In the previous papers (Report nos. 74, 69, 67), Matsushima et al. stressed the necessity of the ideal plant types for maximizing grain-yields of rice. In the present paper the authors further studied a method no obtain high yields by making the plant into ideal plant types. Two conditions are subjected to making the ideal plant type, i.e. (1) ensuring the number of spikelets per unit area corresponding to a target yield by the time of 69 leaf-number index (which is the time just before the neck-node differentiation and roughly corresponding to 43 days before heading) and (2) restricting nitrogen supply during the period from 69 to 93 in the leaf-number index (the period is approximately corresponding to the duration from 43 days to 20 days before heading) in which the plant type is definitely predetermined. For ensuring the number of spikelets correspondig to high yields, much ammonium nitrogen must usually be supplied, but when much ammonium nitrogen has been used in a paddy field, the control of nitrogen absorption by the plant during the critical period in which the plant type is definitely predetermined is hardly possible on account of the ammonium nitrogen having been adsorbed by the soil. On the othr hand, when nitrate nitrogen is applied to a paddy field, it is by no means adsorbed by the soil, but it is always dissolved in irrigation water so far as the irrigation water remains in the field. In this occasion, if one wants to stop the supply of nitrogen, one can easily do so at any time by changing the irrigation water which remains in the paddy field for new water which contains no nitrogen. Getting a hint from a circulating irrigation method in which identical water is repeatedly irrigated by a pump and which has long been practised economically in Toyama Prefecture, the authors devised a method by which one can easily take off the nitrogen from a paddy field at any time as follows. Putting much nitrate nitrogen into water in a paddy field and making water circulate by pumping up ditch-water which comes out through underdrains of the paddy field, the authors could always supply much nitrate nitrogen to rice plants for encouraging their tillering with little leaching of nitrogen (some amount of nitrate nitrogen is, however, lost by denitrification). By changing the irrigation water for new water at the time of 69 leaf-number index (approximately 43 days before heading), they succeeded in stopping the supply of nitrogen to the plant and thereafter they irrigated the plant with nitrogen-free water until the time of 93 leaf-number index (approximately 20 days before heading). At the time of 93 leaf-number index and again at full heading time they top-dressed with ammonium nitrate to encourage the carbon assimilation of the plant. By this method they succeeded in, (1) obtaining the necessary number of tillers per unit area corresponding to a target yield by the time of 69 leaf-number index, and (2) decreasing the nitrogen content of the plant, paling of leaf-colour, decreasing the dry weight increment, of the plant at the critical period, decreasing the length of leaves, culms and internodes, and as a result, (3) raising the grain-yield by 5-27% as compared with the control plot respectively and obtaining 7.1 tons of brown rice per hectare as the highest yield which has never been obtained by any other means so far in their experimental paddy fields. By the way, the amount of water consumed for evapo-transpiration in the circulating irrigation method was less by 14-23% than the ordinary irrigation (flooded) method, and a tentative proposition was made on the application of nitrogen for ensuring the number of spikelets per unit area to maximize the yield of rice.

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In the previous report the authors reported that one could easily obtain high yields by using a circulating irrigating method combined with the application of nitrate nitrogen. By this method one could exactly take the nitrogen off the soil at a given growth stage for controlling the growth of rice plants. In the present experiment, furthermore, the authors tried to apply the same principle as the above to an ordinary paddy field without the circulating irrigation method. The main points in conducting the experiment were the following three points: (1) In order to ensure the necessary and sufficient number of bearing-tillers for obtaining a terget yield by the time of 70 in 'leaf-number-index', and to take nitrogen off the soil without difficulty during the critical period in which the plant type after heading is definitely predetermined, much amount of nitrate nitrogen in stead of ammonium nitrogen was given at the early growth stage. (2) In order to take nitrogen off the soil immediately during the critical period, logged water which contained nitrate nitrogen in the paddy field was completely drained out, and fresh water which contained no nitrogen was again irrigated. (3) In order to increase the rate of carbon assimilation after the critical period, nitrogen was again top-dressed at the end of the critical period (about 20 days before heading) and at the full heading time. Water permeability in the experimental field was at a rate of 10∼15 mm per day. The results might be summarized as follows. 1. Nitrate nitrogen applied at the early stage of growth was quite effective for increasing the number of tillers, and it could be taken off the soil by exchanging logged water in the field for fresh water at the begining of the critical period. The success in restricting the nitrogen supply in the paddy field mentioned above could be recognized directly by the remarkable decrease in the nitrogen content of leaf-blades, and be checked indirectly by the discoloration of the plant and the retardation in increasing rate of the number of tillers and the dry-matter during the period, and furthermore by shortening of leaf-blades, culms and internodes in length at maturity. 2. Accordingly, the type of plants was improved to a near ideal type by the above-mentioned treatment, and, as a result of it, treated plots were higher than the control in the percentage of ripened grains and in the grain yield as seen in table 3. 3. It was quite noticeable that the treated plants (1) had gained a high lodging resistance which was mainly ascribed to the shortening of lower internodes in length, and (2) has yielded high percentages of ripened grains which was largely ascribed to abundant accumulation of starch in culms and leaf-sheaths before heading. 4. From the results of the present experiments it was strongly proved that if one would utilize nitrate nitrogen at the early stage of growth, one could make the plant type ideal with ease by taking nitrogen off the soil at the critical period, and could obtain high grain yield through the "ideal plant".

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Leaf tobacco cultivation in eary growing season has been based on the cover-culture technique. Young tobacco plants, after transplanted to field, are generally covered with polyethylene-film or melamin coated paper, and tightly closed in the cover-culture. Under such enviromental closed system, the ploblems which should be clarified are that what kind of methods and materials for cover-culture are required in order to protect young plants from frost or low temperature and to make photosynthetic condition favorable for promorting the growth of plants. As the first approach to this problems, we carried out the work with the purpose of how to manage the photosynthesis of young tobacco plants under the eviromental closed system on the field. (1) The photosynthesis, plant respiration and some enviromental factors under the cover-culture which has been brought into practical use in early season cultivation of leaf tobacco were measured on the field. The cover-culture has been found generally in Kyushu district and many other production area of leaf tobacco, and the ordinary cover-materials were polyethylene-film and melamin coated paper. (2) The diagram for measuring was based on the circulation system of the air (closed system); the air in the cover-culture was circurated through two chambers both of photosynthesis and soil respiration, and on the process of air circuration photosynthesis of tobacco plants and soil respiration were measured separately and simultaniously. Besides, by passing the outside air through the chamber (open system), the photosynthesis, soil respiration and plant respiration were measured to compare them with the results of the closed system. (3) In the closed system of the cover-culture, CO₂ concentration decreased as plants grew and the day went by. In addition, the heigher the air temperature rises in. day time, the more the amount of plant respiration increased. Consequently, the photosynthesis were strongly surpressed; the amount of photosynthesis per plant never increased or rather decreased in spite of growing of plants during the latter half of covering period, and the amount of photosynthesis per unit leaf area remarkably decreased as the leaf area per plant increased. (4) In the open system of the cover-culture, the photosynthesis per plant remakably increased and the rate of plant respiration decreased relatively. The amount of apparent photosynthesis per plant was, 2.6 times that of closed system at the end of covering period. (5) The greater amount of soil respiration was obtained when the air of low CO₂ concentration was sent to the chamber of soil respiration in the closed system as compared to the open system. The amount of soil respiration which goes in such closed system should be grasped not only as the biochemical activity of soil micro-organism, but also the diffusion of CO₂ from soil to the ground. (6) CO₂ concentration under the cover-culture could be an index of degree of causal relation between photosynthesis and soil respiration. (7) Covering method which would positively produce enviromental conditions favourable for photosynthesis under the cover-culture in early season cultivation of leaf tobacco should be re-discussed on the following viewpoints; giving the air of heigher CO₂ concentration to tobacco plants; promoting soil respiration; and not giving rise to excessive air temperature.

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The present investigation was undertaken to confirm the presence of the endogenous natural cytokinin (s) in the potato tubers. The methanol extract of potato tuber was separated by ascending paper chromatography using n-butanol: acetic acid: water (12:3:5) solvent system. Several violet or blue fluorescent spots on the test strip of chromatogram were detected by UV-lamp, and two of them (Rf 0.40-0.50 and Rf 0.55-0.60) not only reacted positively by Vischer's reagent but showed strikingly absorption by the UV-lamp at 260mμ. Accordingly, one (Rf 0.40-0.50)is nucleotide and the other (Rf 0.55-0.60) is a kind of the purine derivatives. While the addition of the former fraction to the medium exerted no significant influence on the tobacco callus growth, a marked stimulation of its growth was observed due to the latter fraction. As to the effect of the fraction (Rf 0.55-0.60) on the potato tissue culture, this factor not only resulted in likewise stimulation of callus growth but enchanced to elicit the root formation at its relative high concentration. Consequently, this factor closely resembles kinetin in its cytokinin activity. It was also ascertained a considerable cytokinin activity in this factor by means of the chlorophyll-retention assay using the barley leaf section. These results are interpreted to indicate, therefore, that there is a endogenous natural cytokinin in the potato tubers.

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1. Rice products mainly consist of normal, green, rusty, milky-white, deformed and opaque grains, and inspection grade is principally decided according to the percentage of normal grains present in the whole lot, because most of the factors, affecting gradation closely relate to this percentage. 2. Quality of normal grains is indicated by the density of starch accumulation in peripheral region of rice grain which has negative correlation with percentage of basal white grains present in normal grains. This percentage is correlated with percentage of bran to grain in weight and milling-loss of rice, then negativly correlated with specific gravity of rice. In general, high grade rice in national inspection shows a low number of this percentage. 3. The correlation between cooking quality and inspection grade of rice is not recognized, because cooking quality is more or less affected by environmental conditions during the ripening period of rice but usually, depends on varietal charactoristic.

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Data presented in the previous paper have demonstrated that the strength of plumule-elongation at the stage of 5.0-6.0 cm long measured with unbonded gauge type transducer was the strongest in corn; oats comes second; next in order are wheat, barley, rye, sorghum and rice; the weakest was italian millet. In this paper, relation between the strength of plumule-elongation and emergence vigor or emergence ability was studied. Results were as follows. 1. No positive correlation between the strength of plumule-elongation and emergence ratio or emergence rate index under hardened texture of convering-soil of 5.5 cm depth was obtained (Table 1-a, b). On the other hand, partial correlation was obtained between the strength of plumule-elongation per unit cross section in the largest portion of plumule and emergence ratio (Table 2, Fig. 2). 2. From the above results following relationship is expected. EV=R·St EV: Emergence vigor. R: coefficient of resistance elimination at the time of emergence. St: Strength of plumule-elongation measured with unbonded gauge type transducer. In this case, shape of plumule and ecological and physiological character of plumule are involved in R. From Table 1 and Table 2, it is thought that R is greater in italian millet, sorghum and paddy rice in indica type than in barley and rye. Under the condition of none or a few hardened, however, it is probably that R is negligible in EV and St is highly correlated with EV. 3. In field condition, length from seeding to emergence is very important. So the following relationship is suspected. EA=R·St·SP EA: Emergence ability. Sp: Speed of plumule-elongation under covering-soil. From the above result, it is thought that EA is the greatest in corn and sorghum; oats, wheat and paddy rice in indica type comes second; next are upland rice in japonica type, rye and barley (normal); the weakest are paddy rice in japonica type, naked barley (uzu) and italian millet under condition of 5.5 cm depth of covering-soil at 25°C in this experiment. As the shape of plumule and ecological and physiological character is almost the same in each cereal, it is probable that EA is highly correlated with St and Sp.

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Growth responses of three clones (NL: narrow leaf with abundant tillers, no head after a spring sowing, BL: Broad leaf with less tillers, no head after a spring sowing; ML: Intermediate leaf width, with head after a spring sowing) selected from a cultivar "Frode", were studied under the compinations of 3 photo-period and 4 air temperature treatments. Eight hours of natural daylight (SD) were supplemented with a 40 Watt incandescent lamp in each cabinet to supply 12 (MD) and 16 hours (LD) photoperiods, respectively. Within the limits of the experiment, 20°C day-15°C night temperature was most favorable for tillering under short-day condition. Under long-day, tillering was markedly deppressed. In general, the ratio of dormant buds to total tiller buds increased as the temperature raised. Tillering capacity (fig. 11) was progressively larger as the temperature declined and it was smaller under long-day than under short-day condition, while the eloegation of each tiller was greater under long-day and higher temperatures (fig. 5). Tillering capacity has a close relationship with the storage of available carbohydrate and nitrogen compounds in the tops, especially with the concentration of non-protein soluble nitrogen in the leaf-sheath and stem. When the growth of the shoot was checked under lower temperatures and shorter day-lengths, carbohydrate reserves and nitrogenous labile structural compounds were accumulated more in the tissues resulting in the greater tillering capacity and in the less T/R ratio (fig. 6, 8, 11). Dry matter production was greatest at 25°C day-20°C night and declined at higher or lower temperatures under short-day condition. Under long-day codition, a little lower temperatures such as 20°C day-15°C night or 25-20°C (when stem elongation occurred) were most favorable for the growth. The plant induced into reproductive stage with culm elongation under long-day condition was more productive in the shoot growth as compared with the vegetative plant under short-day condition. The exsistence of a clone such as ML which headed and flowered after a spring sowing was contrary to the general view that orchardgrass has an obligatory winter requirement for floral induction.

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Forecast of tuber yield by haulm growth, if possible, may mean a lot for the potato breeding and cultivation. Since it has been said that there is no high correlation between haulm growth and tuber yield in potatoes, we have tried to classify ecological types according to the different processes of haulm growth, thus studying relations between ecological type and tuber yield. The stem length from the first peduncle of main stem to soil surface was named the stem length under peduncle, and that from the first peduncle to the growing point the stem length above peduncle. The stem length under peduncle was revealed to have a close connection with haulm growth from early to middle stage of growing season, and the stem length above peduncle with that from middle to late stage. In many cases high positive correlations were found between the stem length under peduncle and starch yield from tubers, while relatively high negative or low positive correlations were found between the stem length above peduncle and starch yield from tubers. Haulm growth, showing longer stem length above the peduncle, especially provided with shorter stem length under the peduncle, resulted delayed growth, excessive foliage growth and lodging. Consequently growing conditions were unfavolable for tuber bulking and accumulation of starch in tubers. By means of laies the stem length under the peduncle on the X axis and the stem length above the peduncle on the Y axis, dividing both by their mean values, were obtained four ecological types. From the table 5, it was known that type I and IV, accompanied by longer stem length under the peduncle produced more starch yield than type II and III that have shorter stem length under the peduncle. Comparing type II with IV, although each type had nearly equal stem length, features of the growth are different and accumulation of starch in tubers was greater in the type IV than in the type II. In conclusion, it was suggested that studies of cultivation method accelerate the stem length under the peduncle must be done and in breeding potatoes, elimination of such type as II would be desirable.

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[in Japanese]

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[in Japanese]

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Photosynthetic system of plant population were investigated with two early soybean varieties, Shirobana-Sai No. 1 and Tachisuzunari, growing in the field with particular reference to its structure, formation process, light regime and photosynthetic properties of leaves composing the system. The results obtained were as follows: (1) Primary branches are classified into two groups, that is, "branches on lower nodes of mainstem" and "branches on upper nodes of mainstem". The former are formed on lower nodes of mainstem in early stage of growth, having relatively many leaves and can form secondary branches. On the contrary, the latter are formed on upper nodes of main stem in later stage of growth, having only a few leaves at the most and cannot form secondary branch. The development of the latter branches begins when the uppermost leaf attains to full size, after a rest period following the termination of forming the former branches. (2) Leaves formed either on mainstem or on those branches develop successively in accordance with order of the positions on stems. Time interval of unfolding of succesive leaves is longer for leaves on lower nodes of mainstem compared with those on middle or higher nodes. The interval is longer for leaves of branches than for those of mainstem. (3) Duration from unfolding to defoliation varies from leaf to leaf. The duration of the leaves of mainstem is moderate for lower leaves, short for middle leaves and long for upper leaves. That of braches, however, is shortest for lowermost leaves and the higher the position of leaves the longer the duration. (4) At early stage of growth, only the leaves of mainstem constitute photosynthetic system of the population. Leaf area density in space is sparse, particularly at the space between rows, resulting in a good light penetration into the canopy. At the beginnig of flowering, the leaves of main stem and those of "branches on lower nodes of main stem" constitute the photosynthetic system. As the result of vigorous development of these leaves, population is luxuriated: leaf canopy is thick and space between rows is also filled up by leaves, though leaf area density is somewhat lower at this space. The top part of photosynthetic system is constituted with upper leaves of main stem, while the botom part is constituted with lower leaves of "branches on lower nodes of main stem" and with aged lower leaves of main stem. Owing to the luxuriance of the population light penetration into leaf canopy decrease considerably. At the middle of ripening period photosynthetic system is constituted with those leaves of main stem, of "branches of lower nodes of main stem", of "branches of upper nodes of main stem" and of some secondary branches. Height and LAI of the population continue to increase after the beginning of flowering, accompaning noticable cnange in spatial distribution of leaf area. At lower half of population leaf area density decreases as the result of defoliation of lower leaves and of upward shifting of some leaves from lower space to upper space. The gap built is partially filled by newly developed leaves of some "branches on upper nodes of main stem" and those of secondary brances. But this replacement is insufficient, and extensive hollow is formed at the bottom of leaf canopy. On the other hand, in upper hallf of population, leaf area density increase remarkably due to formation of new leaves, expansion of existing leaves and upward shifting of some leaves from lower space. Consequently, the photosynthetic system of this stage is characterized by relatively thin but danse leaf canopy under which thick empty layer extends. Light flux, therefore, decreases steepy as it penetrates the leaf canopy. (5) Light condition of leaf during the development varies with the position on main stem on branches. [the rest omitted]

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A hybrid corn, Tomorokoshi Ko No. 7, was planted on 7 different dates in 1964. To denote heat requirements for silking and maturity, the term "heat-unit accumulation in the effective degrees" as a modification of the degree-days calculation to take into account temperature above or below the effective degree range for growth of corn was used. The effective degree ranges for the heat requirements were evaluated by the coefficient of variations among planting date. The use of the effective degree range, 10∼25°C, gave the least coefficient of variation, 1.43%, and 95% confidence interval, 807±11°C, for silking. In the same way, the use of the range, 1∼23°C, gave the least coefficient of variation, 2.41%, and 95% confidence interval, 786±18°C, for maturity after silking. From the above facts, it may be concluded that the heat-unit accumulations in the effective degrees required for silking from planting and for maturity after silking were assumed to be constant regardless of planting dates.

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The inhibitors of IAA-oxidase contained in dark-grown wheat seedlings are studied in this paper. Boiled water extract from dark-grown wheat seedlings showed an inhibiting effect on the IAA-oxidase activity when in higher concentration. It showed, however, a promoting effect when in lower concentration. Moreover, it showed a little interference with Salkowski's color reaction of IAA. The inhibitors were extracted from the fresh materials with methanol, n-butanol, iso-propanol, acetone, acetonitrile or ethylacetate with ease. But with benzene, n-hexane or petroleum ether, extraction was difficult. In order to identify the inhibitors, we have undertaken some experiments using paper chromatography and obtained the following results: these inhibitors showed positive color reactions with FeCl₃ and diazo (alkaline) reagents, but negative with Al⁺⁺⁺ and diazo (acid) reagents. As a result, it is suggested that these inhibitors are phenolics encluding flavonoids and catechins. From further studies using two-dimensional paper chromatography, it may be concluded that the IAA-oxidase inhibitors contained in dark-grown wheat seedlings are ferulic acid and other less active phenolcarboxylic acids.

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The mechanism of IAA-destroying system in the wheat seedling is discussed in this paper. The IAA-oxidase activity in the crude homogenate of dark-grown wheat seedlings is masked by the existence of the IAA-oxidase inhibitors in the homogenate, but the addition of H₂O₂ to the homogenate removes this masking and the high IAA-oxidase activity becomes visible. Then, the ferulic acid, one of the IAA-oxidase inhibitors, H₂O₂ and the dialysed enzyme solution from whet coleoptile were mixed and incubated for detecting the changes in UV-absorption spectrum of the mixture. As a result, it was observed that the ferulic acid in the mixture was oxidized by the H₂O₂-peroxidase system. The masking of IAA-oxidase activity in the crude homogenate is also removed by the addition of riboflavin (FR) or flavin mononucleotide (FMN) and light instead of H₂O₂, but the enhancement of IAA-destroying action by FR (FMN) and light is observed without enzyme preparation in the mixture. This sesult suggests that it is the non-enzymatic destruction of IAA. It was also observed that this non-enzymatic destruction of IAA by FR (FMN) and light is inhibited by IAA-oxidase inhibitors, phenolics, contained in wheat seedlings. From the above-mentioned results, the authors have supposed the scheme of IAA-destroying system in wheat seedling as shown in Fig. 5.

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The present paper dealt with the survival process of seeds during winter and early spring and the rate of sprouting seeds which were seeded on cropless fields or between rows of barley or wheat from November to April. 1. The earlier the seeding time was, the more the rate of sprouting seeds was decreased. Moreover the rate of sprouting seeds became lower in the order of cropless fields, between rows of barley and between rows of wheat. The time of sprouting was approximately same in seedings from December to March, delaying slightly in those in November and April. 2. Seeding in November showed more dead seeds three months after seeding than that in January. The rot of seeds in soil began at a part of the embryo and extended to the endosperm. 3. Water content of seeds reached to 32%, 3.0% and 29% one month after seeding in case of the seeding in November, December and January, respectively. 4. In view of the above facts, assumably, seeds are liable to rot in the low temperature period (i. e. January), when their physiological phase in germination proceeds during the preceding period of corn-paratively high temperature (i. e. November).

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The present investigation was undertaken to clarify the physiological process of the survival of seed kept in wet soil, being tested mainly in laboratory. 1. The rot of seeds was observed when they were kept in wet soil under the temperature of 10°C or 5°C for 40 to 80 days and it was more remarkable in changes of the temperature from 13°C to 5°C or 40 days than in those from 5°C to 13°C or in case of the constant temperature of 5°C or 10°C. These facts corresponded to the previous results obtained in the field tests. 2. Being soaked in pathogen-free condition, however, seeds showed much higher germination rate than in wet soil under low temperature. 3. When seeds were kept in wet soil under low temperature, the elongation of seminal root was suppressed, while that of plumule showed no obvious change, according as the period of low temperature became long. This may mean that the vitality of sprouting is decreased. 4. In view of the above facts, assumably, soaking seeds hold the germination capacity in a long term of low temperature, while the power of resistance to the infection of micro-organism is decreased. Thus the death of seeds is primarily caused by the multiplication of micro-organism in fields, moreover the low rate of sprouting seeds is owing to the decreased vitality of sprouting of survival seeds.

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The present paper dealt with the comparison of several varieties in the rate of sprouting seeds and the effect of fungicide coating on seed surface for preventing the seed rot, 1. The samples of 14 varienties were tested in November and February seedings and the respective rates of sprouting seeds were 36∼9% and 79∼43% on cropless fields, 21∼3% and 56∼26% between rows of barley and 19∼2% and 54∼18% between rows of wheat. Varietal difference showed the same tendency in each time of seeding and each field condition. 2. Negative correlation was shown between the rate of sprouting seeds and the germination speed, therefore the difference of dormancy in varieties is said to be related to the rate of sprouting seeds. 3. Coating of seeds with the fungicide showed the high effect on prevention of the seed rot, while it gave some injuries on roots of young seedlings. Accordingly, a proper dose of the fungicide for coating is required. 4. The rate of sprouting seeds in November seeding was raised with the combination selected varieties and the fungicide coating.

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[in Japanese]

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This experiment was carried out to find out that the thickening ratio of mother tubers was influenced by several conditions in cutting piece of seed tubers. The results obtained were as follows; (1) The correlation between the weight of mother tubers and the weight of fresh tubers was negative about some varieties. (2) The thickening ratio difference for the seed tubers weight was not so much, even if seed tubers were divided between 8 and 16, but the difference of the thickening ratio for the yield was remarkable, and the smaller of cutting piece, the lower thickening ratio of mother tubers for the yield. (3) The seed tubers was chosen in the three weight grades such as large, medium and small, and they were divided into 8 parts, respectivlp. The small seed tubers thickened most in the harvest time. In case of the same weight of cutting piece of their three weight grades tubers, the thickening ratio of the small tuber was larger, too. And the head and tail part showed a tendency to thicken more than the center part. (4) The thickening ratio of mother tubers varied according to the difference of characters of seed tubers. Namely, in case of cutting piece of seed tubers, the young seed tubers caused high thickening ratio of mother tubers. On the other hand, old tubers caused low. Here, the former was produced in late transplanting of sprouts in previous year, and the latter in early transplanting. (5) Physiological changes in mother tubers from planting time to early thickening period were studied. The activity of some enzyme of thickening tubers increased in early stage, and then the starch accumulated gradually, but they decreased in the non-thickening tubers.

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In the present investigation, we observed the changes in the quality of rough rice grains in the course of stroge for 30 days. For this purpose, four different groups of samples of moisture content of 16.4% to 24.2% were stored at temperature of 23°C, 28°C, and 32°C (Expt. 1); and 13°C, 18°C, and 23°C (Expt. 2). The results are summarized as follows: 1. Moisture contents of rough rice remained comparatively unchanged, except the later stages of storage of high moisture content grains (22 to 24.2%). 2. The occurrence of deteriorated grains in the course of storage for 30 days showed an increasing trend according as the moisture content and storage temperature became higher. In the case of grains of moisture content of 18% or of less than 18.7% little or no deteriorated grains were noticed during the 30 days storage at the respective temperatures ranging from 13°C to 32°C. 3. Viability of embryos (TZ values) at the later stages tended to decrease more rapidly according as the moisture content and the storage temperatures became higher. 4. In case where 24.2% moisture content grains were stored at higher temperatures than 28°C, grains could be stored safely only for one day, while in case where grains of 18% moisture content or of less than 18.7% were stored at temperatures of 13°C to 32°C, grains could be stored safely for 30 days without any deterioration in their quality.

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In order to make clear the reality of winter injury of forage crops in the Apline Resion of Central Japan, the aspect of decrease in stolon number caused by low temperature during winter and early spring season and the influence of it on yield in the sward of Ladino white clover (Trifolium repens L.) which is the most sensitive plant to winter injury among forage crops were studied in this experiment. The following results were obtained. 1) The remarkable decrease in stolon number of Ladino white clover was observed in early spring season rather than during winter season. 2) The stolon number reduction which occured in early spring were caused by the cutting and heaving of root and soil erosion by the alternate freezing and thawing in the upper soil layer and by the direct cold injury to bare stolon originated in the frequent alternation of air temperature at above and below freezing point in this season. 3) The cutting yields in the sward from spring to summer and the intervals to recovery in yield from winter injury were proportional to the reduction rates of stolon number in early spring. 4) There were significantly high correlations between the reduction rate of stolon number in early spring or the stolon number at the first cutting time and total dry matter yield per year respectively. These results seem to show that total dry matter yield of Ladino white clover sward in a year is influenced by the reduction of stolon number in early spring. 5) The correlation coefficients between yield in each cutting time and total yield a year showed a tendency to decrease with the advancement of cutting time. And there was not a significant correlation between both factors at the last cutting time in autumn season (Fig. 5). These facts indicate that total yield a year of Ladino white clover sward in Alpine Region of Central Japan is influenced by the amount of yield from spring to summer, that is, by the intensity of winter injury to stolon of this plant.

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In tobacco plants the lateral root originates in the pericyclic cells of the diarch root between one protoxylem and one protophloem, but in the root more than triarch opposite to a protophloem, whereas all adventitious root primordia arose from the outer part of cambium. On the lateral root primordia, some neighbouring pericyclic cells undergoes periclinal division to in two layer (fig. 2-3) followed by anticlinal division (fig. 4-5). In this process, endodermis cells undergo anticlinal division until calyptrogen differentiation (fig. 4-7). On the other hand, in the adventitious root formation, the phloem ray cells undergoes periclical division to in two layer, and developed to root primordia by random division (fig. 8-12). In the tobacco plants root dimorphism were recognized the same as woody plant, one was thicker in diameter than the other. The distinction between big and fine roots has been shown to be based upon a number of development characteristics including the size in the apex cell, the degree of primary growth and arrangement of primary vascular tissues in the stele (fig. 19-22). The primordia of the two types appear to be distinct in origin, fine root arise from pericycle in diarch root, while the origin of big root is pericycle in multiarch root or phloem ray outer cambium. A according as the mother root became thickening the number of the root primordia increased to high at from 1 to 2 mm in diameter (fig. 23). In this stage, the organization in the root vascular cambium, now a cylinder, has produced additional secondary tissues (fig. 29). Poor branching capacity of may be related to their formation of periderm. On the other hand, the formation of multiseriate rays makes possible the development of root primordium and is an important means of excentric growth of root.

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In oder to determine the optimum value of soil air capacity on the plant root development, the auther studied the effects of different bulk densities and moisture contents in the soils upon the thickening growth and branching of tobacco tap root. 1. The root thickening growth and branching in artificially compacted soil: The soils used were taken from Hatano, Utsnomiya, Okayama and Shizunami, and seedings of the variety Bright Yellow were grown on the pots with soils of various moisture contents ranging from 40 to 100%. The auther obtained the air capacity for the optimum thickening growth of tap root as follows: Hatano soil, 20%; Utsunomiya and Okayama soil, 10%; Shizunami soil, 10∼15% (fig. 3) and for the branching of tap root: Hatano soil, 20%; Utsunomiya soil, 15%; Okayama soil, 1∼3%; Shizunami soil, 12∼14% (fig. 5). From these facts, the soil air capacity required for the thickening growth of tap roots was supposed to be different from that equired for the branching of the roots. 2. The root growth and branching in the field: It could not be found that air capacity in the soil was related to the thickening growth of the secondary roots (fig. 7). High level of the soil air content seemed to inhibit the thickening growth of roots. The root penetration was not inhibited in the region of tis experiment by high bulk density of the soil, but number of branching per unit root length was accelerated obviously.

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As the surface temperatures of roof glass, plant leaf, bed etc. have been proved to be almost the same by the survery in an air-conditioned glasshouse, we can simplify the heat balance equation of leaf layer omitting the long wave terms from it. LE=(L+β)S_i↓a_l+C By measuring, therefore, the transpiration (LE) and the radiation (S_i↓), the coefficient of short wave absorption (a_l) and the heat conductance (C) of the tobacco leaves are obtained directly at the same time. Experimental results show that on a fine day; a_l=0.55, C=-4.6 cal/cm²·hr, mean value in half a year; a_l=0.38 and C=57.4 cal/cm²·day respectively. The author have calculated the heat balance of the leaf layer in summer using these values: the total radiant energy into the leaf layer is distributed 60 per cent to re-radiation, 4 per cent to heat conductance and residual 27 per cent to transpiration respectively. The results of trial calculation using these measured values agree considerably well with the water supply in every month in two rooms of the air-conditioned glasshouse. (fig. 8).

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[in Japanese]

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