panicle was selected as shown in Fig. 1. Results are summarized as follows; 1. The superior caryopsis (I) at the upper position on panicle, in the control, accumulated the dry matter and nitrogen rapidly and in a short duration at the first half of ripening period. On the other hand, the inferior caryopsis (VI) at lower position on panicle accumulated these materials slowly and over a long duration at the second half of ripening period. 2. Nitrogen supply at heading increased markedly the rate of accumulation of dry matter and nitrogen in all caryopses, but had little influences on the duration of the accumulation and on the time of the rapid accumulation in ripening period, as compared with the control. 3. Nitrogen content of all caryopses at maturity was clearly increased as the quantlty of nitrogcn supplied increased. Grain weight also increased but not so much as the nitrogen content. The ratios of increase of both grain weight and nitrogen content by the nitrogen supply were very remarkable in the inferior caryopsis (VI) which was ill-ripened ln the control. 4. The increase of grain weight and grain nitrogen content by the nitrogen supply at heading was caused by the rise of accumulating rate of these materials in caryopsis throughout the ripening period. 5. Nitrogen supply at heading maintained the photosynthetic activities and the nitrogen contents of leaf blades at relatively high level during ripening period. Nitrogen contents of leaf blades in each plot began to decrease abruptly at 10 days after heading and reached the lowest level at 25 days after heading relatively. 6. It was suggested that the occurrence of the early increased rate of accumulation of translocated substantes might be need for the improvement of ripening of inferior caryopsis and the factors controlling the accumulation rate of inferior caryopsis might involve not only the supplylng ability of source organs but also the function of inferior caryopsis for sink organ.

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Intact mesophyll cells were isolated from tea (Camellia sinensis) leaves using an enzymatic (macerozyme) technique. About 15% of the leaf cells on a chlorophyll basis from 1 or 2 grams of leaves could be isolated in 3 hours. The optimal concentration of sorbitol was 1.0 M in the case of single cells isolated from immature leaves and 0.4 M in the case of mature leaves. Cells were slightly stable when stored at 0°C. Cells isolated from immature leaves showed higher photosynthetic activity (20-30 μmoles/mg chl/hr) than that of cells isolated from mature leaves (6-10 μmoles/mg chl/hr). Photosynthetic rate of cells (immature leaves) was saturated at 5 mM of bicarbonate and the Km(CO₂) for cell photosynthesis was about 40 μM. The light intensity at maximal velocity of CO₂ fixation was about 40 klx. The optimal pH for CO₂ fixation was 7.8 and the optimal temperature was between 30 and 35°C. These results were discussed in relation to leaf photosynthesis.

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We tried to ascertain that how thc growth habits of plants would be altered where the nutrition levels of cultural solution were changed in the mid course of vegetative growth stage from the viewpoint of top-root relationships. Materials used were Lolium multiflorum LAM., Mammos italian B sp. and Mammos A sp. as erect type and weeping type respectively. The experiments were carried out in a green house, and water culture with Hewitt's solution was adopted (Treatment N-L: nutrition level was changed 10 ppm→ 10 ppm→ 10 ppm→ 50 ppm, Treatment N-N: nutrition level was changed 50 ppm→ 10 ppm→ 50 ppm→ l0 ppm). The results obtained were as follows; 1. There was no remarkable change in the pattern of increase in the total plant dry weight under circumstances where the nutrition levels were changcd in the mid course of the growth stage of the plant. In the later stage of growth the total plant dry weight, however, was larger under high nutrition level than under the low nutrition level. 2. The value of relative growth coefficient h (h=tan θ) was altered parallel with increase or decrease in nutrition level. 3. The value of T/R 3-D ratio's, however, was changed elastically parallel with the change in nutrition level. 4. Change in mean stem nos/root nos. ratio (S/R nos. ratio) over each period among successive samplings with advance of growth stage was the same as the pattern of the change in T/R 3-D ratio. 5. The value of the estimated root surface area by using the area meter (Hayashi denko AAM-5) in low nutrition level were larger than those in high nutrition level. The value in low planting density were always larger than those in high planting density, i.e. D(9) > D(6) > D(3), throughout the experimental period. 6. The top-root relationships, however, showed the elastic reaction in accordance with the change in nutrition levels. From the viewpoint of community structure, it was considered that the change of two dimensional plane S/R nos. ratio and three dimensional T/R 3-D ratio in accordance with the nutrition level seemed to have the influence, in the result, on the change in the value of relative growth coefficient (h = tan θ).

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1. Mesocotyl and coleoptile length and mesocotyl-coleoptile elongation ratio (M-C ratio) in darkness were determined for 30 species of gramineous crops and grasses consisting of 22 genera and 4 subfamilies. 2. In common wheat, barley and rye, mesocotyl did not elongat, but coleoptile elongated up to 38-69 mm. 3. In the greater part of summer cereals and tropical grasses, the mesocotyl elongated up to 34-211 mm, whilc the coleoptile length was less than 10 mm. The M-C ratios of these crops and grasses varied from 6 to 36. 4. In rice, maize, oat and temperate grasses, both mesocotyl and coleoptile elongated; the M-C ratios of these crops and grasses were less than 5, and many of them were 2-3. 5. From the result of this investigation, gramineous crops and grasses were classified into 3 types (i.e., coleoptile elongation type, mesocotyle elongation type and intermediate type), based on the elongation of mesocotyl, coleoptile, and the M-C ratio. Wheat, barley and rye, which belong to the Triticeae of Festucoideae, showed the coleoptile elongation type. Panicoideae and Eragrostoideae showed the mesocotyl elongation type with the exception of maize. Oryzoideae and the Festuceae and Aveneae of Festucoideae showed the intermediate type, in which both mesocotyl and coleoptile elongate. 6. Mesocotyl length and the weight of 1000 seeds were positively and highly significantly correlated within the mesocotyl elongation type. 7. The M-C ratio of wild species was greater than that of cultivated species in the same genus.

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Ripening characters were compared between the japonica and the improved semi-dwart high-yielding indica varieties. The results obtained are as follows: 1. At the heading stage, there was a tendency that improved indica varieties had more spikelets per m₂. Especially, the receptive capacity (sink) of dry matter per m², which is represented by the number of spikelets per m² × weight of a hull, was larger in improved indica than in japonica varieties. 2. Improved indica varieties had smaller LAI (source) irrespective of growth duration not only in early variety group but also in middle and late variety group. 3. Accordingly, there was a tendency that improved indica varieties had smaller leaf area per spikelet at the heading stage. In addition, their hull size was large considering leaf area per spikelet, resulting in lower ripening percentage. As a result, there was no significant difference in yield between improved indica and japonica varletles. 4. There was no correlation between grain weight and leaf area per spikelet at the heading stage, but was a high positive correlation between grain and hull weight. 5. At the heading stage, among the varieties whose nitrogen contents in leaf blade were almost same, the improved indica varieties showed lower starch and higher sugar contents in culm and leaf sheath than japonica varieties. 6. Among the japonica varieties, the very early varieties whose yields were low had smaller LAI at the heading stage considering their number of spikelets per m².

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The influcnce of cropping season on lipid content and fatty acid composition of brown rice was investigated on six lowland non-glutinous varieties by early, normal, and late season cultures at Chugoku National Agricultural Experiment Station in 1977. The earlier the cropping season, the higher the lipid content and the significant difference between three cropping season cultures was observed. As to the fatty acid composition, the earlier the cropping season, the more the myristic acid, palmitoleic acid, stearic acid, oleic acid, and arachidic acid contents were revealed. On the other hand, the later the cropping season, the more the linoleic acid and linolenic acid contents were revealed. The significance of variation was observed between three cropping season cultures on oleic acid, linolcic acid, and linolenic acid contents and between late and normal season cultures and also bctween late and early season cultures on other fatty acid contents. The daily mean temperature during ripening showed significantly positive correlations with lipid content and myristic acid, palmitoleic acid, stearic acid, oleic acid, and arachidic acid contents and negative correlations with linoleic acid and linolenic acid contents. With respect to the fatty acid composition, there was highly negative correlation between oleic acid and linoleic acid contents. From the regression equations between oleic acid and linoleic acid contents and between ripening temperature and both the fatty acid contents in the previous and this papers, it was shown that the equal value of both the fatty acids was about 38.7% and both the fatty acids come to the same valuc at about 20 to 22°C on the daily mean temperature during ripening.

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Photorespiration competes with photosynthetic CO₂ fixation in C₃ plant and causes the decrease of net CO₂ uptake by about 5O per cent. It has been clarified that the rate of photorespiration is affected significantly by temperature and the concentrations of CO₂ and O₂. However, little has been known about the effects of nutrient conditions on photorespiration. In the present studies, the effects of nutrient deficiencies on photosynthesis, photorespiration and carboxylating enzyme activities were studied in rice plant (Oryza sativa L. cv. IR-8). The first experiment was conducted to survey the effects of nitrogen, phosphorus and potassium deficiencies on photosynthetic rates and carboxylating enzyme activities. Seeds were sown on the soil containing standard fertilizer. After fourth leaf had emerged, the plant was grown in water culture. Nutrient deficiencies were induced by withholding nitrogen, phosphorus and potassium from the culture solution respectively. The measurements were conducted at ripening stage when the symptons of nutrient deficiencies were clearly presented. The second experiment was conducted to confirm the effects of phosphorus deficiency on photosynthetic rates and carboxylating enzyme activities. Seedlings were grown in solutions containing different amount of phosphorus for four weeks. Thereafter phosphorus was withheld from each medium except that of control plants. The measurements were conducted at tillering stage and ripening stage. The rates of photosynthesis in terms of unit area of the fully developed uppermost leaf were measured in 3 per cent O₂ and 21 per cent O₂ by infrared gas analyzer. The measurements were done under the conditions of O.O3 per cent in CO₂ concentration, 5O klux in light intensity and 25°C in leaf temperature. Transpiration rate was measured by electric hygrometer simultaneously. Enzymes were prepared from 0.5 g fresh leaves mortaring with l0 ml of homogenizing medium and small amount of sand. The medium contained 0.05 M HEPES buffer (pH 7.7), 1 mM EDTA and 1 mM dithiothreitol. The extracts were centrifuged at 20000 g for 15 minutes and the supernatants obtained were offered to the determinations of the enzyme activities. Each procedure mentioned above was conducted at 5°C. The activity of RuBP-carboxylase (RuBPc) was assayed by measuring the rate of ¹⁴C (NaH¹⁴CO₃) incorporation into the acid-insoluble compounds in the reaction mixture containing 50 μmole tris (pH 8.5), 5 μmole MgCl₂, 20 μmole (2.5 μCi) NaH¹⁴CO₃, 0.5 μmole RuBP and 25 μl enzyme preparation. They made the final volume of 0.5 ml. After several minutes preincubation at 30°C, assay was conducted for 5 minutes initiating by the addition of RuBP to the mixture and stopped by adding 0.1 ml of 20 per cent acetate. The activity of RuBP-oxygenase (RuBPo) was assayed by determining the rate of O₂ consumption in the reaction mixture by oxygen electrode. Reaction mixture was 100 μmole Amediole (pH 9.3), 10 μmole MgCl₂, 1 μmole EDTA, 1 μmole RuBP and 200 μl enzyme preparation. They made the final volume of 1ml. Reaction was initiated by adding RuBP to the mixture at 30°C. The activity of PEP-carboxylase (PEPc) was assayed by determining the rate of ¹⁴C (NaH¹⁴CO₃) incorporation into acid-insoluble compounds in the reaction mixture containing 25 μmole tris (pH 8.5), 2.5 μmole MgCl₂, 0.05 μmole NADH, 0.55 IU MDH, 10 μmole (2.5 μCi) NaH¹⁴CO₃, and 25 μl enzyme preparation. They made the final volume of 0.25 ml. After 10 minutes preincubation at 30°C, assay was conducted for 5 minutes initiating by the addition of PEP to the mixture and stopped by adding 0.l ml of 20 per cent acetate. [the rest omitted]

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Mesophyll protoplasts of Nicotiana tabacum. cv. Bright Yellow mutant Aurea and N. glutinosa and of N. tabacum. cv. Burley 21 and N. alata were prepared from leaf tissue by enzymatic digestion and were fused with the aid of polycthylcne glycol. When the fused protoplasts were platcd on an agar medium or in a liquid medium for cell culture, new cell walls were regenerated from them and the cell division could be seen beginning on the 14th day of culture in the combination of N. tabacum and N. glutinosa, whereas in that of N. tabacum and N. alata 10th day of culture. Cell division process took place over again after that. After one month culture, almost all of survived protoplasts grew to cell colonies of 1-2 mm in diameter. The cell colonies were placed on an agar medium containing 3.0 mg/l l-Naphthalenacetic acid and 1.0 mg/l 6-Benzylaminopurine in order to induce callus formation. On the medium, they grew vigorously and formed calli of 2 cm in diametcr after 2 months culture. However, it was too difficult to select the hybrid callus. They were trans-fered to a modified LINSMAIER and SKOOG medium containing 1.0 mg/l kinetine and 1.0 mg/l indoleacetic acid. After one month of culture on this mcdium, the hybrid calli, showing greenish white with a compact appearance werc selectcd in contrast to the parental type calli tinged with a white or green color. Thirty-three somatic hybrid calli of the combination of N. tabacum and N. glutinosa and 2 calli of the combination of N. tabacum and N. alata were obtained. Many plantlets were differentiated from these calli when transfered to enriching zeatin. All of the mature flowering plants showed to be perfectly somatic hybrid, and the shape of the leaves and flowers indicated that many somatic hybrids were of an intermediate characteristic between N. tabacum and N. glutinosa and between N. tabacum and N. alata. A few plants had a strong resemblance to a parent or a scxual hybrid. The plant height of the many somatic hybrids were higher than that of the parental plants, and the male sterility of the greater part of the hybrid plants was visible under investigation, and it was possible to back cross. They were highly resistant to the tobacco mosaic virus. The chromosomc number of the somatic hybrids of the combination of N. tabacum and N. glutinosa was determined: fivc were amphidiploid, twenty-eight showed aneuploid with 50 to 88 chromosomes. On the other hand, thc chromosome number of the somatic hybrids of the combination of N. tabacum and N. alata also was determined : one was amphidiploid and the other aneuploid.

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除草剤ベンチオヵーブがヒエにおよぼす影響について,組織的な観察を行った. その結果,ベンチオカーブを処理した個体では,(1)発育中の葉の周縁生長に異常がおこり,筒状葉や,葉周縁部に抱合様式の変化,内側屈曲,外側屈曲,截形化,波状化や密着などの現象を結果している. (2)鞘葉基部の隆起,葉の蛇行状弯曲,葉表面の波状起伏,連続する二枚の葉の癒着,葉組織の壊死,葉の垂直伸長や維管束発達の歪曲などがみられる. (3)茎頂鞘層部の尖端附近,ときには最尖端部に並側分裂が誘発されており,茎頂組織の細胞にいちじるしい液泡化や異常な伸長生長が認められ,茎頂は全体的に長い形となる,などの諸点が明らかになった. これらの結果は,ホルモン系の除草剤の作用にきわめて類似したものであり,ベンチオカーブは非ホルモン系除草剤であるが,それ自体またほその分解産物が何らかの機作を通して生長調節的な作用を発揮し,ヒエに形態形成的な影響をおよぼすものと考えられる.

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Ten varieties were grown under the field conditions at the two locations, and number, diameter and dry weight of root were measured at the 4th leaf stage, the initial flowering stage and the full leaf expanding stage. The results obtained are summarized as follows: 1. Number, diamcter and dry weight of root attained to the maximum value about the initial flowering stage, and maximum diameter and dry weight of root were greater in late varieties than in early ones. 2. Number of roots per plant indicated a positive correlation with shoot numbcr (r=0.743), but dry weight of root per plant was correlated with dry weight of root per stem (r=0.792), not with shoot number. Moreover, maximum root diameter and dry weight of root correlated positively with stem length, number of leaves on main stem and stem diameter. 3. Root dry weight of each variety reached the maximum value several weeks earlier than shoot dry weight at each location. 4. During the period from the 4th leaf stage to the initial flowering stage, there were distinct differences among varieties in root and tuber growth rates. The growth rates in late varieties were higher in root, but lower in tuber, compared with early ones, and there was a highly negative correlation between them. However, varietal differences in growth rate per plant were very litte except Shimakei No. 161, and not related with the earliness. In addition, growth rates in each organ were correlated with their distribution ratios, not with growth rate per plant. 5. Root dry weight was significantly correlated with tuber yield. However, leaf and stem dry weight were greater in late varieties than in early ones and showed also highly significant correlations with tuber yield. Therefore, it was assumed that the relationship between root system and tuber yield was not due to the direct contribution of root system, but due to the pleiotropic expression of the earliness.

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夏期にガラス室で育成したC₃型作物(イネ,ダイズ)およびC₄型作物(ヒエ,トウモロコシ)幼植物を供試した. これらをグロース・チャンバーに移し,光(強光;48klx,弱光;27klx),気温(高温;昼28°/夜23℃,低温;昼23°/夜20℃)およびCO₂濃度(高濃度;1000ppm,標準濃度;300ppm)を組合せた処理を各5日間行った. 処理前後に生育調査を行い,特に全乾物重と葉面積の値から乾物生長速度(GR),純同化率(NAR)および期間中の平均葉面積(A)を計算して比較検討したところ,以下の事柄が明らかとなった. 1. 光の効果 (1)標準濃度CO₂・高温条件下では,弱光はNARの反応を低下させ,GRを抑制した. (2)高濃度CO₂によるGRの促進は,光の強弱にかかわらずC₃型作物がC₄型作物よりも著しく大きかった. これは前者のCO₂濃度に対するNARの反応が大きいからである. また,C₃型作物ではCO₂施与効果が強光によってさらに助長されることはなかったが,C₄型作物ではNARを媒介とした,CO₂と光によるGRの相加的促進が認められた. 2.温度の効果 (1)標準濃度CO₂・強光条件下では,低温はNARと葉面生長の両者を抑制することを通じてGRを抑制した. (2)全ての作物においてCO₂施与効果は高温により相加的に助長されたが,これは主としてNARの,一部は葉面生長の,促進に基ずくものである. ここでも温度の高低にかかわらず,C₃型作物のGRの反応はC₄型作物に比べてはるかに大であった.

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We conducted this work to get the informations about the shape and quality of rice kernel in the improved indica varieties, comparing with the japonica varieties. The results obtained are as follows: 1. In all varieties, a high positive correlation (r=0.9065) was found between the hull weight and the length × width of the kernel. 2. In all varieties, there was no correlation between the hull weight and the thickness of the kernel, but the varieties, which had bigger hulls, had a greater thickness in the kernel in the japonica varieties. On the other hand, the varieties which had bigger hulls and whose kernel's length × width were over 16 mm², had a smaller thickness in the kernel in the improved indica varieties. 3. Varietal differences of the increase in the grain weight were observed. Among the early varieties, the increase in the grain weight stopped more rapidly in Chosaeng Tongil which belongs to the improved indica variety than in Gohyakumangoku and Reimei which belong to the japonica variety. 4. White belly kernels occured more in the very early varieties and the improved indica varieties except SML 680 2/1 which is long slender kernel. At the heading stage, they had a much smaller leaf area per spikelet than the other japonica varieties. 5. In the japonica varieties, Gohyakumangoku Llnd Jinheung had a much bigger hull than the other japonica varieties (almost the same with IR-8, Chosaeng Tongil, SML 680 2/1, Namking 11, which belong to the improved indica variety.) and their grain weight were much larger than the improved indica varieties. But the percentage of the occurrence of white belly kernel was much lower in these than in the improved indica varieties. At the heading stage, they had 1.2 to 2.2 times larger leaf area per spikelet than the improved indica varieties. 6. A long slender kernel variety SML 680 2/1 produced 18.8% of white belly kernel, though the percentage was much smaller than that of the other indica varieties. 7. The opaque part of the white belly kernel was small in the very early varieties which had a small hull, and very large in the improved indica varieties which had a large hull.

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