Journal of the Japanese Society for Horticultural Science
Online ISSN : 1880-358X
Print ISSN : 0013-7626
ISSN-L : 0013-7626
Volume 30, Issue 2
Displaying 1-15 of 15 articles from this issue
  • Effect of the composition of atmosphere in the cold storage on the fruit quality of Fuyu variety
    T. TARUTANI
    1961 Volume 30 Issue 2 Pages 95-102
    Published: June 30, 1961
    Released on J-STAGE: December 25, 2008
    JOURNAL FREE ACCESS
    This experiment was carrid out in 1959 in order to clarify the influence of the concentrations of carbon dioxide and oxygen in the atmosphere of storage on the quality of Fuyu fruits in cold storage. The fruits were enclosed in sealed bags of plastic film, and were stored at 0°C. The concentrations of carbon dioxid and oxygen in the sealed bags were determined at intervals of 5-7 days and were adjusted to the desired levels by adding adequate amount of carbon dioxide, oxygen or nitrogen.
    1. The influence of both the carbon dioxide and oxygen concentrations in the storage atmosphere on the rate of softening was examined by pressure tester and it was found that in the atmosphere containing 5 per cent or more carbon dioxide the softening was retarded.
    2. The growth of microorganisms, the appearance of black spots on the epidermis and the advance of after ripening during the storage period, were usually increased in the atmosphere containing 10 per cent or more oxygen and 5 per cent or less carbon dioxide. When the oxygen level was consistently low, decay usually decreased.
    3. When stored in the atmosphere containing 20 per cent or more carbon dioxide, a considerable carbon dioxide injury was induced on the flesh. It bore a striking resemblance to the case when the Fuyu fruits were enclosed in dessicator.
    4. The higher the concentration of oxygen in the storage atmosphere, the more the decrease of the contents of sugar, acid and ascorbic acid in the fruits.
    5. From these results it may be concluded that the most desirable composition of the storage atmosphere for Fuyu fruits are about 5-10 per cent of carbon dioxide and about 5 per cent of oxygen.
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  • The effect of fruit thinning on the control of alternate bearing
    T. IWASAKI
    1961 Volume 30 Issue 2 Pages 103-110
    Published: June 30, 1961
    Released on J-STAGE: December 25, 2008
    JOURNAL FREE ACCESS
    In order to control the alternate bearing of Satsuma orange, the effects of fruit thinning on the fruit growth and yield in the current year and on number of flowers, shoot growth and yield in the following year were investigated from 1935 to 1950.
    1. The decrease in the yield of the current year by the fruit thinning was only slight, because of the increase in size of the remaining fruits. Increases in the number of flowers and yield were obtained in the following year. The total yield of the two succeeding years was increased and annual amount of crop obtained by the fruit thinning was nearly equal in the two years.
    2. Removing all the fruits on a particular branch increased markedly the number of flowers and fruit set in the following year on the branch, and the larger the branch, the greater the effect of thinning.
    3. It was found that the most desirable ratio of fruit to leaves for the current year's crop and the following year's fruiting was 20 to 25 leaves per fruit for Satsuma orange on trifoliate orange rootstock, and 15 to 20 leaves per fruit for the one on Yuzu (Citrus junos) rootstock.
    4. The earlier the fruits were thinned (including flower thinning), the more the effect was, though the thinning even in as late as mid-November showed some effect. However, the appropriate time of fruit thinning for Satsuma orange seems to be the early part of August in Okitsu, as physiological fruit dropping has been over by the end of July.
    5. Even when the number of flowers was increased by the fruit thinning in the previous year, the number of shoots and their growth were not decreased, but rather increased in most cases.
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  • 1961 Volume 30 Issue 2 Pages 110
    Published: 1961
    Released on J-STAGE: December 25, 2008
    JOURNAL FREE ACCESS
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  • Seasonal changes in inorganic nutrient contents
    T. HIROYASU
    1961 Volume 30 Issue 2 Pages 111-116
    Published: June 30, 1961
    Released on J-STAGE: December 25, 2008
    JOURNAL FREE ACCESS
    Two vines each, of uniform bearing Black Queen were dug up nine times during the period from April, 1954 to March, 1955, and leaves, shoots and berries were separately analized for their contents of nitorogen, phosphorus, potassium, calcium and magnesium. Seasonal changes in absorption and translocation of inorganic nutrients were estimated basing on the analytical data.
    The contents of inorganic constituents in the leaves decreased as the season advanced, excepting calcium which increased on the contrary. The seasonal changes in the stems and roots were rather slight.
    The leaves were highest in the content of any constituent among the various organs. The content decreased generally in the order of roots, berries and stems, although there were some exceptions. A tendency was found that the younger the shoots, the higher the content, excepting that of calcium, which was higher in older shoots.
    The tatal amount of each constituent in the whole vine reached its highest value on September 30, when berries matured. On this date, the ratios of the amount in the newly formed organs (leaves, fruits and current year's shoot) to the one in the other organs (canes, stems and roots) were 77: 23 for nitrogen, 63: 37 for phosphorus, 56: 44 for magnesium, 85: 15 potassium and 70: 30 for calcium.
    Absorption of nitrogen was estimated to be high in the period from May to July. Absorption of phosphorus and magnesium was similar to that of nitrogen, while calcium and potassium were absorbed gradually from May until September.
    Calcium ranked highest in the total amount in the vine, followed by nitrogen and potassium, and phosphorus and magnesium being roughly equal in the lowest.
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  • Nitrogen fertilization and harvest time in relation to the spot-development
    T. TOMANA
    1961 Volume 30 Issue 2 Pages 117-124
    Published: June 30, 1961
    Released on J-STAGE: December 25, 2008
    JOURNAL FREE ACCESS
    1. In this study, influences of nitrogen fertilization and harvest time on the development of Jonathan spots were investigated with the Jonathan apples stored at 0-3°C with 95% relative humidity from September 1956 to February 1957.
    2. The fruits on which many spots developed, generally contained more nitrogen than those on which few spots occurred. This relation was also found in the result of fertilization experiment. In the plot with heavy N and without P, leaves and fleshes contained the most abundant nitrogen and fruits caused the spot most severely.
    3. The fruits picked at early time of the harvest were apt to suffer from the spots. Even in the above mentioned plot of heavy N and non P, the spot never developed on the fruits which were picked as late as at the end of October.
    4. The nitrogen content and its distribution in the tissues were determined as the fruit grew. When the seed development ceased and the fruit began to enlarge, nitrogen increased rapidly in the flesh, causing many cracks of the skin around the lenticels.
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  • On the polyphenolic substances and the oxidizing enzymes of chestnuts in storage
    N. HARADA
    1961 Volume 30 Issue 2 Pages 125-129
    Published: June 30, 1961
    Released on J-STAGE: December 25, 2008
    JOURNAL FREE ACCESS
    1. Present study was carried out to investigate polyphenolic substances and oxidizing enzymes which have some connection with the discoloration of canned chestnuts in storage.
    2. The peroxidase seemed to distribute wholly in the flesh of nuts, and the cytochrome-oxidase localized mainly in the vascular bundles, while the polyphenol-oxidase could not be detected as far as this experiment was concerned.
    3. Both ascorbic acid (0.05_??_0.2% solution) and citric acid (0.1_??_1.0% solution) could not affect the prevention of discoloration of nuts, but the solution containing ascorbic acid (0.1_??_0.2%) and citric acid (0.25_??_0.5%) could perfectly show the prevention of the discoloration.
    4. Concentration of polyphenolic substances in the flesh of nuts showed little change during the storage, suggesting that the partial accumulation of those substancec took place in the suture part and the vascular bundles.
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  • Correlation between the number of crown buds in autumn and the number of stalks produced in the following season
    E. SAWADA, T. YAKUWA, N. IWAKI
    1961 Volume 30 Issue 2 Pages 130-136
    Published: June 30, 1961
    Released on J-STAGE: December 25, 2008
    JOURNAL FREE ACCESS
    During the summer and the autumn, after the cutting season, the majority of crown buds of asparagus which produce edible spears in the following spring are formed.
    The present study was made to determine the relationship between the number of crown buds in the preceding autumn and the number of stalks produced in the following season.
    The experimental arrangements were as follows:
    Plot A: Left natural without cutting the spears.
    Plot B: Spears are cut soon after appearance up to the end of June and thereafter the stalks are allowed to grow until frost.
    Plot C: The same as Plot B, except that the cutting season was lengthened until the end of August.
    1. The correlation between the number of crown buds in the preceding autumn and sum of spears and stalks produced in the following season varies with the length of cutting season. Namely, in the three plots tested, no definite correlation was observable in Plot A, while a limited positive correlation was seen in Plot C.
    2. A high positive correlation was observed between the sum of spears and stalks produced in a growing season and the length of the cutting season. The longer the cutting season, the more the sum of spears and stalks.
    3. The number of crown buds and roots newly formed in the current year decreased with the increase in the length of the cutting season. The amount of reserve food stored in the fleshy roots was the highest in Plot A, and the lowest in Plot C.
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  • Role of the leaves
    T. SAITO, H. ITO
    1961 Volume 30 Issue 2 Pages 137-146
    Published: June 30, 1961
    Released on J-STAGE: December 25, 2008
    JOURNAL FREE ACCESS
    There can be little question that the green leaves are the organs which perceive the photoperiodic stimulus. The pistillate flower formation of the cucumber plant being remarkably influenced by the photoperiodic stimulus, the role of the green leaves played in the sex determination was dealt with in this report.
    The sensitivity seems to depend somewhat on the age of the leaves. The youngest fully-expanded leaves are the most sensitive, the young expanding and the oldest mature leaves being less sensitive.
    When four foliage leaves developed, they were divided into five sets and the sensitivity of the different portions of leaves to photoperiodic treatment was examined. The sensitivity of the leaf portions is in the following descending order: 1) whole, 2) basal half, 3) longitudinal half, 4) apical half and 5) one quarter.
    Greater foliage area or/and greater number of foliage leaves induce pistillate flower formation more remarkably.
    If plants receive three or four short days and are then defoliated, no pistillate flower results. If plants receive three or four short days and are defoliated two days after the treatment, pistillate flower formation results. It seems that a certain substance(s) is produced in the leaves as the result of stimulus to induce the pistillate flower differentiation, proportionately to the foliage area and the duration of the stimulus.
    Provided any leaves and/or a growing point were continuously exposed to long day, no pistillate flower formation results. A few pistillate flowers appeared, however, on the plants identically treated, provided the room temperature was maintained at 17°C.
    The successive defoliation of the apical leaves just unfolding results in hastening of the production of the pistillate flowers at the early growth stage and also in the production of the pistillate flowers, later, in the staminate flower clusters at the basal portion of the main stem. The existence of unfolding young leaves seems to restrict the pistillate flower differentiation. In case of the experiment conducted in the greenhouse, however, the defoliation of the young unfolding leaves failed to induce the production of the more vigorous pistillate flower differentiation. It seems that in this case the mature leaves failed to produce and accumulate enough substances for the favorable sex differentiation because of the rather high temperatures (25°C_??_30°C) prevailed in the greenhouse.
    The receptor branch (maintained on long day) of a two branched cucumber plant, one branch (receptor branch) continuously exposed to long day and the other (donor branch) on short day, formed one pistillate flower. The photoperiodic stimulus was transmitted to the receptor branch maintained on long day. When mature leaves were removed from the receptor branch, the pistillate flower production tended to increase and when the young unfolding leaves were removed, the pistillate flower production tended to decrease. Provided the donor branch (maintained on short day) was pinched away, and the mature leaves on the receptor branch (maintained on long day) were removed, the receptor branch showed the most abundant pistillate flower production.
    It seems that the photosynthetic substances produced in the receptor branch, flowing through the same path in the plant, inhibit the flow of the flower inducing substance(s) into the receptor branch, and the apical portion of the donor branch (and/or the donor branch) tends to dominate the flow of the flower inducing substances.
    It may be reasonably explained that the flower inducing substance in the lower concentrations induces the staminate flower production and in the higher concentrations induces the bisexual and further the pistillate flower production.
    Individual plants become more sensitive in forming the pistillate flowers as they grow older.
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  • Manifestation of characters in F1 hybrids of crossings among local varieties of turnip native to eastern Japan
    T. AOBA
    1961 Volume 30 Issue 2 Pages 147-152
    Published: June 30, 1961
    Released on J-STAGE: December 25, 2008
    JOURNAL FREE ACCESS
    There have been cultivated for long time many local varieties of turnip in Japan. The author has collected about thirty of such local varieties belonging to the European type. Studies were carried out on the manifestation of characters in F, hybrids to elucidate the relationships among such varieties. 48 hybrids were obtained using 17 varieties, and their characters were examined (Tables 1 and 2). The results are summarized as follows.
    1. Leaf and root shape and plant form in the hybrids were nearly intermediate between those of the parents.
    2. Anthocyan pigment was dominant over green coloring of hypocotyle. The hybrids between Atsumi (purple hypocotyle) and green varieties, however, had green and in some cases light purple hypocotyle.
    3. Purple color of petiole was dominant over green. Purple was resulted in the hybrids between red and green.
    4. hairy. was dominant over Glabrous
    5. Color of root in the F1 hybrids was as follows (Fig. 1)
    On the above-ground portion, green and purple were dominant over white, and purple appeared in the hybrids between red and white.
    On the under-ground portion, white was dominant over purple or red.
    Purple was dominant over red.
    6. The A type of seed coat structure was dominant over the B type.
    7. Mutual relationships among the local varieties and utility of F1 hybrids of these varieties were discussed basing on the above mentioned results.
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  • VI. The influence of hormone spray on the growth and pigment contents of fruits
    T. TAKAHASHI, M. NAKAYAMA
    1961 Volume 30 Issue 2 Pages 153-160
    Published: June 30, 1961
    Released on J-STAGE: December 25, 2008
    JOURNAL FREE ACCESS
    Experiments were carried out to investigate the effect of hormone sprays on the plant growth and pigment and carbohydrate contents of tomato fruits, in 1959 at Shinshu University farm. The variety Aichi-tomato was used. Hormones and their concentrations used were þ-chlorophenoxyacetic acid, 30 ppm; gibberellin, 50 ppm; α-naphthaleneacetic acid, 50 ppm; 2, 4-dichlorophenoxyacetic acid, 10 ppm. Aqueous solutions of these hormones were sprayed on the flowers from the first to the third cluster at each flowering time.
    1. Plant height of hormone sprayed lots increased over that of control plant, but there was no difference in the number of leaves between the control and the hormone sprayed lots.
    2. The numbers of flowers and of fruits set in each flower cluster of hormone sprayed lots did not increase, but on the total of three flower clusters, the gibberellin sprayed lot was the greatest and the 2, 4-D sprayed lot the smallest. The fruit set percentage of PCPA sprayed lot was the highest of all lots. The fruit development, in the hormone sprayed lots except in the gibberellin lot was accelerated over that of the control lot, but the gibberellin sprayed fruits were smaller than the control, and their development was checked.
    3. The fruits of PCPA and 2, 4-D sprayed lots were seedless as the result of parthenocarpy, but the gibberellin and NAA sprayed fruits produced seeds. Among the seed-containing fruits, the larger the fruits, the more seeds they contained.
    4. The fruit yield of gibberellin sprayed lot was greater than that of the control, but among the other hormone sprayed lots, there was hardly any difference. The early yield was greater in PCPA, NAA and 2, 4-D sprayed lots, but gibberellin spray delayed the harvest.
    5. Chlorophyll content of fruits sprayed with PCPA, NAA and 2, 4-D decreased, but carotene, lycopene and xanthophyll contents of these fruits increased compared with the control. In the gibberellin sprayed lot the disappearance of chlorophyll was slower, and carotene and xanthophyll contents were less than the control fruits.
    6. Differences in sugar contents of fruits between the hormone sprayed and control lots were not significant, and the sugar content increased as the fruits matured. Starch content of fruit decreased in all lots as the fruits matured.
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  • On root vegetables
    T. OSAWA
    1961 Volume 30 Issue 2 Pages 161-166
    Published: June 30, 1961
    Released on J-STAGE: December 25, 2008
    JOURNAL FREE ACCESS
    As a part of the studies on the salt tolerance of vegetable crops, three root vegetables, radish, turnip, and carrot were grown in sand cultures under glass at various concentrations of NaCl. HOAGLAND's solution was used as the basic solution (control), and the concentration of NaCl added to it was 1000, 2000, 4000, 8000, or 16000 ppm.
    1. With increasing concentration of NaCl, in general, plants were dwarfed and both number of leaves and fresh weight of plants were reduced. In radish, however, the growth was not particularly affected by the NaCI treatments up to 4000 ppm, and the 1000 ppm treatment had rather favourable effects on the growth and on the yield of both tops and roots. In turnip and carrot, the plants finally died in the 16000 ppm treatment. The concentration of NaCl in the nutrient solution corresponding to a 50 per cent reduction in the fresh weight of tops of radish, turnip, and carrot was found to be about 9000, 8000, and 5000 ppm respectively, while that of roots was about 6000, 2500, and 4000 ppm respectively, hence the difference of response to salt concentration between tops and roots was especially remarkable in turnip. The percentage of dry weight of tops did not vary so markedly in any crop, while that of roots, especially in radish, tended to increase with increasing salinity.
    2. Specific symptoms of salt injury were as follows: In radish, leaves at 16000 ppm became temporarily dark green in the early stage of growth, while a similar symptom was observed in the later stage at 1000 to 8000 ppm; moreover, early at 16000 ppm and later at 8000 ppm, marginal burn occurred on older leaves, then younger leaves were progressively affected and older leaves died off. In turnip, leaves at 16000 ppm became entirely chlorotic soon after the treatment was initiated, and subsequently the plants died. In carrot, leaves became dark green at 2000 to 16000 ppm ; moreover, at 16000 ppm, leaves curled upwards and then the plants died.
    3. With increasing concentration of NaCl in the nutrient solution, the accumulation of both Na and Cl in leaves increased in any crop, but the accumulation of Na and Cl in radish and Cl in turnip was exponential rather than linear. Radish, which was more salt-tolerant than turnip or carrot, accumulated higher concentration of Na in leaves than did the other two crops. In general, Na accumulated in leaves in greater equivalent amounts than Cl. Antagonistic relations were found between Na and other essential cations, i. e. K, Ca, and Mg, but the total amont of these four cations in leaves increased with increasing salinity in any crop. The content of N in leaves tended to increase in high salt treatments, and P in leaves similarly increased in radish and carrot. However, the variation of the contents of N and P in leaves was rather slight as compared with that of cations. With increasing salinity, carbohydrate content in leaves decreased markedly in radish, but varied only slightly in turnip or carrot.
    In general, the variation of the content of mineral constituents in roots was not so marked as in leaves, although the tendency was almost similar to that observed in leaves.
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  • II. Effects of a prolonged vernalization treatment and influence of gibberellin applied during vernalization
    E. NAKAMURA, Y. HATTORI
    1961 Volume 30 Issue 2 Pages 167-170
    Published: June 30, 1961
    Released on J-STAGE: December 25, 2008
    JOURNAL FREE ACCESS
    In the previous report, on an experiment where slightly germinated seeds of cabbage were exposed to u cold at 1±1°C for 20 days, the senior author made it clear that with the given variety of cabbage (cv. Yoshin) germinated seeds are in some degree susceptive to a vernalizing low temperature. And in this connection, though the result of the seed-vernalization was very meagre, an increased vernalization effect was expected with longer duration of cold treatment. Further, in recent years, gibberellin has proved itself an agency for vernalization in some biennial plants.
    Thus, an experiment has been carried out to examine the effects of a longer duration of seed-vernalization and chemical vernalization with gibberellin on the floral development in cabbage (cv. Yoshin), with the following methods and results. 1. Slightly germinated seeds of cabbage were kept at 1±1°C for 20 or 40 days (V20 and V40), half of them being given gibberellin (G) with a concentration of 5ppm throughout the vernalization treatment.
    The treated seeds(V20, V20G and V40) along with the control (VO and VOG) were sown on 20 March, 5 April and 20 April in 1960.
    2. An accelerated floral development was seen in the vernalization lots, but between 20- and 40-day cold treatment no significant difference in vernalizing effect was observed.
    3. Gibberellin applied during seed-vernalization failed to exhibit accelerating influence on the vernalization effect.
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  • On the temperature and the heat balance in an empty unventilated glasshouse
    K. YABUKI, T. IMAZU
    1961 Volume 30 Issue 2 Pages 171-177
    Published: June 30, 1961
    Released on J-STAGE: December 25, 2008
    JOURNAL FREE ACCESS
    Summer glasshouse temperatures in Japan are too high for plant growth, so it is emphasized that glasshouse temperature should be controlled. As a fundamental investigation into temperature control the temperature distribution and heat balance in an empty, unventilated glasshouse was measured in July 1959.
    One of the questions arising is that the temperature difference between the inside and the outside is very small at night, whereas in daytime it is considerably large. The daytime difference between the inside and the outside of the glasshouse has often been attributed to the optical properties of the glass that transmit a high proportion of solar radiation but prevent the direct exchange of longwave radiation between the internal surface and the atmosphere. This, so called “greenhouse effect” does not explain the temperature differences observed at night.
    Table 1 shows that the maximum internal temperature was about 60°C, 28°C higher than the external temperature; but the minimum air temperature (26.5°C) was only 2.9°C above the external temperature. The temperature distribution revealed an up-draft in the centre of the house with a downdraft along the walls; the direction of the circulation was reversed at night.
    The “greenhouse effect” was unimportant because the loss of solar radiation by reflection and absorption exceeded the gain in long-wave back radiation from the glass.
    The difference in the amount of heat that is advected to the internal and external surfaces of the glass appeared to be considerably more important than it was previously supposed and it has a great influence on the net radiation of the soil surface. Excess heating of the internal air should be attributed to decreased turbulent transfer of sensible and latent heat.
    At night the net radiation measurements showed a marked “greenhouse effect, ’ but heat was lost rapidly in two important ways, by convection to the walls, which are cooled by radiation from their outer surfaces, and by horizontal conduction in the soil. (Fig. 4, 5). This explains why glasshouses cool rapidly after sunset and why the temperature difference is very small throughout the night.
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  • Y. SANO, K. KATAOKA, K. KOSUGI
    1961 Volume 30 Issue 2 Pages 178-182
    Published: June 30, 1961
    Released on J-STAGE: December 25, 2008
    JOURNAL FREE ACCESS
    Observation on the flower bud differentiation and experiments on the effect of gibberellin on forcing in Bletilla striata REICHB. were carried out.
    Initial primordia of tepals were observed on the 25th of August and pollens were formed on the 3rd of November in 1959 in Kagawa Prefecture (Table 1 and Fig. 1).
    In order to examine the effect of gibberellin on forcing, four groups of bulbs were soaked in gibberellin of 50 ppm, 10 ppm, 1 ppm solutions and in water for 30 minutes, and then forced. These treatments and forcings were started on the 17th of November, the 1st and the 15th of December.
    Growth_??_nd flowering of the plants were enhanced by gibberellin. Mean flowering dates of the plants treated with gibberellin of 50 ppm, 10 ppm and 1 ppm on the 17th of November were the 24th of December, the 29th of December and the 3rd of January respectively. This is 12 days earlier in the 50 ppm treatment than the control. The plants treated in later times were enhanced by gibberellin but the effects were less than those of the earlier treatments (Fig. 2 and 3).
    From the results obtained, gibberellin treatment is effective for earlier forcing of Bletilla striata.
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  • Further studies on the method of promoting seed germination
    Y. TACHIBANA
    1961 Volume 30 Issue 2 Pages 183-188
    Published: June 30, 1961
    Released on J-STAGE: December 25, 2008
    JOURNAL FREE ACCESS
    Germination of Hibiscus seeds, especially in perennial species, is usually very slow and insufficient due to the high percentages of hard grains. Artificial promotion of seed germination by H2SO4 treatment proved satisfactory (TACHIBANA et al. 1957). In this paper, further examinations of the method are presented in some detail.
    1. Six species, including an unidentified species from Nepal Himalaya (collected by S. NAKAO in 1953), were newly examined with respect to the characteristics of their seed germination. Germination test of untreated seeds generally resulted in low germination rate, but the promoting effect of H2SO4 treatment was remarkable in all of the species. According to the classification proposed in the preceding paper(TACHIBANA et al. 1957), they were included in the following categories.
    Germination of untreated seeds
    Germination of seeds treated with H2SO4 acetosella Group III Group Ill Himalaya 665 N N Mallow Marvels N Ill militaris VI III gossypinus N Ill peduculatus N N It was noticed that the seeds of certain uncultivated annual species such as Himalaya 665, gossypinus, acetosella, Trianum etc. contained many hard grains while most of the annual species in cultivation produce few hard seeds.
    2. Germination of treated seeds was accelerated by high temperature during incubation, but no significant interaction existed between the temperature and the duration of H2SO4 treatment(Fig. 4, Table 2).
    3. At 20°C, the acid solution 40% in concentration was ineffective for seeds of H. Moscheutos. The lowest effective concentration is probably 45%. The product, [effective concentration of H2SO4 (actual concentration minus 45%)] × [duration of H2SO4 treatment in minutes], was closely correlated with the per cent germination throughout the treatments tested (Fig. 5). The correlation showed that high percentage (>70%) of germination was always assured by the range of the product 900-6, 000 (% min).
    4. Using 98% H2SO4, the combined effect of temperature and duration of H2SO4 on germination of H. Moscheutos seeds was examined. The higher the temperature during treatment, the earlier the germination percentage was reached, but the severer the damage due to longer duration of the treatment (Fig. 6). The relation between per cent germination and accumulated temperature during the treatment could be described by a single optimum curve (Fig. 7), which suggested that the treatments between 150 and 2, 000 (°C min) were most effective.
    5. Relative humidity during 4 months of seed storage before germination had only a slight influence on the effect of H2SO4 treatment (Fig. 8).
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