Effects of Soil Texture and Seed Placement on Emergence of Four Subshrubs

Weed Science ◽  
1983 ◽  
Vol 31 (3) ◽  
pp. 380-384 ◽  
Author(s):  
H. S. Mayeux
Keyword(s):  
Seed Bank ◽  
Soil Texture ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Seed Burial ◽  
Seed Placement ◽  
Buried Seed ◽  
Rate Of Emergence ◽  
Gutierrezia Sarothrae

Seedling emergence of broom snakeweed [Gutierrezia sarothrae(Pursh) Britt. & Rusby], threadleaf snakeweed [G. microcephala(DC.) Gray], common goldenweed [Isocoma coronopifolia(Gray) Greene], and false broomweed (Ericameria austrotexanaM.C. Johnston) was studied in the glasshouse. Germination of these species is known to be light-stimulated. Seed of all four subshrubs germinated readily if placed on the surface or partially pressed into the soil. Emergence was reduced by covering seed with soil to a depth of less than 1 mm. Few seedlings emerged from a depth of 1 cm, and none emerged from a depth of 2 cm. Rate of emergence also decreased with increasing depth of placement. Soil texture had little effect on emergence. Rapid germination on the soil surface is consistent with other aspects of the regenerative strategy of common goldenweed and false broomweed, which do not depend upon a buried seed bank for regeneration. Seed burial probably provides a form of enforced dormancy in the small, long-lived seeds of the two snakeweed species.

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

Factors affecting seed germination of annual sowthistle (Sonchus oleraceus) in southern Australia

Weed Science ◽  
2006 ◽  
Vol 54 (5) ◽  
pp. 854-860 ◽  
Author(s):  
Bhagirath S. Chauhan ◽  
Gurjeet Gill ◽  
Christopher Preston
Keyword(s):  
Seed Germination ◽  
Osmotic Potential ◽  
Field Experiments ◽  
Soil Depth ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Factors Affecting ◽  
Control Programs ◽  
Buried Seed ◽  
Ph Range

Annual sowthistle has become more abundant under no-till systems in southern Australia. Increased knowledge of germination biology of annual sowthistle would facilitate development of effective weed control programs. The effects of environmental factors on germination and emergence of annual sowthistle seeds were examined in laboratory and field experiments. Seeds of annual sowthistle were able to germinate over a broad range of temperatures (25/15, 20/12, and 15/9 C day/night temperatures). Seed germination was favored by light; however, some germination occurred in the dark as well. Greater than 90% of seeds germinated at a low level of salinity (40 mM NaCl), and some seeds germinated even at 160 mM NaCl (7.5%). Germination decreased from 95% to 11% as osmotic potential increased from 0 to −0.6 MPa and was completely inhibited at osmotic potential greater than −0.6 MPa. Seed germination was greater than 90% over a pH range of 5 to 8, but declined to 77% at pH 10. Seedling emergence was the greatest (77%) for seeds present on the soil surface but declined with depth, and no seedlings emerged from a soil depth of 5 cm. In another experiment in which seeds were after-ripened at different depths in a field, seed decay was greater on the soil surface than at 2 or 5 cm depth. At the end of the growing season, there was a much greater persistence of buried seed (32 to 42%) than seeds present on the soil surface (8%). Greater persistence of buried seed could be due to dormancy enforced by dark in this species.

Microsite Requirements for Establishment of Annual Rangeland Weeds

Weed Science ◽  
1972 ◽  
Vol 20 (4) ◽  
pp. 350-356 ◽  
Author(s):  
Raymond A. Evans ◽  
James A. Young
Keyword(s):  
Bromus Tectorum ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Atmospheric Moisture ◽  
Downy Brome ◽  
Seed Burial ◽  
Soil Movement

Seedling emergence and growth of downy brome(Bromus tectorumL.), medusahead(Taeniatherum asperum(Sim.) Nevski), and tumble mustard(Sisymbrium altissimumL.) were favored by seed burial, pitting of the soil surface, and soil movement. These conditions maintained temperatures and soil and atmospheric moisture in the range required for establishment.

A technique to estimate the pre-fire depth of burial of Grevillea seeds by using seedlings after fire

2005 ◽  
Vol 53 (5) ◽  
pp. 401 ◽  
Author(s):  
Tony D. Auld ◽  
Andrew J. Denham
Keyword(s):  
Seedling Emergence ◽  
Seed Mass ◽  
Soil Surface ◽  
Small Scale ◽  
Residual Soil ◽  
Seed Burial ◽  
Soil Seed Banks ◽  
Below Ground ◽  
The Mean ◽  
Depth Of Burial

In a glasshouse experiment, we used the shrub Grevillea speciosa to examine the reliability of estimating the depth of seed burial based on the distance from the soil surface to the junction of the swollen hypocotyl with the radicle. We then examined the applicability of the technique in the field by using post-fire seedling emergence. We found that the mean length of the swollen hypocotyl in seedlings was a good predictor of the depth of seed burial (R2 = 0.97). Most variation occurred for seeds buried near the surface at 2-cm depth, where the swollen hypocotyl overestimated the depth of seed burial by about 1 cm. There was a decline in the ability of seeds to successfully emerge from soil depths below 2 cm, with seedlings of G. speciosa able to emerge from soil depths up to 8 cm in the glasshouse. This corresponds with the estimated maximum emergence depth based on seed mass. In the field, seedlings were estimated to have emerged from depths of 1–7 cm after an intense wildfire. There was an approximately normal distribution of seedling emergence depths; however, the mode of this distribution varied among locations. The technique gave comparable results to a similar technique developed for Acacia spp., allowing consideration of a greater range of species and post-fire locations. Use of the technique has the potential to provide insights into the impacts of fires below ground, including the nature of post-fire germination, residual soil seed banks, the depth-related action of fire-induced germination cues and small-scale spatial variation.

Seed-bank properties of an Appalachian sphagnum bog and a model of the depth distribution of viable seeds

1987 ◽  
Vol 65 (10) ◽  
pp. 2028-2035 ◽  
Author(s):  
James B. McGraw
Keyword(s):  
Depth Profile ◽  
Seed Bank ◽  
Soil Surface ◽  
High Elevation ◽  
Seed Rain ◽  
Historical Change ◽  
Seed Burial ◽  
Depth Profiles ◽  
A Minor ◽  
Sphagnum Bog

Seed banks were examined in four plant communities in a high-elevation sphagnum bog in West Virginia, U.S.A. A germination assay was used to detect germinable seed densities. Vertical depth distributions were determined for one community in which the soil cores were transported intact to the greenhouse. Seed densities ranged from 12 874 in a Sphagnum-dominated community to 377 041 seeds m−2 in a sedge-dominated community. The seed bank in all communities was dominated numerically by Juncus effusus, although this species comprised a minor part of the aboveground vegetation. Three types of depth profiles were observed, including one distribution showing a simple decline in seed numbers with depth, another showing a unimodal peak below the soil surface, and a third with two distinct peaks at depth. A matrix model of seed burial was devised to account for the different depth profiles. By assuming that soil compression occurred and that the rate of compression declined with time, the model showed that either of the first two depth profiles could be produced with no need to invoke a historical change in the seed rain. The model was unable to account for the bimodal depth profile with the assumption of a constant seed rain. However, the fact that the model of seed burial could explain a unimodal peak in the depth profile suggests that simple historical interpretations of past abundance using a buried seed profile are difficult.

scholarly journals Seed bank dynamics of an invasive alien species, Helianthus annuus L.

2020 ◽  
Vol 13 (3) ◽  
pp. 313-322
Author(s):  
Alejandro Presotto ◽  
Fernando Hernández ◽  
Mauricio Casquero ◽  
Roman Vercellino ◽  
Claudio Pandolfo ◽  
...  
Keyword(s):  
Helianthus Annuus ◽  
Seed Bank ◽  
Seedling Emergence ◽  
Seed Banks ◽  
First Year ◽  
Seed Burial ◽  
Wild Sunflower ◽  
Seed Persistence ◽  
Seed Bank Dynamics

Abstract Aims The ability to form persistent seed banks is one of the best predictors of species’ potential to establish in new ranges. Wild sunflower is native to North America where the formation of persistent seed banks is promoted by disturbance and it plays a key role on the establishment and persistence of native populations. However, the role of the seed banks on the establishment and persistence of invasive populations has not been studied. Here, we evaluated the role of seed bank and disturbance on the establishment and fitness, and seed persistence in the soil in several sunflower biotypes collected in ruderal (wild Helianthus annuus) and agrestal (natural crop–wild hybrid) habitats of Argentina as well as volunteer populations (progeny of commercial cultivars). Methods In a seed-bank experiment, we evaluated emergence, survival to reproduction, survival of emerged seedlings, inflorescences per plant and per plot under disturbed and undisturbed conditions over 2 years; in a seed-burial experiment, we evaluated seed persistence in the soil over four springs (6, 18, 30 and 42 months). Important Findings Overall, seedling emergence was early in the growing season (during winter), and it was promoted by disturbance, especially in the first year. Despite this, the number of inflorescences per plot was similar under both conditions, especially in ruderals. In the second year, emergence from the seed bank was much lower, but the survival rate was higher. In the seed-burial experiment, genetic differences were observed but seeds of ruderals and agrestals persisted up to 42 months while seeds of the volunteer did not persist longer than 6 months. The agrestal biotype showed an intermediate behavior between ruderals and volunteers in both experiments. Our findings showed that wild and crop–wild sunflower can form persistent seed banks outside its native range and that disturbance may facilitate its establishment in new areas.

Seed banks of forested and disturbed soils in southwestern British Columbia

1993 ◽  
Vol 71 (12) ◽  
pp. 1574-1583 ◽  
Author(s):  
Ann McGee ◽  
M. C. Feller
Keyword(s):  
British Columbia ◽  
Seed Bank ◽  
Forest Floor ◽  
Vascular Plant ◽  
Seedling Emergence ◽  
Mineral Soil ◽  
Soil Surface ◽  
Seed Banks ◽  
Grass Species ◽  
Burial Depth

The species composition and density of seed banks in the forest floors and mineral soils of several undisturbed (immature, midseral forests) and disturbed (transmission line rights-of-way) ecosystems in southwestern British Columbia were estimated using the seedling-emergence method. The total soil surface area sampled was 9.4 m2. Germination behaviour of seven dominant species in response to depth of burial and substrate was also studied in a greenhouse experiment. A total of 16 289 seedlings germinated, representing 62 native and naturalized vascular plant species and several unidentified grass species. Most seedlings emerged from the forest floor, and the number of germinants generally decreased with increasing sample depth. Drier ecosystems had the lowest number and density of germinants. Burial depth significantly affected germination of all species tested. Mineral soil was equal, or superior, to forest floor as a germination substrate for all species tested. Depth–substrate interactions for several species indicated that the pattern of influence of burial depth in relation to substrate varied with species. Caution is urged extrapolating greenhouse seed-bank studies to potential weed populations in the field. Establishment of species from the seed bank will be a function of the depth to which the soil is disturbed and the kind of disturbance (burning, scarification) imposed. Key words: British Columbia, Coastal Western Hemlock zone, seed bank, seed germination, seed diversity, seed density.

Germination of Fresh Horse Purslane (Trianthema portulacastrum) Seeds in Response to Different Environmental Factors

Weed Science ◽  
2011 ◽  
Vol 59 (4) ◽  
pp. 495-499 ◽  
Author(s):  
Jihyun Lee ◽  
Bhagirath S. Chauhan ◽  
David E. Johnson
Keyword(s):  
Seed Germination ◽  
Environmental Factors ◽  
Seedling Emergence ◽  
Soil Surface ◽  
The Philippines ◽  
Integrated Weed Management ◽  
Burial Depth ◽  
Seed Burial ◽  
Soil Burial ◽  
Two Populations

Horse purslane, a C4 species, is a branched, prostrate, and annual weed of upland field crops throughout the tropics. Experiments were conducted to determine the influence of various environmental factors on seed germination and seedling emergence of two populations of horse purslane. Seeds were collected from rice fields of the International Rice Research Institute (the IR population) and from sorghum fields of the University of the Philippines (the UP population); the two sites were 5 km apart in Los Baños, Philippines. Germination response of both populations was greater at 30/20 C and35/25 C day/night temperatures than they were at 25/15 C alternating day/night temperatures. Germination of both populations was greater in the light/dark regime than in darkness. In dark, depending on the temperature, seed germination of the UP population ranged from 37 to 62%, whereas seed germination of the IR population was < 20%. Exposure to 5 min at 117 and 119 C for the IR and UP populations, respectively, reduced germination to 50% of maximum germination. Osmotic potential of −0.26 MPa inhibited germination to 50% of the maximum for the UP population, whereas the corresponding value for the IR population was −0.37 MPa. Seeds placed on or near the soil surface had maximum emergence, and emergence declined with increase in seed burial depth. Seedling emergence of the UP and IR populations was 74% and 13%, respectively, for seeds placed on the soil surface. For both populations, no seedlings emerged from a soil burial depth of 6 cm or more. Germination and emergence responses to light and seed burial depth differed between the two populations of horse purslane. Residues on the soil surface of up to 6 Mg ha−1 did not influence seedling emergence of either populations. Knowledge gained in this study could contribute to developing components of integrated weed management strategies for horse purslane.

Weedy rice (Oryza sativa) II. Response of Weedy Rice to Seed Burial and Flooding Depth

Weed Science ◽  
2012 ◽  
Vol 60 (3) ◽  
pp. 385-388 ◽  
Author(s):  
Bhagirath Singh Chauhan
Keyword(s):  
Seedling Emergence ◽  
Soil Surface ◽  
Production Costs ◽  
The Other ◽  
Weedy Rice ◽  
Burial Depth ◽  
Rice Accession ◽  
Seed Burial ◽  
Seedling Biomass ◽  
Flooding Depth

Weedy rice is a serious problem of cultivated rice in most of the rice-growing areas in Asia, causing increased production costs and yield losses in rice. A study was conducted to determine the response of weedy rice accessions from India (IWR), Malaysia (MWR), Thailand (TWR), and Vietnam (VWR) to seed burial and flooding depths. The greatest emergence for each weedy rice accession (97% for IWR, 82% for MWR, 97% for TWR, and 94% for VWR) was observed in seeds placed on the soil surface. Seedling emergence decreased with increase in burial depth. For the IWR accession, 0.5% of the seedlings emerged from 8-cm depth, whereas for the other three weedy rice accessions, no seedlings emerged from this depth. When seeds were sown on the soil surface, flooding depth ranging from 0 to 8 cm had no or very little effect on seedling emergence of different weedy rice accessions. On the other hand, flooding decreased seedling emergence in all weedy rice accessions when seeds were sown at 1 cm deep into the soil. Compared with seedling emergence, flooding had a more pronounced effect on seedling biomass for all weedy rice accessions. A flooding depth of 2 cm reduced seedling biomass by an amount greater than 85% of each weedy rice accession. The results of this study suggest that emergence and growth of weedy rice could be suppressed by deep tillage that buries seeds below their maximum depth of emergence (i.e., > 8 cm for the accessions studied) and by flooding fields as early as possible. The information gained from this study may help design cultural management strategies for weedy rice in Asia.

Hard-seededness and seed bank dynamics of six pasture legumes

1992 ◽  
Vol 2 (4) ◽  
pp. 231-241 ◽  
Author(s):  
L. Russi ◽  
P. S. Cocks ◽  
E. H. Roberts
Keyword(s):  
Seed Bank ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Pasture Legumes ◽  
Seed Bank Dynamics ◽  
Hard Seeds ◽  
Initial Seed ◽  
Highly Correlated ◽  
Carry Over

AbstractSix pasture legumes, common in Syrian grasslands, were investigated. Medicago orbicularis and M. rotata had the largest number of hard seeds, with >90% still hard 5 months after shedding; Trifolium stellatum had the least with <30% of hard seeds; T. campestre, M. rigidula and T. tomentosum were intermediate. Hard-seededness in M. orbicularis and M. rotata varied between years. Scarification of hard seeds resulted in almost complete germination in all species. Alternating temperatures (10/20°C) reduced the rate of germination of scarified T. campestre seeds, but had no effect on germination of scarified or unscarified seeds of T. stellatum. The breakdown of hard-seededness in the field in Syria did not begin until 3 months after shedding and greatly increased when seeds overwintered. Breakdown of hard-seededness was slower when seeds were buried at 5 and 10 cm than when seeds remained on the soil surface. Seedling emergence after the rains started in November was highly correlated with the number of soft seeds observed in October. Similarly, a high correlation was found between the percentage of hard seeds in October and carry-over in the seed bank. In small-seeded species (Trifolium spp.), 39% of the initial seed bank was lost in 2 years by causes other than emergence as seedlings. Such losses were only 7% in larger-seeded species (Medicago spp.). The implications of hard-seededness on the utilization and survival of legumes in grasslands are discussed.

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