Investigations were carried out to determine the appropriate concentration of α-naphthaleneacetic acid (NAA) and 6-benzylaminopurine (BA) for the regeneration of intact plants and multishoot formation from the apex culture of axillary-buds (0.25_??_0.3mm) of ‘Kyoho’ vines. 1. To enhance the survival rate, a preliminary test was performed using various modified Murashige and Skoog (MS) media. The survival rate of inoculated apex was highest (higher than 80%) in a modified MS medium containing one tenth amount of nitrogen, 0.1mg/l NAA, 1.0mg/l BA, 30g/l sucrose, and 7.0g/l agar. Therefore, this modified MS medium was adapted in this study. 2. The effect of BA was very marked in the stage from the greening and enlargement of inoculated plantlets to the development of shoots and multishoot formation (stages 1_??_3); The optimum concentration was found to be 1mg/l in all the stages. In view of the fact that supplementation with 1mg/l NAA resulted in callus formation from plantlets and inhibition of shoot formation, either the concentration of NAA should be lower than 0.1mg/l, or no NAA should be supplemented. 3. Supplementation with BA at the forth stage enhanced callus formation, but inhibited rooting from the basal part of shoots. This stage was, therefore, carried out without supplementing with BA. NAA promoted the elongation of shoots at a low concentration (0.05mg/l or less), making potting easy. Rooting rate was high, but the elongation of shoots were poor when supplemented with 0.1mg/l NAA or more. The rooted shoots were, therefore, transferred to a medium containing either no NAA or a low concentration of NAA to ensure elongation before potting. 4. Intact plants of ‘Kyoho’ vines were regenerated successfully from apex culture by supplementing a modified MS medium with NAA and BA.
Experiments were carried out to know whether self-incompatibility reaction is altered in various stages of floral development of Japanese pear. Bud pollination (3-6 days before anthesis) was effective to overcome self-incompatibility but the most effective stage was altered from year to year over 3 years. The percentages of fruit set decreased as pollinated in the later stage of floral bud development and no fruit was obtained as pollinated on and after the day of anthesis. In the fruit obtained by bud self-pollination, several fully developed seeds were formed and they germinated at almost the same rate as compatible ones, though the percentage of fully developed seeds was considerably lower than that of crossed ones. The period of floral development to get the sufficient fruit set following compatible pollination ranged from 4th day before anthesis to 4th day after anthesis.
In order to clarify the mechanism of flower bud formation in Japanese pear (Pyrus serotina Rehd.), the relationsips between the flower initiation on an extention shoot and the nutrient elements and endogenous growth regulators in various portion of the shoot of cvs. ‘Shinsui’ and ‘Hosui’, were investigated. ‘Shinsui’ is characterized by having few flower buds on extention shoots, while ‘Hosui’ has many flower buds. 1. The shoot of ‘Hosui’ ceased growing on June 30, while that of ‘Shinsui’ ceased on July 20, twenty days later than in ‘Hosui’. 2. In axillary buds of ‘Hosui’ there was a rapid increase in the number of nodes and in flower bud differentiation and development immediately after shoot growth ceased. On the other hand, in axillary buds of ‘Shinsui’ the first visible signs of flower initiation were found on July 30, twenty days later than in ‘Hosui’. Thereafter differentiation and development did not occur. The final percentage of flower bud formation was 15.5% in ‘Shinsui’ and 79.0% in ‘Hosui’. 3. There was no marked difference in total nitrogen content of axillary buds between the two cultivars, but the total sugar content, starch content and C/N ratio were higher in ‘Shinsui’ than in ‘Hosui’. 4. IAA and gibberellin contents in the shoot tip of ‘Shinsui’ were higher than those of ‘Hosui’ during the period of vigorous shoot growth. 5. Throughout the growing season both gibberellin and ABA contents in the axillary buds of ‘Hosui’ were lower than those of ‘Shinsui’, while the cytokinin content in the axillarybuds of ‘Hosui’ was higher than that of ‘Shinsui’. From these results it was concluded that flower initiation in Japanese pear is determined by a rapid increase in the number of nodes followed by formation of twelve scales and is closely related to endogenous growth regulators, in which gibberellin and cytokinin play important roles.
Arginine-ε-15N2 was supplied to intact 1-year-old shoots of a 21-year-old satsuma mandarin tree, and arginine-ε-15N2, urea-15N2 and ammonium-15N were each fed to excised 2-year-old stem sections. The 15N was traced in the bark, wood, new shoots, and new leaves. Arginine-ε-15N2 was steadily metabolized via γ-guanidinobutyric acid in the bark and wood. The 15N of arginine was most markedly incorporated into the glutamine-amide N, but also into glutamine-amino N, alanine and γ-aminobutyric acid. Some 15N was also used for proline formation. The labelling patterns of amino compounds when urea-15N2 or ammonium-15N was fed were both similar to when arginine-ε-15N2 was fed. This finding strongly suggests that the 15N of arginine-ε-15N2 is used for amino compound synthesis via urea and/or ammonium. Arginine-ε-15N2 was translocated, and appeared in an unmetabolized form in new shoots where it was incorporated into protein. The 15N of arginine was also transferred to other amino compounds, and then incorporated into protein in new shoots. Several differences in N metabolism were found between the bark and wood: whatever the source of 15N, asparagine-amino N had a higher 15N enrichment than aspartic acid in the bark, but a lower enrichment in the wood. Glutamine, asparagine and proline were more actively synthesized and accumulated in the bark, while in the wood, arginine was.
Seasonal changes in the concentration of ethanol and acetaldehyde of satsuma mandarin (Citrus unshiu Marc.) fruit were examined to determine whether these components afford an additional measure of maturity to the Brix-acid and total sugar-acid ratio. Samples of ‘Okitsu Wase’, an early maturing cultivar, and ‘Silverhill’, a common cultivar, were harvested at intervals of approximately 15 days from September 3, 1973 to January 28, 1974. The concentration of ethanol and acetaldehyde in the juice and peel of both cultivars increased gradually during maturation; ethanol increased from 9.74 to 19.92 mg and from 8.15 to 18.43mg per 100ml of juice in the early maturing and common cultivars respectively, while acetaldehyde increased from 0.188 to 0.836mg and from 0.183 to 0.823mg per 100ml of juice respectively. These low concentrations and narrow range seem to preclude these components as useful indicators of maturity. The rapid increase in Brix-acid and total sugar-acid ratio during the season provides a more sensitive indication of maturity in both cultivars.
Inheritance of astringency in Japanese persimmon (Dyospiros kaki Thunb.) was investigated using data collected over 30 years in Okitsu Horticultural Research Station. PCNA (pollination constant non-astringent) and non-PCNA were qualitatively inherited. The former was recessive to the latter. Backcrosses between PCNA and the progeny (PCA) derived from the cross of PCNA×non-PCNA yielded PCNA of approximately 15 percent. Inheritance of astringency in non-PCNA seemed to be quantitative. Few PVNA (pollination variant non-astringent) progenies occured from crosses among PCA (pollination constant astringent) cultivars. Many PCA progenies occured from crosses among PVNA cultivars. In crosses between PCNA and PCA, more PVNA or PVA (pollination variant astringent) progenies were obtained between ‘Fuyu(PCNA)’ and PCA cultivars, compared to crosses between other PCNA cultivars and PCA cultivars.
Overcoming self-incompatibility of Raphanus sativus cultivars. ‘Motohashi-taibyo Minowase’(M-Mino) and ‘Minowase’(Mino) was studied by application of 15 different kinds of amino acids, two kinds of vitamines, four kinds of phytohormones and three kinds of phenolic substances. Effects differed between the two cultivars. In “M-Mino”, arginine (100mg/l), serine and tyrosine (500mg/l), alanine, valine and cystine (1000mg/l), leucine (100 and 1000mg/l), lysine, threonine and phenylalanine (500 and 1000mg/l) were significantly effective. On the other hand, in “Mino”, arginine and leucine (200mg/l) and histidine (1000mg/l) were significantly effective. Phytohormones and vitamines tended to increase some fruit development and setting, although rate of them were not statistically significant. Besides, these chemicals induced some parthenocarpic fruits.
Effects of ratios of NO3/NH4 and temperature of the nutrient solution on growth of Japanese honewort (Cryptotaenia japonica Hassk.), garland chrysanthemum (Chrysanthemum coronarium L.) and welsh onion (Allium fistulosum L.) were studied on a practical scale. Ratios of NO3/NH4 in the nutrient solution were 12/0, 9/3, 6/6 and 3/9 in me/l for all vegetables. Temperature regimes of solution were 11, 18 and 25°C for Japanese honewortsand garland chrysanthemum and 14, 21 and 28°C for welsh onion. In general, top growth of tested vegetables was increased with raising solution temperature and increasing ratio of NH4 to NO3 in the solution. However, too much high ratio of NH4 to NO3 in the solution under low solution temperature gave the possibility to cause NH4 toxicity on the early stage of growth of Japanese honewort. The combined application of NO3 and NH4 provided better condition for not only enhancing growth but also changing leaf color from light green to green or dark green and lowering NO3 content in Japanese honewort.
For establishing clonal propagation through bulbils in Dioscorea opposita cv. Yamatoimo, stem segments with a node of lateral shoots were cultured aseptically on Murashige & Skoog(M. S) basal medium supplemented with sucrose (20g/l or 40g/l) and growth regulators, 6-benzylaminopurine(BA), α-naphthaleneacetic acid (NAA) and abscisic acid(ABA). The cultures were kept under a schedule of 14 hours light(2000lx): 10 hours dark at a constant temperature of 25°C. 1. Effect of BA and NAA on bulbil formation: Stem segments were inserted upright or inverted in M. S and 1/2 M. S (-NH4NO3) basal medium. There was no significant difference on bulbil formation between the stem segments inserted upright and those inverted in BA stimulated sprouting of axillary bud, which were observed in the node of stem segments, but inhibited bulbil formation. NAA stimulated bulbil formation at concentrations of 0 to 1mg/l, but was inhibitory at 10mg/l. 2. Effect of length of stem segments on bulbil formation: There was no significant difference between 1, 2 and 3cm long stem segments in inducing bulbil formation. However, the growth of bulbils was significantly different, being best with 3cm long stem segments. 3. Effect of ABA on bulbil formation: ABA was effective in inducing bulbil formation, and 100% bulbil formation was obtained at 1mg/l. 4. Effect of concentration of M. S medium on bulbil formation: Six types of the basal medium, M. S, M. S(-NH4NO3), 1/2 M. S, 1/2 M. S(-NH4NO3), 1/5 M. S and 1/5 M. S(-NH4NO3) were tested for their effect on bulbil formation. 1/2 M. S basal medium gave the highest percentage of bulbil formation, followed by 1/2 M. S (-NH4NO3) and M. S basal medium, but there was no significant difference between them. 1/5 M. S and 1/5(-NH4NO3) basal medium were inferior to the others in terms of bulbil formation, but were effective for the sprouting of axillary buds.
In Brassica juncea (designated as B. cernua in the preceding papers of this series) and B. carinata, when freshly harvested seeds are stored in the desiccator, the breaking of their dormancy is partially prevented. The similar preventing effect is also recognized when seeds are preserved in harvested fruits without separation. On the other hand, it has been reported that mustard oils, mostly allyl-isothiocyanate and β-phenethyl-isothiocyanate, contained in fruits and seeds of some cruciferous vegetables are germination-inhibiting substances. The present investigation was undertaken to examine whether or not allyl-isothiocyanate is a substance which prevents the breaking of seed dormancy in Brassica juncea and B. carinata. After the harvest of mature fruits, they were divided into two groups. In one group seeds were isolated separately from fruits, and in the other group seeds were left intact in fruits. Then, seeds in each group were either placed on the desk in the room or stored in the desiccator (containing silica gel). After that, the germination percentage, allyl-isothiocyanate content, and water content of seeds were examined at one or two week intervals during 13 weeks. Allyl-isothiocyanate was analyzed by liquid-chromatography. Results obtained are as follows. The breaking of dormancy was prevented only when the seeds preserved in fruits were stored in the desiccator. There were little differences in seed germination among three other treatments, in which dormancy was broken almost completely in 5 to 6 weeks after harvest. The prevention of breaking of dormancy in the seeds with fruits in the desiccator was due to the germination-inhibiting effect of desiccation, as demonstrated by the rapid decrease of water content of seeds; in other treatments there was no such decrease of water content in early stages after harvest. In the separated seeds in the desiccator, water content did not reach the percentage low enough to inhibit germination until 5 to 6 weeks. This was perhaps caused by the close packing of seeds in a bag, which might prevent the drying of seeds. The germination of seeds was not affected by fruits in B. juncea, but in B. carinata the breaking of dormancy was prevented in some degree when seeds were preserved in fruits. The content of allyl-isothiocyanate showed similar variations through the process of seed storage after harvest in all treatments. Differences in allyl-isothiocyanate were hardly noticed between seeds with and without fruits and between seeds in the room and in the desiccator. Therefore, it is considered that allyl-isothiocyanate had no relation to a germination-inhibiting substance(s) which may prevent the breaking of dormancy. In each treatment, however, the curve of allyl-isothiocyanate presented similarity to the curve of germination percentage though the latter showed the lag of time. This similarity may suggest that a certain physiological change (such as so-called biorhythm) occurred in seeds, and that mustard oils and germination-inhibiting substances were influenced by this physiological change in their respective ways.
Lilium rubellum Baker bulb-scales excised from bulbs growing in vitro were cultured at different temperatures, in various lengths of light period, or in a medium containing different concentrations of α-naphthaleneacetic acid (NAA) and 6-benzylaminopurine (BA). Temperature affected the percentage of regenerating bulb-scales, the number of bulblets per scale, and the growth of bulblets. The optimum temperature for each of the parameters was 25°C. The percentage of regenerating bulb-scales and the number of bulblets per scale were stimulated in a lighted environment, but the fresh weight of bulblets formed in this environment was lower than the weight of those formed in darkness. NAA at concentrations of 0.05 and 0.1mg/l gave a stimulatory effect on each of the parameters, but the higher concentrations suppressed bulblet formation. BA scarcely affected any of the parameters, except in the combination of 0.1mg/l BA with 1.0mg/l NAA, which enhanced the fresh weight of the bulblets.
Effects of the concentration of 2-chloroethyl-phosphonic acid (ethephon) and its application frequency on stem elongation and flower formation in chrysanthemum plants were studied. It was also investigated whether the ethephon simply inhibits the stem elongation for its active period or it induces rosette formation. When an aqueous solution of ethephon at 1, 000ppm or higher was applied 3 times at 7 day intervals, a strong inhibition of the stem elongation and flower formation was observed. Elongation of the plants was inhibited only for a short period when high concentration of ethephon was treated in spring and summer, and then the stems started to elongate about 15 days after the last ethephon applications. In contrast, the plants treated in September stopped elongation and remained rosette form untill the following spring. The ethephon application in late August or earlier did not induce the rosette formation even in short day and cool conditions. The rosette formation was induced only when ethephon was applied later than early September. It appears that ethephon or ethylene lowers the growth activity and induces the rosette formation in chrysanthemum plants which have experienced high temperature in summer.
After removing roots, gerbera plants were separated into divisions. Each division was stripped off the leaves leaving only the last unexpanded leaf, which was shortened to 2cm in length. With the periderm of the rhizome peeled off, they were again shortened to 1cm in length. These shoot-tip pieces were sterilized in 1% NaOCl solution for 10min., then rinsed three times with sterilized distilled water, and further cut to 2-3mm tall shoot-tip explants. This hygienic procedure efficiently reduced the high infection rate of the initial shoot tip. The shoot-tips were cultured on medium containing 1/2 MS, organic constituents of MS(1962), 5mg/l BA, 0.1mg/l IAA, 2% sucrose and 1.0% Bacto-agar. The pH of the medium was adjusted to 5.6 prior to autoclaving. The cultures were placed under 16-hour daily illumination at 3000lx, at 27±2°C. After four weeks of culturing, 10 shoots per explant were found. Shoots of 1-2cm in length were subcultured on the pretrans-planting medium described by Pierik et al. (9). Shoots which were 2cm or more in length were treated with 0.1% IBA solution for 30 seconds, and were planted in a balanced mist propagating bed of sand. Roots developed in about two weeks. After transplanting, the rooted shoots from in vitro or in vivo culture survived very easily.
Phalaenopsis plants, three to six years of age were transferred from lowland (Koshigaya, Saitama Prefecture) to highland (Nasu, Tochigi Prefecture) in summer 1979 and 1980 to see if plants flower earlier. 1. Koshigaya is located close to sea level and the height of Nasu is around 500 meters from sea level and it is cool enough to induce orchid flowering. The plants used in this experiment had reached the stage at which plants differentiate flowers by cooling. 2. Plants, when transferred to highland, formed flower-stalk two months earlier and flowered three months earlier than plants kept at lowland. 3. Although number of flower-stalks were few on three year-old plants which had not flowered before, the plants aged four or more years and had flowered before tended to produce more flower-stalks with age. 4. Plants, when transferred to highland, formed first flower-stalk at one higher node than those at lowland, regardless of their age or time of transfer. 5. The node where flower-stalk was formed decreased in number and in length as well. The spikes and number of flowers per stalk also decreases in number by transferrence, no matter when transferred or what age of plants were used. 6. Concerning the length of time from start of cooling to flowering, the younger plants flowered later. The time of bringing down the plants from highland to lowland caused time of flowering to be delayed, when they were brought down too late.
Extensive browning due to rind-oil spot was found in peels of Murcott(Citrusreticulata×Citrus sinensis) and Funadoko(Citrus funadoko hort. ex. Y. Tanaka) which were stored for three months at room temperature. Absorption spectra and difference spectra of extracts of injured and healthy sections of these fruit peels were measured. In Murcott, the difference spectra of these extracts showed a negative peak at 325nm and were in good agreement with spectra obtained when extracts of healthy sections were oxidized by polyphenol oxidase. Similar difference spectra were found in the enzymatic oxidation of chlorogenic acid. Chromatographic determination indicated that the extract of healthy sections contained chlorogenic acid analogues, but the analogues were not detected in the extracts from injured sections. In Funadoko, the difference spectra of the extracts of healthy and injured sections showed negative peaks at 325nm and 265nm. The peak at 325nm was similar to that found in Murcott peel extract. The peak at 265nm was also found in difference spectra obtained when extracts from healthy sections were oxidized by ascorbic acid oxidase, and the spectra were in good agreement with those for the enzymatic oxidation of L-ascorbic acid. From the above results, it seems that the oxidation of chlorogenic acid analogues and L-ascorbic acid plays an important role in the browning due to rind-oil spot.
To determine the cause of a greasy phenomenon of the peel of apple cv. ‘Jonagold’, the main lipids of the peel were analyzed by gas chromatograph-mass spectrometer, particularly noting the unsaturated fatty acids which were fluid at normal temperature. As harvest was delayed, the number of components and the quantity of the lipids of the peel increased. The compositions of 17 aliphatic lipids were identified. In the stages before ripening, palmitic acid, stearic acid, oleic acid, linoleic acid and triacontane were scarcely detected, whereas in the stages after ripening, these lipids increased. Among them, lipids fluid at normal temperature were oleic acid and linoleic acid. Oleic acid was detected later than linoleic acid. The time of the increase in linoleic acid coincided with the appearance of greasiness of the peel. When commercial linoleic acid was painted on peel which had not shown the greasiness, the wax of the peel was melted and the greasy phenomenon similar to the natural appearance was produced. It was concluded that the natural greasiness of the ‘Jonagold’ peel was caused by linoleic acid and oleic acid.