Anatomical Aspects of Pollen Release from Staminate Flowers of Ambrosia trifida (Asteraceae)

1995 ◽  
Vol 156 (1) ◽  
pp. 29-36 ◽  
Author(s):  
John D. Curtis ◽  
Nels R. Lersten
Weed Research ◽  
2021 ◽  
Author(s):  
Aleksandra Savić ◽  
Mostafa Oveisi ◽  
Dragana Božić ◽  
Danijela Pavlović ◽  
Markola Saulić ◽  
...  

2021 ◽  
pp. 1-23
Author(s):  
Bruno Chauvel ◽  
Guillaume Fried ◽  
Swen Follak ◽  
Daniel Chapman ◽  
Yuliana Kulakova ◽  
...  

Plant Biology ◽  
2021 ◽  
Author(s):  
T. Bochorny ◽  
L. F. Bacci ◽  
A. S. Dellinger ◽  
F. A. Michelangeli ◽  
R. Goldenberg ◽  
...  

2021 ◽  
Vol 104 (3) ◽  
Author(s):  
Matheus Hansen ◽  
Gabriel C. Lanes ◽  
Vinícius L. G. Brito ◽  
Edson D. Leonel

1975 ◽  
Vol 85 (2) ◽  
pp. 301-307 ◽  
Author(s):  
P. Cremades ◽  
E. W. Bean

SUMMARYThe reproductive development and seed production characters of a Lolium multiflorum × Festuca pratensis tetraploid hybrid and a Lolium perenne × Festuca pratensis tetraploid hybrid were compared with those of their tetraploid parental cultivars. Experiments were carried out under glasshouse and natural conditions; single plants were studied as only small quantities of seed were available from the breeder. The lowtemperature/short-day requirements for inflorescence induction of the two hybrids were in between those of the corresponding parental species. The variance of the date at which vegetative primordia changed to the reproductive condition was greater in the hybrids than in the parental cultivars, but the variance of the dates of inflorescence emergence were similar for the hybrids and parental cultivars. Inflorescences ranged from the Lolium type with only sessile spikelets to the Festuca type with primary branches. Inner glumes, which are absent in the Lolium parents but present in Festuca pratensis, were found in the hybrids, though not in all spikelets. In the Lolium perenne × Festuca pratensis hybrid pollen release, potential pollen viability and floret fertility were low, but the Lolium multiflorum × Festuca pratensis hybrid produced large amounts of pollen with a higher potential viability and had floret fertilities similar to those of its two parental cultivars. There was sufficient variation in reproductive characters for further selection, particularly in the Lolium perenne × Festuca pratensis hybrid.


2021 ◽  
Vol 23 (4) ◽  
pp. 921-926
Author(s):  
N. N. Zhukova ◽  
M. V. Manzhos ◽  
L. R. Khabibulina ◽  
E. Yu. Syrtsova

Allergic rhinitis and bronchial asthma are widespread respiratory allergic diseases. In some territories of the Russian Federation, the dominant cause of pollinosis is ragweed. The aim of the study was to evaluate the clinical and immunological efficacy of ASIT with the allergen Ambrosia artemisiifolia in patients sensitized to Ambrosia trifida in the Samara region. Patients with proven sensitization to Ambrosia trifida was held immunotherapy with Ambrosia artemisiifolia allergoid preseason. After treatment, patients had a decrease in the severity of symptoms of allergic rhinitis according to VAS (p = 0.00001), a decrease in the need for medications (p = 0.0003), as well as the need for corticosteroids against the background of therapy from 34.6% to 0% (p = 0.00001). In 8% of cases, the result of treatment was good, in 69% satisfactory, in 23% unsatisfactory. In the control group, there were no changes in the severity of symptoms (p = 0.858). Also, in the control group, the need for medications remained unchanged and 14.3% of patients continued to use corticosteroids.After ASIT, there was a decrease in the level of IL-4 (p = 0.002), and a decrease in the ratio of IL-4/ IL-10 (p = 0.0063); at the same time, changes in the level of other cytokines (IL-10; IFNγ) were statistically insignificant (p > 0.05). Before treatment, the levels of IL-4/ IL-10 in both groups were comparable, and after treatment, the differences became statistically significant (p = 0.031). We did not get a statistically significant change in the level of IgG4 Amb a 1 or IgG4 Amb trifida. There was no correlation between the level of individual cytokines and the results of treatment. As a result of the conducted ASIT, positive clinical and immunological results were obtained. In most patients, the disease has acquired a controlled course. At the same time, the lack of excellent and low number of good results of ASIT is probably due to the intraspecific allergenic properties of ragweed. 


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Wenxuan Zhao ◽  
Tong Liu ◽  
Yan Liu ◽  
Hanyue Wang ◽  
Ruili Wang ◽  
...  

Abstract Background Ambrosia artemisiifolia and Ambrosia trifida are globally distributed harmful and invasive weeds. High density clusters play an important role in their invasion. For these two species, the early settled populations are distributed at low densities, but they can rapidly achieve high population densities in a short period of time. However, their response to intraspecific competition to improve the fitness for rapid growth and maintenance of high population densities remains unclear. Therefore, to determine how these species form and maintain high population densities, individual biomass allocations patterns between different population densities (low and high), and plasticity during seedling, vegetative, breeding and mature stages were compared. In 2019, we harvested seeds at different population densities and compared them, and in 2020, we compared the number of regenerated plants across the two population densities. Results Most biomass was invested in the stems of both species. Ambrosia trifida had the highest stem biomass distribution, of up to 78%, and the phenotypic plasticity of the stem was the highest. Path analysis demonstrated that at low-density, total biomass was the biggest contributor to seed production, but stem and leaf biomass was the biggest contributors to high-density populations. The number of seeds produced per plant was high in low-density populations, while the seed number per unit area was huge in high-density populations. In the second year, the number of low-density populations increased significantly. A. artemisiifolia and A. trifida accounted for 75.6% and 68.4% of the mature populations, respectively. Conclusions High input to the stem is an important means to regulate the growth of the two species to cope with different densities. These two species can ensure reproductive success and produce appropriate seed numbers. Therefore, they can maintain a stable population over time and quickly form cluster advantages. In the management, early detection of both species and prevention of successful reproduction by chemical and mechanical means are necessary to stop cluster formation and spread.


Author(s):  
O. Marieva ◽  
O. Zhuiboroda

The expansion of trade and economic relations with other countries increased the risk of importing new invasive types of weeds into the state. One of them is a serious danger weed — giant ragweed (Ambrosia trifida L.). This weed with high speed and aggressiveness inhabits and displacing native species in agricultural and non-arable land, including landscapes of big cities. A. trifida extends to non-arable lands with disturbed natural vegetation. This species is spreading through the contamination of seeds and agricultural equipment. It damaged soybeans, legumes and corn, as well as other grain crops. Increasing of this weed pollen in the air is a source of a massive disease with allergies. At present, there is danger of entry by this weed to Ukraine from neighboring countries.


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