Considering annual variation of the potato shoot growth and its relation with the meteorological factors, fresh weight of shoot (shoot weight) in three main cultivars was weighed at four to six times during the growing season (June to September) through ten years (1972-1981) at the Hokkaido National Agricultural Experiment Station. 1. Annual variation of shoot weight in each variety increased after sprouting to late July, then decreased slightly on August, when the early variety (Danshakuimo) reached the harvesting stage. Thereafter, in two late varieties (Norin No. 1 and Benimaru). it turned to increase again and showed the maximum value on late September (Fig. 1). Comparing it among the varieties, Danshakuimo showed the larger value than the other two varieties since middle July (Fig. 1). Shoot weight, however, showed significant positive relations among the varieties at most of the sampling date. It indicated that, when shoot weight was larger in one variety, it tended to be larger in the other two varieties (Table 2). 2. Annual variation of the date of sprouting influenced little on shoot weight of July 1 (just before the first flowering stage), which depended mostly on the growth rate of shoot weight (shoot GR) from sprouting to July 1 (Tables 1, 3). Shoot GR from July 1 to 15 showed large effect on shoot weight from middle July to late August. Annual variation of shoot weight on late September was, however, mainly affected by the rate of shoot senescence since late August (Fig. 2, Table 3). 3. Shoot GR from sprouting to July 1 was larger when maximum and minimum temperature was higher. The simple correlation coefficients of shoot GR with these factors were, however, realtively low. It seemed also to be effected by solar radiation and precipitation (Figs. 3, 4). In addition, shoot GR from July 1 to 15 showed remarkable relation with maximum temperature in three varieties, i.e. it was smaller when maximum temperature was within 22°-23°C and precipitation was less than 0.5 mm/day (Fig. 5). 4. The relations of solar radiation with shoot GR on July and with shoot weight on August, and of solar radiation with shoot weight of September were significantly negative. The results indicated that potato plants increased the shoot growth and retarded the shoot senescence when solar radiation was limited, which would result in minimizing the decrease of solar radiation interception by the shoot (Figs. 5, 6, 7).

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Thermal reaction in the growth of rice plants at the vegetative stage was compared among different ecotypical groups. Eighteen varieties including 4 japonica, 2 javanica, 5 indica, 4 Chinese-indica and 3 Tongil group (an indica-japonica-cross variety group bred in Korea) were used (Table 1). Treatment temperature was set at a day-night regime (0600-1800 hours) of 20∼10°C, 25∼15°C, 30∼20°C or 35∼25°C in a natural light room of the phytotron. The treatments for 20 days started at the 4-, 6- or 8-leaf stage in Experiment I, at the 4- or 6-leaf stage in Experiment II, and at the 4- leal stage in Experiment III. The increments in plant height, stem number, leaf age and leaf dry weight were followed in the course of the temperature treatments (Figs. 1∼8). As for plant height, japonica and javanica varieties showed higher elongation activities (comparative values with the 30∼20°C plot) than the varieties of other types under the cool temperature conditions, and indica and Tongil group varieties were higher in elongation activity under the high temperature condition (Fig. 9, Tables 2 and 3). The data on stem number showed inconsistencies among repeat experiments and also among different varieties in the same type, and thus no clear tendencies were found (Fig. 10, Tables 2 and 3). Leaf age did not show much difference among different ecotypical groups. The comparative increments tended to be larger in Tongil group, Chinese-indica and indica varieties at the cool temperatures, while at the high temperature in japonica, Tongil group and Chinese-indica varieties (Fig. 11, Tables 2 and 3). As for leaf dry weight, japonica and javanica varieties showed larger comparative increments at the cool temperature regimes, and Tongil group did the largest at the high temperature regime (Fig. 12, Tables 2 and 3). Table 4 summarizes the above-mentioned results. Generally speaking, japonica varieties showed the highest adaptability to the cool temperatures, Javanica type was close to japonica, and the other 3 types were clearly lower in adaptability. At the high temperature, Tongil, indica and Chinese-indica types showed higher adaptabilities than japonica and javanica types though the difference was comparatively small. This paper confirmed general ideas, which have been induced from many data in papers on related subjects, on the difference in the thermal reactions among different ecotypical groups of rice plants. Further elaborate studies on this line is expected, particularly studies based on physiological analysis of metabolism using a larger number of varieties in each ecotypical group.

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Even when rice seedlings with uniform size and age were planted as the singling in each pot containing the same amounts of nutrients and were precisely cultured at outdoor, a difference of one leaf frequently appeared in the total leaf number of the main shoots, one had N leaves and the other N-1 leaves. It is already known that the difference is a kind of individual variation. However, morphological aspects of the difference are not yet clearly demonstrated. Morphology of the main shoots were compared between the plant group having N leaves and that with N-1 leaves in total leaf number on the main stems. Morphological characters analyzed were the changes in the length of leaf laminae, leaf sheaths and elongated internodes successively developed on the main stems. Morphological variations based on the changes were clearly revealed inter groups but not intra groups (Figs, 1 and 2). The variations inter groups as follows. 1) Although the change in successive lamina length resembled in both groups up to the N-1 leaf position on the stem, the flag leaf lamina of N leaf group is conspicuously shorter than that of N-1 leaf group. 2) Although the change in successive sheath length resembled in both groups up to the N-2 leaf position on the stem, a quite different pattern was shown at the leaf positions more than N-2 leaf 3 on the stem. 3) The successive internode length on the main stem with N-1 leaves, which had five elongated internodes, linearly increased. The main stem with N leaves had six elongated inter-nodes. Culm length of the main stem was relatively greater in N-1 leaf group than N-1 leaf group. However, the length of each two successive internodes in upper positions was relatively greater in N-1 leaf group than N leaf group. Two different morphological types, which are indicated by the above-mentioned characters can be regared as a kind of "growth type". These two growth types are responsible for the variation shown at the total leaf number on the main stem under this experiment precisely cultured, and they occur within single cultivars assumed to be a "pure line". Even these types appeared in the precisely culture condition, therefore they seems to be present in the culture condition of conventional breeding experiment.

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The effects of seed-blends row seeding on lodging and yield were examined at five nitrogen levels with direct sowing on well drained paddy field. Two varieties "Koshihikari", tall and lodging-susceptible, and 'Kanto 100', short-statured and lodging-resistant, were used. The two varieties were sown in different mixing rate, including the pure stands. Results of the experiment can be summarized as as follows: 1. Compared on the same nitrogen level, the higher the relative mixing rate of Kanto 100, the less the lodging of community and the more the lodging resistance of Koshihikari in itself. The lodging resistance of Koshihikari was increased in the mixtures by means of the shortening in culm length and the increase in breaking resistance, while that of Kanto 100 was decreased. The less the rate of variety in the mixtures, the more the changes in characteristics of the variety. 2. The positive effect of mixed planting on yield increase was observed in plot of medium fertility level where Kanto 100 successfully prevented Koshihikari from lodging, but no effects were observed in low fertility plots with no occurrence of lodging, nor in too fertile plot where Kanto 100 faild to prevent lodging. 3. Koshihikari had more the percentage of ripened grains and the yield when grown in the mixtures than when grown in the pure stand. Therefore Koshihikari showed the strong competitor in these characters in mixed planting the same as previously in alternate rows planting. However, the panicles and the spikelets number of Kanto 100 increased, while those of Koshihikari tended to decrease in the mixtures especially in low fertility level. These results suggested that the relative competitive ability of variety was reversed during growth process. 4. The lodging of community was highly and positively correlated with the lodging index. Multiple regressions where applied to estimate the lodging index (I) and the yield (y) using the following equations : I = a + bx₁ - cx₂ + dx₂² y = e + fx₁ + gz - hz² where x₁ is The fertility level, x₂ is the percentage of Kanto 100 in the mixtures, z is the degree of lodging at 30 days after heading and the characters from a to h are all positive coefficients.

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Nitrogen fertilizer as ammonium sulfate was applied to soybeans [Glycine max (L.) Merrill cv. Bonminori and Enrei] at flowering stage to examine effects of application rate and placement on seed yield and protein yield. Seed yield of "Bonminori" was increased from 306g/m² to 360g/m² by the application of supplemental nitrogen in the range of 0gN/m² to 18gN/m². The result indicated that higher rate than that at basal application was required for the significant increase (20 to 30 g/m² of seed yield. When development of roots was poor and seed yield was low without the supplemental nitrogen, the effect of the application on the seed yield was remarkable. In "Enrei", furrow placement of the supplemental nitrogen at one side of plant rows allowed the larger yield response than both-sided furrow placement and also as deep application (40cm deep in soil) did than surface application. Nitrogen content of seeds was also increased with application rates of the supplemental nitrogen in the similar way as seed yield. The increase was mainly due to increase of protein-nitrogen. Ratio of 11S globulin to 7S globulin of seeds was not affected by the increase of protein content caused by the application of the supplemental nitrogen.

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The objective of the present study is to obtain fundamental knowledge to monitor remotely the physiological-ecological status of crops in fields (Figs 1, 2). In this paper the relationships between transpiration rate, stomatal resistance, canopy temperature, vapor pressure deficit (VPD) and photosynthetically active radiation (PAR) were investigated. A model for estimating transpiration, which was constructed using the heat balance equations, was also examined. 1. The transpiration rate had close positive correlations with the canopy temperature, VPD and PAR, although the coefficients were not significant in some cases (Table 1). 2. The stomatal diffusion resistance was closely correlated to the canopy temperature and PAR by negative coefficients and slightly correlated to the VPD. The PAR had a relatively larger negative influence on the stomatal resistance than the canopy temperature (Table 1). 3. The transpiration rate was estimated by a multi-regression equation of the canopy temperature, VPD and PAR with a coefficient of 0.84. The stomatal resistance was also estimated by a multi-regression equation of the canopy temperature and PAR with a coefficient of 0.73. These regression coefficients were relatively small, indicating that the relationship between some factors were non-linear, and that factors such as windspeed may have influenced the results (Eq. 1, 2). 4. Although those relationships described above were qualitatively ascertained, correlation coefficients obtained were not high (0.6∼0.8) enough to be used for the monitoring. 5. A model for estimating transpiration was presented, which was constructed of heat balance equations with a single leaf (Eq. 3∼7). The estimated transpiration rate calculated by substituting remotely sensed data into the model was closely correlated to the transpiration measured by means of a steady state porometer (Fig. 3, r=0.95^**). As a result, the possibility was suggested to be able to estimate remotely and in real time the transpiration rate of field crops by means of the multi-sensing. An estimation model of stomatal resistance was also examined for the remote monitoring (Eq. 8∼10).

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Development of all axillary shoots was investigated using tillering cultivars (delegated by cv. Longfellow) and no-tillering cultivars (delegated by cv. Yellow Dent) in maize. There was a buttress or axillary bud with only prophyll at the axil just above the topmost fertile ear node in both cultivars (Figs. 1, 2), but this did not develop any more (Fig. 3). Axillary buds differentiated acropetally, but ultimately the upper the node, the more the shoot developed exclusive on the tillers from lower nodes (Fig. 4). When shoot apex turned into reproductive stage (33 and 34 days after planting in Longfellow and Yellow Dent, respectively), the apices of upper axillary buds developed more rapidly than those of the lower buds, and initiation of young head occurred basipetally exclusive of the tillers which elongated at earlier stage (Tables. 1, 2). In vegetative stage, there was a similarity between Longfellow and Yellow Dent in respect to development of axillary buds. In Longfellow, lower buds developed into tillers, the shoot apices of them were tassel in the lower tillers, androgynous with both staminate and pistillate spikelets in the middling tillers (Table 1). Axillary buds at upper nodes than 5 formed ear, the upper the node, the longer their length exclusive of. the tillers (Table 1). In Yellow Dent, when shoot apex initiated inflorescence, the development of lower axillary buds (node 2-6) became slow and died during vegetative stage (Table 2). The inflorescence upper than node 6 was female, the upper the node, the longer their length (Table 2). Each secondary shoot produced tertiary shoots. The relation between secondary and tertiary shoots resembled to the relation between primary and secondary shoots.

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Effects of shoot apex excision, leaf cutting and upper axillary shoot excision at four developmental stages (Table 1) on development of axillary shoot in tillering (cv. Longfellow) and no-tillering maize (cv. Yellow Dent) were investigated. When shoot apices were excised (upper internodes and upper axillary buds were excised at the same time) at vegetative and apical inflorescence initiation stages, axillary buds at lower node developed into tillers in both cultivars. Excision of developing apical inflorescence a little promoted development of axillary shoots at middle nodes. Excision at tasselling stage had no effect on axillary shoots (Figs. 1, 3). Leaf cutting at any stage resulted in suppression of development of all axillary shoots (Figs. 2, 4). When uppermost axillary shoot which had developed into fertile car was excised before silking, the axillary shoot just below it developed into fertile ear.

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We developed the new direct sowing method of paddy rice to get better seedling establishment and higher lodging resistance than those by the former method, namely direct sowing on the surface of flooded soil. In the new method, seeds are coated with calcium peroxide, which promotes emergence and seedling establishment, and sown into flooded soil (to the depth of 1 - 2 cm) after puddling and leveling. We named this method "DIPPS" which is short for "(Di)___-rect Sowing of P__-addy Rice into P__-uddled and Leveled S__-oil". In the recent years, cultivation experiments by DIPPS have been carried out. In some cases of the experiments the yields were even higher than those by the conventional transplanting method. But it was also found that the percentage of emergence of seedling establishment was sometimes seriously low. Several researches in this problem showed that soil reduction is one of the factors that restrains emergence, and further research is required from this viewpoint. We investigated the oxidation-reduction state (ORS) of flooded soil in the vicinity of the seed coated with calcium peroxide (coated seed) and the non-coated seed in two ways, one by an oxidation-reduction electrode (Figs. 6 and 7) and the other by oxidation-reduction indicator (methylene blue) added to soil (Figs. 1-5). 1. The vicinity of the coated seed sown into reduced soil immediately formed a locally oxidized spot (Fig. 3). But it was only until germination (3-5 days after sowing) that the soil-oxidizing effect of calcium peroxide lasted. Thereafter, the soil in the spot was more reduced than that outside the spot (Fig. 4). 2. The vicinity of the coated seeds sown into oxidized soil was in oxidized state for 3 days after sowing. Then, after germination, the vicinity of the seeds was, in some cases, more rapidly reduced than the outside of the vicinity (Fig. 1). The reduction in the vicinity of the coated seed was more temperate in oxidized soil than in reduced soil. 3. The soil was reduced more rapidly within the vicinity of the non-coated seed than the outside from the next day after sowing whether it is sown into oxidized or reduced soil (Figs. 2 and 5). But the degree of the reduction was higher in reduced soil. 4. These observations show the difference in ORS between the soil within and outside the vicinity of the seed coated or not coated and also indicate the specificity of ORS in the vicinity of the seed. Thus, in order to elucidate the relationship between soil reduction and emergence or seedling establishment, ORS of the soil in the vicinity of the seed should be noticed. 5. A part of the promotive effect of calcium peroxide on emergence and seedling establishment could be explained as local oxidation of soil, by which the soil in the vicinity of the coated seed was kept in oxidized state which is supposed to be favorable for germination. But it remained unknown exactly how calcium peroxide stimulates elongation of coleoptile which is essential for the promotion of emergence and seedling establishment. We suspected that unstableness in emergence and seedling establishment had much to do with the shortness of soil-oxidizing effect of calcium peroxide.

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Physiological activities of hulls of unclosed and wounded spikelets were compared with those of normal one during ripening. The results are as follows : 1. In the checking at early and middle stage of ripening, fresh weight, percentage of water content and chlorophyll content were lower in hulls of unclosed and wounded spikelets than in those of normal one. And respiratory and photosynthetic activities were also lower in these. 2. Increase in dry weight of hulls and kernels was lower in these spikelets, of which physiological activity declined. 3. There was a negative correlation between degree of damage on spikelets by Typhoon and dry weights of hull and kernel. From these results, it was demonstrated that decline in physiological activity of hull of spikelet cause to decline in sink activity, i.e., pumping up carbohydrates from leaf and stem.

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茶葉光合成の低温阻害に及ぼす生長調節剤の影響を検討するため, 葉片または個葉をABA, BA, GAまたはIAAを含んだ溶液に浮かべ, 照明下(12klx), 12℃の低温処理を2日間行なった. 対照として, 温度を20℃にした区を設けた(BA と ABAのみ). 蒸留水に比べて, 12℃の光合成はGAで, やや促進され, IAA でやや阻害された(第1図). BA (40μmole)は20℃での光合成速度を促進し, 12℃の光合成及び光飽和のヒル反応活性の阻害を助長した(第2図). 一方, ABA (5μmole)は20℃での光合成を阻害し, 光合成及び光飽和のヒル反応活性の低温阻害を軽減した. ABAとBAの効果は低温処理前に投与しても認められた(第2表). また, ABAとBAにより葉身のショ糖とデンプン量は影響されなかった(第1表). 光合成低温阻害の感受性に対するABAとBAの作用機構について検討した.

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1. 粒莢重比(莢がら重に材する粒重の比)を同化産物の子実への分配効率を表わす形質の一つと規定した. 個体内部位別の粒莢重比を調査し, この形質の変動を検討するとともに, 多数品種の粒莢重比および莢がらの厚さを調査し, 粒莢重比の品種間差およびその要因を検討した. 2. 個体内莢間の粒莢重比の変動は, 粒重や莢がら重の変動より安定していた. これは粒重と莢がら重が密接な上の相関関係にあるためで, 粒の充実のためには莢がらの充実が重要であることが推察された. 3. 下位節莢は上位節莢より粒莢重比が高かった. これは下位節莢が個体の中央周辺にあり, 開花の早い莢が多く, したがって, 粒の充実期間が比較的長くなるためと推察された. 4. 莢がらの厚さと粒莢重比は密接な関係があり, 粒莢重比の品種間差の要因の一つは莢がらの厚さにある. 更に, その厚さを一定にしても粒莢重比に品種間差が認められた. これは粒重が等しくとも莢がら重に差があるからで, 莢がらの大きさに対する粒の充実程度も品種間差の要因になっていると推察された.

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3. Tuberosum親に比べ, 雑種系統のうちただびとつNo.40は生育初期の葉面積展開速度が大きかった. 大部分の雑種系統では8月後半に葉面積指数(LAI)が最大となリ, その値はTuberosum親に比較して大きかった. 極晩生のNo.6およびNo.40は10月上旬まで大きなLAIを維持した(第2図). 調査期間中(萌芽から10月4日)の平均個体群生長速度(CGR)では,雑種系統の平均値はTuberosum 親に比べわずかに大きく, 平均純同化率(NAR)では小さかった. また, 塊茎形成期以降ではほとんど雑種系統および親品種で下均CGRならびに平均NARが増大する傾向があった. 葉積(LAD)では大部分の系統がTubcrosum親に比較して大きな値となった. 塊茎形成期から10月4日の平均塊茎乾物増加速度(TGR)では, 雑種系統および両親の間に大きな差異は認められなかったが, No.23ならびにNo.40はTubCrosum親に比べ有意に大きかった(第3表). 全乾物重および塊茎乾物収量は,平均CGR, LADおよび平均「FGRと有意な正の相関を示したが, 塊茎乾物収量とLADとの間には有意な関係は認められなかった(第4表). CGRは萌芽から6月19日の期間ではLAIと, 7月7日から7月24日ならびに8月12日から8月28日の期間ではNARと有意な上の相関を示した. また, CGRとTGRの間には7月25日から8月10日期間を除く全生育期間で有意な正の相関が認められた(第5表).

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種子根をつけたイネの胚盤組織を, ニ培地法を用いて無菌的に培養した. ショ糖を胚盤に与えて根に供給し, 種子根から1/4濃度の MS無機塩類を吸収させた. 根の生体重と種子根長は, 培養期間が長くなるにつれて増加し, 培養根は3か月後でもなお正常に生長した. 培養3か月後の胚盤の微細構造を, 透過型電子顕微鏡を用いて観察し撮影した. 胚盤細胞の多くは, 培養3か月後でも正常であり, 核・プラスチド・ミ卜コンドリア・脂質粒・小胞体・ライボゾームなどの細胞内容物を含んでいた. 発芽2週間後の胚盤細胞に大型液胞が存在し, この時期すでに胚盤細胞の崩壊することが前報で観察されているが, このような液胞の形成は, 培養3か月後の多くの正常な胚盤細胞においては観察されない. 胚盤上皮細胞の先端部及び胚盤維管束付近の胚盤柔細胞内に, しばしば多層の粗面小胞体が観察された. また細胞質内に蛋白質性の結品構造が見られ, その格子間隔は約12nmと測定された. これらの事実は, 胚盤上皮細胞及び胚盤柔細胞において, 蛋白合成活性の高いことを示唆しており, 培養根の生長に対する合成酵素系の働きを推測させるものである. 以上の観察結果から, イネの発芽後期における胚盤細胞の劇的な崩壊は, 幼芽または胚乳あるいは両者の存在と関係する現象であり, 胚盤細胞自体に内在した要因にもとづくものではないと思われる. すなわち, 無菌培養など好適な外囲条件が与えられるならば, イネの胚盤細胞は長期間生存し, 3か月以上ものあいだ活発な生理機能を営みつづけるものと言うことができる.

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卜ウモロコシの一代雑種における雑種強勢の発現および収量性を既報の生育相の慨念モデルおよびそれに関連する形態的・生理的形質の観点から明らかにするため, 5系統の近交系とそれらの総当り交配で得られた一代雑種20系統を用いて比較検討した. その結果, 一代雑種では近交系と比べて次のような変化が認められ, 収量成立上有利に作用しているものと考察された. 1. 出芽期から雄穂分化期に至る第一相の期間は顕菩に短縮された(第1表). これは, 葉原基分化速度において超優性および完全優性が認められ(第3表), これらが著しく速められたためであった(第1図). 2. 雌穂分化期から絹糸伸長始期に至る第二相の第二期では, 頴花原基分化速度において超優性および完全優性が認められ, その結果, 分化頴花数が増加した(第3表). このことは, sinkの潜在的拡大を意味すると考えられた. 3. 絹糸伸長始期から絹糸抽出期に至る第二相の第三期の期間は, 展葉速度が速くなったことにより, 明らかに短縮された(第2表, 第2図). この期間は相互遮蔽の最も著しい時期であるが, 雌穂より上位の節間の急激な伸長およびこれに同調する雌穂の発達, すなわち, 絹糸の急激な突出によって, この収量成立上のクリティカル・ステージを回避しているものと考えられた.

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小胞子初期の冷温処理による不稔の発生は, 穎花分化期から小胞子初期までの水温(前歴水温)および窒素供給量(前歴窒素)によって著しく変動した(第1表および第2図). 小胞子初期のイネの耐冷性は, 前歴期間の高水温(25℃)および低窒素(10ppm)によって増大し, 低水温(20℃)および高窒素(80 ppm)によって減少した. 前歴低水温による耐冷性の低下は水深によって異なり, 水深10 cmで大きく, 水深1cmでは小さかった(第2表). 穎花分化期以前および小胞子初期以後の水温および窒素供給量による耐冷性の変動は, 全くないかもしくは小さかった(第1表, 第2図). 上述の前歴期間はわずか10日間余にすぎないが, この期間の栽培条件によってイネの耐冷性が大きく変動する重要な時期である.

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