Role of mucilage in seed dispersal and germination of the annual ephemeral Alyssum minus (Brassicaceae)

2012 ◽  
Vol 60 (5) ◽  
pp. 439 ◽  
Author(s):  
Ying Sun ◽  
Dun Y. Tan ◽  
Carol C. Baskin ◽  
Jerry M. Baskin
Keyword(s):  
Water Stress ◽  
Seed Dispersal ◽  
Incubation Temperature ◽  
Water Reservoir ◽  
Soil Surface ◽  
Moisture Stress ◽  
West China ◽  
North West ◽  
Seed Age

Seeds of Alyssum minus, an annual ephemeral in shrublands of north-west China, can produce a large amount of mucilage. The primary aim of this study was to explore the role of mucilage in seed dispersal, settlement onto the soil surface and germination of this species. Width of imbibed seeds with mucilage was three times greater than that of seeds without mucilage, and mass of mucilage increased 167 times after imbibition. Expanded dry mucilage significantly increased wind dispersal of seeds. Floating time on water was greatest for seeds without mucilage, and adherence of soil particles to seeds was greater for seeds with mucilage than for those without mucilage. Mucilage increased rate of water uptake and decreased rate of water loss, and it significantly decreased germination of 0- and 4-week-old seeds. Gibberellic acid promoted germination of 0- and 4-week-old seeds with and without mucilage, but its effect depended on seed age and incubation temperature. Seeds with mucilage subjected to water stress during imbibition and/or incubation germinated faster than those without mucilage. Presence of mucilage on seeds during imbibition significantly increased germination percentages under increased water stress, a first report of this phenomenon. The study has shown that the mucilage of A. minus plays an important role in seed dispersal, seed adhesion to soil (thereby minimising removal by water and predators), seed hydration via increasing surface contact with the substrate, and can serve as a water reservoir for germination, especially under moisture stress.

scholarly journals Johnsongrass (Sorghum halepense) Seed Dispersal in Corn Crops under Mediterranean Conditions

Weed Science ◽  
2012 ◽  
Vol 60 (1) ◽  
pp. 34-41 ◽  
Author(s):  
Judit Barroso ◽  
Dionisio Andújar ◽  
Carolina San Martín ◽  
César Fernández-Quintanilla ◽  
José Dorado
Keyword(s):  
Seed Dispersal ◽  
Soil Surface ◽  
Dispersal Pattern ◽  
Natural Factors ◽  
Vacuum Device ◽  
Combine Harvester ◽  
The Difference ◽  
Dispersal Distances ◽  
Natural Dispersal

Natural dissemination of johnsongrass seeds as well as the effect of combine harvesting on this process were studied in corn fields. The estimation of natural dispersal was carried out by two different methods, collecting seeds throughout the season using seed traps and sampling soil–surface seed abundance before harvest using a vacuum device. Both methods showed the same dispersal pattern. A minimum of 84.6% was dispersed in the first 2 m from the focus and a maximum of 1.6% was dispersed beyond the first 5 m. An average of 76.3% of these dispersed seeds were lost or buried after shedding but before harvest. Seed dispersal by the combine harvester was estimated from the difference between soil–surface seed abundance in the same sites pre and postharvest. Although the quantity of seeds dispersed by the combine was similar to those dispersed by natural factors, dispersal distances were significantly higher. Around 90% of the dispersed seeds were found in the first 5 m forward and backward of the combine direction from the infestation source, and 1.6% of the seeds were found beyond 22 m forward and 10 m backward of the combine direction from the infestation source. A large proportion of the seeds dispersed were dormant or not viable. It is concluded that the major role of sexual reproduction in johnsongrass population dynamics may be to spread the risks, promoting dispersal in time and space.

Microbially mediated dolomite in Cambrian stromatolites from the Tarim Basin, north-west China: implications for the role of organic substrate on dolomite precipitation

Terra Nova ◽  
2013 ◽  
Vol 25 (5) ◽  
pp. 387-395 ◽  
Author(s):  
Xuelian You ◽  
Shu Sun ◽  
Jingquan Zhu ◽  
Qing Li ◽  
Wenxuan Hu ◽  
...  
Keyword(s):  
Tarim Basin ◽  
Organic Substrate ◽  
West China ◽  
North West ◽  
Dolomite Precipitation

TBE in China

2020 ◽  
Keyword(s):  
Western China ◽  
Ixodes Persulcatus ◽  
West China ◽  
North West ◽  
Haemaphysalis Concinna ◽  
Viral Subtype ◽  
Japanese Military ◽  
Natural Foci ◽  
Far Eastern ◽  
The Brain

The first TBE patients in China were reported in 1943, and the TBEV was isolated from the brain tissues of 2 patients in 1944 by Japanese military scientists,1 and from patients and ticks (Ixodes persulcatus and Haemaphysalis concinna) in 1952 by Chinese researchers.2 The Far Eastern viral subtype (TBEV-FE) is the endemic subtype that has been isolated from all 3 known natural foci (northeastern China, western China, and southwestern China).14 Recently a new “Himalayan subtype” of the TBEV (TBEV-HIM) was isolated from wild rodent Marmoata himalayana in the Qinghai-Tibet Plateau15. The main vector of the TBEV in China is I. persulcatus.3 One recent report suggests that the TBEV-SIB is prevalent in the Uygur region (North West China)13 but epidemiological modelling indicates that the TBEV may occur even widely all over China (Figure 3).4 Likely, the disease is often missed by clinicians due to a lack of the availability of specific diagnostic assays16.

scholarly journals An increasing role of pyrethroid-resistant Anopheles funestus in malaria transmission in the Lake Zone, Tanzania

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nancy S. Matowo ◽  
Jackline Martin ◽  
Manisha A. Kulkarni ◽  
Jacklin F. Mosha ◽  
Eliud Lukole ◽  
...  
Keyword(s):  
Malaria Transmission ◽  
Anopheles Funestus ◽  
Sub Saharan Africa ◽  
North West ◽  
Vector Population ◽  
Lake Zone ◽  
Sub Saharan ◽  
Long Lasting Insecticidal Nets ◽  
Study District

AbstractAnopheles funestus is playing an increasing role in malaria transmission in parts of sub-Saharan Africa, where An. gambiae s.s. has been effectively controlled by long-lasting insecticidal nets. We investigated vector population bionomics, insecticide resistance and malaria transmission dynamics in 86 study clusters in North-West Tanzania. An. funestus s.l. represented 94.5% (4740/5016) of all vectors and was responsible for the majority of malaria transmission (96.5%), with a sporozoite rate of 3.4% and average monthly entomological inoculation rate (EIR) of 4.57 per house. Micro-geographical heterogeneity in species composition, abundance and transmission was observed across the study district in relation to key ecological differences between northern and southern clusters, with significantly higher densities, proportions and EIR of An. funestus s.l. collected from the South. An. gambiae s.l. (5.5%) density, principally An. arabiensis (81.1%) and An. gambiae s.s. (18.9%), was much lower and closely correlated with seasonal rainfall. Both An. funestus s.l. and An. gambiae s.l. were similarly resistant to alpha-cypermethrin and permethrin. Overexpression of CYP9K1, CYP6P3, CYP6P4 and CYP6M2 and high L1014S-kdr mutation frequency were detected in An. gambiae s.s. populations. Study findings highlight the urgent need for novel vector control tools to tackle persistent malaria transmission in the Lake Region of Tanzania.

Phytotoxic Effect of Decaying Quackgrass (Agropyron repens) Residues

Weed Science ◽  
1979 ◽  
Vol 27 (6) ◽  
pp. 595-598 ◽  
Author(s):  
T. V. Toai ◽  
D. L. Linscott
Keyword(s):  
Incubation Temperature ◽  
Soil Surface ◽  
Water Soluble ◽  
Water Extracts ◽  
Phytotoxic Activity ◽  
Phytotoxic Effect ◽  
Effects Of Temperature ◽  
Incubation Temperatures ◽  
Toxin Formation ◽  
Agropyron Repens

We studied the effects of temperature (5, 10, 20, and 30 C) on the phytotoxic activity of decaying quackgrass [Agropyron repens (L.) Beauv.] leaves and rhizomes that were incubated in soils for 0, 1, 2, 4, and 6 weeks. Alfalfa (Medicago sativa L.) seeds were grown for 96 h in water, water extracts of control soils, and water extracts of soil with quackgrass rhizomes or leaves. Dried quackgrass rhizomes and leaves contained water-soluble toxins that inhibited alfalfa seedling development and growth. There was a strong interaction between incubation time and temperature on the development of additional toxins by decomposing quackgrass. High incubation temperature (30 C) accelerated toxin formation and ultimate decay. Intermediate temperature (20 C) delayed toxin formation and decay. Low incubation temperatures (5 C and 10 C) prevented formation of additional toxin. In all extracts of quackgrass and soil that had been incubated for 6 weeks, normal alfalfa seedling number equaled that in water. However, seedling growth varied with incubation temperatures.Treatment of quackgrass with glyphosate [N-(phosphonomethyl) glycine] in the greenhouse did not influence the toxicity of decaying quackgrass leaves. The highest toxic effect was noted after 1 week of decay on the soil surface.

scholarly journals The role of accommodation environments in student mental health and wellbeing

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Joanne D. Worsley ◽  
Paula Harrison ◽  
Rhiannon Corcoran
Keyword(s):  
Mental Health ◽  
First Year ◽  
Student Mental Health ◽  
North West ◽  
Human Element ◽  
Health And Wellbeing ◽  
Physical Attributes ◽  
Attachment To Place ◽  
Pastoral Staff

Abstract Background Due to the increasing concern over student mental health and wellbeing, attention has turned to the matter of creating environments, communities, and institutions which enable students to flourish. Methods To explore the role of accommodation environments in first year student mental health and wellbeing, eight focus groups were conducted in two universities in North West England and analysed using thematic analysis. Results Three overarching themes were identified: ‘The betwixt space’; ‘Accommodations as vessels to cultivate friendships and communities’; and ‘The importance of accommodation-based pastoral staff’. As attachment to place and relationships with significant others are disrupted by the transition, this leaves young people vulnerable whilst they go through a process to re-attach to new people and a new environment, and loneliness and social isolation were keenly felt during this period. Physical attributes of place that prevent social cohesion further exacerbated feelings of loneliness. Conclusions As it is common for students to withdraw physically and psychologically when they do not form friendships within their flat, accommodation-based pastoral staff have an important role to fulfil. Although these findings demonstrate the importance of the human element within accommodation, designing places that facilitate community, a sense of we-ness, and belonging is crucial.

Haloechinothrix aidingensis sp. nov., an actinomycete isolated from salt lake in Xinjiang province, north-west China

2021 ◽  
Author(s):  
Li Yang ◽  
Ya-Rong Kou ◽  
Tong-Wei Guan ◽  
Min Yin ◽  
Bing-Bing Liu ◽  
...  
Keyword(s):  
Salt Lake ◽  
West China ◽  
North West

Long-term vegetation restoration promotes the stability of the soil micro-food web in the Loess Plateau in North-west China

CATENA ◽  
2021 ◽  
Vol 202 ◽  
pp. 105293
Author(s):  
Yang Wu ◽  
WenJing Chen ◽  
Wulan Entemake ◽  
Jie Wang ◽  
HongFei Liu ◽  
...  
Keyword(s):  
Food Web ◽  
Loess Plateau ◽  
Vegetation Restoration ◽  
The Loess Plateau ◽  
West China ◽  
North West ◽  
The Stability
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