1. The present study was intended to confirm the existence of the toxic substance excreted from the roots of peaches by conducting the spacing experiment with peach and Japanese persimmon seedlings. Seedlings were regularly planted over the plots in regular square arrangement at five different grades of density (6.25-400plants/m2). 20-32 plants were sampled from each plot, and the results of growth measurement were discussed mainly based on total dry matter (yield) per unit area. 2. In the case of Japanese persimmons, the yield per unit area (y) increased with the density of existing plants (ρ), approaching an almost constant level toward highest range of density. The result well fitted the reciprocal equation of density effect, 1/y=A+(B/ρ), proposed by SHINOZAKI and KIRA (1956), regardless of the differences in experimental period, amount of fertilizer and soil texture, although the asymptotic yield (1/A) at higher densities differed according to different treatments (Fig. 1). 3. The yield-density relations in peaches were quite the same with those in Japanese persimmons when the experimental period was 112 days after the sowing, or when peach seedlings were planted in sand. However, when the experiment with peaches was continued for 163 days or more in clay loam, the yield was the highest at intermediate range of density (initial density 25-44plants/ m2) and decreased distinctly at very high density (100-400plants/m2) (Fig. 3, 4 and 5). In the latter case, the reciprocal equation failed to fit in with the experimental results. 4. It may be concluded that in certain kinds of fruit trees under very high density, the growth is inhibited, not only by the deficiency of light, nutrients, etc, but also by the accumulation of toxic substance excreted from their roots. The reduction in growth seems more intense in the species as peaches which produce abundant toxin. The intensity seems to be also influenced by such factors as soil texture.
To make clear the cause of alternate bearing of citrus trees from the nutritious point of view, the seasonal change of nitrogen, phosphoric acid and potassium absorption was observed in Kanagawa Prefecture with mature alternate and annual bearing Unshu orange trees on poncirus rootstocks. 1. The ratio of non-fruiting to fruiting shoots by number was 7:1 on the off-year tree, 2:1 on the on-year tree and 2.3:1 on the annual bearer. Number of fruits per tree was the least on the off-year tree, but the percentage of dropped fruits was nearly the same in either tree of the on- or off-year, showing 69.1-66.4%. 2. The growth of current shoots on length and fresh weight ceased at the end of June. The growth rate on fresh weight was the greatest in June on the off-year tree, and in May on both the on-year tree and the annual bearer. The growth of fruit on fresh weight was very active from August to October, its maximum rate being in August. The ratio of fruits to current shoots by fresh weight was 20:1 on the on-year tree, 15:1 on the annual bearer and 3:1 on the off-year tree. Therefore, the total growth of shoots and fruits of a tree based on fresh weight was greatly affected by a load of fruits, its maximum rate being between August and October. But, when observed on dry weight, its maximum rate was greatest in May on the off-year tree, and in later than July on both the on-year tree and the annual bearer. 4. The total amount of nitrogen contained in shoots and fruits of a tree was greatest in June and September, particularly in June on the off-year tree, and in August on the on-year tree. However, on the annual bearer it was greatest in May-August and October, the maximum value being in August. The total amount of phosphoric acid in shoots and fruits of a tree was greatest in May-June, August and October on the on-year tree. In either case, non-fruiting or fruiting, the amount of potassium contained in current shoots decreased in September and October, the decreasing rate having no connection with a fruit load. The total amounts of nutrients contained in all of shoots and fruits on a tree of different bearing habit are as follows: Fugures in parentheses indicate the amount contained only in fruits.
Further studies of the effect of soil pH on the growth of young Unshu orange trees were attempted, applying two forms each of nitrogenous and potassium fertilizers. 1. The favorable soil pH for the growth of trees based on shoot length, and total fresh and dry weights was 6.23-7.25 in the case of NH4-N and KCl, and 623-7.18 in the case of NH4-N and K2SO4. However, when NO3-N was applied, the growth was nearly the same in most of the plots except the plot of strongly acid soil (nearly pH 4), regardless of the soil pH and the form of potassium fertilizer. 2. Total amounts of N, P2O5 and K2O contained in a tree increased as its growth became greater. MgO was however absorbed more abundantly in various plots of NO3-N than in corresponding plots of NH4-N. With lowering soil pH, the total amount of CaO decreased, while that of Mn increased evidently, independently of the growth. The absorption of N and P2O5 in plots of NH4-N was much promoted by an application of K2SO4 than that of KCl. 3. A significantly positive correlation existed between the isoelectric point of root tissues, and their buffer capacity became greater with lowering soil pH.
1. A method of preventing the appearance of the white turbidity in canned mandarine orange by means of the action of hesperidinase is presented. 2. The enzymic method was shown to be extremely effective when the enzyme acted either prior to (soaking method) or after (filling method) processing. However the latter is preferred in commercial canning because of the simplicity. 3. Sufficient reduction of the turbidity was demonstrated when only the first step of the two of the enzymatic decomposition (hesperidin…hesperetin -7-glucoside……hesperetin) proceeded. The enzymic method was more effective than the addition of methyl cellulose.
The acid contents of tomato fruits (Fukuju No. 2) were determined at weekly intervals from flowering to one week after the turning colour stage. Three stages were recognized in the changes of free, total, and combined acidities of the fruits during development. In the first stage (from the flowering to one or two weeks after the flowering) total and combined acidities were very high, while titratable acidity remained low. In the second stage (from two or three weeks after the flowering to the turning colour stage) total and combined acidities fell suddenly to the minima at the beginning. Thereafter total acidity progressively increased to the peak value at the turning stage, while combined acidity remained low or continued to decrease, So the titratable acidity increased. During the third stage (after the turning stage) total and titratable acidities tended to decrease, while the combined acidity showed no change. The titratable acidity expressed as percentage of the total acidity rose almost linearly from 17-19% at the first week after flowering to 56-59% at the turning stage and then became constant. About 90% of the total cations was occupied by potassium, the change of which was similar to that of combined acidity during fruit development. In both the gelatinous pulp and the outer wall, the acidities followed the similar pattern to that of the whole fruits, except that the gelatinous pulp had higher acidities than the outer wall. Changes in the contents of citric and malic acids had the similar pattern to that of the total acidity, while acetic, formic, hydrochloric, and phosphoric acids continued to decrease throughout the fruit development. The sum of citric and malic acid contents occupied about 60% in the total acidity. The ratio of malic to citric acid content remained about 1:5 before the turning stage, and later became to about 1:10 due to the comparatively rapid decrease in malic acid content.
This paper deals with the. changes of pectic contents in radish root during the process of pithy tissue formation. The pectic substances decrease in content in dry weight basis during the process of thickening growth or of pithy tissue formation. So that, the fractionation of fractions was tried for the first time, by the usual way. In general, the middle lamella fraction was large and the protopectin fraction was medium and the water soluble fraction was very small in amount. It appears that the root contains little water soluble pectin. Each fraction decreased in amount on fresh weight basis during the process of pithy tissue formation. Secondly, the fractionation of pectic substances in dry material was carried out by the extraction with one per cent ammonium oxalate at room temperature (F1), with N/30 hydrochloric acid at 85°C (F2), and again with one per cent ammonium oxalate at room temperature (F3). It seems that the fractions F1, F2, and F3 correspond to the easily soluble pectic acid or its salts, protopectin, and the highly insoluble pectic acid or its salts, respectively. If this is true, protopectin was high in the normal tissue, but low in content in the pithy tissue and the very insoluble pectate increased in percentage during the process of pithy tissue formation. It is possible that the pectic substances in pithy tissue was tansformed from protopectin into the highly insoluble pectic acid or its salts and this transformation was related to the cause of the sclerosis of the cell wall. Use of the intense marceration agent, the mixture of N/30 hydrochloric acid and one per cent ammonium oxalate, decreased the fraction of pectic acid or its salts in amount. If the middle lamella pectin consists mostly of pectic acid, the amount of pectic acid should show an inverse relationship between the normal tissue and pithy one. For that reason the middle lamella contains the pectic substances such as the protopectin in addition to the pectic acid. It seems therefore that the fractions of water soluble pectin, protopectin and the middle lamella pectin in the plant do not correspond to the fractions obtained by marceration agents in the chemical analysis. Furthermore, the amount of esterified pectins in flesh roots is determined by the histochemical test for pectin based on the reaction of hydroxamic acid with ferric ion. There is a linear relationship between the reflection density reading on the absorbance scale and the color intensity in the test sections. If the test sections are stored overnight in 0.5N hydrochloric acid in dry methanol, completely esterified sections are obtained. Total pectic subutances are estimated, using these sections. According to this method, it is clear that total pectic substances and the esterified pectin decreased markedly in content in a cross section area basis during the process of thickening growth or of pithiness and the esterified pectin was localized in the middle lamella and the primary cell wall of young parenchymatous cells, sclerenchymatous cells and meristematic tissues. And also these tissues had a high pectinesterase activity. As the non-pithy tissue has a number of vascular bundle in a cross section area basis, the reflectance density of color in test sections is given high values. In other words, there is a closer relationship between the reflecatance density of color and the number of coducting tissue or meristematic one. If the flesh tissue in radish root has a high distribution density of meristematic island, it seems impossible to suppose that the pithiness occurs.
In order to establish the physiological mechanism concerning the dormant phenomena of onion bulbs, firstly the distribution between the rest and dormant period of bulbs and then the effects of some factors and chemicals on their periods were investigated. 1. It was approximately demonstrated by periodical planting bulbs from storage that bulbs generally had a rest period of about 30 days and successively a dormant pariod of 60 days. Immediately before bulbs commence to sprout, elongation activities were restored not only in the newest leaf primordia but also in root ones in netforming zone. These situations were most promoted in bulbs stored at about 17°C. 2. The rest period was remarkably shortened by removal of outer thickened leaves of bulbs. 3. Time of sprout emergence was not different among bulbs grown under the same conditions, but among bulbs grown under different light intensity and/or with different topdressing of nitrogen fertilizer. 4. Early top-failed bulbs sprouted more quickly than late ones. It was considered to be a close correlation between maturity of bulb and time of sprouting. 5. Limited supply of oxygen during storage retarded sprout emergence of bulbs, but gave a physoiological disorder. 6. Chemical treatment of naphthalene acetic acid, glutathion, thiamin and pyridoxin retarded sprout emergence, but removal of outer thickened leaves nullfied their retardation of sprout emergence. Gibberellin treatment promoted sprout emergence of dormant bulbs, but did not promote that of rest ones. 7. From the foregoing results it may be concluded that dormancy of onion bulbs is induced by the internal conditions unfavorable for elongation of leaves and root primordia and is different from that of potato tuber and gladiolus corms.
1. The growth injury symptoms of muskmelon which were observed at Nakaohara, Iwata, Shizuoka Pref., were characterized by development of brownish roots, curling and marginal scorch of leaves followed by progressive chlorosis or leaf necrosis toward the base, as growth of young fruit has proceeded. Therefore, to clarify the cause of this injury, chemical analyses were made on irrigation water used by muskmelon growers at Nakaohara district, and on plants and bed soils irrigated with the irrigation water of this district.
This study was carried out to examine the growth and flowering of Aster Savatieri MAK. var. hort. MAK. as affected by the temperature and the daylength given prior to the low temperature and gibberellin treatments, and also by various regulators sprayed before and after flower initiation. 1. The growth and flowering were accelerated when the plants had been grown at 10°C for 3 weeks prior to the low temperature treatment, but the plants grown at 15°C for 3 weeks were not sufficiently accelerated. The plants grown at 20° and 25°C for 3 weeks showed no budding. No distinct influence of the day-length on the growth and flowering was noted. 2. The commercial shipping of cut flowers before the middle of December will be possible when the plants are grown under the following program: 3 weeks at 10°C from the middle of September to early October for accelerating flower initiation, 4 weeks under 1°-2°C from the middle of October to early November for breaking rosette, then 3-time applications of 40ppm of gibberellin at 2-week intervals from early November to early December. 3. Applications of 10 and 50ppm of NAA, 50 and 100ppm of TIBA, 50 and 100ppm of RNA accelerated the flower formation even if the plants were under an unfavorable temperature for flower initiation, but the effect of the concentration and the number of times of applications of those chemicals on the flower formation was not obvious. 50 ppm of gibberellin application, on the other hand, showed a marked effect on stem elongation, but no effect on flower initiation. 4. 10 and 50ppm of NAA, 10, 000 and 50, 000 ppm of ethylen-chlorohydrin, and 50 and 100ppm of kinetin applications to the plants which had already initiated flower primordia and which were under an unfavorable temperature for breaking rosette, could not break the rosette, but the plants flowered in rosette form. Six applications of 50ppm of gibberellin after flower initiation, however, could break the rosette and accelerated the flowering. 5. There was a close relationship between flower initiation and stem elongation. Consequently, gibberellin and low temperature treatments for the plants before flower initiation could not break the rosette. Though the gibberellin applications temporarily promoted the internode elongation, the plants formed the rosette leaves again on the top soon after a series of the applications. Gibberellin and low temperature treatments could break the rosette only when applied after flower initiation.
The process of flower bud formation, and the effects of photoperiod on flower initiation and development in dahlia were investigated. Especially, the difference between the optimum photoperiod for flower initiation and that for flower development was examined. Also, the difference of the lower critical photoperiod between these two stages was examined. 1. Depending on the results of observations, the seven stages in development of flower bud were set up, including the vegetative stage, (1) Vegetative stage. (2) Dome forming stage. (3) Early stage of involucre and bractlet formation. Less than nine scales are formed in this stage. The inflorescence of dahlia consists of more than one hundred florets and about eight involucral scales. The involucral scale is leaf-like in form, while there is a bractlet of thin membraneous form at the each of floret. It is, however, impossible to distinguish the bractlet from the involucral scale at the early stage of flower bud differentiation. Strictly speaking, as the flower head of dahlia has generally about eight involucral scales, this stage is involucre fromation stage′, and floret fromation follows. (4) Late stage of involucre and bractlet formation. (5) Early stage of floret formation. (6) Middle stage of floret formation (petal formation stage). (7) Late stage of floret formation (petal elongation stage). 2. The flower primordia initiated under any photoperiods ranging from 8 to 16 hours, while they were retarded under longer photoperiods. The lateral shoots grown under 10 hours or shorter day length had already started to initiate flower buds on the fifth day after cutting back. These facts seem to indicate that dahlia is a non-obligate short-day plant in regard to flower initiation. 3. The optimum day-length for flower initiation was 10 hours or less. As the flower bud proceeded to further stages, both the optimum and the critical photoperiod for flower development became longer, and at last they reached 13 and 12 hours respectively. 4. When the plants were grown under the favourable photoperiod for 40 days after the decapitation, and then were transfered to the photoperiods shorter than 12 hours, many of their flower buds did not develop normally and remained blind. The flower bud of dahlia seems to become blind, when the photoperiod is changed, within 15 days after budding, to unfavorable day-length shorter than the lower critical one.
Nowadays ionizing-radiation treatment is becoming one of the influential techniques in plant breeding programs. Since 1959 the author tried continuously to expose the dry seeds of various annual and biennial flower plants, including total 49 species (one hundred and more varieties and strains), to acute gamma rays from 60Co at the Japan Atomic Energy Research Institute, Tokai, intending to ascertain the reliable influence of radiation effect upon the plants growth and to obtain any useful mutants for breeding materials. As the result, some noticeable biological phenomena were found out. Firstly, there appeared distinguishable interspecific differences of radiosensitivity among them. Many plants examined were classified conveniently into the following five groups, regard to their radiosensitivity for survival: much resistant (for examples, Malthiola incana, Cheiranthus cheiri), resistant (Brassica campeslris, Brassica oleracea), medium (Glycine Max, Cleomespinosa), susceptible (Porlulaca gradiflora, Lychniscoronaria), and much susceptible (Capsicum annum, Cosmos sulphureus). Secondly, some interesting and noteworthy variants were obtained in X1 generation or the successive descendants. The conspicuous examples are fasciation of main stems (Cosmosbipinnalus), defasciation of broadly flattened stalks (Celosia cristata), color change of petals(Moricandiasonchifolia), formation of polyfoliaged leaves (Trifoliumrepens), and duplication of petals (Cheiranthuscheiri). Although a part of these variants were sterile and went out soon, some of the remainder were viable and still now are segregating the peculiarly characterized seedlings in their progenies.