Seed dormancy release in three common pasture grasses from a Mediterranean-type environment under contrasting conditions

1999 ◽  
Vol 39 (2) ◽  
pp. 143 ◽  
Author(s):  
T. P. Bolger ◽  
R. Chapman ◽  
I. F. Le Coultre
Keyword(s):  
Seed Bank ◽  
Dormancy Release ◽  
Annual Ryegrass ◽  
Bromus Diandrus ◽  
Pasture Legumes ◽  
Pasture Grasses ◽  
Hordeum Leporinum ◽  
Winter Annuals ◽  
Brome Grass ◽  
Summer Rain

Pastures in the Mediterranean region of Australia are typically comprised of a mixture of winter annuals, including grasses and legumes, which utilise a seed bank to survive the long, dry summer. The risk of out-of-season summer rain requires species from such environments to adopt appropriate strategies to protect their seed banks. The seed bank strategies of the grasses from these environments have, so far, received little attention. We conducted an experiment to observe the dormancy release characteristics of 3 grasses common to these environments when stored under contrasting thermal regimes. The grasses studied were great brome grass (Bromus diandrus Roth), annual ryegrass (Lolium rigidum Gaud.), and barley grass (Hordeum leporinum Link). The different species displayed contrasting dormancy release characteristics over the summer. Two of the species examined (great brome grass and annual ryegrass) displayed relatively late release from dormancy which gave high levels of protection from false breaks. The other (barley grass) displayed earlier release from dormancy which would enable it to better exploit earlier true breaks but make it more sensitive to false breaks. Unlike pasture legumes, high and fluctuating temperatures were not necessary for the seeds of these grasses to become germinable. In fact, exposure to high temperatures appeared more likely to suppress release from dormancy.

Alleviation of dormancy in annual ryegrass (Lolium rigidum) seeds by hydration and after-ripening

Weed Science ◽  
2004 ◽  
Vol 52 (6) ◽  
pp. 968-975 ◽  
Author(s):  
Robert S. Gallagher ◽  
Kathryn J. Steadman ◽  
Andrew D. Crawford
Keyword(s):  
Seed Germination ◽  
Relative Humidity ◽  
Germination Rate ◽  
Dormancy Release ◽  
Annual Ryegrass ◽  
Dormant Seed ◽  
Lolium Rigidum ◽  
Time Model ◽  
Treatment Regimens ◽  
Two Populations

The effect of hydration (priming) treatment on dormancy release in annual ryegrass seeds from two populations was investigated. Hydration duration, number, and timing with respect to after-ripening were compared in an experiment involving 15 treatment regimens for 12 wk. Seeds were hydrated at 100% relative humidity for 0, 2, or 10 d at Weeks 1, 6, or 12 of after-ripening. Dormancy status was assessed after each hydration treatment by measuring seed germination at 12-hourly alternating 25/15 C (light/dark) periods using seeds directly from the hydration treatment and seeds subjected to 4 d postpriming desiccation. Seeds exposed to one or more hydration events during the 12 wk were less dormant than seeds that remained dry throughout after-ripening. The longer hydration of 10 d promoted greater dormancy loss than either a 2-d hydration or no hydration. For the seed lot that was most dormant at the start of the experiment, two or three rather than one hydration event or a hydration event earlier rather than later during after-ripening promoted greater dormancy release. These effects were not significant for the less-dormant seed lot. For both seed lots, the effect of a single hydration for 2 d at Week 1 or 6 of after-ripening was not manifested until the test at Week 12 of the experiment, suggesting that the hydration events alter the rate of dormancy release during subsequent after-ripening. A hydrothermal priming time model, usually used for modeling the effect of priming on germination rate of nondormant seeds, was successfully applied to dormancy release resulting from the hydration treatments.

scholarly journals Lolium multiflorum seeds in the soil: I. Soil seed bank dynamics in a no til system

2008 ◽  
Vol 30 (2) ◽  
pp. 100-110 ◽  
Author(s):  
Fernanda Costa Maia ◽  
Manoel de Souza Maia ◽  
Renée M. Bekker ◽  
Rogério Previatti Berton ◽  
Leandro Sebastião Caetano
Keyword(s):  
Seed Bank ◽  
Management Practices ◽  
Transition Period ◽  
Soil Seed Bank ◽  
Lolium Multiflorum ◽  
Storage Period ◽  
Annual Ryegrass ◽  
Seed Population ◽  
Seed Bank Dynamics ◽  
One Year

The objective of the study was to characterize annual ryegrass seed population dynamics, managed for natural re-sowing, in no til systems in rotation with soybean, in different chronosequences An area was cultivated for two years with soybean, left as fallow land for the next two years and then cultivated again with soybean for the next two years. The four chronosequences represented different management periods, two with soybean (6 and 8 years old) and the other two resting (3 and 9 years old). Soil samples were taken every month during one year and divided into two depths (0-5 and 5-10 cm). Vegetation dynamics were also evaluated (number of plants, inflorescences and seedlings). Soil seed bank (SSB) dynamics showed structural patterns in time, with a "storage period" in summer, an "exhausting period" during autumn and a "transition period" in winter and spring. Pasture establishment by natural re-sowing was totally dependent on the annual recruitment of seeds from the soil. The influence of the management practices on the SSB was more important than the number of years that these practices had been implemented. Places where soybean was sown showed the largest SSBs. Most of the seeds overcame dormancy and germinated at the end of the summer and beginning of the autumn, showing a typically transitory SSB, but with a small proportion of persistent seeds

Plant factors influencing the nutritive value of some temperate annual pasture species

1973 ◽  
Vol 13 (63) ◽  
pp. 404 ◽  
Author(s):  
JG McIvor ◽  
DF Smith
Keyword(s):  
Nutritive Value ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Growth Cycle ◽  
Matter Content ◽  
In Vitro Digestibility ◽  
Dry Matter Content ◽  
Hordeum Leporinum ◽  
Brome Grass

Changes in herbage production, dry matter content, nitrogen content and in vitro digestibility of two sown species-subterranean clover (Trifolium subterraneum) and annual ryegrass (Lolium rigidum) - and five common volunteer species-capeweed (Arctotheca calendula), musky crowfoot (Erodium moschatum), barley grass (Hordeum leporinum), ripgut brome grass (Bromus rigidus) and soft brome grass (Bromus mollis)-were measured throughout their growth cycle. The volunteer species compared favourably with the sown species for these measurements and should be capable of providing nutritious grazing for animals.

Biological nitrification inhibition by weeds: wild radish, brome grass, wild oats and annual ryegrass decrease nitrification rates in their rhizospheres

2017 ◽  
Vol 68 (8) ◽  
pp. 798 ◽  
Author(s):  
Cathryn A. O'Sullivan ◽  
Kelley Whisson ◽  
Karen Treble ◽  
Margaret M. Roper ◽  
Shayne F. Micin ◽  
...  
Keyword(s):  
Root Exudates ◽  
Pure Culture ◽  
Nitrification Inhibition ◽  
Annual Ryegrass ◽  
Wild Radish ◽  
Weed Species ◽  
Wild Oats ◽  
Biological Nitrification ◽  
Brome Grass ◽  
The Impact

This study investigated the ability of several plant species commonly occurring as weeds in Australian cropping systems to produce root exudates that inhibit nitrification via biological nitrification inhibition (BNI). Seedlings of wild radish (Raphanus raphanistrum), great brome grass (Bromus diandrus), wild oats (Avena fatua), annual ryegrass (Lolium rigidum) and Brachiaria humidicola (BNI-positive control) were grown in hydroponics, and the impact of their root exudates on NO3– production by Nitrosomonas europaea was measured in a pure-culture assay. A pot study (soil-based assay) was then conducted to confirm the ability of the weeds to inhibit nitrification in whole soils. All of the tested weeds slowed NO3– production by N. europaea in the pure-culture assay and significantly inhibited potential nitrification rates in soil-based assays. Root exudates produced by wild radish were the most inhibitory, slowing NO3– production by the pure culture of N. europaea by 53 ± 6.1% and completely inhibiting nitrification in the soil-based assay. The other weed species all had BNI capacities comparable to that of B. humidicola and significantly higher than that previously reported for wheat cv. Janz. This study demonstrates that several commonly occurring weed species have BNI capacity. By altering the N cycle, and retaining NH4+ in the soils in which they grow, these weeds may gain a competitive advantage over species (including crops) that prefer NO3–. Increasing our understanding of how weeds compete with crops for N may open avenues for novel weed-management strategies.

High Seed Retention at Maturity of Annual Weeds Infesting Crop Fields Highlights the Potential for Harvest Weed Seed Control

2014 ◽  
Vol 28 (3) ◽  
pp. 486-493 ◽  
Author(s):  
Michael J. Walsh ◽  
Stephen B. Powles
Keyword(s):  
Seed Production ◽  
Wild Oat ◽  
Annual Ryegrass ◽  
Wild Radish ◽  
Weed Seed ◽  
Seed Retention ◽  
Total Seed ◽  
Annual Weeds ◽  
Brome Grass ◽  
Crop Maturity

Seed production of annual weeds persisting through cropping phases replenishes/establishes viable seed banks from which these weeds will continue to interfere with crop production. Harvest weed seed control (HWSC) systems are now viewed as an effective means of interrupting this process by targeting mature weed seed, preventing seed bank inputs. However, the efficacy of these systems is directly related to the proportion of total seed production that the targeted weed species retains (seed retention) at crop maturity. This study determined the seed retention of the four dominant annual weeds of Australian cropping systems - annual ryegrass, wild radish, brome grass, and wild oat. Beginning at the first opportunity for wheat harvest and on a weekly basis for 28 d afterwards the proportion of total seed production retained above a 15 cm harvest cutting height was determined for these weed species present in wheat crops at nine locations across the Western Australian (WA) wheat-belt. Very high proportions of total seed production were retained at wheat crop maturity for annual ryegrass (85%), wild radish (99%), brome grass (77%), and wild oat (84%). Importantly, seed retention remained high for annual ryegrass and wild radish throughout the 28 d harvest period. At the end of this period, 63 and 79% of total seed production for annual ryegrass and wild radish respectively, was retained above harvest cutting height. However, seed retention for brome grass (41%) and wild oat (39%) was substantially lower after 28 d. High seed retention at crop maturity, as identified here, clearly indicates the potential for HWSC systems to reduce seed bank replenishment and diminish subsequent crop interference by the four most problematic species of Australian crops.

scholarly journals Seed biology of brome grass weeds (Bromus diandrus and B hordeaceus) and effects of land management

2010 ◽  
Vol 63 ◽  
pp. 78-83
Author(s):  
F. Dastgheib ◽  
N. Poole
Keyword(s):  
Land Management ◽  
Seedling Establishment ◽  
Management Practices ◽  
Detrimental Effect ◽  
Soil Surface ◽  
Seed Burial ◽  
Bromus Diandrus ◽  
Seed Biology ◽  
Brome Grass ◽  
Brome Grasses

Aspects of seed biology of ripgut brome (Bromus diandrus) and soft brome (B hordeaceus) were studied in relation to land management practices Among the practices tested burning stubble had a detrimental effect on seed survival The majority of seeds close to the soil surface were charred or nonviable following a stubble fire Overall higher brome infestation was measured in notillage compared to minimum tillage or burning treatments More than 80 of the seeds of both species emerged in the field within the first couple of months after planting and full germination was achieved by spring Seed burial at depths from 1 to 20 cm did not significantly affect germination but seedling establishment and vigour was reduced with seed depth Implications of these results in management of brome grasses are discussed

Tolerance of wheat cultivars to metribuzin and implications for the control of Bromus diandrus and B. rigidus in Western Australia

1990 ◽  
Vol 30 (3) ◽  
pp. 373 ◽  
Author(s):  
GS Gill ◽  
DG Bowran
Keyword(s):  
Western Australia ◽  
Field Experiments ◽  
Wheat Cultivars ◽  
Bromus Diandrus ◽  
Brome Grass

Field experiments were carried out in Western Australia to investigate the response of 9 wheat cultivars to metribuzin and to evaluate its potential for the control of Bromus diandrus and B. rigidus in wheat. The wheat cultivars differed significantly in their response to metribuzin; a South Australian cultivar (Blade) was markedly more tolerant than all other cultivars investigated. Metribuzin alone (100-150 g/ha) or as a tank-mix with pendimethalin, incorporated by sowing, combined reliable brome grass control with good crop safety when used on Blade. Post-emergence application of metribuzin was generally less effective on brome grass and more phytotoxic to the crop than incorporation by sowing. This herbicide-cultivar package gives farmers an opportunity to selectively control brome grass in wheat.

Sulfur nutrition of temperate pasture species. II. A comparison of subterranean clover cultivars, medics and grasses

1984 ◽  
Vol 35 (3) ◽  
pp. 389 ◽  
Author(s):  
MA Gilbert ◽  
AD Robson
Keyword(s):  
Maximum Yield ◽  
Subterranean Clover ◽  
Nitrogen Supply ◽  
Sulfur Deficiency ◽  
Barrel Medic ◽  
Pasture Legumes ◽  
Sulfur Supply ◽  
Wimmera Ryegrass ◽  
Brome Grass ◽  
Sulfur Nutrition

The external and internal requirements for sulfur of five pasture legumes and three grasses of temperate origin were examined in a pot experiment in which plants were grown with seven levels of sulfur supply for 58 days. Nitrogen supply was non-limiting. There was no distinct difference between legumes and grasses in their external requirement for sulfur (i.e. the amount of sulfur required for 90% of maximum yield) or in their sensitivity to sulfur deficiency (i.e. yield at the lowest sulfur supply expressed as a percentage of maximum yield). The requirement for sulfur (mg/pot) fell in the following order: Hunter River lucerne (24) > Jemalong barrel medic (19) > brome grass and Wimmera ryegrass (18) > barley grass (15) > Clare subterranean clover (13) > Trikkala subterranean clover (11) > Seaton Park subterranean clover (10). The high external requirement for sulfur of Hunter River lucerne appears to be due to its poor ability to distribute sulfur from root to shoot and to its high internal requirement for sulfur. However, for Jemalong barrel medic, the high external requirement was solely due to its high internal requirement for sulfur. The higher external requirement for sulfur of the grasses compared with the subterranean clover cultivars appears to be due to the poorer ability of the grasses to obtain sulfur from the soil used in this experiment, rather than to differences in the transfer of sulfur from root to shoot, or in their internal requirement for sulfur.

Detecting karrikinolide responses in seeds of the Poaceae

2011 ◽  
Vol 59 (7) ◽  
pp. 610 ◽  
Author(s):  
Rowena L. Long ◽  
Jason C. Stevens ◽  
Erin M. Griffiths ◽  
Markus Adamek ◽  
Stephen B. Powles ◽  
...  
Keyword(s):  
Dose Response ◽  
Seed Bank ◽  
Avena Fatua ◽  
Grass Species ◽  
Lolium Rigidum ◽  
Weed Seed ◽  
Seed Burial ◽  
Bromus Diandrus ◽  
Phalaris Minor ◽  
Growing Body

The smoke-derived chemical karrikinolide commonly triggers seeds in the Brassicaceae, Solanaceae and Asteraceae families to germinate, yet species in the Poaceae – another major understorey and weed family – have responded to the chemical with mixed results. This study aimed to understand why some grass species respond to karrikinolide while others do not. Using a field-based seed-burial trial, dose-response experiment, and stratification experiment, we investigated whether karrikinolide could alleviate dormancy and trigger seeds to germinate for seven global agronomic weeds: Avena fatua L., Lolium rigidum Gaudin, Eragrostis curvula (Schrad.) Nees, Phalaris minor Retz., Hordeum glaucum Steud., Ehrharta calycina Sm. and Bromus diandrus Roth. Seeds of A. fatua were consistently stimulated to germinate with karrikinolide in all experiments, whether seeds were freshly collected or dormancy had been partially alleviated. In contrast, seeds of L. rigidum failed to respond to karrikinolide when the seeds were fresh, after-ripened in the laboratory, and even during natural dormancy loss in the field. Interestingly, although karrikinolide did not stimulate freshly collected E. curvula seeds to germinate, it hastened dormancy loss when applied during stratification. These findings are helpful for understanding the responses of grass species following fire. They also contribute to a growing body of research aimed at using karrikinolide as a tool for triggering uniform germination of seeds for enhancing restoration efforts and depleting the weed seed bank.

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