Time Of Flower Bud Differentiation Research Articles

Metabolic analysis of the regulatory mechanism of sugars on secondary flowering in Magnolia

BackgroundMagnolia, a traditional and important ornamental plant in urban greening, has been cultivated for about 2000 years in China for its elegant flower shape and gorgeous flower color. Most varieties of Magnolia bloom once a year in spring, whereas a few others, such as Magnolia liliiflora Desr. ‘Hongyuanbao’, also bloom for the second time in summer or early autumn. Such a twice flowering trait is desirable for its high ornamental value, while its underlying mechanism remains unclear.MethodsParaffin section was used to show the flowering time and phenotypic changes of M. liliiflora ‘Hongyuanbao’ during the twice flowering periods from March 28 to August 25, 2018. Gas chromatography-mass spectrometry (GC-MS) was then performed to explore the chemical metabolites through the twice flower bud differentiation process in ‘Hongyuanbao’, and the metabolites were screened and identified by orthogonal projection to latent structures discriminant analysis (OPLS-DA). Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis (KEGG) was used to reveal the relationship between the sugar metabolites and twice-flowering characteristic. To further investigate the potential role of sucrose and trehalose on flowering regulation of ‘Hongyuanbao’, the plants once finished the spring flowering were regularly sprayed with sucrose and trehalose solutions at 30 mM, 60 mM, and 90 mM concentrations from April 22, 2019. The flower bud differentiation processes of sprayed plants were observed and the expression patterns of the genes involved in sucrose and trehalose metabolic pathways were studied by quantitative reverse transcription PCR (qRT-PCR).ResultsIt showed that ‘Hongyuanbao’ could complete flower bud differentiation twice in a year and flowered in both spring and summer. The metabolites of flower bud differentiation had a significant variation between the first and second flower buds. Compared to the first flower bud differentiation process, the metabolites in the sucrose and trehalose metabolic pathways were significantly up-regulated during the second flower bud differentiation process. Besides that, the expression levels of a number of trehalose-6-phosphate synthase (TPS) genes including MlTPS1, MlTPS5, MlTPS6, MlTPS7 and MlTPS9 were substantially increased in the second flower differentiation process compared with the first process. Exogenous treatments indicated that compared to the control plants (sprayed with water, CK), all three concentrations of trehalose could accelerate flowering and the effect of 60 mM concentration was the most significant. For the sucrose foliar spray, only the 60 mM concentration accelerated flowering compared with CK. It suggested that different concentration of trehalose and sucrose might have different effects. Expression analysis showed that sucrose treatment increased the transcription levels of MlTPS5 and MlTPS6, whereas trehalose treatment increased MlTPS1, showing that different MlTPS genes took part in sucrose and trehalose metabolic pathways respectively. The expression levels of a number of flowering-related genes, such as MlFT, MlLFY, and MlSPL were also increased in response to the sprays of sucrose and trehalose.ConclusionsWe provide a novel insight into the effect of sucrose and trehalose on the flowering process in Magnolia. Under the different sugar contents treatments, the time of flower bud differentiation of Magnolia was advanced. Induced and accelerated flowering in response to sucrose and trehalose foliar spray, coupled with elevated expression of trehalose regulatory and response genes, suggests that secondary flower bud formation is a promoted by altered endogenous sucrose and trehalose levels. Those results give a new understanding of sucrose and trehalose on twice-flowering in Magnolia and provide a preliminary speculation for inducing and accelerating the flowering process in Magnolia.

Influence of warming climate and the green revolution on the optimum range of weather parameters of longan yield in Taiwan since 1909

Longans are the fruits of a subtropical evergreen tree (Dimocarpus longan Lour.) and are widely distributed in Southern China and Southeast Asia. However, there is a lack of historical records of these fruits. In addition to air temperature, other factors, such as the green revolution effect (GRE), sunshine duration, flower bud differentiation, flowering, and production period, may also be important for longan yield. This study incorporated Duncan’s multiple range tests, linear regression models, and multi-regression models, using the forward stepwise method. The results showed that a warming climate was unfavourable to the longan fruits yield (LFY), as the mean negative impact of climate change on LFY was 2489.6 ± 1072.2 kg/ha (mean difference ± 95% CI) under GRE. When considering warming climate and GRE, the results showed that, at the time of flower bud differentiation, the optimum ranges of mean air temperature and relative humidity (RH) were 18.0–19.4 °C and 73.9–75.7%, respectively; during flowering, the optimum ranges of cloud cover, sunshine-hour, and rainy days were 6.8–7.3 oktas, 381.3–476.6 h, and 28.9–41.9 days, respectively; during the production period, the optimum ranges of mean diurnal temperature and RH were 6.8–7.4 °C and 75.1–79.4% respectively. A smaller optimum range of weather parameters aids in a greater slope of the accumulated frequency of the LFY. The GRE and small optimum ranges of weather (stable weather conditions) were found to assist in ensuring stable LFY.

Differential gene expression in banana roots in response to Fusarium wilt

Banana wilt disease, caused by Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4), is a devastating disease in the banana industry. The molecular mechanism underlying the wilt resistance of AAA-type banana cultivars has not been fully characterized. Our objective was to analyse the genes differentially expressed in roots during the time of flower bud differentiation in plants grown in fields infested with Foc TR4. We compared the Foc TR4-tolerant ‘Formosana’ banana and the susceptible ‘Brazil’ banana. cDNA libraries were constructed from RNA isolated from the roots of both cultivars, and generated approximately 40 million and 35 million high-quality reads, respectively. We mapped 28 353 810 ‘Formosana’ reads and 26 917 421 ‘Brazil’ reads to the banana genome. A search of the NR (non-redundant) database resulted in the annotation of 34 408 genes. Additionally, 107 genes were differentially expressed between the two cultivars. Among the 48 differentially expressed genes with known functions, 41 were expressed more highly in ‘Formosana’ than in ‘Brazil’. These genes were divided into several categories, including specific resistance mechanism-related enzyme genes and phytoalexin synthesis-related genes. The expression levels of eight genes were validated by a quantitative real-time polymerase chain reaction. Our results indicate that ‘Formosana’ may enhance its tolerance to Foc TR4 by increasing the expression of defence-related genes (possibly constitutively). This cultivar also exhibits up-regulated expression of non-specific stress-related genes, which may enhance its overall disease tolerance. This study provides important transcript-level details potentially useful for clarifying the molecular mechanism underlying the disease resistance of Cavendish banana cultivars.

Effect of Pruning Severity on Flowering and Fruiting of Mango (Mangifera indica) cv. Alphonso in Off-Year Season

THIS study was conducted in two successive seasons 2011-2012 and 2012-2013 in a private orchard to evaluate the effect of after setting pruning (at the first week of June) of non bearing shoots in the On-year for enhancing some flowering and fruiting attributes in the next off-year of Alphonso mango cultivar . Trees were subjected to four pruning treatments, removing half length of the terminal shoots, removing the whole terminal shoots , tipping and the control (without pruning). The highest number of emerged shoots per pruned shoot was achieved by removing half length of the terminal shoots, this treatment recorded the highest reserve of total sugars and C/N ratio in the leaves at the time of flower bud differentiation, moreover this treatment was fulfilled the highest number of flowering shoots, number of panicles per tree, panicle length, perfect flowers percentage, fruit retention and yield. Removing half length of the terminal shoots in On-year of Alphonso mango cultivar proved to be the most effective treatment to regulate tree yield of Alphonso cultivar.

Variation in Flower Bud Differentiation and Progression of Floral Organs with Respect to Crop Load in Olive

The differentiation of olive floral buds during winter is strictly correlated with flowering in the spring and ultimately with fruit production in autumn and the determination of the time of flower bud induction is important for determining the possible causes of alternate bearing and for improving management practices to correct alternate bearing. The aim of this research was to study the time of flower bud differentiation and developmental steps in the ‘Gemlik’ olive cultivar in 2008 (off year) and 2009 (on year). The sequence of initiation of the floral organs in each flower bud was sepals, stamens, petals, and gynoecium. There was no visible difference between the time of differentiation and the developmental stage of the floral organs with respect to the ‘on’ and ‘off’ years during the study.

Patterns of Flower- bud Differentiation, Development, and Growth Habits of Several Blueberry (Vaccinium spp.) Cultivar Types Grown in Japan and New Zealand

The time of flower-bud differentiation and development in relation to harvest time was examined in New Zealand and Japan by using 15 blueberry cultivars that belong to 4 types; half-high-, northern highbush-, southern highbush-, and rabbiteye-types. The numbers of flower buds and compactness in young plants were examined in Japan by using 17 cultivars that belong to the above 4 types. The cultivars were divided into 3 groups, depending on the time of flower-bud differentiation; (1) cultivars that differentiate flower buds mainly during the harvest period, i.e., half-high-type, northern highbush-type, and some southern highbush-types, (2) cultivars that start differentiating flower buds about a month after the end of the harvest period, such as some southern highbush-types, and (3) cultivars that differentiate flower buds after the peak of the harvest period, e.g., rabbiteye-types. In group (1), the period from flower differentiation to pistil formation was shorter in early-ripening cultivars than in late-ripening ones. The relationship between the time of flower-bud differentiation and that of harvest was almost similar in the southern and northern hemispheres. In New Zealand, however, anthesis in both ‘O'Neal’ and ‘Reka’ occurred immediately after harvest. Numerous flower buds formed on potted young plants of ‘Bluebelle’ (rabbiteye-type) and ‘Sunshineblue’ (southern highbush-type). ‘Sunshineblue’ and ‘Tophat’ (half-high-type) have a very compact vegetative profile.

デルフィニウムの開花特性に関する研究

Delphinium seeds were sown early each month throughout the year and the seedlings were transplanted to an unheated greenhouse to study the seasonal change on the flowering behaviour of delphinium. The formation of flower buds was observed microscopically, whereas the effect of temperature on bolting and flowering was macroscopically studied in a phytotron. Furthermore, the bolting characteristics of several cultivars in a heated house under natural day-length were also studied.1. Flower bud differentiation occurred under a wide range of temperatures almost year-round. When seedlings were planted in warm and hot seasons, the period from sowing to flower bud differentiation was shortened, whereas, when they were planted during the cool or cold seasons, the period was prolonged. Therefore, the flower bud differentiation process is hastened by high temperatures.2. Delphinium seedlings react sensitively to the higher temperature; when the temperatures were kept constant at or higher than 20 °C, seedlings bolted after the plants developed 5 or more leaves. However, plants kept at 15 °C remained in the juvenile phase for an extremely prolonged period and about half assumed the rosette form.3. When the seeds were sown in March-July and the seedlings were transplanted in summer, the plants differentiated flower buds at a lower node and produced poor spikes with few florets. Plants derived from seeds sown in August-February developed many leaves below the first floret, produced spikes of higher quality with more florets. Thus, the greater the ratio of leaves to floret, the more florets per spike were formed.4. Low temperature did not act as vernalization inducing in the flower bud initiation, but caused the rosette to break or expanded the temperature range the plant could grow to lower side. Thus, low temperature acted to make growth activity higher.5. Flower bud differentiation was always accompanied with bolting even under un-heated conditions, so that the time of flower bud differentiation could be estimated easily.Therefore, early bolting plants resulting in a low cut flower quality can be eliminated atan earlier stage before transplanting.6. When delphinium were grown in a heated house under natural day-length, many cul-tivars formed rosettes. Plants, which formed rosettes, were slow to bolt and producedmalformed spikes.

アボカド (<i>Persea americana</i> Mill.) の花芽分化及び発育について

1. In order to clarify the time of flower bud differentiation and subsequent development in avocado trees (Persea americana Mill.) in Japan, flower buds of the cultivars, ‘Zutano’ (6 to 7-year-old), ‘Jalna’ (5-year-old) and ‘Fuerte’ (20 to 28-year-old) were studied morphologically using a stereoscope and a scanning electron microscope (SEM) during 1979-81.2. In 1979-80, flower bud differentiation was observed on November 11 in ‘Zutano’ and ‘Fuerte’, and on November 25 in ‘Jalna’. In 1980-81, the differentiation was observed on November 9 in ‘Fuerte’, and on November 23 in ‘Zutano’ and ‘Jalna’. As the results of this two-time examination, it was shown that time of flower bud differentiation in the south-western warm area of Japan was in November in the three cultivars.3. The stages and times of flower bud development were as follows:1) No differentiation (flatness of growing point) ... late in October2) Differentiation of flower bud (protuberance of growing point) ... November3) Perianth formation, pistil and stamen primordia formation ... early in December4) Anther dehiscence valve and staminodium formation ... middle in January5) Pollen grain and ovule formation ... early in February6) Carpel suture and floral formation ... middle in March4. In the south-western warm area of Japan, time of flower bud differentiation in avocado trees was later than in deciduous fruit trees, and earlier than in evergreen fruit trees (except loquat).5. In 1980-81, flower bud development was inhibited for a short period by the low temperatures of winter, which were lower in the avocado orchard than in 1979-80.

日本自生ユリの花芽分化期について

Time of flower bud differentiation in 18 lily species native to Japan was surveyed and the species classified into 4 groups as follows.Type 1-a. L. rubellum and L. dauricum. Flower buds were initiated in early fall and completed in early winter within bulbs, before sprouting.Type 1-b. L. concolor var. pulchellum (Chosenhimeyuri), L. japonicum, L. maculatum (native to Sadoga-shima) and L. hansonii. Flower buds were initiated in late fall within bulbs, before sprouting and completed next spring when the plants sprouted from the ground.Type 2-a. L. longiflorum, L. alexandrae, L. nobilissimum, L. speciosum, L. auraturn, L. platyphyllum, L. leichtlinii var. maximowiczii, L. medeoloides, L. callosum, L. brownii, L. concolor (Tosahimeyuri) and L. maculatum (native to Miyake-jima). Flower buds were initiated just after sprouting.Type 2-b. L. lancifolium and L. henryi. Flower buds were initiated about one month after sprouting.

キウイの花芽分化, 花芽の発育について

The flower bud differentiation and development in a pistillate cultivar ‘Bluno’ and a staminate cultivar ‘Matua’ of kiwi (Actinidia chinensis Planch.) were studied at Kanagawa Prefecture from 1981 to 1982.1. Both ‘Bluno’ and ‘Matua’ differentiated flower buds in mid-March.2. The flower bud development in these cultivars progressed very rapidly after differentiation and the initial formation of stamens was observed on April 5 in ‘Bluno’ and March 30 in ‘Matua’.3. Full bloom was observed in ‘Bluno’ about 65 days after flower bud differentiation and the blooming period was 5-7 days.4. Full bloom in ‘Matua’ was observed about 62 days after flower bud differentiation and flowering continued to the end of May.5. Thus, the time of flower bud differentiation in kiwi is different from those in most of the deciduous fruit trees. That is, most of the deciduous fruit trees initiate the flower bud differentiation during the season preceding the year in which the flowers bloom, but kiwi does not until mid-March of the current year of flowering.

Seasonal Changes in Growth and Yield of Sugarcane Plants in Southwestern Islands of Japan : I. Progress of leaf-emergence on main stem

We traced the progress of the leaf-emergence on the main stem of sugarcane plants and examined relationships between seasonal changes in the leaf-emergence and climatic factors, effective heat unit summation for unfolding leaf turning point of leaf-emergence rate and leaf number at the beginning time of floral induction. Four varieties, F160, NCo310, H37-1933 and H32-8560, were used as materials and were planted monthly from June in 1980 to May in 1981 in Ishigaki Island, southwesternmost island of Japan. Results obtained were as follows. 1. Quadratic regression relationships were found between mean soil temperature at a depth of 5 cm and days from planting to first emergence (Fig. 2). By those equations obtained in the four varieties, it was estimated that the optimum soil temperature minimizing the days to the first emergence was 31°to 33°C. 2. The seasonal changes showed in the progress of the leaf-emergence on the main stem were summarized as follows: May to September; period of rapid increase in the leaf-emergence rate, October to November; period of gradual increase in the rate, December to February; period of slight increase in the rate, March to April; period of gradual increase in the rate (Fig. 3). 3. Mean air temperature was significantly correlated with leaf-emergence rate during unfolding 20 leaves on the main stem (Fig. 5, Table 1). Using linear regression equation (y=ax-b) obtained between the leaf-emergence rate (y) and mean air temperature (x), it was derived that lower limit of effective temperature and effective heat unit summation for unfolding leaf were given b/a and l/a, respectively. In three varieties of F160, NCo310 and H37-1933, the lower limit of effective temperature and effective heat unit summation were 11.1-11.4°C and 81.3-90.9°C, respectively. Those in H32-8560 were 9.9°C and 106.4°C, respectively (Table 2). 4. The leaf-emergence rate on heading stems during two months before unfolding flag leaf was faster than that on non-heading stems during the same period (Fig. 4). Therefore, it was suggested that turning point of the leaf-emergence rate existed about two months before unfolding the flag leaf when coincided with time of flower bud differentiation. 5. In the plants of NCo310 and H37-l933 planted in June and July of 1980, some stems headed by January in 1931, others did not. The difference of heading among stems is considered to arise from plant age at the beginning time of floral induction, when is estimated to be at the beginning of September in Ishigaki Island. From relationships between leaf number on the stem at the beginning of September and heading percent by January in 1981, it was satisfactory to consider that plant age in the leaf number at the time of ripness to flower was 6 in H37-l933 and was 15 in NCo310 (Table 3).

On rossetting of suckers and measures for breaking the rossetting in chrysanthemums

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.

A study on breeding of freesia, Freesia refracta KLATT

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.

On the time of flower bud differentiation of Japanese larch (I)

On the time of flower bud differentiation of Japanese larch (I)

Studies on the flower bud differntiation and development in freesia III

1. The responses of freesia to photoperiod was studied by shading and lightening before and after the flower bud differentiation. 2. By shading, the time of flower bud differentiation of the plants was hastened a little, about 10 days, but was neither hastened nor prolonged by lightening, as compared to the check plants. 3. By lightening, the flower bud development of the plants was promoted more or less. 4. Total number of flower buds on a plant was increased by shading, and was reduced by lighten-ing. 5. Height of plants in the shaded and lightened plots was slightly taller than the height of plants in the check. 6. No significant difference was found about stem length, number of leaves, term of harvest, and number of flower buds on a main stalk, by the treatments.

Studies on the flower bud differentiation and development in some ornamental trees and shrubs. III

1. The flower buds in Daphne odora appear in the terminal buds on current shoots, and the time of flower bud differentiation in Tokyo was at the beginning of July in 1950. 2. In Osmanthus aurantiacus, the flower bud formation occurrs in the lateral buds on curre shoot, and the time of flower bud differentiate, in Kagawaprefecture was at the beginning August in 1953.

標高と蔬菜類の生態 (第7報)

To find out the proper seasons for lettuce growing in the regions of different altitudes, two varieties, New York No. 12 and Great Lakes, were planted successively at Nagano and Sugadaira in 1951 and 1952. Factors affecting flower bud differentiation and its development, favorable temperature range for vegetative growth, and damages to diseases were also examined.It was revealed that Great Lakes, a slow bolting variety, could be grown even in midsummer in the region of 800-900m high above the sea level. In the regions of lower altitudes, lettuce should be sown early in the spring so as the compact head would be formed before the hot season came in or should be grown late enough the head be formed in the cool period of the fall.Flower bud differentiation was induced in the lettuce when heat summation above 5°C attained to about 1, 700°C for Great Lakes or to about 1, 500 °C for New York No. 12. Bolting was accelerated by high temperature and were checked by low temperature below 15°C.There was no difference between the two varieties in the speed of seed stalk development, but the time of flower bud differentiation was later in Great Lakes, a slow bolting variety, than New York No. 12, an early bolting variety.Length of photoperiod seemed to have no effect on the time of flower bud differentiation or its development.In the early stage of growth (about 75 days after germination) lettuce was rather insensitive to temperature or diseases, but in the late stage of growth when it grew vigorously and formed head, it became sensitive to temperature and susceptible to bottom rot and tipburn. Most favorable growing temperature range for the lettuce in its late growing stage was proved to be 18-21°C in daily mean.

Responses of fall-flowering chrysanthemum varieties to photoperiod and temperature (2)

(1) Experiments were conducted with 16 varie-ties of fall flowering chrysanthemum on their sensi-tivity to photoperiod and temperature in 1953. They were grown in the two localities (Nagano, 360m. and Osamura 850m. above the sea-level) having different temperature conditions, and under short day of 10 hours for 20 days or until flowering period, or under natural daylength. (2) Five out of 16 varieties tested, Hatsunishiki, Harukoma, Shochiku, Hitomesenryo and Hoyoku, differentiated flower bud at the same time irre-spective of photoperiod. Another 11 varieties differentiated flower bud when daylength had been reduced to below 14.5 hours. Time of flower bud differentiation in Shintoa, Ayamurasaki and Shiki-nohikari was somewhat earlier than that of the other varieties. (3) Development of flower bud in the five var-ieties, Hatsunishiki, Harukoma, Sh6chiku, Hitome-senryo and Hoyoku was not affected by photoperiod, but for the most part by temperature; temperature the cooler, flowering the later. In another 11 varieties, development of flower bud was affected by photoperiod and temperature. Flower bud developed when daylength had been reduced to 13.5 hours. In the four varieties, Shintoa, Ayamurasaki, Shikinohikari, and Shikinomidori, bud development was not retarded by higher temperature, while in other seven varieties, Kyowashiro, Renzannotsuki, Shuho, Sakuranohikari, Kurokoma, Hoen and Shin-ginga, it was retarded by higher temperature even, under the short day condition. (4) When influenced by extreme variation on daylength and temperature conditions before the differentiation of floret primordium, there appeared many crown buds resulting from imperfect flower bud development. (5) The chrysanthemum varieties tested were classified in the following groups in relation to their responses to temperature and photoperiod. A. Flowering was influenced mainly by temper-ature ature: Hatsunishiki, Harukoma, Shochiku, Hitome senryo, Hoyoku. B. Flowering was influenced mainly by daylengtft (flower bud differentiated when daylength had beenn reduced to 14.5 hours, flower bud developed when daylength had been reduced to 13.5 hours or less), (a) Flowering was forced by rather higher temper-ature; Shintoa, Ayamurasaki, Shikinohikari, Shikinomidori. (b) Flowering was retarded by higher temper-ature; Kyowashiro, Renzannotsuki, Shuho, Sakurano-hikari, Kurokoma, Hoen and Shinginga.

秋キク品種の感光性, 感温性について (第1報)

1. Expriments were conducted with 17 varieties of fall-flowering chrysanthemum on their sensitivity to photoperiod and temperature in 1952. They were grown in the two localities (Nagano, 360m and Osamura, 850m above the sea-level) having different temperature conditions, and under short day of 10 hours for 20 or 30 days, or under natural day-length.2. Three out of 19 varieties tested, Tatsunami, Shinanogawa and Hakuba, differentiated flower bud at the same time irrespective of photoperiod. Another 14 varieties differentiated flower bud when day length had been reduced to 14.5 hours. Time of flower bud differentiation in Shintoa, Pinktoa, Shingetsuyu and Minori, was somewhat earlier than that of the other varieties.3. Development of flower bud in the three varieties, Tatsunami, Shinaogawa, and Hakuba, was not affected by photoperiod, but only by temperature ; temperature the cooler, flowering the later.In another 14 varieties, development of flower bud was affected by photoperiod and temperature. Flower bud developed when daylength had been reduced to 13.5 hours. In the four varieties, Shintoa, Pinktoa, Shingetsuyu and Minori, bud development was not retarded by higher temperature, while in other ten varieties, Okayamaheiwa, Ruster, H. Koido, Shirasagi, Murakumo, Tamaorihime, Kuninohikari, Benishio, Beniaki and Hatsugasumi, it was retarded by higher temperature even under short day condition.4. In 20 days' treatment of shading (10 hours photoperiod), there appeared many crown bud resulting from imperfect flower bud development. No variety formed perfect flower by such a short treatment. In 30 days' treatment, stages of flower bud development affected the appearence of crown bud, which was influenced by both factors.5. Earliness of flowering was determined only by the temperature conditions in the varieties of temperature sensitive type. With the varieties, which were sensitive to both temperature and photoperiod, earliness of flowering was determined by the length of time from bud differentiation to flowering. In practical shade culture it should be recommended to use the varieties which need relatively short period from the start of treatment to flowering.6. Chrysanthemum varieties tested were classified in the following groups in relation to their responses to temperature and photoperiod.a. Flowering was influenced only by temperature: Tatsunami, Shinanogawa, Hakuba.b. Flowering was influenced mainly by daylength (flower bud differentiated when daylength had been reduced to 14.5 hours, flower bud developed when daylength had been reduced to 13.5 hours).i. Flowering was forced by rather higher temperature; Shintoa, Pinktoa, Minori, Shingetsuyu.ii. Flowering was retarded by higher temperature: Okayamaheiwa, Ruster, H. Koido, Shirasagi, Murakumo, Hatsugasumi, Tamaorihime, Kuninohikari, Benishio, Beniaki.

Studies on flower forcing of tulips for export. II

This experiment was carried out in order to clarify the effects of high temperature treatments (30°C., 35°C., and 40°C.) on flower forcing of the tulip bulbs for export. The bulbs were treated without ventilation in 1951, and under ventilation in 1952. High tempera-ture treatment under ventilation was more favor-able and promoted flower bud differentiation a few days than the treatment without ventilation. The higher the temperature of the treatment, the more the flowering time promoted; but higher temperature increased the blind. For “Feu Bril-liant”, as 40°C. treatment caused higher percent-age of blind, 35°C. seemed to be suitable. For “William Pitt”, the more drastic treatments (40°C. -one day, or 35°C.-one day-40°C.-one day) were best. The bulbs treated by these methods bloom-ed about ten days earlier than the untreated ones. In the bulbs recieved the high temperature treatments under ventilation, the time of flower bud differentiation was delayed for five days, but the flowering time was distinctly promoted. It is considered form these results that the tulip bulbs treated with high temperature had passed through the rest period more quickly and became percep-tive of the effects of the following cool tempera-ture. As the bulbs treated with high temperature produced weeker flowers, stems and leaves, the bulbs which will be treated for flower forcing with high temperature should be the ones of ex-cellent quality.