• Korean Journal of Plant Resources
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• v.33 no.6
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• pp.682-688
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• 2020

Hemp (Cannabis sativa L.) is a dioecious plant, although monoecious plants are bred in some cultivars for fiber or seed production. Recently, hemp has received attention for medicinal use with some cannabinoids, including cannabidiol. Self-fertilization for breeding inbred lines is difficult because of dioeciousness and anemophily in hemp. This experiment was conducted to develop a self-fertilization method by forming female flowers and seeds from male plants of dioecious hemp. To induce the formation of female flowers on male plants, 500 mg L^-1 of ethephon was sprayed on plants at soon, seven and fourteen days after primordia formation. The plant ratio of female flowers formation and the number of harvested seeds were increased by ethephon treatment. Female flowers of male plants have 5 stigmas in contrast to the dual stigma of female 1plants. Male plant seeds were lighter and smaller than those from female plants. Although the germination rate was lower than that of normal seeds from female plants, the seeds from male plants germinated to grow seedlings. Thus, we suggest that hemp plants should be treated with ethephon at soon after primordia formation to induce the formation of more female flowers on the male plants.

• Journal of Ecology and Environment
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• v.42 no.2
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• pp.50-59
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• 2018

Background: Duodichogamy is the rarest form of dichogamy in angiosperms, which is characterized by flowering in the sequence of male${\rightarrow}$female${\rightarrow}$male. Disentangling factors promoting duodichogamy require the discovery of more duodichogamous species in angiosperms. However, extremely limited information on duodichogamous species makes it difficult to make general conclusions. Given the inflorescence morphology and flowering characteristics, the Meliaceae family is highly likely to contain duodichogamous species. Methods: We selected 48 individuals from 20 populations in Korea and investigated their flower morphology, arrangement of flowers by sexual condition within inflorescences, and flowering phases and duration of male and female flowers of Toona sinensis (Meliaceae) for 5 years (2011-2015) to determine if the species shows duodichogamous flowering. Results: Toona sinensis belonging to Meliaceae possessed functionally unisexual flowers with rudimentary parts of the opposite sex. The floral organs in male were larger than those in female, except for ovary length and width. In dichasium, male flowers were observed on primary or lateral branches, whereas female flowers were borne only on lateral branches. Overall, individuals from six different populations flowered in the male${\rightarrow}$female${\rightarrow}$male sequence, thereby male is blooming far longer than female flowers at the level of individual trees (male vs. female = 17-20 days vs. 2-4 days). Conclusions: This is the first study to report a duodichogamously flowering species, T. sinensis, within Meliaceae. Several flowering characteristics observed from T. sinensis may be important clues used to discover additional duodichogamous Meliaceae species. Short flowering period and relatively small number of female flowers, which is analogous to reduced ovule numbers observed in other duodichogamous species, may intensify male-male competition in T. sinensis. This study contributed to narrowing down potential candidates of duodichogamy based on their geographic distributions and flowering time.

• Journal of Plant Biotechnology
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• v.44 no.3
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• pp.229-234
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• 2017

Photoperiod is one of the factors affecting productivity of cucumber plant by inducing ethylene hormone production and so triggering flower sex differentiation into female flower. However, only few studies have been perfomed in order to reveal the effect of photoperiod in molecular level in relation to the flower differentiation. Therefore, in this study, Mercy cultivar of cucumber (andromonoecious) was treated with photoperiod of 8, 12, 16 hours of light, while control received no treatment of additional light. Photoperiod of 8 hours was achieved by blocking the sunlight with shade net and 16 hours by giving longer light exposure using white LEDs. Cucumber's flowers were quantified and the apical and lateral shoots were extracted to evaluate the gene profile related to the photoperiod, ethylene production, and female flower differentiation, which were CsACS2, CsETR1, CsCaN, and CsPIF4 using PCR method. Photoperiod of 8 hours affected the production of female flower with average number of 6.7 flowers in main stem and 8.0 flowers in lateral stem, compared to photoperiod of 12 and 16 hours which produced 3.7 and 2.0 flowers in main stem with 7.0 and 11.3 in lateral stem, respectively. In silico studies in this experiment resulted in proposed model of signal transduction that showed the connection between ethylene production and flower differentiation. PCR analysis confirmed the expression of CsACS2, CsETR1, and CsCaN, that was positively correlated with numbers of female flowers in cucumber, but the expression of CsPIF4 that represent photoperiod haven't been confirmed correlated with the ethylene production and flower differentiation.

• Journal of Forest and Environmental Science
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• v.38 no.4
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• pp.275-283
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• 2022

A study was designed to investigate the pattern of sexual dimorphism in a plantation of Garcinia kola. Twenty trees were randomly selected for the study and have been observed to flower regularly. A total of 100 inflorescence were randomly collected from the crown of each tree and 500 flowers randomly assessed within the period of four (4) flowering seasons. Floral sex assessment was done visually and with a hand magnifying lens; floral morphometric measurements (i.e. pedicel and perianth length and breadth), inflorescence length, and breadth) was taken using a veneer caliper; number of flowers per inflorescence and inflorescence per twig was counted; while, data analysis was conducted on excel using analysis of variance and pairwise t-test comparison. Four floral sexes were identified in the G. kola plantation studied which were unisexual male flowers, unisexual female flowers, cosexual unisexual male flowers, and cosexual hermaphrodite flowers. Three tree sexes were identified viz: inconstant male, invariant female, and cosexual trees. The plantation was significantly sexually dimorphic in floral sex and phenotypic traits (i.e. pedicel and perianth size), and as well as sexually dimorphic in tree sex and reproductive phenotypic traits (i.e. inflorescence size, number of inflorescences per twig, and number of flower bud per inflorescence). The sexual system of the plantation was therefore trioecious with features suggestive of evolving dioecy through the gynodioecious pathway.

• Journal of Forest and Environmental Science
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• v.26 no.2
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• pp.95-102
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• 2010

Jatropha curcas is an oil bearing species with multiple uses and considerable economic potential as a biofuel plant. Plant flowering and breeding characteristics are important for us to understand the reproduction of plant populations. The present study describes the floral biology and flowering phenology of J. curcas which is a prerequisite for hybridization program for genetic improvement through conventional breeding. The plant produces flowers in dichasial inflorescences. Normally, the flowers are unisexual, and male and female flowers are produced in the same inflorescence. Only a few male flowers are produced in an inflorescence, and fruits are produced only through pollination between different flowers from the same or different plants. This study includes a description of the inflorescence, flower anatomy of both male and female flowers, female : male ratio, pollen : ovule ratio, flowering phenology, pollen viability, stigma receptivity, comparison of selfing methods and a comparison of geitonogamy and xenogamy. This information may be useful in J. curcas breeding programmes.

• Journal of Korean Society of Forest Science
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• v.103 no.1
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• pp.43-50
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• 2014

The purpose of study was to analyze secreted nectar volume, nectar sugar content and amino acid in addition to estimating honey quantities that can ultimately reap in male and female flowers of Evodia daniellii Hemsl.. The maximum blooming period of male flowers was on 24 to 26 July in 2012. On average, nectar volume secreted by nectary was $2.73{\pm}0.73{\mu}L$ from one male flower and nectar concentration showed 17.4%. The maximum blooming period of female flowers was on 7 to 9 August in 2012. Nectar volume secreted by nectary was $0.63{\pm}0.49{\mu}L$ from one female flower and nectar concentration showed 25.7%, averagely. As results of correlation analysis between the meteorological factors and nectar characteristics, we found that nectar quantities and concentration were influenced by temperature and relative humidity. Sugar content was calculated at $48.0{\pm}5.2{\mu}g$ per a male flower and $37.8{\pm}8.7{\mu}g$ per a female flower, which meant that both values were not significantly different (Mann-Whitney's U-test, p=0.400). The minimum estimates of honey harvest for a male and female inflorescence were 67.8 g and 53.5 g, respectively. Analysis of amino acid showed that Serine, Glycine and Alanine were more abundant in male flowers, however Asparatate, Glutamate, Asparagine and Glutamine were more abundant in female flowers.

• Korean Journal of Plant Taxonomy
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• v.31 no.4
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• pp.359-373
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• 2001

One of Korean Typha species has been used two scientific names, T. angustifolia L. and T. angustata Bory et Chaubard without taxonomic examinations. Typha angustifolia has a longer females flowers than bracteoles and equal length of bracteoles and hairs in female flowers whereas T. angustata has equal length of female flowers and bracteoles and longer bracteloes than hairs in female flowers. In this study, the pattern of morphological variation of T. angustifolia in Korea is examined using numerical analysis to determine their taxonomical identities. Univariate analysis using morphological characters such as female flower length/bracteole length and bracteole lengh/hair length reveals that Korean T. angustifolia is composed of one group. The result of principal components analysis shows that Korean T. angustifolia is closely related to T. angustifolia distributed in Japan, Russia, and USA. Therefore, T. angustifolia L. (in Korea) is suggested as a legitimate scientific name.

• Journal of Forest and Environmental Science
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• v.37 no.1
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• pp.35-43
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• 2021

The interspecific hybrid of Salix caprea and Salix gracilistyla has never been identified or studied in Korea. Accordingly, this study investigated the flower morphological characteristics of the interspecific hybrid between S. caprea and S. gracilistyla and compared the interspecific hybrid with S. caprea and S. gracilistyla, respectively. The female flowers were investigated for 12 characteristics and the male flowers were investigated for nine. For the female flowers, those of the hybrids were larger than those of S. caprea and S. gracilistyla in terms of catkin length (CL), bract length (BL), and bract width (BW). The hybrids are intermediates between S. caprea and S. gracilistyla in terms of ovary length, width, and stipitate length as well as gland length (GL). For the male flowers, those of the hybrids were bigger than those of S. caprea and S. gracilistyla in terms of CL, BL, and BW. The hybrids are intermediates between S. caprea and S. gracilistyla in terms of catkin width and stamen length (SL). A principal component analysis (PCA) of the female data showed that the first principal component (PC) explained 57.5% of the total variation. The first PC highly correlated the ovary stipitate and pistil style lengths. The analysis was divided into three groups of S. caprea, S. gracilistyla, and the hybrid by the first PC. The results of a PCA of the male data showed that the first PC explained 35.7% of the total variation. The first PC highly correlated with the adelphous SL and was divided into three groups of S. caprea, S. gracilistyla, and the hybrid. The results of the discriminant analysis showed that S. caprea, S. gracilistyla, and the hybrid were distinguishable by flower morphological characteristics. Therefore, the hybrid was distinctly separated from S. caprea and S. gracilistyla by flower characteristics.

• Horticultural Science & Technology
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• v.34 no.5
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• pp.701-707
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• 2016

The charantin contents of leaves, stems, female and male flowers, and fruits in bitter gourd (Momordica charantia) were analyzed at different harvest seasons to investigate the availability of potential edible parts other than fruits. The charantin contents of fruits ranged from 14.7 to $16.0mg{\cdot}g^{-1}$ dry weight (DW) and those of leaves ranged from 131.4 to $138.0mg{\cdot}g^{-1}DW$, which was eight times higher than in fruits. The charantin contents of female and male flowers and stems were also significantly higher than those of the fruits. The ratio of total charantin content was highest in leaves (48%) of DW, followed by female flowers (20-21%), male flowers (14%), stems (12-13%), and fruits (5%). The charantin contents of fruits harvested 14 days after fruit setting was higher in June to mid-July (20.2 to $23.3mg{\cdot}g^{-1}DW$) than in late July to late August (13.3 to $19.4mg{\cdot}g^{-1}DW$). The higher the fruit weight, the lower the charantin contents, which showed that a negative correlation exists between fruit weight and charantin contents in bitter gourd. These results suggest that to obtain bitter gourd fruits with high charantin contents, fruits should be harvested until mid-July when fruit growth is fast and temperature is high. In addition, leaves, stems, and female and male flowers of bitter gourd can be used as for food, which are known to reduce blood sugar level.

• The Korean Journal of Ecology
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• v.14 no.4
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• pp.415-433
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• 1991

Seasonal variation in size and number of floral structures was examined in two massachusetts populations of chelidonium major, a self-compatible herb. All floral charcters except for anther number per flower declind significantly during a 3 week period. However, temporal patterns were not identical among characters or between popolations. The result indicate that floral characters varied in conjunction with flower diameter,but that the pattern of changes in floral characters in response to environments may not be easy to predict. Principal components analysis was conducted to environments may not be easy to predict. principal compenents analysis was conducted tl identify the functional relationship among floral male function, and female function, respectively, perhaps reflecting the functional distinction of floral characters. Based on this pattern, the relative allocation to sexual structures within flowers was examined: male allocation was relatively greater than female allocation eary or in the middle of flowering season, depending upon populations. Temporalvariation in relative allocation within flowers was not independent of seed tield components:; different combinations of the size and number of floral characters were correlated with different seed yield components, for example, either seed size or number per fruit, during a season. in particular, allocations to attractive and male structures were highly correlated with mean seed weight only earlier in the season. These result provide some evidence that flowering phenolgy is an important comportant to be considered in the study of sexual allocation.