scholarly journals Pollination ecology of Synedrella nodiflora (l.) Gaertn. (Asteraceae)

2018 ◽  
Vol 10 (11) ◽  
pp. 12538-12551
Author(s):  
B. Usharani ◽  
A.J. Solomon Raju
Keyword(s):  
Feeding Activity ◽  
Intermediate Form ◽  
Invasive Weed ◽  
Disc Floret ◽  
Secondary Pollen Presentation ◽  
Wide Range ◽  
Pollen Presentation ◽  
Ray Florets ◽  
And Bisexual ◽  
Synedrella Nodiflora

Synedrella nodiflora (L.) Gaertn grows almost throughout the year if the soil is damp. It produces heterogamous capitula with female ray florets anthesing first day and bisexual disc florets anthesing on the next three consecutive days. Disc florets are dichogamous, herkogamous, self-compatible, self-pollinating (vector-mediated) and display secondary pollen presentation through an intermediate form of brush mechanism. Ray and disc florets exhibit facultative xenogamy. Butterflies are principal pollinators while bees, wasps and flies are supplementary pollinators. Thrips, Microcephalothrips abdominalis uses the florets as breeding and feeding sites; the feeding activity effects pollination. The ray and disc florets produce cypselas; the cypselas produced by ray florets are  heavier, elliptical, membranous with upwardly-pointing teeth along the margins and 2 short terminal awns while those produced by disc floret are lighter, cylindrical and tangentially compressed with 2 or 3 stiff terminal divaricate awns. Seed dispersal is polychorous and represented by anemochory, anthropochory, zoochory and ombrohydrochory. Cypselas of ray florets disperse to short distances and germinate germinate under specific germination conditions either at parental sites or in similar habitats while those of disc florets disperse farther away from parental sites and germinate readily under a wide range of conditions. Therefore, bimorphic cypselas with different germination abilities enable the plant to grow as a widespread weed but not as an invasive weed.

Seed germination response of a noxious agricultural weed Echium plantagineum to temperature, light, pH, drought stress, salinity, heat and smoke

2018 ◽  
Vol 69 (3) ◽  
pp. 326 ◽  
Author(s):  
Singarayer Florentine ◽  
Sandra Weller ◽  
Alannah King ◽  
Arunthathy Florentine ◽  
Kim Dowling ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Drought Stress ◽  
Invasive Weed ◽  
Germination Response ◽  
Elevated Salinity ◽  
Wide Range ◽  
Agricultural Weed ◽  
Soil Seedbank ◽  
Response To Temperature ◽  
Salinity Management

Echium plantagineum is a significant pasture weed in the Mediterranean climatic zone of several countries, including Australia. This invasive weed, introduced as an ornamental into Australia (where it is known as Paterson’s curse), quickly became established and is now a significant weed of agriculture. Although E. plantagineum is a well-established, highly competitive weed that thrives under disturbance and is tolerant of a wide variety of conditions, including varying soil moisture and drought, and some aspects of its ecology remain unknown. This study investigated germination response to temperature and light, pH, soil moisture, salinity, and pre-germination exposure of seed to heat and smoke. Temperature was found to be more influential on germination than light and the species is tolerant to a wide range of pH. However, available moisture may limit germination, as may elevated salinity. Management of this weed requires approaches that minimise soil seedbank input or prevent germination of soil seedbanks.

Secondary Pollen Presentation in Angiosperms and Its Biological Significance

1993 ◽  
Vol 41 (5) ◽  
pp. 417 ◽  
Author(s):  
GJ Howell ◽  
AT Slater ◽  
RB Knox
Keyword(s):  
Close Association ◽  
Biological Significance ◽  
Selective Advantage ◽  
Floral Organ ◽  
Pollinator Behaviour ◽  
Secondary Pollen Presentation ◽  
Male Function ◽  
Increased Risk ◽  
Pollen Presentation ◽  
Male Phase

Secondary pollen presentation is the developmental relocation of pollen from the anthers onto another floral organ which then functions as the pollen presenting organ for pollination. Nine different types have been identified in sixteen angiosperm families according to which organ is used for presentation, whether the pollen is exposed or concealed within a structure and how pollen is loaded onto the presenting surface: (1) Enveloping bloom presenters (Araceae); (2) Perianth presenters with exposed pollen presentation (Epacridaceae); (3) Androecial presenters (Santalaceae); (4) Terminal stylar presenters with passive pollen placement and concealed stigmas (Rubiaceae and Proteaceae); (5) Terminal stylar presenters with passive pollen placement and sub-terminal stigmas (Marantaceae and Polygalaceae); (6) Terminal stylar presenters with active pollen placement (Asteraceae, Calyceraceae and Lobeliaceae); (7) Sub-terminal stylar presenters (Campanulaceae, Cannaceae, Fabaceae and Myrtaceae); (8) Exposed stigmatic presenters (Rubiaceae); (9) Indusial stigmatic presenters (Goodeniaceae and Brunoniaceae). Secondary pollen presentation occurs in three monocotyledon and thirteen dicotyledon families. The presentation types appear to have been independently derived indicating that secondary pollen presentation is a character with a selective advantage. In all but the enveloping bloom type of secondary pollen presentation, developmental relocation of pollen requires simultaneous, introrse anther dehiscence and a close association of the presenting organ to the anthers prior to anthesis. The various secondary pollen presentation systems may be modified to promote xenogamy or autogamy and this can even change during anthesis. Most plants which have secondary pollen presentation, display reduced herkogamy within the flower to facilitate pollination. Increased risk of self-pollination due to this may be overcome through dichogamy, herkogamy within inflorescences, dry stigmas, self-incompatibility systems and passive or active control over pollinator behaviour. Enhanced male function of the flowers of secondary pollen presenting plants is also evident through extension of the male phase by the protection, controlled release and precise placement and receipt of pollen. Plants displaying secondary pollen presentation are almost always protandrous.

Self-interference is reduced in a secondary pollen presentation species, Duperrea pavettifolia (Rubiaceae)

Flora ◽  
2012 ◽  
Vol 207 (12) ◽  
pp. 895-902 ◽  
Author(s):  
Hua Lin ◽  
Xuli Fan ◽  
Xiang Zhou ◽  
Jiangyun Gao
Keyword(s):  
Secondary Pollen Presentation ◽  
Pollen Presentation

The phenology and seed production of Cucumis melo as an invasive weed in northern Iran

2016 ◽  
Vol 64 (3) ◽  
pp. 227 ◽  
Author(s):  
Sima Sohrabi ◽  
Javid Gherekhloo ◽  
Behnam Kamkar ◽  
Ali Ghanbari ◽  
Mohammad Hassan Rashed Mohassel
Keyword(s):  
Seed Production ◽  
Weed Management ◽  
Cucumis Melo ◽  
Sowing Date ◽  
Growth Cycle ◽  
Future Research ◽  
Degree Days ◽  
Northern Iran ◽  
Invasive Weed ◽  
Wide Range

Accurately representing plant development is essential for applying phenology knowledgement to investigate the effects of climate on weed management. Development in wild melon (Cucumis melo L.) is driven by temperature; thus, it could be simulated by thermal-time (TT) accumulation using limited accumulation when a lower optimum temperature (Topt) is exceeded. Experiments were conducted to investigate wild melon phenology (development rate) and seed production in soybean (Glycine max L.) at seven different sowing dates (April to August) in a completely randomised design (CRD) at Research Farm of Gorgan University of Agricultural Sciences and Natural Resources, Iran, during 2012. Results indicated that a slight shift in developmental rates occurs among plantings dates, except for those plants sown in August. The estimated TT for April–August planting dates were ~411 Celcius degree days, 448 Celcius degree days, 733 Celcius degree days, 672 Celcius degree days, 604 Celcius degree days, 558 Celcius degree days and 251 Celcius degree days respectively. Depending on planting date, weed emergence occurred at 5–20 days after planting. During the 79, 75, 92, 81, 71, 67 and 61 days of wild-melon growth, the mean number of fruits per plant and seeds per fruit were significantly different at each sowing date. Wild melon could produce a lot of fruits and seeds (up to 5000) within a growth cycle (average in 75 days) and also weed management is needed during the May and June because of the highest seed production of wild melons that emerged during May. The results attained here suggest that temperature alone could not reflect the effect of environment on C. melo development at each given growth stage. Thus, other environmental factors, such as daylength, maybe needed to better estimate weed development. Future research may use multiplicative models to clarify this claim. These results highlighted the value of testing a model over a wide range of environments.

scholarly journals First Report of Zonate Leaf Spot Caused by Hinomyces moricola on Japanese Hop in Korea

Plant Disease ◽  
2013 ◽  
Vol 97 (8) ◽  
pp. 1117-1117 ◽  
Author(s):  
S. E. Cho ◽  
J. H. Park ◽  
S. H. Hong ◽  
H. D. Shin
Keyword(s):  
Its Region ◽  
The United States ◽  
Infected Leaf ◽  
Invasive Weed ◽  
Voucher Specimen ◽  
First Report ◽  
Leaf Spots ◽  
Initial Symptoms ◽  
Wide Range ◽  
Humulus Japonicus

Japanese hop (Humulus japonicus Siebold & Zucc. = H. scandens (Lour.) Merr.), native to East Asia, is an annual, climbing or trailing vine. The vines can spread to cover large areas of open ground or low vegetation, eventually blanketing the land and vegetation. Pollen of H. japonicus is allergenic, and this species is considered as one of the important causes of pollinosis in Korea and China. It is a notorious invasive weed in the United States and also in France, Hungary, and Italy (1). In September 2012, zonate leaf spots were observed on Japanese hops growing in wetlands in Yeongdong County of Korea. A voucher specimen was preserved in the Korea University Herbarium (KUS-F26901). Initial symptoms included grayish-green to grayish-brown spots without border lines. As the lesions enlarged, they coalesced, leading to leaf blight. Sporophores on the leaf lesions were dominantly hypophyllous, rarely epiphyllous, solitary, erect, easily detachable, and as long as 700 μm. The upper portion of the sporophores consisted of a pyramidal head was ventricose, 320 to 520 μm long and 110 to 150 μm wide. The fungus was isolated from leaf lesions and maintained on potato dextrose agar (PDA). Sclerotia were produced on PDA after 4 to 5 weeks at 18°C without light, but conidia were not observed in culture. These morphological and cultural characteristics were consistent with those of Hinomyces moricola (I. Hino) Narumi-Saito & Y. Harada (= Cristulariella moricola (I. Hino) Redhead) (3,4). An isolate was preserved in the Korean Agricultural Culture Collection (Accession No. KACC46955). Genomic DNA was extracted using the DNeasy Plant Mini DNA Extraction Kit (Qiagen Inc., Valencia, CA). The complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced. The resulting sequence of 452 bp was deposited in GenBank (Accession No. KC460209). A BLAST search in GenBank revealed that the sequence showed an exact match with those of C. moricola (JQ036181 ex Acer negundo and JQ036182 ex Glycine max). To determine the pathogenicity of the fungus, according to the procedure of Cho et al. (2), sporophores with the pyramidal head were carefully detached from a lesion on the naturally infected leaf using a needle. Each sporophore was transferred individually onto five places of four detached healthy leaves. The leaves were placed in dew chambers and incubated at 16°C. Symptoms were observed after 2 days on all inoculated leaves. A number of sporophores and immature sclerotia which were morphologically identical to the ones observed in the field were formed on the abaxial surface of the leaf 2 weeks after inoculation. The pathogen was reisolated from lesions on the inoculated leaves, confirming Koch's postulates. No symptoms were observed on the control leaves kept in humid chambers for 2 weeks. H. moricola was known to cause zonate leaf spots and defoliation on a wide range of woody and annual plants (3). To the best of our knowledge, this is the first report of Hinomyces infection on Japanese hops in Korea. References: (1) Anonymous. Humulus japonicus (Cannabaceae): Japanese hop. Eur. Medit. Plant Prot. Org. (EPPO). 2012. (2) S. E. Cho et al. Plant Dis. 96:906, 2012. (3) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., Online publication, ARS, USDA, Retrieved December 8, 2012. (4) S. A. Redhead. Can. J. Bot. 53:700, 1975.

scholarly journals Preliminary phytochemical screening of Lantana camara, L., a major invasive species of Kerala, using different solvents

2017 ◽  
Vol 6 (11) ◽  
pp. 1794
Author(s):  
Sushma Raj
Keyword(s):  
Biological Activities ◽  
Modern Medicine ◽  
Lantana Camara ◽  
Phytochemical Screening ◽  
Invasive Weed ◽  
Natural Form ◽  
Large Reservoir ◽  
Standard Procedures ◽  
Medicinal Use ◽  
Wide Range

Plants and plant extracts have important role in modern medicine as their chemical and medicinal constituents are found in natural form. The secondary metabolites represent a large reservoir of structural moieties which work together exhibiting a wide range of biological activities. Plants and plant based products are bases of many modern pharmaceuticals that are currently in use for various diseases. Lantana camara, L., also known as big – sage or wild – sage is one of the major invasive weed in India. Six different solvents viz; distilled water, acetone, alcohol, chloroform, petroleum ether and benzene were used to obtain extracts from powdered leaves and roots of Lantana camara, L. The extracts were subjected to qualitative phytochemical screening using standard procedures. Of the 15 phytochemicals tested, 10 were found in various solvent extracts of Lantana camara, L. By this study, it was confirmed that the selected plant species is a potent source of useful drugs. Present day, particularly in India, Lantana camara, L. is considered as a threat to our biodiversity. So a controlled management is necessary to make use its medicinal use.

scholarly journals Melilotus officinalis (yellow sweet clover).

2020 ◽  
Author(s):  
Julissa Rojas-Sandoval
Keyword(s):  
North America ◽  
National Parks ◽  
Soil Conditions ◽  
Nitrogen Fixing ◽  
Invasive Weed ◽  
Tropical Regions ◽  
Melilotus Officinalis ◽  
Natural Fires ◽  
River Floodplains ◽  
Wide Range

Abstract Melilotus officinalis is a herbaceous legume species, native to parts of Asia and possibly Europe (sources differ on this), that has been extensively introduced to be used as a forage and nitrogen-fixing crop. It has escaped from cultivation and become an invasive weed in many temperate and tropical regions; it can also be toxic to livestock. It is a prolific seeder, and its seeds can remain viable in the soil for many years. It is fast-growing and can grow in a wide range of environmental conditions. Like other nitrogen-fixing legumes, M. officinalis has the potential to alter soil conditions and nutrient cycling. It is allelopathic and so forms dense monospecific stands that displace and inhibit the establishment of native vegetation. In North America, infestations reduce the occurrence of natural fires and degrade native grassland communities that depend on frequent fires. In Alaska and Canada, this species is a serious problem on waterways because it is invading glacial river floodplains. Currently, it is recognized as a conservation problem in North America because it is invading critical natural areas such as national parks and protected lands.

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