Grain size is one of the important yield components and it has influences on grain yield as well as grain quality. However, it has not been well understood how grain size is determined. Certainly, glume size is one of the important factors affecting grain size. We analyzed in detail the growth of glume (floral glume) of several rice varieties differing in sizes of their glumes. 1. The growth of glume in both length (lemma length) and width (floret width) were well fitted to a logistic curve (Fig. 1). This indicates that the growth pattern of glume can be characterized by parameters estimated from the logistic curve. In every variety, the growth of the glume in length ceased earlier than that in width (Figs. 2 and 3). Thus, the growth of glume in length did not synchronize with that in width. The intervarietal differences of growth period did not correspond with those of the glume length. However, the maximum growth rate of glume in length correlated highly with the final glume length, indicating that the differences in the final glume length was due to the differences in the maximum growth rate of glume length among the variesies (Table 1, Fig. 2). on the other hand, in the glume width, we could not detect any distinct intervarietal differences in growth period or maximum growth rate (Table 2, Fig. 3). It must be noticed that the relatively wide glume of "Arborio" was caused by the prolonged growth but not by the high growth rate (Table 2). 2. The growth patterns of glume in length and in width are different and the length and width of glume may be controlled by different regulatory systems. In this point, we need to analyze the growth pattern of glume and the mechanism of determination of its size in more detail. 3. Intersecting lines comprising three straight lines could be fitted to the allometric growth between the glume length and width (Fig. 4). In every variety, the coefficient of allometry was minimum in the second section and maximum in the last (Table 3). Intervarietal differences were detected in the coefficients of allometry and the positions of intersecting points. It is clarified that the shape of glume is affected by both the ratio of growth rate in length and to that in width of glume and the time lag of the growth period in the width relative to that in the length. 4. The present results show that the size and shape of rice glume are controlled by various parameters and we cannot assign any single factor determining the size or shape of glume during its growing process.

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The purpose of the present investigation was to get the informations on breeding for high protein rice variety. Parents used were a high protein cv. Brimful (Scented rice from Nepal) and a Japanese ordinary rice cv. Koshihikari. A crossing was carried out in 1977. F₆ and F₇ generations derived from the hybrid were grown in paddy field in 1983 and 1984. Protein and amino acid contents in grains and some agronomic characters were determined. The results summarized as follows : 1. Mean value of protein content in F₆ and F₇ plants was varied from 10.1% to 12.5% and nearly equal to that in F₄ and F₅ plants. By examining variance of protein content from F₆ and F₇ populations, it was shown that they decreased gradually since F₆ generation (Tables 1 and 4). The variance was nearly equal to that of cv. Koshihikari. The results showed the tendency of being bred actually connected with high protein content in F₇ generation. 2. In F₆ generation, although there was a significant negative correlation between protein and ear length, no significant correlation was observed between protein and other agronomic characters (Tbale 2). There was no significant correlation between high protein property and grain yield in F₇ plants (Fig.2). 3. In F₆ generation, significant differences were observed among plants in lysine and threonine contents per dry weight, and those two amino acids in F₆ and F₇ generations were much higher than those in cv. Koshihikari (Tables 3 and 5). 4. Significant correlations were observed among protein content and lysine per dry weight in F₆ generation (Fig. 1). But, significant correlation was not observed between protein content and lysine content per protein. 5. From the results, it was suggested that high protein content in rice grain could be increased by breeding without decreasing grain yield.

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In our previous studies on diurnal courses of photosynthesis, transpiration and diffusive conductance of the leaf in the rice plants grown in the paddy field, it was recoginized that the photosynthetic rate decreased with the decreasse of diffusive conductance due to high vapor pressure deficit under sufficient light intensity in the fine midday. It has been pointed out that water stress affects photosynthetic rate through the decrease of both CO₂ supply to mesophyll through stomata and photosynthetic activity in mesophyll. This study was conducted to examine whether high vapor pressure deficit reduced photosynthetic activity by measuring light and CO₂ utilization efficiencies at low quantum flux density and CO₂ concentration under different vapor pressure deficit, respectively. The results were as follows : 1) Transpiration rate increased rapidly, and photosynthetic rate, diffusive conductance and intercellular CO₂ concentration (Ci) decreased gradually with changing vapor pressure deficit from low to high (Figs. 1 and 2). 2) Light utilization efficiency, which was shown by the degree of inclination of light dependent straight line of photosynthesis under low quantum flux density, decreased under high vapor pressure deficit (Figs. 3 and 4). And also CO₂ utilization efficiency, shown by the degree of inclination of the straight line expressing the relation between photosynthetic rate and low intercellular CO₂ concentration, decreased under high vapor pressure deficit (Figs. 5, 6 and 7). As light and CO₂ utilization efficiencies were thought to indicate photochemical and carboxylation activity of photosynthesis, respectively, it was suggested that not only diffusive conductance but also photosynthetic activity related to photochemical and carboxylation activities were affected by high vapor pressure deficit. 3) Intercellular CO₂ concentration decreased with the decrease of photosynthetic rate and diffusive conductance under high vapor pressure deficit (Fig. 1). Furthermore, it was found that the degree of inclination of the straight line, expressing the relation between ambient CO₂ and intercellular CO₂ concentrations, was smaller under high vapor pressure deficit than that under low vapor pressure deficit (Fig. 9). These facts indicated that the decreasing of diffusive conductance was more effective on the decrease of photosynthesis under high vapor pressure deficit than the decreasing of photosynthetic activity. 4) The three following equations were obtained on the basis of the relation between intercellular CO₂ concentration and photosynthetic rate (Fig. 6) and on the fact that transpiration rate was proportional to diffusive conductance under constant vapor pressure deficit. In this case, GAASTRA's concept was also considered. P=(44.99×C)/(C+0.377) Ci=(350×C+18.86)/(C+0.377) T=3.43×C The figure (Fig.8) drawn by using these equations showed that the relations between diffusive conductance (C) and photosynthetic rate (P) and between diffusive conductance and intercellular CO₂ concentration (Ci) were hyperbollic, while the relation between diffusive conductance and transpiration rate (T) was linear. Thus, if diffusive conductance were decreased without decreasing the photosynthetic activity in mesophyll, water use efficiency (photosynthetic rate to transpiration rate ratio) could be increased.

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In order to study the difference in the growth of excised seminal roots (root-tips) in vitro culture between Japonica and Japonica-Indica hybrid rices, different concentrations of sucrose, casamino acids (casein acid hydrolysate) or vitamins (thiamin, pyridoxin and nicotinic acid) in the culture medium were investigated. Effect of cultural temperature and degree of pH value of the medium on the excised seminal root growth were also tested. Unless otherwise mentioned, a Japonica rice cultivar (Nipponbare) and a Japonica-Indica hybrid rice cultivar (Milyang 30) were used as materials. All the experimental procedures were same with those described in the previous paper⁵⁾. 1. Under the temperatures of 19° to 34°C, the excised seminal root growth of the Japonica-Indica hybrid rice was better than that of the Japonica rice (Fig. 1). 2. The optimum pH value of culture medium for the excised seminal root growth were 4.0 to 4.5 in the Japonica rice and 4.5 to 5.5 in the Japonica-Indica hybrid rice (Fig. 2). The optimum concentrations of sucrose for the root growth were 6 to 8% in the former and 4 to 6% in the latter (Table 1). On the other hand, effect of concentrations of vitamins on the root growth remained unclear in the both type of rices (Table 4). In all the culture media, however, the excised seminal root growth were better in the Japonica-Indica hybrid rice than in the Japonica rice. 3. In the Japonica rice, the excised seminal root grew well with increasing of concentration of casamino acids in the culture medium. On the other hand, in the Japonica-Indica hybrid rice, the dry root weight increased with increasing the concentration of casamino acids in the medium, while the main root length decreased with the casamino acids concentration (Table 2). When the excised seminal roots of each 20 cultivars of Japonica and Japonica-Indica hybrid rices were cultured in the medium containing 0% and 0.2% casamino acids, the root growth of all the Japonica rice cultivars and that of about one-third of Japonica-Indica hybrid rices were better in the 0.2% casamino acids medium than in 0% casamino acids. In the two-thirds of Japonica-Indica hybrid rices, however, the main root length was longer in the 0% casamino acids than in the 0.2% casamino acids, but the dry root weight was larger in the latter than in the former (Table 3). Thus, the effect of casamino acids on the excised seminal root growth clearly differed between the Japonica rice cultivars and the majority of the Japonica-Indica hybrid rices.

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This investigation has been carried out to group soybean varieties into several types by yield components and to characteraize these types as to plant type and growth habit. Out of one hundred three varieties, collected from western part of Japan and examined, data of 84 varieties which yielding more than 200g/m² were analyzed. And the following informations were obtained. 1) Soybean varieties were grouped into five types (Grain-Number type, Semi Grain-Number type, Medium type, Semi Grain-Size type, Grain-Size type) on the basis of Seed Number·100-Seed Weight ratio. Grain-Number (GN) type has the largest Seed Number·100-Seed Weight ratio and Grain-Size (GS) type has the smallest one. 2) GN type included more blanched type and blanch-spreaded type, based on the plant type classification suggested by WATANABE et al.¹⁴⁾ in 1975. 3) GN type had longer vegetative period, whereas GS type had longer reproductive period. 4) On growth habits, GN type had more vigorous both vegetative and reproductive growth than GS type, and GN type had more vigourous growth of branches. 5) GN type was supposed to be advantageous under favourable conditions and GS type vice versa. 6) Recent soybean breeding in Japan seems to give too much weight to seed size. It might be necessary to consider balance of seed number and seed size.

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Patterns of starch accumulation and ethylene evolution during the course of regrowth in different types of alfalfa, cultivars from tropical and temperate areas, were examined. Results were discussed in relation to the differences between cultivars and seasonal changes. 1. No changes were detected in plant hight in varieties of extremely non-hardy, non-hardy and intermediate type, however in the extremely hardy type, the plant height was less than the others (Fig. 2). 2. Stem number of the tropical and the extremely hardy types were larger than those of the others, and the former showed rapid increase but the latter did not (Fig. 3). 3. After cutting, regrowth in the top took precedence to that in the root, and when there were not enough assimilation products, starch was retranslocated from the root to the top. So starch accumulation in the root arose from surplus assimilation products ln the top. The differences in starch accumulation in the root might be brought about by differences in the top (Figs. 4, 6). 4. The decrease in starch accumulation in the root was brought about mainly by growth in the top ; when growth in the top was high in activity, the changes in starch accumulation were less (Figs. 5, 7). 5. The cause of the differences in ethylene evolution was thought to arise from differences in growth activity. These differences may be mainly caused by aging of plants at the beginning of the flowering stage. Ethylene evolution rates changed at each growth stage. After flowering, ethylene evolution was decreased (Figs. 8, 9). 6. Starch accumulation and ethylene evolution during the regrowth period accompanied with each other ; therefore, ethylene may promote the increase and decrease of starch accumulation. So, in the future, it is necessary to clarify the relationship between starch accumulation and ethylene evolution.

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In the present paper the factors associated with the cracking of tuberous roots of sweet potatoes (Ipomoea batatas Lam.) were analyzed. Emphasis was placed on the observation of cracking under low temperature and dry conditions during the early stage of tuber formation, using rooted leaf pot culture. The development of cracking in the field was also studied. The results obtained are summarized as follows : 1. Three typical symptoms consisting of white-cracking (Fig. 2A), white-flatness (Fig. 2B) and red-flatness (Fig. 2C) were observed in the tuberous roots of the cv. Beniazuma that were exposed to low temperature and/or dryness for 5 days at 20 and 25 days after transplanting. Low temperature treatments (16/12°C, 12/12h) during periods ranging from 20-25 days and 25-30 days after transplanting increased the incidence of white-cracking (Fig. 3). The dry treatments associated with moisture percentages of the vermiculite medium below 120% on a dry weight basis (Fig. 1) during a period ranging from 20-25 days after transplanting also promoted white-cracking (Fig. 3). An increase in the incidence of cracking was observed when the normal tuberous roots developed under the low temperature and dry treatments were put in water, and especially those subjected to dryness during a period from 20-25 days exhibited considerable cracking 24 hours after being placed into water (Fig. 3). Those tuberous roots subjedted for 5 days to the low temperature and/or dry conditions described above showed thin cortices (Table 1). 2. White-cracking, which is considered to be a symptom occurring immediately after cracking, was observed on the 20th day after transplanting, and white-flatness, which is considered to be an early healing symptom, was observed on the 25th day in plants not subjected to the low temperature and dry treatments. Furthermore, on the 30th day some of the white-flatness symptoms on the tuberous roots are considered to be changed to red-flatness symptoms (Fig. 4). Based on these findings it is considered that the cracking of the tuberous roots of sweet potatoes which occurs easily even without exposure of the plants to low temperature and/or dry conditions, may heal through the occurrence of flatness symptoms under favorable conditions. 3. The white-cracking symptoms on the 25th day after transplanting remained until the 35th day under the low temperature treatment and/or dryness induced by 10% solution of polyethylene glycol (PEG 6, 000) treatments (Fig. 5). This result suggests that low temperature and dry conditions delay the healing of cracking. 4. It was also found that cracking occurred and healed at the early stages of tuber formation in the cvs. Beniaka, Kokei No.14 and Beniazuma in the field. The white-cracking symptoms observed in the 5th week after transplanting was considered to be changed to red-cracking and red-flatness symptoms in the 10th week. The red-cracking symptoms, which correspond to cracking at harvesting time, may represent an incomplete healing symptom of cracking. Red-cracking of the tuberous roots grown under the polyethylene-mulch treatment in the 10th week was more frequently observed than in the nontreated materials (Fig. 6). It is considered that the healing can not take place easily due to the rapid swelling of tuberous roots and the cracking symptoms persisted under the polyethylene-mulch treatment. From these results, it is suggested that cracking is induced when tuberous roots grow fast in the early stages of tuber formation, and heals readily under favorable conditions. Thus low temperature and dry conditions may prevent healing, and consequently increase the incidence of cracking.

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?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? IAA, ABA ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? . ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? . 1. ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? 15 ??, ?? ?? 14 ?? ?? ?? 10 ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ( ?? 2 ?? ). 2. ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? 15 ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ( ?? 3 ?? ). ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? . ?? ?? ?? ?? 5-10 ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? . ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? 14 ?? ?? ?? 5-10 ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ( ?? 4 ?? ). 3. ?? ?? ?? ?? ?? IAA ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? . ?? ?? ?? ?? ?? ABA ?? ?? ?? 5-10 ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, 15 ?? ?? ?? ?? ABA ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ( ?? 1 ?? ). 4. ?? ?? ?? ?? ?? ?? ??, 5-10 ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? . ?? ??, ?? ?? IAA ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? .

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?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ??, ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ??, ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ( ?? 1 ?? ). ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? 3 ?? ??, ?? ?? ?? ?? ?? ?? ?? ( ?? 1 ?? ), ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? . ?? ??, ?? ?? ?? 4 ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? . ?? ?? (28.4kg/10a) ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ( ?? 2 ?? ), ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? 115∼125% ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? . ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ( ?? 3 ?? ), ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? -1 ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? 110∼120% ?? ?? ?? ?? ?? . ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? 5∼18% ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? -1 ?? ?? ?? ?? ?? ?? 6∼8% ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? . ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??, ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? .

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