The role of seed reproduction in the dynamics of established populations of Hieracium floribundum and a comparison with that of vegetative reproduction

1975 ◽  
Vol 53 (24) ◽  
pp. 3022-3031 ◽  
Author(s):  
A. G. Thomas ◽  
H. M. Dale
Keyword(s):  
Population Dynamics ◽  
Seedling Establishment ◽  
Vegetative Reproduction ◽  
Soil Surface ◽  
Growing Season ◽  
Population Based ◽  
Early Spring ◽  
Viable Seed ◽  
Density Patch

In the crowded parts of patches of Hieracium floribundum Wimm. and Grab., which were established for at least a decade in an ungrazed pasture, 7–10% of the population (3700 individuals/m2) flowered. Of the plants that flowered, 94% were alive a year later, but only 5% of these flowered. Abortion of flower heads was common; one half of all those which were initiated in early June had aborted by flowering time in early July. Freshly dispersed seed had a viability of 57%, which was reduced to 17% a year later, after its storage close to the soil surface. Less than 6% of the viable seed was innately dormant. Dry, laboratory-stored seed retained its viability for the year but was slower to germinate than soil-stored seed. In field conditions, germination was temperature inhibited during most of the growing season. Maximum daytime microsite temperatures of less than 32 °C, which is necessary for germination, were found to occur only in early spring and late fall. Successful seedling establishment accounts for 1% of the individuals in a crowded population. Based on the maximum sexual reproduction from plants in crowded populations, a seed has a probability of 1 in 20 000 of becoming an established seedling. A model of population dynamics in a high-density patch traces the fate of seedling establishment, surviving adults, and stolon-derived rosettes for a single year.

scholarly journals The role of variety and forecrop in the population dynamics of Rhizoctonia solani in soil

2021 ◽  
Vol 51 (1) ◽  
pp. 25-32
Author(s):  
A. A. Malyuga ◽  
N. S. Chulikova
Keyword(s):  
Population Dynamics ◽  
Rhizoctonia Solani ◽  
Growing Season ◽  
Steppe Zone ◽  
Climatic Conditions ◽  
Forest Steppe ◽  
The Difference ◽  
Two Peaks

Long-term studies (2014–2019) of the population dynamics of the fungus Rhizoctonia solani Küch. were carried out in the soil on the Purple Majesty, Vitelotte and Fioletovy potato varieties and preceding crops (potatoes, oats and tendergreen). The study was carried out in Novosibirsk region in the soil and climatic conditions typical of the forest-steppe zone of Western Siberia. To study the peculiarities of R. solani fungus population dynamics in potato plantations, soil samples were taken from under the plants during the entire growing season. The accumulation of rhizoctonia propagules in the soil was determined using the method of multiple soil pellets. The difference in the amount and rate of accumulation of the fungus R. solani on different varieties, as well as the influence of previous crops on this process, was established. Two peaks of the fungus accumulation were observed on the Purple Majesty variety: the first (48.7 propagules/100 g of soil) – during the full germination period, the second (57.2 propagules/100 g of soil) – at the end of the crop maturation phase. One peak was observed in the population dynamics of the fungus on Vitelotte and Fioletovy varieties, at the end of the ripening period (59.0 and 49.1 propagules/100 g soil, respectively). The smallest amount of R. solani fungus in the soil on average during the growing season was noted on the Fioletovy variety – 33.3 propagules/100 g of soil. In the Purple Majesty and Vitelotte varieties, this figure was 41.5 and 40.4 propagules/100 g of soil, respectively. When potato variety Agata was cultivated as monoculture, there was a rapid and significant accumulation of the fungus R. solani in the soil (from 34.6 to 126.8 propagules/100 g of soil). When this variety was cultivated following tendergreen or oats, the amount of the pathogen varied to a lesser extent (25.1–52.2 and 19.8–41.0 propagules/100 g of soil, respectively). No sharp increases in the number of propagative structures of the phytopathogen in the soil were noted.

scholarly journals Comparison of nitrogen application via a trickle irrigation system with surface banding of granular fertilizer on red raspberry

2000 ◽  
Vol 80 (2) ◽  
pp. 363-371 ◽  
Author(s):  
C. G. Kowalenko ◽  
J. C. W. Keng ◽  
J. A. Freeman
Keyword(s):  
Irrigation System ◽  
Inorganic Nitrogen ◽  
Soil Surface ◽  
Growing Season ◽  
Early Spring ◽  
N Leaching ◽  
Trickle Irrigation ◽  
Climatic Regions ◽  
Soil Inorganic N ◽  
Soil Inorganic

A field trial compared applications of ammonium nitrate N as soil-surface bands of granular fertilizer with applications as a solution through a trickle irrigation system (i.e., fertigation) on yield, plant growth and end-of-season extractable soil inorganic nitrogen of red raspberries (Rubus idaeous L.). The granular application was made once in early spring, and the fertigation was scheduled as eight weekly applications from early to late spring in each of 4 successive years. Three rates of N (33, 67 and 134 kg N ha−1) were applied by both methods and a zero N control was also included. The N treatments had relatively small effects on berry yields, being significant in the last 2 years (1988 and 1989) only. Applications of granular N resulted in equal or greater yields than the control, whereas the fertigation method resulted in equal or lower yields than the control. Granular applications tended to enhance cane growth and N concentrations in the fruiting cluster, laterals and leaves of fruiting canes. Leaching of N during the growing season was greater with the fertigation than with the granular method of application. The poorer performance of fertigation relative to granular application of N was due to the timing of application in relation to crop requirement. Raspberries require a majority of their N early in the growing season. The utility of applying fertilizer N via irrigation systems on crops such as raspberry in climatic regions where water deficits do not usually occur early in the growing season, as in coastal British Columbia, is limited. Key words: Fertigation, soil N, yield, soil inorganic N, leaching, Rubus idaeous L.

Changes with time in the germination of buried scentless chamomile (Matricaria perforata Mérat) seeds

1995 ◽  
Vol 75 (1) ◽  
pp. 277-281 ◽  
Author(s):  
G. G. Bowes ◽  
A. G. Thomas ◽  
L. P. Lefkovitch
Keyword(s):  
Seed Bank ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Growing Season ◽  
Early Spring ◽  
First Year ◽  
Temperature Regimes ◽  
Buried Seed ◽  
Second Year ◽  
Persistent Seed Bank

Change with time in the germination of scentless chamomile (Matricaria perforata Mérat) seeds was investigated. Seeds were placed in nylon net bags, buried 7 cm deep in soil, exhumed at monthly intervals for 2 yr and allowed to germinate in temperature regimes of 10/2 °C, 20/5 °C, 25/10 °C and 35/20 °C (16/8 h), simulating temperatures found during early spring or late fall, spring or fall, summer and mid-summer on the soil surface, respectively. Exhumed and refrigerator-stored (2 °C) check seeds exhibited no yearly dormancy/nondormancy germination cycle, but mortality of buried seed increased to 36%, after 10 mo in contrast with that of the check seeds which remained low for two years. Light was required for germination during the first year but was not required for a portion of the seed during the second year. The retention of viability in buried seed explains the persistent seed bank and seedling emergence throughout the growing season when moisture and temperature are nonlimiting. Key words: Seed burial, germination, Matricaria perforata Mérat

In field survival of Rhizoctonia solani in soil and in diseased sugarbeets

1976 ◽  
Vol 22 (7) ◽  
pp. 983-988 ◽  
Author(s):  
Leonard J. Herr
Keyword(s):  
Rhizoctonia Solani ◽  
Sandy Loam ◽  
Soil Surface ◽  
Growing Season ◽  
Early Spring ◽  
Inoculum Density ◽  
Silty Clay ◽  
Loam Soil ◽  
Low Levels ◽  
Silty Clay Soil

Persistence of Rhizoctonia solani in the field was investigated by ascertaining survival (competitive saprophytic activity) in soil and survival in diseased plants. Except for one instance, low levels of R. solani survived overwinter in artificially and naturally infested soils. In a sandy loam soil, cropped to sugarbeets, inoculum density increased throughout the growing season from low early spring levels to high levels in July and August. In a silty clay soil, cropped to sugarbeets, inoculum density remained low with only a slight increase throughout the growing season. Survival of R. solani in diseased sugarbeets placed on the soil surface was greater than survival in diseased beets buried in soil. Little reduction in percentages of beets yielding R. solani colonies took place from November to April in either buried or unburied beets. The major reduction in survival of R. solani in buried beets occurred during the 6-week interval from April to June.

The Role of Fire in Establishment of Seedlings of Serotinous Species From the Sydney Region

1991 ◽  
Vol 39 (4) ◽  
pp. 347 ◽  
Author(s):  
RA Bradstock
Keyword(s):  
Seedling Establishment ◽  
Woody Species ◽  
Soil Surface ◽  
Bare Soil ◽  
Moderate Intensity ◽  
Burnt Area ◽  
Banksia Ericifolia ◽  
The Relationship ◽  
Germinated Seeds

Observations and experiments were performed to examine the relationship between fire and seedling establishment in the following serotinous/woody species: Banksia ericifolia L.f., Banksia serrata L.f., Petrophile pulchella (Schrad.) R. Br. and Isopogon anemonifolius (Salisb.) Knight. For all species a moderate-intensity fire had no effect on the viability of seeds stored in cones compared to seeds stored in unburnt cones. Germinated seeds of all species, placed in meshed and unmeshed enclosures within an unburnt area, were consumed extensively by an unknown predator within 2 months of placement. No such effect occurred in similar treatments within a recently burnt area. Heating of the soil surface and the nature of substrates (litter, ash, bare soil) had variable effects on seedling establishment. Establishment of B. ericifolia and B. serrata was unaffected by the treatments whereas in P. pulchella and I. anemonifolius substrates and heating had significant effects. In P. pulchella establishment was significantly reduced on litter compared with pure ash. In I. Anemonifolius establishment was significantly higher on treatments with litter or mixed ash, except on soils that had received the low heat treatment, where there was no significant substrate effect. It was concluded that fire could create a more favourable soil-surface environment for establishment in P. pulchella only. In the other species, fire would have no effect or, in I. Anemonifolius, establishment might be enhanced in unburnt conditions. This conclusion does not take into account the effects of cover (overstorey and understorey) on establishment. It was concluded that predation of newly germinated seedlings may be the most important restriction on seedling establishment in unburnt populations.

The Fate of Yellow Nutsedge (Cyperus Esculentus) Seed and Seedlings in Soil

Weed Science ◽  
1990 ◽  
Vol 38 (2) ◽  
pp. 125-128 ◽  
Author(s):  
Jon Lapham ◽  
Donald S. H. Drennan
Keyword(s):  
Soil Moisture ◽  
Field Experiment ◽  
Laboratory Experiment ◽  
Seedling Establishment ◽  
Seedling Survival ◽  
Cyperus Esculentus ◽  
Viable Seed ◽  
Yellow Nutsedge ◽  
Moisture Conditions

Changes in dormancy and viability of freshly harvested seed of yellow nutsedge buried in the field, at depths of 5, 25, and 50 mm, were studied over a 2-yr period. The number of dormant, viable seed decreased most rapidly at 5 mm because more seed lost their dormancy and germinated (up to 30%) than at lower depths. Loss of viability through decay of seed appeared similar at all depths. No seedlings emerged from any depth. In a laboratory experiment, conducted in optimal soil moisture conditions, seedlings emerged from all seed that germinated, demonstrating that adequate soil moisture was critical for seedling establishment. This was substantiated in a second field experiment in which irrigation and mulching greatly increased seedling survival. The number of seedlings surviving in irrigated plots was 0.78% of seed sown and 0.03% in the rain-fed plots. The role of seed in the establishment of yellow nutsedge infestations is probably of little importance in dryland cropping areas despite the longevity and viability of the seed.

scholarly journals Do males matter? The role of males in population dynamics

Oikos ◽  
2007 ◽  
Vol 116 (2) ◽  
pp. 335-348 ◽  
Author(s):  
Daniel J. Rankin ◽  
Hanna Kokko
Keyword(s):  
Population Dynamics

scholarly journals Fire, land cover, and temperature drivers of bat activity in winter

Fire Ecology ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Marcelo H. Jorge ◽  
Sara E. Sweeten ◽  
Michael C. True ◽  
Samuel R. Freeze ◽  
Michael J. Cherry ◽  
...  
Keyword(s):  
Land Cover ◽  
Habitat Management ◽  
Deciduous Forest ◽  
Pinus Palustris ◽  
Growing Season ◽  
Early Spring ◽  
Bat Activity ◽  
White Nose Syndrome ◽  
Dormant Season ◽  
Wind Energy Development

Abstract Background Understanding the effects of disturbance events, land cover, and weather on wildlife activity is fundamental to wildlife management. Currently, in North America, bats are of high conservation concern due to white-nose syndrome and wind-energy development impact, but the role of fire as a potential additional stressor has received less focus. Although limited, the vast majority of research on bats and fire in the southeastern United States has been conducted during the growing season, thereby creating data gaps for bats in the region relative to overwintering conditions, particularly for non-hibernating species. The longleaf pine (Pinus palustris Mill.) ecosystem is an archetypal fire-mediated ecosystem that has been the focus of landscape-level restoration in the Southeast. Although historically fires predominately occurred during the growing season in these systems, dormant-season fire is more widely utilized for easier application and control as a means of habitat management in the region. To assess the impacts of fire and environmental factors on bat activity on Camp Blanding Joint Training Center (CB) in northern Florida, USA, we deployed 34 acoustic detectors across CB and recorded data from 26 February to 3 April 2019, and from 10 December 2019 to 14 January 2020. Results We identified eight bat species native to the region as present at CB. Bat activity was related to the proximity of mesic habitats as well as the presence of pine or deciduous forest types, depending on species morphology (i.e., body size, wing-loading, and echolocation call frequency). Activity for all bat species was influenced positively by either time since fire or mean fire return interval. Conclusion Overall, our results suggested that fire use provides a diverse landscape pattern at CB that maintains mesic, deciduous habitat within the larger pine forest matrix, thereby supporting the diverse bat community at CB during the dormant season and early spring.

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