In order to clarify the common physiological causation responsible for the cytoplasmic male sterility in various crops, the authors have carried out histochemical studies on male sterile plants as compared with fertile plants. The present study describes the results of an observation of maize, Zea mays L., which inherits male sterility through cytoplasm incorporation of the chromogene. Using the ¹⁴C tracer methods, the following results were obtained on the distribution of ¹⁴C-assimilates. 1. At the microspore stage, the translocation of the photosynthates into the anther and the spikelet was obstructed in the male sterile plants. 2. In comparison with the fertile anthers, male sterile anthers have a low distribution ratio in the anionic fraction, but it has a high distribution ratio in the neutral and the cationic fractions. 3. In the fertile anther, one undetermined sugar spot was detected. A remarkable difference between fertile and sterile plants was also detected in ¹⁴C amino acids and ¹⁴C amino acids residues. 4. ¹⁴C-assimilate is incorporated into the lipid fraction in the fertile anthers, but not in the sterile anthers. On the basis of such observations, one of the causes of male sterility was surmised to be insufficient translocation of photosynthates from the rachis to the anther. This may be due to some inactivation or obstruction in the synthetic activities from the primary metabolic products to secondary ones.

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1. Six plants of soybean were grown in a green house in 1972. The length of every compound leaf from the 1st to 13th, which was the last one, was measured every other day. 2. When the leaf length was expressed logarithmically, the growth curve was linear against the days after germination during the most part of the growing period. The regression equation of log L (L is referred to leaf length) on the number of days was calculated for each leaf. The regression coefficients of all leaves were not the same. Some of the differences between two successive leaves were significant. In the range from the 1st to the 7th leaf, upper leaves tended to show larger coefficient than the lower leaves ; in the leaves higher than 7th, however, the coefficient tended to decrease gradually. While higher temperature may be involved in part in higher regression coefficients of higher leaves, it may be true that the coefficients depend to some extent on the nodal location of leaves. 3. At first the standard length for calculating plastochron index (referred to as P.I.) was tentatively defined as 30 mm for leaf blades of central leaflets and as 45 mm for whole compound leaves. Based on these standard lengths, the errors of calculated P.I. derived from following causes were estimated; (a) the bending of regression line or the nth leaf before the P.I. reaches n+1, (b) the difference of regression coefficients between two successive leaves and (c) combination of (a) and (b). As to the maximum errors during plastochron, the largest ones out of 65 plastochrons observed were 0.07 by (a), 0.09 by (b) and by (c) in the case of leaflets, and 0.03 by (a), 0.14 by (b) and by (C) in compound leaves, while the frequencies of errors of those sizes seemed very low. After all, the errors brought about by those causes, even in cases those occurred together, did not seem so large for practical use. 4. The P.I. calculated with the standard length defined tentatively as 30 mm or 45 mm as above were almost linear against days in the case of either leaflets or compound leaves. The correction of above three kinds of errors were too small to be distinguished on the graph. 5. Central leaflets appeared more suitable than whole compound leaves to be measured for estimation of P.I., from the viewpoints of size of errors and easiness of measuring leaf length. In order to use P.I. as an index of plant age of soybean, a certain standard length must be defined suitably. The comparison of size of errors between 10 mm and 2O mm as the standard length suggested that 10 mm may be more suitable. It should be noticed in 10 mm standard, however, that the length of the (n+1)th leaf to be measured is always shorter than 10 mm, sometimes as short as 2 mm, which may make the measurements fairly inaccurate, furthermore the errors of measuring length cause larger errors of P.I. in the case of 10 mm than in 20 mm. 6. The errors of calculated P.I. caused by errors in measuring length are larger when either nth or (n+1)th leaves are nearer the standard length. Therefore, the length should be measured as accuretely as possible, especially for the leaves near the standard length.

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This investigation was conducted to determine the effectiveness of 3-hydroxy-5-methylisoxazole application on the inhibition of non-prasitic damping-off or "Murenae" in young rice seedlings grown in nursery boxes. The results are summarized as follows: 1. Application of 3-hydroxy-5-methylisoxazole before seeding was highly effective in reducing the incidence of damping-off. The compound was very effective when applied ei her as a dust or granule by soil incorporation or as a liquid soil injection methods. 2. The growth of shoots and roots of rice seedlings in treated nursery boxes was inhibited temporarily soon after germination, but growth recovered in a short time. The dry weight or rice seedlings 20 days after seeding was greater in the treated nursery boxes than in the control. 3. The compound increased the rooting ability and growth of root hairs. Consequently, the increase in the number of tillers in rice seedlings occurred much sooner after transplanting as a result of the chemical treatment. 4. It was also observed that both guttation and drought resistance were increased by the chemical treatment. These results indicate that 3-hydroxy-5-methylisoxazole reduces the incidence of non-parasitic damping-off or "Murenae" and damping-off caused by Fusarium sp. and Pythium sp. in rice seedlings. The reduction in both types of damping-off appears to be due to the increased growth activity of roots.

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Following Kihara and Hirayoshi⁴⁾ we have adopted the shrinkage of FAA-fixed microspores as a criterion of classifying the microspore stage. In the present study the possibility that the shrinkage was induced by the fixatives was examined by using three fixatives: acetic acid-alcohol (AA), formalin-acetic acid-alcohol (FAA) and glutaraldehyde (GA). AA and FAA shrank microspores remarkably, while GA did not. This result shows that shrunk configurations of microspores are artifacts induced by the fixatives (AA and FAA) and led us, to revise the terminology of classifying the microspore stage. Hereafter we divide the microspore stage according to the developments of both vacuolcs and exines into three phases (early microspore phase, middle microspore phase and late microspore phase) and divide the pollen stage according to the engorgement of reserve substances into two phases (vacuole pollen phase and engorged pollen phase).

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In the fifth paper of this series, we demonstrated that the most sensitive stage to coolness is at the young microspore stage⁶⁾. At the same time we also suggested the existence of a secondary sensitive stage before the beginning of meiotic division. For precisely estimating the sensitive stage to coolness in the present study, the same procedures in the previous study were adopted as follows : (1) group uniform panicles belonging to every 1cm range in article distance, (2) estimate the pollen developmental stage at every location of the four (second to fifth) spikelets at the cooling time, and (3) compare the pollen developmental, stage with fertility at the respective locations of spikelets. The trough of the secondary sensitive stage is observed in all the four tested locations of spikelets, though it is not so deep as that of the primary sensitive stage. The critical stage corresponds to just before and at the early leptotene stage.

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1) This experiment was carried out to examine the effects of phosphate fertilization on the growth and yield of soybeans subjected to low temperature, at 15°C day and night, under the natural light condition of a glasshouse in the phytotron, for 15 days (L-1), or 3O days (L-2), from about three days before the onset of the flowering of the controls grown in a glasshouse, similar to the open. The plants were grown in a 1/2000-a Wagner pot, filled with about 10 kg of a volcanic ash soil, which is high in the coefficient of phosphate absorbance and lacking in the available phosphate, with and without phosphate fertilization. Either fused phosphate or superphosphate was applied at the rate of 6 g or 18 g per pot. 2) As the phosphate rate increased, seed yield increased in all of three growing conditions. However, the magnitude of reduction in seed yield caused by low temperature treatments was greatest at the 6 g application. No significant difference in seed yield was obtained between fused phosphate and superphosphate at the same fates of application. 3) At the 6 g application, the decrease in seed yield caused by the low temperature treatments was mainly due to the decrease in pod number and pod setting rate of the flowers on branches. 4) The plants applied with superphosphate showed better vegetative growth at early stages and set more flowers in contrast with the plants grown in the same rates of fused phosphate. On the contrary, the plants with fused phosphate produced significantly higher 100-seed weight than those with superphosphate did. These differential responses in yield components might be due to the differential speed of acting of the phosphate fertilizers used. 5) Concentration of phosphorus in leaves and stems was determined for the samples taken at the 15th day under 15°C condition and corresponding samples taken from the control condition. Compared with controls, the concentration of phosphorus in leaves and stems of the plants grown under 15°C condition was lower in minus phosphate plots, kept at the same level at the 6 g application and higher at the 18 g application respectively. 6) The plants grown in the highest rate of phosphate showed best growth during the low temperature treatment and smoothly regained from the stress after the end of treatment. The major cause of yield decrease in the 6 g plots was due to incomplete recovery of growth after the treatments, which resulted from insufficient phosphrus accumulation in the plants throughout the development especially during the period under the low temperature. 7) There were high positive relationships between the seed weight and stem weight or between pod number and node number on branches. Both of the regression equations calculated separately with control or L-2 plots were quite similar. The correlation coefficients for seed yield and stem weight or for the pod number and node number on branches, when the coefficients were pooled with the control and L-2 plots, were 0.962 and 0.966 significant at 0.1% level respectively. It was apparent that the excellent vegetative growth insures better yield even in the L-2 plots. High phosphate application to volcanic ash soils would be effective in reducing the poor-growth type of injury stressed by unfavorable conditions including cool summer weather, through improving the growth of soybeans.

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Effects of ammonium- and nitrate-top dressing on cytokinin contents in the root exudate of rice plant were studied under the field condition. Nitrogen application to the soil resulted in a significant increases in the content of cytokinins in the root exudate. When the plant was top-dressed with nitrate form, total content of cytokinins increased more obviously than with ammonium one. Similar situation was also observed in the leaves after nitrogen fertilization. Degradation of chlorophyll in the leaves detached from the plant top-dressed with nitrogen were significantly retarded: the effect was more remarkable in the lower leaves than in the upper ones. Cultured roots secreted cytokinins into the external medium and their composition was very similar to that of the root exudate. The authors thank Dr. A. Nishi, of the Faculty of Pharmaceutical Sciences, the University of Toyama, for his many helpful discussion and suggestions during this work.

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1) Experimcnts were undertaken to elucidate the direct or indirect effect of P and N nutrition with solution culture, on the yield components of soybeans which were subjected to low temperature at 15°C for 15 days from the early-to mid-reproductive stage. 2) In order to determine the direct effects of low temperature on the yield components, flowers were allowed to set only in a limited period of flowering, besides a restriction in number on each node, in the first experiment. Pod setting rate and fertile seed percentage were decreased with increased levels of N irrespective of P levels in the low temperature treated plots. The magnitude of damage was closely related to the stage of flower development under low temperature. No significant effect was obtained from P application, P×N and P×T interaction. 3) After the complete removal of the flowers that opened in the first 7 days, comparison of the productivity, or potentiality of compensation was made with subsequent flowers on the plants, which were preconditioned under various levels of N and P combinations for 2 weeks for control plants or for 3 weeks for low temperature treated plots, in the second experiment. The increase in levels of N and/or P which were supplied, prior to the onset of the test flowers, promoted the recovery from the damage and produced more seeds per plant through the increase in number of pods, pod setting rate, number of flowers and fertile seed percentage. The authors are indebted to Mr. Y. Masuo, the chief of first crop division of Hokkaido National Agricultural Experiment Station, for his suggestions with the manuscript.

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A clone of alfalfa cv. Du Puits was grown under 3 photoperiods (8, 12, 16 hr in 1965; 12 hr in 1970) combined with 4 temperatures (day-night; 30-25, 25-20, 20-15, and 15-10°C) to determine the effects of these environmental factors on the growth and anatomical characteristics of photosynthetic tissues. Under shorter day and lower temperatures, the leaf/stem ratio and nitrogen concentrations of the both organs were higher as compared with those of longer day and higher temperatures. The leaf expansion rate decreased as temperature decreased. The leaf size was greatest at 20° or 25°, and smallest it 15° under short photoperiod. In general it became larger as photoperiod increased. The leaf thickness and intervein distance increased as temperature decreased. The mean epidermal cell area was greatest at 20°, becoming smaller at higher of lower temperatures. Stomatal density was smallest at 20°, greatest At 30°, while stomata index changed little. Pallisade cell number per unit leaf area increased with a smaller diameter and length as temperature increased. Leaves of plants grown at 20° had the largest intercellular spaces, followed by those grown at 25°, 30°, and 15° in order. The stem diameter was greater under longer photoperiod, and greatest at 20°. The stem chlorenchyma increased in thickness as temperature decreased. The amount of starches deposited at endodermis was greater at 20° or 25° under long photoperiod. RGR had the intimate correlations with both RLGR (relative leaf growth rate) and NAR in 1970 experiment with a small change of developmental phase by temperatures under a definite photoperiod (12 hr), while in 1965 experiment where much developmental change occurred under different photoperiods of longer duration thah in 1970, the correlation with NAR became weaker, although the correlation with, RLGR was still strong. In the regime of the experiments, the total plant weight was highest for plants grown at daily mean temperature around 20° (day-night, 20-15°or 25-20°) under long photoperiod, due probably to the largest leaf area per plant (largest RLGR) with the highest expansion rate and the largest size of leaf, being composed of the largest cells and intercellular spaces with a relatively high nitrogen concentration and a smaller respiration loss, all these resulting in a higher NAR.

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The isolation of rice protoplasts from leaves, roots and callus cultures has been examined following the inoculation in cell wall-degrading enzyme solution. It was achieved within 2 hours at 35°C with the materials cut into small pieces using the mixed solution containing macerozyme, cellulase and mannitol etc. The suitable concentration of enzymes and mannitol to isolate the leaf, root and callus protoplasts was ascertained. The size of protoplasts was measured in their diameter and the frequency distribution was acquired. The size was large in the callus protoplasts and small in the leaf ones. Structure of the protoplasts was investigated with the semithin sections by light microscope. Nature of nuclei, nucleoli and lamellar structure in chloroplasts are illustrated. The spontaneous fusion of protoplasts was assumed from the presence of polynuclear protoplasts. In addition, the protoplast isolation from flower petals was performed successfully using carnation and Freesia. We gratefully acknowledges Dr. T. Katayama and Dr. T. Omura, Faculty of Agriculture, Kyushu University, for encouraging the development of this work. Technical assistance was rendered by Mrs. K. Maeda, to whom we are also very grateful.

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In a previous report⁴⁾ it was made clear that the stomata of leaf blade of rice plants closed to a considerable extent on fine days even when they grew in submerged paddy field. For this time an investigation was undertaken to clarify the diurnal variation of leaf water content on an areal basis in some developmental stages of rice plants under various weather conditions. Maximal water content was obtained for 12th and 13th leaf, fully expanded just at the panicle formation stage. The water content decreased more and more for both upper and lower leaves as away from the relevant leaves. The water content of each successive leaf followed the diurnal variation pattern of taking the maximal value in eariy morning and decreasing towards noon. But the range of variation was wider at the tillering stage, becoming narrower after the booting stage. As for the effect of weather condition, the midday decrease of water content was rather remarkable on fine days accompanied with intense transpiration, but the difference of diurnal variation between fine and cloudy days was small as was expected. From this result it was suggested that the water content of rice plants grown in submerged condition did not debrease below a certain limit, owing perhaps to the increase of water absorption in accordance with intensive transpiration or stomatal closure due to the decrease of water content. In the afternoon of fine days, stomatal aperture became much smaller than on cloudy days. So it was considered that the slight variation of water content gave much influence upon stomatal aperture when water content of leaf blade decreased to a certain limit and that this influcnce became more prominent after the booting stage with narrower range of the variation of water content. Lastly the areal weight or the dry weight per leaf area was much larger in fine days compared with cloudy days, suggesting the effect of dry weight increase upon the decrease of customary leaf water content on a dry weight or fresh weight basis.

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Both ethylene and GAs (GA₃ and GA-like substances extracted from plant materials) stimulated the growth of coleoptiles in rice seedlings under red light. A combined application was shown to be synergistic. Similar synergism was observed also in the growth of the first leaf sheath.

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Heavy-tillering (panicle number type) varieties, Kinmaze and Akibare, and poor-tillering (panicle weight type) varieties, Koganenishiki and Norin No. 22 were grown under natural condition, and Kinmaze and Koganenishiki were grown under controlled conditions varied in light intensity (47, 000 lux and 15, 000 lux) and temperature (30°C and 20°C) in phytotron. 1. Number of tillers was largest under low temperature (20°C) with strong light (LT-SL) and smallest under high temperature (30°C) with weak light (HT-WL). Under high temperature with strong light (HT-SL), abnormal yellowing of leaves took place, and some primary tillers died during the growth. Varietal differences in number of tillers were recognized under natural condition and every condition in phytotron except HT-SL. Under good conditions such as the outdoors and LT-SL, varietal differences in number of tillers were large in secondary and tertiary tillers and small if any in primary tillers. Under worse conditions, however, varietal difference was remarkable in all kinds of tillers, and under the worst condition it was remarkable rather in primary tillers than in secondary tillers. From these results, a model was proposed to explain the varietal difference in reference to environmental condition. 2. The regression equations of leaf age "y" (age of a shoot expressed by number of emerged leaves) of the primary or secondary tillers to the leaf age "x" of their respective mother culms were calculated (y=ax-b). There was no varietal difference at all in regression coefficient under natural and every controlled condition, although some differences due to the conditions and numbers (locations) of the nodes on which the tillers occured were observed. No varietal difference was recognized in the value of "x" when "y"=1 (roughly at this leaf age the tiller appears out of the leaf sheath of the mother culm). 3. The appearance ratios (see Table 4) of the tillers on lower or upper nodes of mother culm in Kinmaze were larger than those in Koganenishiki under every controlled condition. 4. From above results, the varietal difference in number of tillers is thought to be caused by the difference in appearance ratio of tiller on each node (especially on lower and upper nodes) of mother culm.

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Translocation of photosynthetic product was investigated in young mulberry plants using a radio-isotope ¹⁴C as a tracer. The results obtained will be summarized as follows. 1. Most of photosynthetic product translocated from the fed leaf in 3 to 4 days after the administration, remaining 20-30% of photosynthetic product in the fed leaf. ¹⁴C-photosynthetic product was mainly distributed to stem, stump or root, but scarcely translocated to mature leaves. 2. Distribution rate was relatively high to stem tip from upper leaf, while rate to stump or root was high from lower leaf. 3. When the whole shoot was fed with ¹⁴CO₂, the specitic activity of leaf in successive leaves immediately after the administration resembled the variation of photosynthetic activity in successive leaves measured by infrared gas analizer. Plants with longer days after planting distributed larger proportion of photosynthetic product to stump or root. The author wishes to express his sincere thanks to Dr. K. Hazama and Dr. K. Ohyama, Sericultural Experiment Station for their encouragement and guidance throughout this work. Thanks are also due to Dr. M. Hoshino, National Grassland Research Institute for his helpful advice in the isotopic treatment and to Prof. T. Tazaki for valuable criticism in the preparation of this paper.

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These studies in series wrere devoted to clarify the characteristics of white-belly kernel (those grains with opaque part at their ventral position of the endosperm) and to obtain the data on the development of the opaque part in rice grains. This paper described the relation between the appearance of white-belly kernel and the panicle character, the location on the panicle, the kernel weight and the kernel shape. The experimental materials used were Norin-8, Kinmaze and Koshihikari of Japonica type of variety and Koshen of Indica type of variety. 1. The occurrence of white-belly kernels was dependent on the number of the primary and the second-ary branches. White-belly kernels were increased with decreasing number of the primary and the secondary branches. The number of white-belly kernels in the upper branches were larger than those kernels in the lower branches. In the primary branches, many white-belly kernels were observed at the vigorous position except the head position, and in the secondary branches, many white-belly kernels appeared at the head position. On the other hand, Koshen, Indica type, showed the different pattern on the occurrence of white-belly kernels from Japonica type, i.e., the head position of the primary brdnches had also the white-belly kernels. 2. Negative corelations between numbers of white-belly kernels and numbers of ill-ripening kernels were observed. Positive corelations were observed between numbers of white-belly kernels and dry weight of kernels. 3. White-belly kernels in the upper position of the ramified primary branches had larger breadth and weight of grains than perfect kernels. But in lower ramified branches, the thickness and weight of white-belly kernels were less than those of perfect kernels. The white-belly kernels in the non-ramified lower branches had characteristics similar to those kernels in the upper branches. But, white-belly kernels at any position had higher ratio of width to thickness than perfect kernels. This means that white-belly kernels were flatter than perfect kernels. 4. Grains in the vigorous position showed the high increasing rate of dry weight growth at the early stage and the maximum rate was observed at the middle stage. On the other hand, weight of grains in the weak position was slowly increased with the development of the grain to the latter stage. Grains in the upper branches had the characteristics similar to ones in the vigorous position, and grains in the lower branches showed the resemblance with ones in the weak position. From these observations, the appearance of white-belly kernels might be caused by the unbaranced developing rate at the latter period during ripening as compared with the development at the early stage.

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Plastids of various organs and tissues were observed by electron microscope comparing with the observations under light microscope. Leaf mesophyll cells contained chloroplasts with well developed grana and stroma lamellae, containing progressively larger "assimilation starch" inner the mesophyll and nearer the vascular bundle they situated. Plastids in the parenchyma of both vascular bundle (parenchymatous vascular bundle sheath) and midrib were rather amyloplasts with far less lamella structure. The amounts of chlorenchyma of leaf-sheath and stem decreased and those of parenchyma increased basipetally, the former tissues containing chloroplasts almost similar to those of leaf-blade and the latter amyloplasts with a trace of lamella structure. The amyloplasts at their basal parts contained larger compound starth grains which are called "transitory starch". The initials of shoot apex contained no amyloplast. The corpus cells two to three layers beneath the initials and the cells of slightly elongated leaf primordia began to contain small amyloplasts with small compound starch grains, becoming larger as the cells enlarged. These starches are to be consumed by the cells which contain them for the successive rapid cell expansion, which have been called "waiting starch" by Sato. The initials of root apek and periblem cells contained small plastids with starch grains and a trace of lamella structure. Very young meta-vessel cells near the root apex had larger amyloplasts than the other plerome cells. These starches also disappear during the rapid expansion of the cells. Tiny and larger amyloplasts were found in the calyptrogen and mature root cap, respectively, the latter forming the "statolith." Mature pollens prior to anthesis contained many specific starch grains, cach of them being composed of one oval single grain in contrast to the other compound starch grains commonly found in the tissues. The mesocarp of ovary seven days after fertilization contained many large amyloplasts except the inner two layers which had plastids with abundant lamella structure, thw outer layer containing large compound starch drains and the inner very small grains. The amyloplasts of endosperm contained compound starch with a greater number of single grains than those of other tissues. These starch should be called "reserve starch", which enlarge with maturation especially rabidly at the central part of the endosperm.

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