1. The present study was carried out to confirm the effect of gamma radiation on the inhibition of sprouting of onions during the storage and to investigate the physiological changes following the treatment. Onion bulbs were irradiated with the doses of 3000, 7000, and 12000 r. soon after the harvest (June 28) and at the presprouting period when the dormancy ends, i.e., Sept. 20. 2. The sprouting of onion bulbs was completely inhibited even at the dose as low as 3000 r., and the storage period of treated bulbs was eventually prolonged so long as 4-5 months over ordinary storage period. 3. Inner buds of onion bulbs which were inhibited the sprouting by the irradiation were browned and dead, but the injured parts did not extend to the outside of the buds. In the bulbs which had been irradiated on September 20, the browned parts were somewhat larger than that of the bulbs treated soon after the harvest. It means that the elongation and/or differentiation of the inner buds might have occured during the period, so the irradiation in the early stages (during the rest period) would be preferable for practical use. 4. The oxygen uptake in the disk part (bottom part) of the bulbs was not directly influenced by the gamma radiation, while, when the control bulbs had increased the respiratory activity after the presprouting period, the increase of respiration in the treated bulbs was remarkably suppressed. 5. Also the contents of sugar and ascorbic acid in the bulbs were not immediately affected by any dose of radiation used in this study. However, when the non-reducing sugar content in the untreated bulbs was gradually decreasing after the bulbs had commenced sprouting, the contents in the treated bulbs were not affected for any change. 6. The characteristic flavor of onion bulbs did not appneciably alter by the irradiation. 7. No significant differences of the concentra-tions of growth promoting and inhibiting substances in the inner buds were found to exist between the irradiated bulbs and the untreated ones.
1. To compare the physical and chemical chan-ges occurring in maturing stage in the European sweet varities of sugar peas with those in the varie-ties which usually grown in Japan for canning and table use, some experiments were carried out in 1956 and 1957. 2. In the first year, Alaska, GW, and Oracle (sweet variety) were harvested four times at three day intervals from the 19 th to the 28 th day after flowering and were analyzed, It was found that Oracle variety was low in specific gravity, and conta-ined a small amount of alcohol insoluble residue which increased very slowly with ripening, as com-pared with the other two varieties. In Oracle va-riety sugar and soluble nitrogen contents were high, while starch and insoluble nitrogen contents were low regardless of the time harvested. 3. In the second year, Alaska, Usui and two sweet varieties, Provost and Oracle, were harvested from the 22nd to the 37th day after flowering. The results obtained in this year were similar to those of the first year. In grading by brine, it was found that in every harvest most of the peas of Provost and Oracle were in ‘Fancy’ class, while those of Alaska and Usui were in ‘Standard’ or ‘Second’ class. The peas of Alaska or Usui va-riety in ‘Fancy’ class, even if obtaind, were very immature and not available for processing. 4. As it was found that the stages of maturity proper to canning were very long in Provost and Oracle variety, it was possible to obtain the peas of high canning quality in large percentage even if they were harvested only one or two times. On the contrary, Alaska and Usui must be harvested many times because their proper stages of maturity were limited. 5. The canned products of Provost and Oracle variety were of excellent quality on account of their good flavor and clarity of liquid as compared with Alaska and Usui. In canned peas, even of the same class, the solid (drained) weight increased as the peas were harvested late because of increase in starch contents. In this case the Brix degree of liquid in cans increased according to maturity pro-bably because of absorption of water by starch par-ticles during sterilization.
Growth in length of the cauliflowers sown on July 11 in glass house was slow until the period of the flower bud differentiation (Sept. 28), and after that period rapid growth took place. Water content and specific gravity of the tissue powder of the leaf blade and the petiole increased obviously at the time of the flower bud differentiation. Cor-rected concentration indices of the expressed cell sap (cell sap concentration determined by the re-fractometric method×water content then existing in plant) of the leaf blade and the petiole varied in parallel with the concentration of the aqueous ex-tract of the tissue powder. These values increased accompanied with the growth of the plant, their maximum values being at the period of the flower bud differentiation and thereafter these values de-creased. It is presumed that these physiological changes observed in the period of the flower bud differentiation may be associated with the flower ripening of the plant. Electrical specific conducti-vity of the cell sap and that of aqueous extract of the tissue powder of the leaf blade and the petiole were high in the early growing stage, and decreas-ed gradually with the development of abortive floral organs. On the changes by leaf order, of these values such as the corrected concentration indices of the expressed sap, and the concentration of the aqueous extract of the tissue powder, it was observed that the higher the position of the leaf was, the higher the values were until the flower bud differentiated in two portions of the leaves, and after the dif-ferentiation these tendencies were not observed. Such changes of these values by the leaf order were remarkable in the early growing stage, but it was inconspicuous in the period of the formation of abortive floral organs. The higher the position of the leaf was, the lower the values of the electri-cal specific conductivity of the cell sap and that of the aqueous extract of the tissue powder and the change of these values was marked in the period of the flower bud differentiation.
The experiment has been carried out to ascertain the effect of light on coloring of tomato fruit using the variety “Kurihara” in 1958. A half of the flow-er clusters tested were shaded by leaves (shaded fruit) and the other half were exposed to the sun-light (exposed fruit). These fruits were analyzed for pigments and sugar contents from 25 days to 63 days after flowering. The results are as follows. 1. Chlorophyll, carotene and xanthophyll con-tents in exposed fruits were much higher than in shaded ones. The lycopene contents from 40 days to 55 days after flowering were slightly higher in exposed fruit than in shaded, but those on 60 days after flowering were much higher in shaded fruit than in exposed fruit. 2. Reducing and total sugar contents in exposed fruit were higher than in shaded fruit until mature green stage, but at mature stage (60 days after flowering) they increased more in shaded fruit than in exposed one. The difference of contents of non-reducing sugar between exposed and shaded fruit was not significant. 3. On the 25th and the 60th day after flowering, the exposed fruits were cut into the upper and low-er halves, and analyzed for pigments and sugar contents respectively. Chlorophyll, carotene, xantho-phyll and sugar contents in young fruits, and carotene, xanthophyll contents in mature fruits are much higher in lower half than in upper half, but in mature fruit, lycopene and sugar contents of upper half were more increased than in lower half. 4. On the 25th and the 60th day after flowering, the exposed fruits were divided into the exposed and shaded sides, and analyzed for carotenoid contents. Chlorophyll, carotene and xanthophyll contents in immature fruit, and carotene, xanthophyll contents in mature fruit were much higher in exposed side than in shaded side, but lycopene content in mature fruit was higher in shaded side than in exposed side. 5. It is considered that chlorophyll, carotene, xanthophyll and sugar contents in tomato fruits are increased by exposing to the sunlight, and that increase of lycopene content is affected by other factors, especially temperature as well as the ex-posure.
It seems that the calyx of Japanese persimmon fruit has remarkable characteristics compared with that of any other kind of fruit. It is known by many growers that when the fruits suffered from some damages on their calyx lobes (for example, calyx scorch due to the injury caused by spray or insect attack etc.), the develop-ment of the fruits is inferior to that of the normal ones. Therefore, the authors have investigated the de-velopment of the fruits in which all or a part of the calyx lobes consisting of 4 lobes have been removed, with a view to make ascertain the role of the calyx on the development of the fruits, with “Fuyu” variety, since 1951. In this report the authors describe only the in-fluence of the removal of calyx lobes on the fruit development. 1. The young fruits, when all of the calyx lobes were removed in the early stage of fruit develop-ment from flower bud stage to the beginning of July, had been induced to fruit dropping or checked markedly in their development after the'treatment. But in the case of the same treatment in July and August, the fruit development proceeded consider-ably, the rate of dropping was reduced and the fruits continued to enlarge fairly. The same treatment in the last period of fruit enlargement since last Sep-tember, had scarcely influenced the fruit develop-ment. The effect of calyx lobes on the fruit deve-lopment was most significant in the early stage of fruit development, and it became gradually less important as the fruit enlargement proceeded. 2. In the varied degrees (0. 5 to 3. 5 of 4 calyx lobes) of removal, on the 21 st of June, the fruit development was checked more severely, with in-crease of degrees of the removal. Especially, it was significant that in the case of 3. 5 calyx lobes being lost, the fruit did not drop, but developed consider-ably, as compared with the result that the fruit dropped when all calyx lobes were removed. There-fore, it seems that the function of calyx lobes on the fruit development has comparatively great effect in the prevention of dropping of young fruits and the development of them, if the fruit possesses the calyx lobes even a little. 3. It seems that with the function of calyx lobes on the fruit development, there is no difference between their top parts and basic ones. 4. Even when all the leaves on bearing branch were removed, so far as the fruits had all the normal calyx lobes, .they developed very fairly. 5. When the fruit development was checked as the result of the removal of all calyx lobes, the seed growth in that fruit were checked, too. The shortage of carbohydrate was also found in such fruit. From these facts, it may be considered that in order to develop and mature the fruits completely, it is necessary to keep the calyx lobes perfect and healthy in full course of the fruit development.
Young trees of peach (var. Okayamawase) and Japanese persimmon (var. Hiratanenashi), kept in the warm chamber (6-11°C) during winter (Nov. 20 to Mar. 20), were treated with chilling tempera-ture for 15 or 30 days by moving them into the cold .chamber (-1-0°C) at various stages of their dor-mancy (from Dec. 7, 16, Jan. 6, 16 or Feb. 5). Bud-opening and shoot- and root-growth of the treated trees were compared with those of the trees which were kept in the warm chamber or in the open throughout the winter. The results obtained were as follows. 1. The buds on the chilled trees opened 6 to 11 days earlier than those on the non-chilled trees. Also, the treatment increased the number of opened buds and promoted the shoot growth. The 30 days treatment was more effective than the 15 days treat-ment. As to the date of the treatment, the January treatments were most effective, the December treat- ments came to the next, and the February treatment was least effective. It was most desirable for break-ing dormancy of peach trees to chill for 15 to 30 days during late December to late January. In Japanees persimmon, the chilling treatment for 15 days promoted bud-opening and shoot growth, while the treatment for 30 days retarded them. Chilling requirement of persimmon trees seemed to be less that of peach trees. Even the trees kept in the warm chamber throughout the winter opened their bud normally and maintaind their apical dominancy. 2. In Kochi, it is generally cold, and daily mi-nimum temperature falls down to 0° or below 0°C from middle January to middle February. The date of the onset of this cold period seems to be a little late for breaking effectively the dormancy of peach trees, while it is not the case for persimmon trees. Peach trees show little or no ‘prolonged dormancy’ in the year when the cold period comes earlier. The effectiveness of the chilling temperature for breaking the dormancy of fruit trees seems to vary with the date of its onset.
In continuation of the preceding research, layer-ing experiment has been conducted on Japanese and Chinese chestnut trees making use of growth pro-moting substances in lanolin paste. 1. Varieties which were especially hard to root with IBA alone, rooted better with a mixture of IBA and 2, 4, 5-Tp, and with 2, 4, 5-Tp alone. Also by foliar application of 2, 4, 5-Tp to seedlings in layering bed, vigorous rooting was obtained. 2. Rooting ability of cultural variety was great-er after shoots have stopped growing than during their elongating period. 3. The longer the length of shoot of cultural variety, the lower the percentages of rooting. 4. Layers which were grafted on vigorous stock required a longer duration in rooting than those grafted on less vigorous stock. 5. Concerning the rooting percentages and root-ing time, considerable differences were observed among juvenile seedlings and two types of varieties of which one was easy and the other hard to root. Higher rooting percentages were accompanied with shorter rooting time.
Many studies on the physiology of flowering clari-fied that the flowering in short-day plants may be controlled by the application of plant growth regulating substances, the so-called “auxin” or “antiauxin”. It is recognized in the gladiolus culture that the .short day promotes the flowering slightly, but ex-treme short day causes the blindness. It is supposed that the application of growth regulating substance is effective to decrease the number of blindness in gladiolus, For the first step of the study from the point of view mentioned above, the experiments were conducted to know the auxin level in the flower buds of gladiolus which had been held under long photoperiods (24 hours) and short photoperiods (8 hours). The variety used was “Spotlight”. The average-weight of corms which had been grown at Ueno in Mie prefecture was 26. 5g. The corms were plant-ed in the experimental farm of Kyoto University on August 27, 1958. Shading and lighting were made from October 10 to November 6, 1958. Sampl-ings were made at one-week intervals during the .course of the experiments and the avena tests were mad eon each sample. Avena sativa, variety Victory grown at Hokkaido University was used for the .curvature test. And the diffusion method, in which 3 hours diffusion was made at 25°C, was employed for the test. Beside avena test, anatomical obser-vations were made. The results obtained were summarized as follows: 1. Two weeks after the start of treatment, it -was observed that the length of flower spikes in short-day plot was getting shorter than that in long-day plot, nevertheless no difference was observ-ed between long-day and short-day plots on height of plants, number of leaves, and length of stems. And the difference in length of spike increased gradually as the time progressed. Finally, the blindness occurred in short-day plot, four weeks after the start of treatment. 2. The value of avena test with the plants under short-day condition was smaller than that under long-day condition two weeks after the start of treatment. And as the time progressed, the difference in the measurement values between long-day and short-day plots became greater. Finally, few avenas were curved with the plants under short-day. 3. Anatomical observations showed that the death of cells appeared at the top of the flower spike in three week treatments of short-day. Then the death of cells advanced downwards with the succeed-ing of treatment. The perfect death of flower spike was observed in the samples taken from the plants treated with four week short photoperiods. The archesporium formation was observed in the flower buds that died at their most developed stage. 4. From the results mentioned above, it seems that the gladiolus under short-day condition results in the decrease in auxin content in the flower buds, and consequently shows the blindness. 5. Anatomical studies showed that the flower buds, which had reached to the tetrard stage at the end of four week short-day treatments, were not damaged.
This experiment was carried out to study the physiological problems of seed germination and ge-netical feature in freesia, especially paying atten-tion to the seed-strain freesia, Super Giant, from the breeding view point. 1. The optimum temperature for seed germina-tion of freesia is 15°C. No germination takes place at temperatures higher than 25°C. 2, The germinating behavior is very irregular, the duration extending over a long period. This irregular germination may be caused by several environmental factors and genetical factors. 3. The seeds of seed-strain freesia, Super Giant, has weak dormancy as compared with Alba var. and the seedlings of Super Giant grow taller than the Alba seedlings. The time of flower bud differ-entiation is later in Super Giant seedlings than that of Alba regardless to the sowing time. 4. Super Giant seedlings show great variations in various characters such as flowering date, stem length, flower diameter and corolla type. Correla-tion coefficients among these characters are gener-ally low, though they show significant correlation in some cases. Their heritability are also generally low, showing that the greater parts of variations may be due to environmental factors. 5. Freesia, Super Giant, is a cross-pollinated plant consequently the inbreeding depressions are found clearly on several characters. 6. Some possible methods for further breeding are discussed.
The present expriments were performed to study the flowering of Christmas cactus, a-short-day plant, following gibberellin application. 1. Gibberellin applied as an aqueous solution at the beginning of short-days caused delaying of the flowering. This delaying effect of gibberellin decreased when applied 7 or 10 days after the start of short-days. This result was also ascertained by the evidence that the flower buds stopped to increase in number due to the treatment of gibberellin. 2. When gibberellin had been applied before the start of short-days, the delaying effect on flowering decreased as the number of days prior to short-days was increased. The effect of gibberellin was demonstrated to remain in a plants at least for 20 days. 3. Gibberellin applied 20 or more days or even 14 days after the start of short-days caused the acceleration of the flowering. 4. With gibberellin treatment the plants generally produce peculiar flowers, the ovaries and the corolla tubes of which became longer and more slender. When gibberellin was applied 10 days after the start of short-days, it was observed that many unusual buds appeared, sometimes the ovaries of these buds were buried in leaf-like stems. 5. 5, 25 and 100 ppm of gibberellin had almost the same effect in delaying or acceler-ating the flowering. 6. With gibberellin treatment the number of flowers decreased, but increased when the plants were treated 30 days after the start of short--days. On the other hand, the plants. to which NAA was applied at an earlier time of short-days had more flowers than the non-treated control. 7. NAA applied 20 or less days after the start of short-days delayed the flowering by a few days independently of the time of application.
For the production of chrysanthemum flowers in early spring to early summer, rosette suckers are usually planted in winter. They do not elongate well' even under high temperature thereafter unless they are subjected to low temperature for certain period. Therefore, the suckers to be planted early in winter are obtained from the high altitude areas where temperature drops earlier. This study was made to elucidate the developmental process of suckers and factors responsible for rosette formation, and also to find the measures effective to break the rosetting of suckers. Suckers develop from the definite buds on the stem under or a little above the soil surface. Under the natural conditions, suckers start to develop after the end of August, simultaneously with the time of flower bud differentiation. When all the buds were pinched off, or were checked their growth by MH spraying, suckers started to develop before the flower bud differentiation. Therefore, it seemed that the absence of the growing buds on the stem stimulated the growth of the latent buds into suckers. Suckers developed in September or later form rosette, while those developed in July or August do not form rosette. Experiments were carried out to know which was responsible to the induction of rosetting of suckers, low temperature or short day length. The results revealed that suckers of ‘Shin-Toa’ and ‘Okayama-Heiwa’ were induced to rosetting by low temperature of about 15°C under long day condition, while the suckers of ‘Pink-Toa’ were induced to rosetting under short day condition and not under long day condition. The factors responsible for the rosette induction seemed to vary depending on the varieties. Some authors reported that the rosetting could be broken by low temperature. An experiment was made to know how soon the rosetting was broken in winter under the natural conditions in Tokyo. It was found that the suckers of ‘Shin-Toa’ and ‘Okayama-Heiwa’ grown in the open till Dec. 20, then moved into the greenhouse elongated well. So the low temperature period to Dec. 20 seemed to be long enough to break the rosetting of the suckers. An additional experiments was made to clarify the effects of ethylene-chlorhydrin, thiourea, and gibberellin on breaking the rosetting of suckers. Ethylene-chlorhydrin showed some effects, and thiourea not at all. Gibberellin (50 and 100 ppm) showed no effect when it was applied in early stage and also near the end stage of rosetting, while it showed a significant effect when applied on Jan. 10, apparently at the middle stage of rosetting.