• Journal of Plant Biology
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• v.5 no.2
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• pp.1-5
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• 1962

Attempts were made in order to make clear the meiotic irregularities, male gametophyte formation and spermatogenesis for the purpose of applying these embryological facts to taxonomic works. Followings are the results obtained : 1. Meiosis is extremely irregular, giving rise to giant, micro, and empty, pollens. Meiotic division in each PMC is observed synchronizing. 2. In the microspore immediately before the vegetative-generative nuclear division, the nucleus locates appressed to the inner wall, most of the other part of the cell being occupied by large vacuoles. 3. Spindle symmetry in the microspore nuclear division is of intermediate type. 4. Nuclear divisions in each micropore are not synchronized as in meiosis. 5. Generative nucleus is located in close contact with the inner wall, while the vegetative nucleus occupies the central part of pollen grain. The pollen in this stage looks somewhat like broad bean. Afterward the generative nucleus loses contact with the wall, the nuclear shape changing from lenticular to roundsh. 6. The generative nucleus in fully matured pollen grain usually takes the shape of crescence, those in abortive pollen, lenticular or ellipsoidal, etc.

• Journal of Plant Biology
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• v.36 no.3
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• pp.241-249
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• 1993

The pattern of RNA synthesis during male gametogenesis of Brassica napus was studied using 3H-uridine autoradiography. No incorporation of isotope occurred in the newly released microspore and the nonvacuolate, furrowed microspore. Peak incorporation of label during male gametogenesis occurred in the uninucleate, furrowed microspores showing various degrees of vacuolation. In this microspore stage, silver grains were localized in the nucleus and cytoplasm. Moderate incorporation of the isotope occurred in the nulceus of the vacuolated microspore. After the microspore mitosis, isotope incorporation occurred predominantly in the nucleus of the vegetative cell with little or no incorporation in the generative cell. In tricellular pollen, no incorporation of isotope was observed in both the vegetative nucleus and the sperms. Silver grains almost completely disappeared from tricellular mature pollen grains ready to germinate.

• Current Research on Agriculture and Life Sciences
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• v.31 no.2
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• pp.75-82
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• 2013

Haploids are plants with a gametophytic number of chromosomes in their sporophytes. Androgenesis occurs from asymmetric division of pollen grains into generative cells and vegetative cells, followed by re-entry of the vegetative cell during S-phase, which causes microspores progress into G2/M transition in culture. One of the most interesting features of haploids is the possibility to produce doubled haploid (DH) individuals. Doubled haploidy is extremely useful to plant breeders because it enables shortened breeding periods and efficiency in selection of useful recessive agronomic traits. Doubled-haploid technology is not only applicable to breeding, but also to transformation programs of desired genes. In addition to practical breeding programs, DH lines provide useful materials of fundamental genetics including exploitation of QTLs and genes conferred with various agronomic traits by establishing DH populations. This paper provides historical overviews on androgenesis and describes several mechanisms associated with pollen embryogenesis, including mode of actions in pollen embryogenesis, mechanisms of chromosome doubling and factors affecting androgenesis. We also discuss recent progress in application of haploids to breeding, genes associated with in vitro response and drawbacks to anther culture for application of doubled haploids in crop breeding.

• Korean Journal of Plant Tissue Culture
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• v.26 no.3
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• pp.149-156
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• 1999

In order to investigate the effect of low temperature pretreatment on pollen dimorphism and embryo formation in anther culture of Platycodon grandiflorum, the anthers with microspore at the uninucleate stage were cultured on Murashige and Skoog medium supplemented with 0.5mg/L NAA and 1.0 mg/L BA. The low temperature pretreatment have clear effect on the frequencies of S pollen grains, symmetrical binucleate microspores (B type of S pollen), multinucleate and multicelled pollen grains. Especially, after low temperature pretreatment at 8$^{\circ}C$ for 5 days increased the frequency of S pollen grain (20.6%) in vivo. In addition, the highest frequency of callus induction (54.9%) and embryo formation (9.9%) were obtained from the anther pretreatment at 8$^{\circ}C$ or 5 days. Three distinct pathways could be recognized in the androgenesis, one involving mainly the vegetative cell, the second starting with the vegetative and the generative cell, respectively, and the third accompaning with two equal vegetative type cells in the pollen grains.

• Journal of Plant Biotechnology
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• v.2 no.3
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• pp.129-134
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• 2000

Clear visualization of pepper (Capsicum annuum L.) microspore nuclei with common stains such as acetocarmine or propionocarmine is difficult, hindering cytological analysis. The DAPI stain after the addition of ferric chloride solution to fixative resulted in clear visualization of nuclei. For clear visualization of nuclei and slight fluorescence of microspore wall, addition of 40-60 ${mu}ell$ of ferric chloride solution to the 1 $m\ell$ fixative was identified as most effective. At all stages of gametophytic development, the nuclei can be distinctly visualized. Starch granules does not intefere with the fluorochrome, and so the vegetative and generative nuclei were cleary visible in binucleate pollens. With its rapidity and reliability, this technique represents an efficient tool for routine staging or investigation of the nuclear status of the microspore during culture.

• Horticultural Science & Technology
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• v.29 no.1
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• pp.36-42
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• 2011

This research was conducted to investigate the effects of irrigation quantity in irrigation management system controlled by drainage level sensors for perlite bag culture on the growth and yields of tomatoes during different growth stages. Tomato plants were irrigated with four selected methods; supplying small quantity (~70 mL) during entire growth (S-S), large quantity (~145 mL) during entire growth (L-L), small quantity before harvesting the first cluster fruits and large quantity after harvesting (S-L), and large quantity until harvesting the first cluster fruits and small quantity after harvesting (L-S). The irrigation quantity supplied in each time was gradually adjusted along with the ratios as the tomato crop grew during different growth stages. The growth of the tomato plants was unstable and slow during the entire cropping period when the plant was irrigated by small or large quantities (S-S or L-L). In L-S treatment, the growth phase of the tomato was changed from vegetative to generative growth on the basis of the plant development index when each irrigation quantity was changed. The L-S treatment exhibited the largest root volume and yields with stable drainage ratios. Therefore, the optimum irrigation quantity was determined as 145 mL before harvesting the first cluster fruits and 70 mL after harvesting.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1158-1158
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• 2001

Fast and dynamic biochemical, enzymatic and morphological changes occur during the so-called generative development and during the vegetative processes in seeds. The most characteristic biochemical and compositional changes of this period are the formation and decline of storage components or their precursors, the change of their degree in polymerization and an extensive change in water content. The aim of the present study was to detect the maturation processes in seed nondestructively and to verify the applicability of near infrared spectroscopic methods in the measurement of physiological, chemical and biochemical changes in wheat seed. The amount and variation of different water “species” has been changed intensively during maturation. Characteristic changes of three water absorption bands (1920, 1420 and 1150 nm) during maturation were analysed. It was concluded that the free/bound transition of water molecules could be followed sensitively in different region of NIR spectra. Kinetic changes of carbohydrate reserves were characteristic during maturation. An intensive formation and decline of carbohydrate reserves were observed during early stage of maturation (0 -13 days, high energy demand). An accelerated formation of storage carbohydrates (starch) was detected in the second phase of maturation. Five characteristic absorption bands were analysed which were sensitive indicators the changes of carbohydrates occurred during maturation. Precursors of protein synthesis and the synthesis of reserve proteins and their kinetic changes during maturation were followed from NIR spectra qualitative and qualitatively. Dynamic formation of amino acids and the changes of N forms were detected by spectroscopic, chromatographic and by capillary electrophoresis methods. Calibration equations were developed and validated in order to measure the optimal maturation time protein and moisture content of developing wheat seeds. The spectroscopic methods are offering chance and measurement potential in order to detect fine details of physiological processes. The spectra have many hidden details, which can help to understand the biochemical background of processes.

• Korean Journal of Agricultural Science
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• v.46 no.4
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• pp.769-779
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• 2019

Chilli peppers are predominantly cultivated in open field systems under abiotic and biotic stress conditions. Abiotic and biotic factors have a considerable effect on plant performance, fruit quantity, and quality. Chilli peppers grow well in a tropical climate due to their adaptation to warm and humid regions with temperatures ranging from 18 to 30℃. Nowadays, chilli peppers are cultivated all around the world under different climatic conditions, and their production is gradually expanding. Expected climate changes will likely cause huge and complex ecological consequences; high temperature, heavy rainfall, and drought have adverse effects on the vegetative and generative development of all agricultural crops including chilli peppers. To gain better insight into the effect of climate change, the growth, photosynthetic traits, morphological and physiological characteristics, yield, and fruit parameters of chilli peppers need to be studied under simulated climate change conditions. Moreover, it is important to develop alternative agrotechnologies to maintain the sustainability of pepper production. There are many conceivable ideas and concepts to sustain crop production under the extreme conditions of future climate change scenarios. Therefore, this review provides an overview of the adverse impacts of climate change and discusses how to find the best solutions to obtain a stable chilli pepper yield.

• Journal of Pharmacopuncture
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• v.22 no.1
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• pp.16-27
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• 2019

Generative and vegetative parts of the cactuses have had a long-lasting position in folk medicine and their effects could partly be confirmed in scientific experiments. Nowadays, the cactus, fruits, and cladodes are the focus of many studies because of their desirable properties. Therefore, the summarized reports of valuable properties of medicinal plants may be a good way to familiarize researches with a new source of drugs with lower side effects and higher efficacy. Opuntia dillenii, a well-known member of the Cactaceae family, is used as a medicinal plant in various countries and grows in the desert, semi-desert, tropical and sub-tropical areas. It shows diverse pharmacological activities such as: antioxidant, anti-inflammatory, anti-tumor, neuroprotective, hepatoprotective, hypotensive etc. OD fruit also possesses valuable constitutes for instance: betalains, ascorbic acid, total phenol, protein as well as essential elements which suggest the significant potential of this plant as a complementary therapy against several pathological conditions. This review describes experimental evidence about pharmacological and therapeutic potential of OD in order to give the basis of its application in the prevention and treatment of some chronic diseases. More studies on OD can help better understanding of its pharmacological mechanism of action to explain its traditional uses and to identify its potential new therapeutic applications.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.26 no.2
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• pp.185-191
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• 1981

The purpose of this paper is to define and describe a series of growth stages for maize. cv. MTC-l (early) and Suweon No. 19 (late) that are easily identifiable by both professional agronomists and farmers. Plants were grown at a density of 60cm row with plant spacing of 15cm at six different seeding times in 1980. Leaf development indices with ten grades (LDI) were identified and defined in accordance with the development of a leaf blade. Leaf appearance rate (LAR) was ca. 3 days and it was not influenced by the variety or seeding time. The elongation of the first internode above the ground level began in a month after emergence and it corresponded to the 8th or 9th leaf stage. Internodes elongated in regular sequence of node position. The morphological change of silks related closely with the development of kernel. The duration of generative development was not influenced by varieties and seeding time but that of vegetative growth was influenced. A new scheme for the maize which was made by the developed leaves, visible nodes above ground level, morphological change of silks and development of kernel was proposed.