[in Japanese]

View full abstract

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.

View full abstract

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.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

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).

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

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.

View full abstract

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).

View full abstract

[in Japanese]

View full abstract

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.

View full abstract

[in Japanese]

View full abstract

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).

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

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).

View full abstract

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

View full abstract

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.

View full abstract

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).

View full abstract

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.

View full abstract