Relative Canopy Height Influences Wild Oat (Avena fatua) Seed Viability, Dormancy, and Germination

The environment in which a plant grows (maternal environment) can affect seed viability, germination, and dormancy. We assessed the effects of maternal environment on wild oat seed viability, germination, dormancy, and pathogen infection by collecting and analyzing wild oat seed from above and below a barley canopy at three field sites in Montana. The viability of wild oat seed collected below a crop canopy was consistently less than it was for seed from the overstory but varied among sites and years. Reductions in viability because of relative canopy position ranged from 10% to 30%. Effects of position relative to crop canopy on weed seed germination/dormancy rates varied by site and suggest that the direction and magnitude of the effects of maternal environment on dormancy depend on environmental conditions. These effects may be driven by crop competition or by changes in seed pathogen pressure or both. Seven species each of fungi and bacteria were isolated from wild oat seeds. The only fungi causing reductions in seed viability (15%) was isolated from understory seeds, and several bacteria from both overstory and understory sources reduced seed germination. Results suggest that, in addition to the known weed-suppressive effects of using taller or earlier emerging varieties of crops, such crops can reduce weed spread through effects on weed seed demography because weeds growing beneath the crop canopy produce a reduced amount of viable seed that is less likely to germinate in the following year.

Download Full-text

Time of wild oat (Avena fatua) panicle clipping influences seed viability

Weed Science ◽

10.1017/wsc.2020.19 ◽

2020 ◽

Vol 68 (3) ◽

pp. 260-267

Author(s):

Breanne D. Tidemann ◽

K. Neil Harker ◽

Eric N. Johnson ◽

Christian J. Willenborg ◽

Steve J. Shirtliffe

Keyword(s):

Seed Viability ◽

Avena Fatua ◽

Management Technique ◽

Wild Oat ◽

Viable Seed ◽

Crop Canopy ◽

Long Term Effects ◽

Weed Species ◽

Seed Moisture

AbstractWild oat (Avena fatua L.) is one of the most problematic weed species in western Canada due to widespread populations, herbicide resistance, and seed dormancy. In wheat (Triticum aestivum L.), and especially in shorter crops such as lentil (Lens culinaris Medik.), A. fatua seed panicles elongate above the crop canopy, which can facilitate physical cutting of the panicles (clipping) to reduce viable seed return to the seedbank. However, the viability of A. fatua seed at the time of panicle elongation is not known. The objective of this study was to determine the viability of A. fatua seed at successive time intervals after elongation above a wheat or lentil crop canopy. A 2-yr panicle clipping and removal study in wheat and lentil was conducted in Lacombe, AB, and Saskatoon, SK, in 2015 and 2016 to determine the onset of viability in A. fatua seeds at successive clipping intervals. Manual panicle clipping of A. fatua panicles above each crop canopy began when the majority of panicles were visible above respective crop canopies and continued weekly until seed shed began. At the initiation of panicle clipping, A. fatua seed viability was between 0% and 10%. By the last clipping treatment (approximately 6 to 7 wk after elongation), 95% of the A. fatua seeds were viable. Seed moisture and awn angle were not good predictors of A. fatua viability, and therefore were unlikely to provide effective tools to estimate appropriate timing for implementation of A. fatua clipping as a management technique. Based on A. fatua seed viability, earlier clipping of A. fatua is likely to be more effective in terms of population management and easier to implement in shorter crops such as lentil. Investigations into long-term effects of clipping on A. fatua populations are needed to evaluate the efficacy of this management strategy on A. fatua.

Download Full-text

Flowering, Fecundity, Seed Germination, and Seed Viability of Viburnum opulus L. Cultivars

Journal of Environmental Horticulture ◽

10.24266/0738-2898-27.1.31 ◽

2009 ◽

Vol 27 (1) ◽

pp. 31-36

Author(s):

Janine R. Conklin ◽

James C. Sellmer

Keyword(s):

Seed Germination ◽

Seed Production ◽

Seed Viability ◽

Biological Traits ◽

Limited Information ◽

Viable Seed ◽

Invasive Potential ◽

Short Term ◽

Viburnum Opulus ◽

Tetrazolium Test

Abstract Mature specimens of Viburnum opulus and cultivars ‘Leonard's Dwarf’ and ‘Roseum’ were assessed over 2 years for flower and seed production, seed germination, and seed viability as determined by a tetrazolium test to understand their invasive potential. ‘Aureum’, ‘Compactum’, ‘Losely's Compact’, ‘Nanum’, and ‘Xanthocarpum’ were also tested for germination and viability of seeds. Cultivars differed in flower and seed production, seed germination, and seed viability. ‘Roseum’ prolifically produced highly viable seed that germinated at moderate rates under greenhouse conditions (8,354, 100%, and 73%, respectively). Viburnum opulus and ‘Leonard's Dwarf’ produced fewer viable seed which showed moderate to low germination rates (609, 100%, and 53%; 712, 100%, and 5%, respectively). ‘Aureum’ and ‘Xanthocarpum’ seeds germinated at moderate rates (55 and 25%, respectively) and were highly viable (100%). ‘Compactum’, ‘Losely's Compact’, and ‘Nanum’ germinated at low rates or failed to germinate (0, 0, and 5%, respectively), yet seeds were moderately viable (37, 65, and 55%, respectively). Seeds of all cultivars germinated at low rates or failed to germinate at both outdoor sites (0 to 5%) which suggests these plants may be weakly invasive. Short-term studies on biological traits such as these provide only limited information to assess the invasive potential of cultivars.

Download Full-text

Influence of tillage, vertical seed distribution, and pyroxasulfone application timing and rate on control of wild oat (Avena fatua L.)

Canadian Journal of Plant Science ◽

10.1139/cjps-2017-0199 ◽

2018 ◽

Vol 98 (3) ◽

pp. 601-608 ◽

Cited By ~ 1

Author(s):

Amy R. Mangin ◽

Linda M. Hall ◽

Jeff J. Schoenau ◽

Hugh J. Beckie

Keyword(s):

Avena Fatua ◽

Vertical Position ◽

Wild Oat ◽

Weed Seed ◽

Application Timing ◽

Herbicide Resistant ◽

Oat Seeds ◽

Tillage System ◽

Seed Distribution ◽

Oat Biomass

Tillage and new herbicide options may be necessary for the control of herbicide-resistant wild oat. The efficacy of soil-applied herbicides such as pyroxasulfone can be influenced by edaphic factors and weed seed recruitment depth, which varies with tillage system. We investigated the effect of tillage and pyroxasulfone rate when applied in the fall and spring on wild oat biomass at three locations in Alberta in 2014–2015. The vertical position of wild oat seeds, with and without tillage, was examined at each site. Wild oat biomass was greater in untilled plots compared with plots with fall tillage at all locations. In two out of three locations, pyroxasulfone efficacy was superior when applied in the fall compared with spring, possibly influenced by low spring rainfall. A single tillage pass at the Edmonton and Kinsella locations did not affect wild oat seed distribution, but there was an increase in seeds present in the surface layer in the untilled treatment at Lacombe. Tillage, used in combination with soil-applied herbicides, may be an option to achieve acceptable control of herbicide-resistant wild oat.

Download Full-text

THE USE OF SODIUM HYPOCHLORITE IN TESTING THE SEED VIABILITY OF WILD OATS

Canadian Journal of Plant Science ◽

10.4141/cjps79-164 ◽

1979 ◽

Vol 59 (4) ◽

pp. 1047-1052 ◽

Cited By ~ 3

Author(s):

A. I. HSIAO ◽

M. E. MacGREGOR ◽

J. D. BANTING

Keyword(s):

Sodium Hypochlorite ◽

Seed Viability ◽

Avena Fatua ◽

Wild Oat ◽

Maximum Percentage ◽

Wild Oats ◽

Oat Seeds ◽

Viable Seeds

When seeds of wild oats (Avena fatua L.) were imbibed in water for 24 h, followed by 24-h immersion in 6% sodium hypochlorite (NaOCl), the hulls were completely degraded. The embryos were clearly defined before the hull was completely degraded. Several hours were required for the maximum number of sharply defined embryos to develop after NaOCl treatment to dry seeds, and hull degradation was less rapid in these seeds relative to seeds that had been previously imbibed in water for 24 h. The maximum percentage of caryopses with sharply defined embryos was found to be closely correlated to percentage of viable seeds estimated by germination plus tetrazolium tests; thus the NaOCl treatment can be used to estimate the viability of wild oat seeds.

Download Full-text

Interactions Among Ethephon, Nitrate, and After-Ripening in the Release of Dormancy of Wild Oat (Avena fatua) Seed

Weed Science ◽

10.1017/s0043174500026424 ◽

1986 ◽

Vol 34 (1) ◽

pp. 43-47 ◽

Cited By ~ 7

Author(s):

Hargurdeep S. Saini ◽

Pawan K. Bassi ◽

Mary S. Spencer

Keyword(s):

Seed Germination ◽

Experimental Evidence ◽

Shoot Growth ◽

Storage Temperature ◽

Avena Fatua ◽

Natural Process ◽

Wild Oat ◽

Viable Seed ◽

Root And Shoot Growth ◽

Stimulation Of

Germination of dormant wild oat (Avena fatuaL. # AVEFA) seed was examined in response to various concentrations of ethephon (2-chloroethylphosphonic acid), KNO3, or both together in the dark at temperatures ranging from 7 to 32 C. Both chemicals significantly (P = 0.05) promoted germination and their effects were additive. Maximum stimulation of germination in response to all treatments occurred at 7 C, with a gradual decrease in reponse as temperature or duration of after-ripening, the seed that retained dormancy during storage remained responsive to ethephon also occurred during storage of mature seed at 3 to 32 C. The rate and extent of this dormancy loss increased with an increase in storage temperature. Regardless of the temperature or duration of after-ripening, the seed that retained dormancy during storage remained responsive to ethephon and KNO3treatments. Suitable combinations of after-ripening, ethephon, and KNO3induced over 90% germination of seed that was dormant at maturity. Experimental evidence has been obtained that suggests that this percentage may represent the total number of viable seed in the population. While ethephon promoted seed germination, it severely stunted root and shoot growth of the resulting seedlings. It appears that strategies could be developed to combine the use of ethephon and nitrate with the natural process of after-ripening to enhance and synchronize wild oat germination.

Download Full-text

Effects of prolonged light on germination of six lines of wild oat (Avena fatua)

Canadian Journal of Botany ◽

10.1139/b91-182 ◽

1991 ◽

Vol 69 (7) ◽

pp. 1414-1417 ◽

Cited By ~ 8

Author(s):

J. Q. Hou ◽

G. M. Simpson

Keyword(s):

Seed Germination ◽

Genetic Variability ◽

Gibberellic Acid ◽

Red Light ◽

Avena Fatua ◽

Wild Oat ◽

Inhibitory Effects ◽

Light Responses ◽

Light Reaction ◽

Oat Seeds

Effects of prolonged light irradiation on seed germination of wild oat (Avena fatua L.) were studied in three nondormant and three dormant genetic lines. Light responses were observed in each of the lines tested. The expression of the light reaction is related to the genetic variability and dormancy states of the seeds. The light reaction can be observed in the dormant lines by removing the dormancy blocks in the seeds either through afterripening or by treatment with gibberellic acid or azide. Prolonged far-red, blue, and white light are inhibitory to germination. Prolonged red light had neutral, or inhibitory, effects compared with the corresponding dark germination. Germination responses to light depend on both the condition of phyto-chrome established by the light environment and the state of dormancy in wild oat seeds. Key words: phytochrome, dormancy, afterripening, genotype, gibberellin, azide.

Download Full-text

Effect of hypoxia on buried weed seed germination

Weed Research ◽

10.1111/j.1365-3180.1995.tb01629.x ◽

1995 ◽

Vol 35 (5) ◽

pp. 343-351 ◽

Cited By ~ 78

Author(s):

S. BENVENUTI ◽

M. MACCHIA

Keyword(s):

Seed Germination ◽

Weed Seed

Download Full-text

Influence of chaff and chaff lines on weed seed survival and seedling emergence in Australian cropping systems

Weed Technology ◽

10.1017/wet.2020.142 ◽

2020 ◽

pp. 1-22

Author(s):

Michael J. Walsh ◽

Annie E. Rayner ◽

Annie Rutledge ◽

John C. Broster

Keyword(s):

Cropping Systems ◽

Seedling Emergence ◽

Field Studies ◽

Wild Oat ◽

Weed Seed ◽

Weed Species ◽

Environment Effect ◽

Seed Survival ◽

Cropping Seasons ◽

Rigid Ryegrass

Abstract Chaff lining and chaff tramlining are harvest weed seed control (HWSC) systems that involve the concentration of weed seed containing chaff material into narrow (20 to 30 cm) rows between or on the harvester wheel tracks during harvest. These lines of chaff are left intact in the fields through subsequent cropping seasons in the assumption that the chaff environment is unfavourable for weed seed survival. The chaff row environment effect on weed seed survival was examined in field studies, while chaff response studies determined the influence of increasing amounts of chaff on weed seedling emergence. The objectives of these studies were to determine 1) the influence of chaff lines on the summer-autumn seed survival of selected weed species; and 2) the influence of chaff type and amount on rigid ryegrass seedling emergence. There was frequently no difference (P>0.05) in survival of seed of four weed species (rigid ryegrass, wild oat, annual sowthistle and turnip weed) when these seed were placed beneath or beside chaff lines. There was one instance where wild oat seed survival was increased (P<0.05) when seed were placed beneath compared to beside a chaff line. The pot studies determined that increasing amounts of chaff consistently resulted in decreasing numbers of rigid ryegrass seedlings emerging through chaff material. The suppression of emergence broadly followed a linear relationship where there was approximately a 2.0% reduction in emergence with every 1.0 t ha-1 increase in chaff material. This relationship was consistent across wheat, barley, canola and lupin chaff types, indicating that the physical presence of the chaff was more important than chaff type. These studies indicated that chaff lines may not affect the over summer-autumn survival of the contained weed seeds but the subsequent emergence of weed seedlings will be restricted by high amounts of chaff (>40 t ha-1).

Download Full-text

Do applications of systemic herbicides when green fruit are present prevent seed production or viability of Alliaria petiolata (garlic mustard)?

Invasive Plant Science and Management ◽

10.1017/inp.2021.8 ◽

2021 ◽

pp. 1-17

Author(s):

Leo Roth ◽

José Luiz C. S. Dias ◽

Christopher Evans ◽

Kevin Rohling ◽

Mark Renz

Keyword(s):

Seed Production ◽

Seed Viability ◽

Early Spring ◽

Alliaria Petiolata ◽

Late Spring ◽

Garlic Mustard ◽

Viable Seed ◽

Application Timing ◽

Control Seed ◽

Second Year

Garlic mustard [Alliaria petiolata (M. Bieb.) Cavara & Grande] is a biennial invasive plant commonly found in the northeastern and midwestern United States. Although it is not recommended to apply herbicides after flowering, land managers frequently desire to conduct management during this timing. We applied glyphosate and triclopyr (3% v/v and 1% v/v using 31.8% and 39.8% acid equivalent formulations, respectively) postemergence to established, second-year A. petiolata populations at three locations when petals were dehiscing, and evaluated control, seed production and seed viability. Postemergence glyphosate applications at this timing provided 100% control of A. petiolata by 4 weeks after treatment at all locations whereas triclopyr efficacy was variable, providing 38-62% control. Seed production was only reduced at one location, with similar results regardless of treatment. Percent seed viability was also reduced, and when combined with reductions in seed production, we found a 71-99% reduction in number of viable seed produced plant-1 regardless of treatment. While applications did not eliminate viable seed production, our findings indicate that glyphosate and triclopyr applied while petals were dehiscing is a viable alternative to cutting or hand-pulling at this timing as it substantially decreased viable A. petiolata seed production. Management Implications Postemergence glyphosate and triclopyr applications in the early spring to rosettes are standard treatments used to manage A. petiolata. However, weather and other priorities limit the window for management, forcing field practitioners to utilize more labor-intensive methods such as hand-pulling. It is not known how late in the development of A. petiolata these herbicides can be applied to prevent viable seed production. Since prevention of soil seedbank replenishment is a key management factor for effective long-term control of biennial invasive species, we hypothesized late spring foliar herbicide applications to second year A. petiolata plants when flower petals were dehiscing could be an effective management tool if seed production or viability is eliminated. Our study indicated that glyphosate applications at this timing provided 100% control of A. petiolata plants by 4 weeks after treatment at all locations, whereas triclopyr efficacy was inconsistent. Although both glyphosate and triclopyr decreased viable seed production to nearly zero at one of our three study locations, the same treatments produced significant amounts of viable seed at the other two locations. Our findings suggest late spring glyphosate and triclopyr applications should not be recommended over early spring applications to rosettes for A. petiolata management, as our late spring application timing did not prevent viable seed production, and may require multiple years of implementation to eradicate populations. Nonetheless, this application timing holds value in areas devoid of desirable understory vegetation compared to no management practices or mechanical management options including hand-pulling when fruit are present, as overall viable seed production was reduced to similar levels as these treatments.

Download Full-text