With two grape cultivars, Muscat of Alexandria and Kyoho, the effects of CCC sprays in combination with shoot pinching (or topping) were examined on the inflorescence induction and development on lateral shoots arising from the pinched (or topping) shoots. The inflorescence formation on the primary lateral shoots sprayed with CCC greatly increased when they were pinched at 20 leaf stage with Muscat of Alexandria and at 10 leaf stage with Kyoho, but not so at 30 leaf stage with both cultivars. The flower number per inflorescence was greater when the shoots were pinched at 20 leaf stage than at 10 leaf stage with both cultivars. Furthermore, with Muscat of Alexandria, more flowers per inflorescence were differentiated on the secondary lateral shoots emerged from the primary lateral shoots by pinching the latter at 3 leaf stage than the primary laterals.
Effects of the time of fruit thinning on the fruit growth and the variations of sugar and acid contents in the fruit juice of twelve-year-old Hassaku trees (Citrushassaku Hort.) were examined. The numbers of leaves per fruit were 55 in the thinned tree on July 15, and 53 in the thinned tree on August 17, and 31 in the non-thinned tree. Fruit size and sugar and acid contents in the juice were measured on both December 14 and March 24. 1) Fruit growth was superior in the thinned trees in both July and August, and number of L, M size fruits was greater. The ratios of larger fruits above L size were 56.7% in the thinned tree in July, and 44.2% in the thinned tree in August, and 9.7% in the non-thinned tree. The mean fruit weights were 273, 270, and 209g, respectively. 2) The variation of sugar content in the juice examined in December ranged from 9.0 to 10.4% in the thinned tree in July, and from 8.8 to 10.0% in the thinned tree in August, and from 9.2 to 11.0% in the non-thinned tree, and also the variation of acid content ranged from 1.4 to 1.7% and from 1.3 to 1.8%, and from 1.4 to 2.0%, respectively. Average sugar contents were 9.6% in the thinned tree in July, and 9.4% in the thinned tree in August, and 9.9% in the non-thinned tree, and also average acid contents were 1.62, 1.58, and 1.75%, respectively. When the fruits were stored in room temperature after harvested in December, and examined in March, the variation of sugar content ranged from 9.0 to 10.8% in the thinned tree in July, and from 9.0 to 10.6% in the thinned tree in August, and from 9.0 to 11.0% in the non-thinned tree, and also the variation of acid content ranged from 1.1 to 1.5%, and from 1.0 to 1.5%, and from 1.1 to 1.7%, respectively. The acid content was lowered during storage. 3) Significant negative correlations were found between fruit weight and acid content observed both in December and March. Correlation coefficients were r= -0.54 and -0.41 in the thinned tree in July, and r=-0.56 and -0.55 in the thinned tree in August, and r=-0.72 and -0.55 in the non-thinned tree.
To examine the effect of soil temperature on cyclic fluctuations, experiments were carried out under prescribed environmental conditions. Fluctuations in leaf thickness were monitored by a differential transformer and the temperature of the same leaf by a thermocouple. The cyclic fluctuations in leaf thickness followed those of the leaf temperature. Harmonic analysis indicated that the time lag was about 553sec to 641sec. When the soil temperature at the center of the pot was lowered, the absolute leaf thickness decreased in accompanying cycling. However, the cyclic fluctuations disappeared when the soil temperature was further lowered. The critical temperature was 17°C in early October and 11°C in late November. In early October, the cyclic fluctuations appeared again in two and a half hours when the soil temperature was raised and did not disappear even when the soil temperature reached to 36°C. In late November, however, it took more time to recover the cyclic fluctuations and above 35°C they became irregular again. From these results it was postulated that root adaptability to temperature in terms of cyclic phenomenon changed with the advancement of the season. Further study is reqired to clarify how root activity plays a role in stomatal movements.
1. The amounts of flower formation with special reference to the leafy and leafless flowers, and their fruit set were observed in three different orchards of satsuma mandarin (Citrus unshiu MARC.). In this experiment, flowers were divided into two morphological classes; leafless-shoot bearing a flower but no leaves, and leafy-shoot bearing a flower and leaves. On the individual secondary scaffold branch, the percentage distribution of leafless tends markedly more to produce on on-year tree than to do off-year tree. As the position in each tree crown shifts from the outside towards the inside, the percentage of leafy flower was significantly decreased. Leafless flowers on outside of on-year tree comprised 65 to 80 per cent of flowers. Leafy flowers set more fruit than leafless flowers. The percentage of leafy flowers decreases and that of their fruit set increases as the number of leaves per flowering shoot increases. Further, the chance of sitting fruit is greater as the ratio ofleaf area to a flower is higher. 2. To observe the effects of spring leaves (spring cycle leaves of the current year) or old leaves on flowering and fruit set, experiments were conducted with secondary scaffold branches of satsuma mandarin trees grown under field conditions. Treatments were the same method as described in the preceeding paper(16). Flowers bearing old-leaf gave the best development of ovary in weight at anthesis. The development of ovary reduced in the following order, no-leaf, control, and new-leaf plot. Fruit set for one month after full bloom were also greatest in fruit bearing old-leaf. Its ranking in the other plots was; control>no-leaf>new-leaf plots. Not only was the development of ovary in new-leaf plot the poorest among the four plots, most of the fruits abscised in this plot immediately after bloom. In the remaining three treatments, marked fruit drop was observed in early July, particularly, in old-leaf and no-leaf plots. The development of ovary derived from the leafless flowers is inferior to that of the leafy flowers. There was a tendency to increase ovary weight in the control and new-leaf plots as the number of leaves per a leafy flower becomes greater. Fruit set of leafy flower was also superior to that of leafless flower. 3. The effects of spring leaf on fruit growth, and anatomical changes during development were investigated throughout an early developmental stage of satsuma mandarin fruit. Relative growth rates of both fruit diameter and fruit weight had two peaks during a period from full bloom to an early developmental stage. Juice sac primordia appeared already at anthesis. At about the secondary peak of the relative growth rate of fruit growth, locule is full of juice sac. The period from the emergence of juice sac to the beginning of their remarkable elongation was referred to as the cell division period. After this time, the fruit grew rapidly. The increase of fruit growth typically occurred three weeks after full bloom, being one to two weeks behind the time maximizing the leaf area.
Endogenous plant hormone levels in the xylem sap of the grapevine were determined at different stages of development to demonstrate the relationship between top growth arid endogenous plant hormones. (1) The growth of the new shoot was a typical double sigmoid curve. The inception of the second growth was at a full bloom stage. The growth of roots increased rapidly after the shoot growth stopped. (2) Cytokinin activities in the xylem sap were present in n-butanol (Free) and aqueous (Bound) fractions, In each fraction there were at least two major peaks of cytokinin activities. (3) The free cytokinins increased from April to July, and thereafter decreased rapidly. The bound cytokinins were maintained at high levels from May to June as flowers opened. Gibberellin-like activity in the xylem sap was present in May and increased in June as flowers opened and fruits developed, and thereafter decreased rapidly. Auxin and absccisic acid-like activities in the xylem sap were very low during their development. These results lead to the suggestion that gibberellin and cytokinin synthesized in roots may play an important physiological role in controlling the growth of the shoot and flower clusters.
In the present experiment, some observations with the morphological and histological aspects were made concerning self-incompatibility in Hyuganatsu, Citrustamurana Hort. ex Tanaka. The results are summarized as follows. 1. By means of scanning electron microscopy, the pollen behavior on stigmas when self-pollinated was compared with that when cross-pollinated with Hassaku, Citrus hassaku Hort. ex Tanaka. Soon after cross-pollination, the pollen grains began to be covered by the stigma exudate; 12 hours after pollination, the pollen grains were completely covered by the exudate. While the self-pollinated pollen grains were not covered by the exudate so soon as in the case of cross-pollination, and individual pollen grains were observed rather clearly in some parts of the stigma even 12 hours after pollination. 2. By means of fluorescent microscopy, the pathway of pollen tubes in styles was examined. In the upper portion of styles, the pollen tubes grew not only in the stylar canal along the wall of stigmatoid cells but also through the intercellular space of parenchymatous tissues. In the middle and lower portions of styles, all the pollen tubes grew in the stylar canal along the wall of stigmatoid cells. The pollen tubes of Hassaku reached the upper, middle and lower portions of the styles in 1, 3 and 5 days after pollination, respectively. On the 5th day after pollination, some pollen tubes were observed to have penetrated into ovaries. While, almost all the pollen tubes of its own did not reach the uppermost portion of the style even 7 days after pollination.
Fruits of strawberry, Fragaria × ananassa (Duch), cv. ′Hohkoh-wase′, one day prior to anthesis, were cultured in vitro to determine the roles of seeds in fruit development in relation to plant growth regulators. 1. Fruits from which carpels were removed enlarged normally as intact fruits with carpels on the medium with α-naphthaleneacetamide (NAAm). The ripening of intact fruits with carpels on the NAAm medium was suppressed in comparison to that of fruits without carpels. 2. When fruits with or without carpels were cultured on the medium with gibberellic acid (GA3), in either fruit, only the basal portion, which was originally devoid of carpels, swelled, but the upper portion, where there were carpels originally, showed no growth. With addition of GA3 to the NAAm medium, fruits with carpels enlarged into normal shape and their growth and ripening were promoted in comparison to those of fruits on the NAAm medium. 3. When fruits with or without carpels were cultured on the medium with N6-benzyladenine (BA) and NAAm, the growth and ripening were suppressed in either fruit as the concentration of BA increased. 4. When fruits with carpels were cultured on the medium with maleic hydrazide (MH) and NAAm, the browning of the carpels became severe as the concentration of MH increased, and the growth and ripening were promoted. Based on these results, it is suggested that auxin is more essential for the growth of strawberry fruits than gibberellin, and the carpel is the production site of cytokinin, which suppresses the growth and ripening of strawberry fruits.
The characteristics of nutrient uptake by musk melon were examined by two hydroponic cultural methods, water culture and KUNTAN culture. The rate of nitrogen uptake gradually rose before pollination then remarkably increased immediately after pollination. The increased rate of nitrogen uptake was observed for about 15 days then followed by a sudden decrease in the rate down to the levels before pollination. The water uptake showed almost the same fluctuation as nitrogen uptake, but the increase in the rate after pollination was more in nutrient uptake than in water uptake and following decrease was less in the former than in the latter. The uptake of NO3- and Ca2+relatively dominated in the earlier stages while K+ in the later stages. From the results of these experiments, the cultural period of musk melon was divided into three growth stages, vegetative stage, fruit developing stage and fruit maturing stage.
It has been generally recognized that common stocks do not form flower buds at temperatures above 15.6°C. In recent years, however, many cultivars of extremely early flowering have been bred, which flower from October to December when they are sown in the beginning of August. In the previous paper, it was shown that ‘Senshonoyuki’, an extremely early flowering cultivar in Japan, flowered at 3°C- day and 25°C-night temperatures. In this paper, the effect of temperatures above 13°C on flowering of non-branching stocks was investigated. 1. Eight cultivars of extremely early flowering and medium flowering cultivars were sown in the hot bed above 15°C in March of 1972. Seedlings with 2-4 unfolded leaves were grown in glass houses under natural day length, in which minimum temperatures were maintained at 15°, 20° and 25°C. No flowering was observed at any temperatures in medium flowering cultivars. In extremely early flowering cultivars flowering percentages of ‘Christmas Rose’, ‘Senshonoyuki’ and ‘Christmas Blue’ were 100% at 25°C, and that of ‘Christmas White’ was 72%. However, the time of flower budding and flowering at 25°C were later than 15° and 20°C. The number of nodes to inflorescence increased directly in relation to the growing temperature. 2. Eight extremely early flowering cultivars and one early flowering cultivar were sown in September of 1972. Seedlings with two unfolded leaves were transferred to glass houses under natural day length, in which minimum temperatures were maintained at 13°, 18° and 23°C. Flowering percentages of extremely early flowering cultivars, ‘Christmas Rose’, ‘Akinobeni’, ‘Akinomurasaki’ and ‘Kanshio’ were 100% at 23°C, and those of ‘Benihime’ and ‘Tsukinoyosooi’ were 98%. However, those of ‘Christmas Blue’ and ‘Christmas White’ were 70% even at 18°C, and further lowered at 23°C. Flowering of ‘Zuisei’, an early flowering cultivar, were occurred only at 13°C. Differences of the times of flower initiation and flower budding at 13° and 18°C were very slight in all the extremely early flowering cultivars. However, flower initiation and flower budding of ‘Christmas Blue’ and ‘Christmas White’ were later than those of the other six extremely early flowering cultivars at these two temperatures. The higher the temperature, the more nodes to inflorescence in all the extremely early flowering cultivars. Their plant height was the lowest at 23°C and some abnormal flowers were observed above this temperature. These results suggest that the maximum temperature, which induces flowering in most of the extremely early flowering cultivars of non-branching stocks, is 23° -25°C.
Some methods of cutting in a propagation house equipped with intermittent mist and the effect of auxin treatments on rooting were investigated from 1973 to 1977, using as the mature stock plants R. metternichii var. hondoense growing in the mountains of Gifu prefecture. Stem cuttings were taken from 10 to 20 year old plants in the middle of July after the current shoot elongation had ceased. The period of cutting extended over four months. 1. As a propagation bed soil for cuttings, a medium consisting of 7/10 Kanuma- tsuchi and 3/10 peatmoss or akadama-tsuchi were more suitable for rooting than Kanuma-tsuchi alone. Both a medium consisting of 7/10 Kanuma-tsuchi and 3/10 coarse sand, and a common field soil were inferior, and a medium consisting of 7/10 Kanuma-tsuchi and 3/10 chopped sphagnum was the most inferior for cuttings because a lot of dead stem cuttings occured. The physical conditions of the bed soils, investigated at the end of the experiment, had little difference among them, but it was judged that the medium of Kanuma-tsuchi and peatmoss was higher in water holding capacity than the Kanuma-tsuchi alone. 2. Many more two year old branch cuttings rooted than current shoot cuttings, but current shoot cuttings rooted to the same degree in some cases; therefore, the influence of the stem cuttings′ age on rooting could not be made clear. No influence on rooting of different leaf areas among 3, 5 or 7 leaves per stem cutting was found. Within the limits of five leaves per stem cutting, restriction of leaf area due to cutting off half of each blade had no effect on increased rooting. 3. In regard to the effect on rooting of auxin treatment at the base of stem cuttings, IBA had little or no effect, but NAAm was effective. Dipping stem cuttings into 35°C hot water or 2% ethanol as a pre-treatment was not injurious to their growth, and the former effectively increasing the rooting compared with non pretreated stem cuttings. 4. First most of the stem cuttings began the callus formation at their cut surface 10 to 30 days after the beginning of cutting, and then they began the root differentiation 30 to 60 days after. Water content in the leaves of stem cuttings reduced continuously with the beginning of cutting, but it became constant after 60 days. Dry matter content in the leaves of stem cuttings reduced temporarily when they formed a callus and after that recovered slowly, and such stem cuttings survived although they still did not root. 5. The highest percentage, of rooting, 65%, was obtained from only 2 year old branch cuttings from which the current shoot had been removed, and which were treated with NAAm and placed in bed soil consisting of Kanuma-tsuchi and peatmoss. This effectiveness may result from having removed the terminal bud, which contains the developing flower bud. The better cutting results in this experiment were obtained by rooting a current shoot cutting into bed soil consisting of Kanuma-tsuchi and peatmoss, and a two year old branch cutting into bed soil consisting of Kanuma-tsuchi and akadama- tsuchi. The ratio of rooted cuttings in these cases was 53% and 48%, respectively. Although these results may be unsatisfactory in view of practice, the callus formation was vigorous in the case of the cuttings which did not root. Therefore, an increase of rooting could be expected if physiological factors of stem cuttings in relation to rooting could be made clear, and a cutting method and its environmental condition could be improved.
In a study of photoperiod response, twenty-two Japanese cultivars were compared with five cultivars normally grown in English all-year-round (AYR) schedules. Cultivars which naturally flower in Japan in September or earlier (early-flowering) reacted as quantitative short-day plants. Both flower bud initiation and development occurred more rapidly in short days (SD) as compared with long days (LD). Only the cultivar, Mezame, approached day-neutrality. Autumn and winter-flowering (late- flowering) cultivars responded as quantitative short-day plants, as did the English AYR cultivars. The early-flowering cultivars differed from the late-floweringtypes in that lateral flower buds and often the terminal flower buds developed to anthesis in LD. The number of leaves produced in LD before terminal bud initiation by the early- flowering Japanese cultivars increased as natural flowering season became later. It seems likely, therefore, that long-day leaf number plays a part in determining natural flowering season in these cultivars. Similarly bud development time in SD may play a part in determining natural flowering season in the late-flowering cultivars. At least two of the Japanese cultivars possessed characteristics which might usefully be incorporated into English AYR cultivars.
1. Root formation and respiration of the cuttings of Camellia japonica L. (cv. Otome) and Chrysanthemum morifolium Ramat. (cv. Alps) were studied in relation to temperature. The materials were kept in growth chambers of low (17°C) medium (23°C) and high temperature (30°C) during propagation. 2. Callus formation and rooting of camellia were greatly promoted with rising temperature. When the final observations were made 70 days after planting, 16.0 %, 36.0% and 87.5% root formation were_shown in low, medium and high temperature, respectively. 3. Root formation in chrysanthemum was earlier in higher temperatures (23°C and 30°C) than in low temperature (17°C). But, 19 days after planting, both the rooting percentage and number of roots per cutting were lower at higher temperatures. 4. Respiration rates of upper and lower parts of the cutting were determined periodically during propagation. The rates of upperr parts were much higher in chrysanthemum than in camellia throughout the propagation period. In both plants, the rates were higher initially as the temperature was raised and then decreased more rapidly with raising temperature. There were no marked changes in the rates during the subsequent period for those samples. 5. For lower parts of the cutting, the rise in respiration, which was closely associated with rooting, were observed 7 to 11 days and 50 to 60 days after planting for chrysanthemum and camellia, respectively. The peaks were earlier and greater with rising temperature for both plants. 6. From the studies under the different temperatures it was found that in camellia the root formation was greater at higher temperatures when respiration was marked, but the root formation of chrysanthemum was greater at lower temperatures.
Frost hardiness of winter twigs from about 180 tree species of flowering and ornamental trees native to different climates were determined. Dormant one-year- old twigs collected from mature trees wintering under different climates during mid-winter were artificially hardened at sub-freezing temperatures for about 20 days to overcome the differences of the sites of collection and to develop maximum frost hardiness. Almost all of the trees which ranged from tropics to sub-tropics in both Asia and America sustained freezing injury to some of their tissues below -5°C. Evergreen broad-leaved trees native to warm climates survived freezing from -7 to -17°C. Most of the deciduous trees and conifers distributed in temperate climates were observed to be much hardier than evergreen broad-leaved trees, which survived freezing to -20 to -40°C. These hardy trees all can be grown in Sapporo where the annual average minimum temperature is about -20°C. A marked variation in hardiness between flower and vegetable buds was observed in many flowering trees. Also, a considerable variation in hardiness was noted among Japanese camellia from different provenances. Winter minimums seem to be among the important factors governing the northern limits of artificial plantings in most of the flowering and ornamental trees.
These experiments were carried out to study the properties of a plant growth regulator, Diaminomaleonitrile (DAMN). (1) It was apparently recognized that the growth of herbaceous cutting of chrysanthemum was stimulated by treatmant of 24 hourss at 50 to 100 ppmw water solution of DAMN, for such a kind of Gay Anne (American potmum species). And, under conditions both of water cultivation and propagation bed, such as vermiculite plus river sand, the growth effect was shown to be the same as β-IAA or α-NAA, on the root numbers, rooted stamp numbers, root length, root weight and leaf fresh weight. (2) The most adequate concentrations due to the treatment for 24 hours of DAMN water solution for many kinds of chrysanthemum were 25 to 100 ppmw to Gay Anne, Otomezakura (lemon yellow) and Beniotome (violet), 25 ppmw to Ryunotama, 50 to 100 ppmw to Soannoaki, Otomezakura (white) and Shimizunokagayaki, 50 ppmw to Unzen and 100 ppmw to Whitealps. (3) When the talc formulation is treated for chrysanthemum herbaceous cutting, the most effective DAMN concentration is 0.25 to 0.5 percent in active ingredient. (4) The root growth of chrysanthemum herbaceous cutting accelerated particularly in several propagation beds. And the descending order of the effect among them was shown as river sand=Kanuma soil>vermiculite>river sand plus vermiculite. (5) The root growth of chrysanthemum herbaceous cutting was examined by using many DAMN formulations. The most adequate carrier were zeeklite, clay (comercial name is Fubasami clay) and talc. Besides, the formulations of perlite and kaolin were fairly good. (6) When the root of chrysanthemum herbaceous cutting was grown by DAMN talc formulation, the most effective treatment length was the range of 1 to 2cm from cutting section. (7) The chrysanthemum herbaceous cutting treated by DAMN talc formulation, begins the rooting 10 days after treatment. It was assumed that the adequate transplanting time is on the 27 to 34 days after placing in propagation bed.
The object of this experiment is to illustrate the relation between the occurrence of chilling injury and the decrease of L-ascorbic acid (ASA) content in the seeds of stored sweet pepper fruit. We determined the changes of ASA and phenols content during development of chilling injury and the changes of some enzyme′s activities concerning with phenol formation and oxidation of ASA. 1. The ASA content in sweet pepper seeds decreased remarkably during storage at 1°C. And the reducing substances (cysteine, glutathione (reduced form), and NAD(P)H) except ASA were slightly increased during storage at 1°C. 2. The total phenols and O-diphenols content, to form brown pigment, in sweet pepper seeds increased on the second day and then decreased during storage at 1°C. 3. The glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities were high during storage at 1°C rather than at 20°C. The shikimate dehydrogenase activity increased remarkably until the fourth day when the symptom of chilling injury was observed, in seeds during storage at 1°C. The polyphenoloxidase activity increased gradually during storage at 1°C and 20°C with almost no difference between the activities at both temperatures. 4. The ascorbate oxidase and peroxidase activities during storage were lower at 1°C than at 20°C. The catalase activity showed little change during storage at 1°C.
The detection of proteolytic enzyme in the juice of purple passion fruit (Passifloraedulis Sims) was carried out and the properties of the crude enzyme preparations were studied. 1. It has been found that the optimum pH of two types of proteases in the juice of passion fruit was 2.3 and 5.7, using casein as a substrate. The former was designated as PFP-I (Passion fruit protease-I) and the latter, as PFP-II. 2. The maximum activity of PFP-I against temperature was 40°C and that of PFP-II was 50°C. The thermal stability of the enzymes in the solution of pH 6 was shown to be completely inactivated at 70°C and 60°C for PFP-I and PFP-II, respectively. The activity of the enzymes was comparatively stable over a pH range of 2 to 4. Although in the sodium citrate solution at pH 6 PFP-II was inactivated after freezing for 3 days, it was suitable for both of the proteases to be stored at 5°C. 3. The activity of PFP-I was inhibited by incubation with Fe++, Co++, Pb++, Ag+, Zn++ and Hg++, but activated by Mn++, Sn++ and Cd++. On the other hand, that of PFP-II was reduced by Co++, Pb++, Ag+, Ca++ and Cd++, but slightly enhanced by Fe++, Cu++, Mn++ and Zn++. 4. The maximum activity of PFP-I was in the acid pH region and was unaffected by various inhibitors such as PCMB, PMSF and EDTA. Therefore, PFP-I was estimated to be an acid protease. PFP-II was considered to be a SH-protease since its activity decreased markedly by some SH-reagents alone, being increased by cysteine. 5. As fruits matured, the amount of juice per fruit increased, while free organic acid in the juice decreased. The specific activity and the total activity of the proteases were increased remarkably.