We have shown in the previous paper that no difference in absorptivity of solar energy could be found between populations of soybean and rice at later stage of growth with high LAI, while the dry matter increment of soybean was considerably lower than that of rice indicating that soybean population might have lower efficiency for utilization and conversion of solar energy than that of rice population. The present investigation was carried out to elucidate the cause of the lower efficiencies of soybean in terms of absorptivity of solar energy in each layer of both crop canopies. 1. Incident radiation being absorbed and reflected by leaf layers, its flux density attenuates downward in the canopy. On the other hand, the upward radiations reflected by soil surface and leaf layers penetrate in the canopy, and the former attenuates upward for being absorbed by leaf layers and the latter increases upward for being accumulated in the canopy (Fig. 1). To evaluate the absorptivity in each leaf layer of canopy, these two components of upward flux need to be measured separately. But the separation of these components is impossible technically. In this study, therefore, the upward flux was divided into two components numerically. The absorptivities of solar energy in each leaf layer were obtained from calculation using the simulating formula. 2. At the earlier stage of growth with lower LAI, the absorptivities of solar energy in each leaf layer were higher throughout all layers in soybean canopy than in those of rice. At the later stage of growth with higher LAI, the relations tended to differ with height in canpoy; in upper layer of the canopy absorptivities of soybean were higher than those of rice, but in lower layer they were higher in rice. These tendencies were more significant in the case of photosynthetically active radiation (Fig. 7). These relations were considered as one of the determinant factors which made the utilization and conversion rates of solar energy in soybean canopy lower than those of rice at the later stage of growth with higher LAI.

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In the previous paper, it was suggested that non-glutinous rice and glutinous rice differed in lipid content and fatty acid composition of brown rice. In order to confirm lipid content and fatty acid composition of glutinous rice, brown rice and its milled rice of eleven glutinous mutant lines and three non-glutinous mutant lines, which were induced by gamma ray irradiation and ethylenimine treatment of lowland non-glutinous variety "Nihonmasari", and those of four comparative glutinous varieties were investigated. The lipid content of the glutinous lines, the comparative glutinous varieties, and one non-glutinous lines was significantly higher in both brown rice and milled rice in comparison with that of the original non-glutinous variety. The value of the non-glutinous line, however, was significantly lower than that of the glutinous line. As for fatty acid composition of brown rice and milled rice, the glutinous lines and the comparative glutinous varieties showed significantly higher myristic acid and palmitic acid content than the original non-glutinous variety. The stearic acid content showed also the same tendency except two comparative glutinous varieties of brown rice and one glutinous line and one comparative glutinous variety of milled rice, but the oleic acid content was lower. As regards the difference between the non-glutinous and the original non-glutinous variety, there was no significance in the content of above-mentioned four fatty acids of both brown rice and milled rice with some exceptions in oleic acid content. As the results, it was presumed that glutinous rice, as compared with non-glutinous rice, was higher in lipid content and higher in myristic acid, palmitic acid, and stearic acid content and lower in oleic acid content as for fatty acid composition.

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During July-August in 1980 air temperatures were lower and sunshine durations were less than those under the normal climate and heavy meteorological disasters were occured. Influences of the abnormal weather on growth and ripening of paddy rice were studied. 1. In 1980 dates of rice heading were delayed about 7 days compared with those in 1979 when the weather was normal, and it estimated that the delay was caused by low air temperatures. 2. In 1980 growth and ripening of rice were suppressed remarkably by the insufficient solar radiation. However, it was clear that the lower air temperatures had good effects on growth and ripening of paddy rice.

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[in Japanese]

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[in Japanese]

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Interaction of low temperature and water stress on the growth of transplanted rice seedlings was investigated. The results were as follows: 1. Root decapitation inhibited the growth of transplanted rice seedlings through water stress, and the application of antitranspirant or leaf pruning was effective to aleviate the growth inhibition (Table 1). 2. Spindly seedlings due to high temperature and low light intensity exhibited a poor growth as compared with vigorous one grown outdoors. This disparity was more conspicuous at low temperature than at normal one, and magnified by water stress put on the seedlings by ventilation. Rooting of spindly seedlings was completely inhibited by water stress due to ventilation (Table 2). 3. High osmotic pressure of medium solution which presumably put a water stress on the seedlings obviously inhibited their rooting. The same was observed in the elongation of seminal root of germinated seeds. The above inhibitory effect of high osmotic pressure on the rooting and root elongation was also more conspicuous at low temperature than at normal one (Fig. 1, 2, 3). The results obtained here showed that a much attention should be paid to avoid water stress on rice seedlings transplanted under low temperature.

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This experiment was conducted to select adaptable varieties of rice for late culture of direct seeding on well-drained paddy field, to study mechanism of yield stability. Experiment was composed of 2 nitrogen applying methods and 10 varieties and local strains (early and middle maturing) from 1976 to 1980. Yielding ability and yield stability were investigated by FINLAY's regression method and EBERHALT's test of deviation from regression. Results obtained are summarized as follows: 1. FINLAY's regression coefficients between each environmental yield and averaged yield of all environments were significant among varieties and strains except Nipponbare, however deviations from regression were not significant in all varieties and strains (Table 3). 2. Regression coefficients of semi panicle number types and panicle number types were above 1.0, while those of medium types and semi panicle weight types were below 1.0. It is suggested that yield stability was related to plant type. 3. Yield stability was studied in relation to stability of some yield components. Yield stability was less affected to stability of number of panicles per unit area, number of spikelets per unit area, and 1000 grain weight. It was closely related to stability of percentage of ripened grain (Table 4). 4. Ooseto and Saikai No. 137 showed good performance for late culture of direct seeding.

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The topdressing of ammonium sulfate and the foliar application of urea were carried out at the full heading time of rice plants on the paddy field where the nitrogen of 4 levels, that is 0, 5, 10 and 15 kg/10a, applies as the basal dressing, and the changes of nitrogen content of each organ of rice plants, the accumulations of nitrogen in the ear and the differences of protein content of brown rice were investigated. 1. The nitrogen percentages of leaf blade, leaf sheath and culm were high in order of the topdressing, the foliar application and the non-topdressing. The nitrogen percentages of ear were high in order of the foliar application, the topdressing and the non-topdressing. These orders were not changed regardless of the difference of varieties and the difference of the nitrogen amounts of basal dressing. 2. The nitrogen amounts accumulated in the ear were high in order of the foliar application, the topdressing and the non-topdressing. The more the nitrogen amounts of basal dressing, the more the nitrogen amounts accumulated in the ear. 3. The accumulation rate of nitrogen in the ear was higher on the foliar application plots compared with the other plots. It was assumed that the nitrogen absorbed by foliar application accumulated in the ear more immediately than the nitrogen absorbed from the root. 4. The protein percentage of brown rice was highest on the foliar application plots. The protein percentage of brown rice on the foliar application plots increased 9∼13% than that of the topdressing plots and 31∼34% than that of the non-topdressing plots on the average of every basal dressing plot. 5. The protein percentage of brown rice significantly increased by the foliar application of urea regardless of the cool-summer damage due to delayed growth.

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Electron microscopic observations were made on the ultrastructural changes of the chloroplasts of leaf-blade mesophyll cells in the 3rd leaf which was fully expanded and the 5th leaf which was developing at the start of temperature treatments. The temperature treatments were started at 3.2 to 3.3 leaf number stage. The varieties used were Sasanishiki (japonica), IR 24 (indica) and Milyang No. 23 (japonica×indica). 1. Under normal temperature (25°/20°C), the leaf color of the 5th leaf was white when it was 3 to 4 mm length, yellowish white when it elongated to 2 to 3 cm length, and green when it emerged 4 to 5 cm above the 4th leaf sheath. The plastids of mesophyll cells developed from proplastids to chloroplasts along with greening of the leaf, and with increasing of their grana and thylakoid stratum resulted from fusion of vesicles (Fi9. 1-7). 2. Under low temperature (17°/12°C) for 2 weeks, the greening of the 5th leaf was suppressed; the leaf color of Sasanishiki became light green, and yellowish in those of Milyang No. 23 and IR 24. The Chloroplasts of Sasanishiki contained large starch grains and a considerable number of grana, but those of Milyang No. 23 and IR 24 contained small starch grains and numerous vesicles without forming normal grana (Fig. 8-10). The 5th leaf grown under 1 week normal temperature after 2 weeks low temperature pretreatment, restored its color to green. The chloroplasts of mesophyll cells in all varieties rapidly restored grana formation, degrees of the restoration being higher in Sasanishiki, Milyang No. 23 and IR 24 in that order (Fig. 11-13). 3. Under low temperature for 1 or 2 weeks, the 3rd leaf discolored; light green in Sasanishiki, yellow or brown in Milyang No. 23 and IR 24. Under low temperature for 1 week, the chloroplasts of mesophyll cells in all varieties contained large starch granis and limited number of grana-thylakoids (Fig. l7-19). After 2 weeks of low temperature, the chloroplasts in Milyang No. 23 and IR 24 contained macrograna, but no starch grains, and decreased number of grana. Single thylakoids arranged parallel with the chloroplast envelope were often observed (Fig. 20-23). The chloroplasts of the subepidermal cells of the adaxial surface contained numerous vesicles which might be formed from separated thylakoids (Fig. 24, 25). The chloroplasts of mesophyll cells only in IR 24 contained phytoferritin in stroma (Fig. 23). 4. The subepidermal cells of the adaxial surface of the 3rd leaf in Milyang No. 23 and IR 24, which became brown due to low temperature for 1 or 2 weeks, formed dehydrated masses which contained large starch grains. The chloroplast envelope became indistinguishable (Fig. 26, 27).

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Electrical conductivity (EC) and mineral element contents in the water effusate of leaf blades treated at different temperatures were estimated to know a relationship between EC and low temperature resistance of varieties. 1. EC increased far more in the leaf treated at low temperature (5°/5°C) in the dark than that at normal temperature (25°/20°C) in the light, the degree of increase being larger after 96 hr than 48 hr treatment (Fig. 1). Each mineral element content increased more under low temperature than under normal temperature, the degree of increase being K>Ca>Mg>Na in that order (Table 1, Fig. 2). The content of each element and EC showed significantly high positive correlation coefficients (Fig. 3). 2. The ultrastructure of chloroplasts in IR 24 treated for 96 hr at low temperature changed markedly; the grana stacks being broken down into numerous diffused vesicles. The chloroplasts of Sasanishiki changed little (Fig. 4). 3. Under normal temperature, there was no varietal difference in EC, but under low temperature a great varietal difference of EC was shown. In general, the degree of EC increase by low temperature was indica type>japonica×indica>japonica type in that order (Fig. 5). 4. It was suggested that EC values of the water effusate of leaf blades treated at low temperature may be an index of low temperature resistance of rice varieties.

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In the present paper, investigations on the content of zinc, iron, manganese, and copper, and uptake and distribution of ⁵⁹Fe and ⁵⁴Mn in maize plant cultured in the nutrient solutions in which zinc concentration was changed in 0, 0.005, 0.05 and 20 ppm were carried out. Results were obtained as follows: 1. Zinc content in each organ of plant grown at the standard plot (0.05 ppm Zn) was greater than that of both the Zn-lacking plot (0 ppm Zn) and slightly Zn-added one (0.005 ppm Zn). Especially, it was the greatest in the roots at the excess plot (20 ppm zn) and also showed heavily at the other organs (Table 1). 2. Iron content in leaf blades, leaf sheaths and stems at both the lacking and slightly Zn-added plots was greater than that of the standard one after tassel-shooting time, and it was the greatest in roots at the excess plot. In the excess plot this element was prevented from translocating for the top when it was accumulated in roots, moreover it was occurred chlorosis in the upper green leaves (Table 2). 3. Manganese content in each organ at the standard plot was less than that of both the lacking and slightly Zn-added ones. This element was the least in each organ at the excess plot, and it was inhibited to be absorbed into the plant at the excess plot (Table 3). 4. Copper content in the leaf blades and stems was few difference among various plots. Its content in the leaf sheaths and roots of the lacking plot was remarkably increased at the tassel shooting time, and in the roots of all plots it was greater than that of other organs (Table 4). 5. Concerning about Fe-Zn ratio at the harvesting time, it was the greatest in the roots at the standard plot. On the other hand, in other organs it was greater at the lacking and slightly zn-added plots, and very smaller at the excess one. Mn-Zn ratio in each organ at both the lacking and slightly Zn-added plots was greater than that of the standard plot, however, it was the smallest at the excess one. Relating to Cu-Zn ratio at the tassel-flowering time, it was very high in the leaf sheaths and roots at the lacking plot. This ratio was found few difference among the standard, the lacking and the slightly Zn-added plots, and especially the lowest at the excess one (Table 5). 6. ⁵⁹Fe distribution in the leaves was the greatest at the standard plot compared to the others. On the other hand, distribution and distributed concentration of this element in the roots were the greatest at the excess plot, however, in the leaves and stems distribution ratio of ⁵⁹Fe was the least (Table 6). 7. ⁵⁴Mn distribution in the leaves was greater at the standard plot than that of the others, and the least at the excess one. This distribution in the stems was great in between at the slightly Zn-added and standard plots, and in the roots was the greatest at the slightly Zn-added one. Distributed concentration of this element was high in the leaves and stems at the lacking plot, and also in the roots at the slightly Zn-added one. That was the lowest in each organ at the excess plot. Distribution ratio of ⁵⁴Mn was the highest in the leaves at the standard plot and in the roots at the slightly Zn-added one, but lower in the stems at each plot (Table 7).

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The influences of air temperature on the growth of mitsumata under pot conditions, were examined from the view point of dry matter production. The results were summarized as follows: 1. The apparent photosynthetic rate was light-saturated at about 20 klx, though slight depression was observed above 40 klx, when the plants were grown under 50% shading (Fig. 1). The optimum temperature of apparent photosynthesis was found at about 26°C. The respiratory rate increased from 20 to 40°C with 1.98 of Q₁₀ value (Fig. 2). 2. The Relative Growth Rate (RGR) increased with increasing air temperature from 15 to 25°C. The Net Assimilation Rate (NAR) showed the same behaviour to RGR. The Leaf Area Ratio (LAR) decreased with increasing air temperature (Fig. 3). The rate of apparent photosynthesis grown under 25, 20 and 15°C for about 90 days, was the highest at 24, 21 and about 15°C, respectibly (Fig. 4). 3. The length of the new shoot and the thickness of the stem decreased markedly at 30°C, and the ratio of the stem thickness to the shoot length was the highest at 20°C (Fig. 5 and Fig. 6).

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In order to find out a suitable index for the evaluation of palatability, some experiments on the texture of cooked rice of two japonica varieties (Sasanishiki and Nihonbare) were conducted using a General Foods Texturometer. Measurements were done on the cooked rice of different degree of swelling. The degree of swelling was adjusted by adding different amount of cooking water to the kernels. Mechanical parameters analyzed from the texture profile were hardness, cohesiveness, springiness, chewiness, adhesiveness, viscousness and stickiness as shown in Fig. 1. Hardness, cohesiveness, springiness and especially chewiness were decreased with the increase in swelling. The decreases were remarkable at the range over the swelling degree corresponding to the highest palatability which had been made clear in a sensory test (Fig. 3). On the other hand, adhesiveness, viscousness and especially stickiness were increased with the increase of swelling. These increases were particularly rapid up to the swelling for the highest palatability, but the increment was ceased at higher ranges of swelling (Fig. 4). Product values of chewiness and stickiness peaked at the degree of swelling for the highest palatability (Fig. 5). This value was therefore considered to be an appropriate index for the indication of palatability. Rices of indica variety, paticularly of long grain variety were higher in hardness and chewiness but much lower in adhesiveness, viscousness and stickiness as compared with japonica rices. The values of textural palatability index (TPI) were extremely low in the indica rices. Japanese varieties of high popularlity on the whole showed highest TPI values than unpopular varieties (Table 1). This result seems to suggest usefullness of TPI at least for japanese taste.

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Effects of kernel size, apparent quality of brown rice and grain maturity on the texture of cooked rice were investigated using a General Foods Texturometer. The results obtained are summarized as follows: 1. Primary parameters of texture such as hardness, adhesiveness and viscousness which are shown as the strength of force or the amount of work were sharply affected by the size of the test kernel, although the other primary parameters were not affected (Table 1). And it was revealed that the degree of these effects were just proportional to the kernel weight of test rice. Consequently, revising of texture value in consideration of the kernel weight was thought to be necessary for an accurate measurement of rice texture. 2. Rice texture was also affected by apparent quality of brown rice from which the test rice had been made. Cooked rice from white belly kernels and white core kernels showed lower values of stickiness and the textural palatability index (TPI) as compared with normal perfect kernels. Green kernels and rusty kernels were a little low in hardness and chewiness, though they showed rather high values in stickiness. Thus their TPI values were not inferior to the perfect kernels (Table 2). 3. Texture values markedly changed with the progress of maturation (Fig. 1-3). Values of hardness and chewiness were very high at the early stage of ripening, but they were rapidly decreased with maturity. On the other hand, adhesiveness, viscousness and stickiness increased during maturation, and showed their peak values at the right stage of maturity. Overripening seemed to increase the values of hardness and chewiness and decrease those of adhesiveness, viscousness and stickiness. TPI, therefore, were almost the highest at the right time of maturation (Fig. 4). Above results suggest that harvest of rice should be done at the right time of grain maturation to secure the palatability of cooked rice.

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