Seed germination ecology of Sumatran fleabane (Conyza sumatrensis) in relations to various environmental parameters

Weed Science ◽  
2021 ◽  
pp. 1-26
Author(s):  
Gulshan Mahajan ◽  
Asheneel Prasad ◽  
Bhagirath Singh Chauhan
Keyword(s):  
Seed Germination ◽  
Light Intensity ◽  
Chloride Concentration ◽  
Soil Surface ◽  
Control Treatment ◽  
Effect Of Temperature ◽  
Burial Depth ◽  
Germination Ecology ◽  
Wide Range ◽  
Dark Conditions

Abstract Sumatran fleabane [Conyza sumatrensis (Retz.) Walker] is an emerging weed in the Australian cropping region. Populations resistant to glyphosate have evolved in Australia, creating the demand for information regarding the seed germination ecology of glyphosate-resistant (R) and glyphosate susceptible (S) populations of C. sumatrensis. A study was conducted to examine the effect of temperature, light intensity, salt stress, osmotic stress, and burial depth on the germination and emergence of two populations (R and S) of C. sumatrensis. Both populations were able to germinate over a wide range of alternating day/night temperatures (15/5 to 35/25 C). In light/dark conditions, the R population had higher germination than the S population at 20/10 and 35/25 C. In the dark, the R population had higher germination than the S population at 25/15 C. In the dark, germination was inhibited at 30/20 C and above. Averaged over populations, seed germination of C. sumatrensis was reduced by 97% at zero light intensity (completely dark conditions) compared with full light intensity. Seed germination of C. sumatrensis reduced by 17 and 85% at an osmotic potential of −0.4, and −0.8 MPa, respectively, compared with the control treatment. The R population had lower germination (57%) than the S population (72%) at a sodium chloride concentration of 80 mM. Seed germination was highest on the soil surface and emergence was reduced by 87 and 90% at burial depths of 0.5 and 1.0 cm, respectively. Knowledge gained from this study suggests that a shallow-tillage operation to bury weed seeds in conventional tillage systems, and retention of high residue cover in a zero-till system on the soil surface may inhibit the germination of C. sumatrensis. This study also warrants that the R population may have a greater risk of invasion over a greater part of a year due to germination over a broader temperature range.

scholarly journals Germination Ecology of Two Troublesome Weeds of Arid Chickpea: Euphorbia dracunculoides and Astragalus Species

2019 ◽  
Vol 37 ◽  
Author(s):  
R.M. IKRAM ◽  
A. TANVEER ◽  
H.H. ALI ◽  
M.E. SAFDAR ◽  
M.M. JAVAID ◽  
...  
Keyword(s):  
Seed Germination ◽  
Seedling Emergence ◽  
Chloride Concentration ◽  
Ecological Factors ◽  
Cropping System ◽  
Soil Surface ◽  
Growth Patterns ◽  
Burial Depth ◽  
Germination Ecology ◽  
Wide Range

ABSTRACT: The species Euphorbia dracunculoides and Astragalus are problematic weeds of arid chickpea in the chickpea mono-cropping system in Pakistan. The influence of various ecological factors on germination and seedling emergence characteristics of these weeds was determined under laboratory conditions. The results suggested that seed germination of both species was 50% at 15 oC under light conditions, and germination decreased when the temperature was increased. The increase in drought stress from 2.5 to 15% significantly decreased germination of E. dracunculoides and Astragalus spp. Both species failed to germinate at the osmotic potential of -3.02 MPa. The increase in field capacity from 25 to 100% increased emergence percentage and emergence index of both weeds. A pH range of 6 to 9 did not influence seed germination of both species and they were able to germinate at a wide range of pH conditions. Both weeds were very sensitive to salinity; however, a few seeds (10%) of Astragalusspp. germinated even at a 150 mM sodium chloride concentration. To check the effect of burial depth, seeds were placed in pots under seeding depths of 0 to 6 cm at an interval of 1 cm, respectively. Maximum emergence was attained at the soil surface and emergence declined with increasing depths. Seedling emergence of E. dracunculoides was higher than that of Astragalusspp. at all burial depths. Studies on germination ecology of these two weeds will offer insights into their behavior under different environmental conditions. Their germination responses and growth patterns under different ecological factors will help us to design an efficient management strategy to control these two troublesome weeds.

Seed-germination ecology of glyphosate-resistant and glyphosate-susceptible biotypes of Echinochloa colona in Australia

2019 ◽  
Vol 70 (4) ◽  
pp. 367 ◽  
Author(s):  
Navneet Kaur Mutti ◽  
Gulshan Mahajan ◽  
Bhagirath Singh Chauhan
Keyword(s):  
Water Stress ◽  
Sodium Chloride ◽  
Seed Germination ◽  
Seedling Emergence ◽  
Chloride Concentration ◽  
Soil Surface ◽  
Burial Depth ◽  
Solution Ph ◽  
High Sodium ◽  
Wide Range

Echinochloa colona L. (Link) (awnless barnyard grass) is one of the top three most problematic weeds of summer crops in Australia. This weed has evolved resistance to glyphosate. A study was conducted to evaluate the effect of environmental factors on the germination and seedling emergence of a glyphosate-resistant (GR) and a glyphosate-susceptible (GS) biotype of E. colona. The two biotypes had similar germination and emergence responses to light and temperature conditions, water stress, solution pH, sorghum residue cover and seed burial depth. Light stimulated germination more than dark conditions, and seeds germinated at a wide range of alternating day/night temperatures, from 20°C/10°C to 35°C/25°C, whereas no seeds germinated at 15°C/5°C. These results suggest that E. colona can emerge in spring, summer and autumn in Queensland. The sodium chloride concentration required to inhibit 50% germination was greater for the GR biotype (209 mm) than the GS biotype (174 mm). Seed germination was not affected by pH in the range 4–10. Water stress reduced germination by 50% at an osmotic potential of –0.44 MPa. In a shade-house study, retention of sorghum residue cover on the soil surface reduced the seedling emergence of E. colona. Emergence was 70% in the absence of crop residue, whereas a residue amount of 8 t ha–1 reduced emergence to 47%. Emergence was greatest for seeds placed on the soil surface and declined linearly with increasing burial depth; no seedlings emerged from 8 cm depth. The GR biotype had higher germination than the GS biotype under high sodium chloride concentrations; therefore, this biotype may be highly competitive with crops under highly saline conditions. Because germination was high on the soil surface and was stimulated by light, this weed will remain problematic under no-till farming systems in Australia.

Effect of Environmental Factors on Germination and Emergence of Shortawn Foxtail (Alopecurus aequalis)

Weed Science ◽  
2017 ◽  
Vol 66 (1) ◽  
pp. 47-56 ◽  
Author(s):  
Ning Zhao ◽  
Qi Li ◽  
Wenlei Guo ◽  
Lele Zhang ◽  
Lu’an Ge ◽  
...  
Keyword(s):  
Seed Germination ◽  
Osmotic Potential ◽  
Control Strategies ◽  
Abiotic Factors ◽  
Germination Rate ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Burial Depth ◽  
Effective Measure ◽  
Wide Range

Shortawn foxtail is an invasive grass weed infesting winter wheat and canola production in China. A better understanding of the germination ecology of shortawn foxtail would help to develop better control strategies for this weed. Experiments were conducted under laboratory conditions to evaluate the effects of various abiotic factors, including temperature, light, pH, osmotic stress, salt concentration, and planting depth, on seed germination and seedling emergence of shortawn foxtail. The results showed that the seed germination rate was greater than 90% over a wide range of constant (5 to 25C) and alternating (15/5 to 35/25C) temperatures. Maximum germination occurred at 20C or 25/15C, and no germination occurred at 35C. Light did not appear to have any effect on seed germination. Shortawn foxtail germination was 27% to 99% over a pH range of 4 to 10, and higher germination was obtained at alkaline pH values ranging from 7 to 10. Seed germination was sensitive to osmotic potential and completely inhibited at an osmotic potential of −0.6 MPa, but it was tolerant to salinity: germination even occurred at 200 mM NaCl (5%). Seedling emergence was highest (98%) when seeds were placed on the soil surface but declined with the increasing burial depth. No seedlings emerged when seeds were buried 6-cm deep. Deep tillage could be an effective measure to limit seed germination from increased burial depth. The results of this study will lead to a better understanding of the requirements for shortawn foxtail germination and emergence and will provide information that could contribute to its control.

Germination Ecology of Two Australian Populations of African turnipweed (Sisymbrium thellungii)

Weed Science ◽  
2018 ◽  
Vol 66 (6) ◽  
pp. 752-757 ◽  
Author(s):  
Gulshan Mahajan ◽  
Amar Matloob ◽  
Michael Walsh ◽  
Bhagirath S. Chauhan
Keyword(s):  
Seed Germination ◽  
Management Strategies ◽  
Soil Surface ◽  
Wheat Crop ◽  
Burial Depth ◽  
Negative Effects ◽  
Wide Range ◽  
Water Ph ◽  
Winter Crops ◽  
Residue Study

AbstractAfrican turnipweed (Sisymbrium thellungiiO. E.Schulz) is an emerging problematic broadleaf weed of the northern grain region of Australia. Laboratory experiments were conducted to evaluate the effects of temperature, light, salinity, pH, seed burial depth, and the amount of wheat crop residue on germination and emergence of two AustralianS. thellungiiweed populations (population C, cropped area; population F, fence line). Both populations behaved similarly across different environmental conditions, except in the residue study. Although the seeds of both populations ofS. thellungiicould germinate under complete darkness, germination was best (~95%) under light/dark conditions at the 20/10 C temperature regime. Both populations ofS. thellungiigerminated over a wide range of day/night temperatures (15/5, 20/10, 25/15, and 30/20 C). Osmotic stress had negative effects on germination, with 54% seeds (averaged over populations) able to germinate at −0.1MPa. Complete germination inhibition for both populations was observed at −0.8MPa osmotic potential. Both populations germinated at sodium chloride (NaCl) concentrations ranging from 50 to 100 mM, beyond which germination was completely inhibited. There were substantial reductions in seed germination, 32% (averaged over populations) under highly acidic conditions (pH 4.0) as compared with the control (water: pH 6.4). Seed germination of both populations on the soil surface was 77%, and no seedlings emerged from a burial depth of 1 cm. The addition of 6 Mg ha−1of wheat (Triticum aestivumL.) residue reduced the emergence of the C and F populations ofS. thellungiiby 75% and 64%, respectively, as compared with the control (no residue). Information gathered from this study provides a better understanding of the factors favorable for germination and emergence ofS. thellungii, which will aid in developing management strategies in winter crops, especially wheat, barley (Hordeum vulgareL.), and chick pea (Cicer arietinumL.).

Germination ecology of wild mustard (Sinapis arvensis) and its implications for weed management

Weed Science ◽  
2021 ◽  
pp. 1-27
Author(s):  
Aseemjot Singh ◽  
Gulshan Mahajan ◽  
Bhagirath Singh Chauhan
Keyword(s):  
Salt Stress ◽  
Seed Germination ◽  
Seedling Emergence ◽  
Radiant Heat ◽  
Burial Depth ◽  
Sinapis Arvensis ◽  
Germination Ecology ◽  
Wild Mustard ◽  
Differential Adaptation ◽  
Wide Range

Abstract Wild mustard (Sinapis arvensis L.) is a widespread weed of the southeastern cropping region of Australia. Seed germination ecology of S. arvensis populations selected from different climatic regions may differ due to adaptative traits. Experiments were conducted to evaluate the effects of temperature, light, radiant heat, soil moisture, salt concentration, and burial depth on seed germination and seedling emergence of two [Queensland (Qld) population: tropical region; and Victoria (Vic) population: temperate region] populations of S. arvensis. Both populations germinated over a wide range of day/night (12 h/12 h) temperatures (15/5 to 35/25 C), and had the highest germination at 30/20 C. Under complete darkness, the Qld population (61%) had higher germination than the Vic population (21%); however, under the light/dark regime, both populations had similar germination (78 to 86%). At 100 C pretreatment for 5 min, the Qld population (44%) had higher germination than the Vic population (13%). Germination of both populations was nil when given pretreatment at 150 and 200 C. The Vic population was found tolerant to high osmotic and salt stress compared with the Qld population. At an osmotic potential of −0.4 MPa, germination of Qld and Vic populations was reduced by 85% and 42%, respectively, compared with their respective control. At 40, 80, and 160 mM sodium chloride, germination of the Qld population was lower than the Vic population. Averaged over the populations, seedling emergence was highest (52%) from a burial depth of 1 cm and was nil from 8 cm depth. Differential germination behaviors of both populations to temperature, light, radiant heat, water stress, and salt stress suggests that populations of S. arvensis may have undergone differential adaptation. Knowledge gained from this study will assist in developing suitable control measures for this weed species to reduce the soil seedbank.

Germination Ecology of Four African mustard (Brassica tournefortii Gouan.) Populations in the Eastern Region of Australia

Weed Science ◽  
2021 ◽  
pp. 1-28
Author(s):  
Sohraab Singh ◽  
Gulshan Mahajan ◽  
Rajandeep Singh ◽  
Bhagirath S. Chauhan
Keyword(s):  
Temperature Regime ◽  
Soil Depth ◽  
Seedling Emergence ◽  
Chloride Concentration ◽  
Burial Depth ◽  
Eastern Region ◽  
Germination Ecology ◽  
Wide Range ◽  
Brassica Tournefortii ◽  
Winter Annual

Abstract African mustard (Brassica tournefortii Gouan) is a problematic winter annual weed in Australia. Germination ecology of B. tournefortii may change in response to the maternal environments or habitats in which they grow. A study was conducted to evaluate the effect of environmental factors on germination and emergence of four populations of B. tournefortii that were collected from different fields. Averaged over populations, germination was stimulated by dark and was higher at 25/15 C (92%) as compared with 15/5 C (76%) and 35/25 C (45%). Averaged over light/dark regimes, at the lowest temperature regime (15/5 C), population A had higher germination than population D ; however, at the highest temperature regime (35/25 C), population D had higher germination than population A. Population B and C had higher germination in the temperature range of 25/15 C and 30/20 C compared with 15/5 C, 20/10 C, and 35/25 C. Seeds germinated at a wide range of alternating day/night temperatures (15/5 to 35/25 C), suggesting that seeds can germinate throughout the year if other optimum conditions are available. Population A was more tolerant to water and salt stress than population D. The sodium chloride concentration and osmotic potential required to inhibit 50% germination of population A was 68 mM and -0.60 MPa, respectively. Averaged over populations, seeds placed at 1cm soil depth had the highest emergence (54%), and burial depth of 8 cm resulted in 28% seedling emergence. Averaged over populations, wheat residue retention at 6000 kg ha-1 resulted in greater seedling emergence than the residue amount of 1000 kg ha-1. The results suggest that B. tournefortii will be favored in no-till systems and the seed bank of B. tournefortii could be managed by tillage regimes that bury its seeds below 8 cm depths and restrict seedling emergence and growth of new plants.

Germination ecology of hairy fleabane (Conyza bonariensis) and its implications for weed management

Weed Science ◽  
2020 ◽  
Vol 68 (4) ◽  
pp. 411-417
Author(s):  
Deepak Loura ◽  
Sahil ◽  
Singarayer Florentine ◽  
Bhagirath Singh Chauhan
Keyword(s):  
Weed Management ◽  
Cropping Systems ◽  
Negative Relationship ◽  
Soil Surface ◽  
Effect Of Temperature ◽  
Burial Depth ◽  
No Till ◽  
Conyza Bonariensis ◽  
Wide Range ◽  
Hairy Fleabane

AbstractHairy fleabane [Conyza bonariensis (L.) Cronquist] is a problematic weed in Australian no-till cropping systems. Consequently, a study was conducted to examine the effect of temperature, light, salt stress, osmotic stress, burial depth, and sorghum crop residue on germination and emergence in two populations (C and W: collected from chick pea [Cicer arietinum L.] and wheat [Triticum aestivum L.] fields, respectively) of C. bonariensis. Both populations were able to germinate over a wide range of alternating day/night temperatures (15/5 to 35/25 C); however, the C population had optimum (and similar) germination over the range of 20/10 and 30/20 C, while the W population showed maximum germination at 25/15 C. A negative relationship was observed between osmotic potential and germination, with 31% and 14% germination of the C and W populations at −0.6 MPa, respectively. These observations suggest that population C was more tolerant to higher osmotic potentials than population W. Seeds of both populations germinated when exposed to a wide range of sodium chloride levels (NaCl, 0 to 200 mM); however, beyond 200 mM NaCl, no germination was observed in either population. Maximum germination of the C (70%) and W (41%) populations was observed on the soil surface with no emergence from a burial depth of 1 cm. The application of sorghum residue at an amount of 6,000 kg ha−1 reduced emergence of the C and W populations by 55% and 58%, respectively, compared with the no-residue treatment. Knowledge gained from this study suggests that the following strategies could be used for more efficacious management of C. bonariensis: (1) a shallow-tillage operation to bury weed seeds in conventional tillage systems, and (2) retention of sorghum residue on the soil surface in no-till systems.

scholarly journals Germination and emergence of trumpet flower (tecoma stans) under different environmental conditions

2014 ◽  
Vol 32 (2) ◽  
pp. 283-290 ◽  
Author(s):  
F.C. Reis ◽  
J.F. Medina Sotomayor ◽  
D.B. Garcia ◽  
A.A.M. Barroso ◽  
A.J.P. Albrecht ◽  
...  
Keyword(s):  
Seed Germination ◽  
Light Intensity ◽  
Constant Temperature ◽  
Block Design ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Effect Of Temperature ◽  
Experimental Unit ◽  
Total Percentage ◽  
Randomized Block Design

The aim of this work was to analyze the effect of temperature and light intensity on trumpet flower seed germination, as well as the effect of seeding depth on its emergence. To study the influence of temperature, nine temperature intervals were evaluated, ranging from 15.0 to 40.0 ºC. A randomized block design experiment was used with five replications and 20 seeds per replication, and performed twice. To evaluate light intensity on seed germination, a randomized experimental design was used with eight replications and 25 seeds per replication. The treatments applied were: photoperiod with temperature alternation; photoperiod with constant temperature; darkness with temperature alternation; and darkness with constant temperature. The photoperiod consisted of 8 hours of light and 16 hours of darkness, and the constant temperature was 25 ºC. The treatments with temperature alternations were established with 8 hours at 30 ºC, and 16 hours at 20 ºC. Germination was assessed daily to calculate the total percentage of germination as well as the Germination Velocity Index (GVI). To study the influence of seeding depth on plant emergence, 25 seeds were seeded at 0, 20, 40, and 80 mm in pots with sieved soil. The experiment was arranged in a randomized block design with four replications. Seedling emergence was monitored daily until the 15th day after seeding. After that period, the total percentage of emergence was calculated for each experimental unit, as well as the Emergence Velocity Index (EVI). Formation of normal seedlings and the Germination Velocity Index were different among temperatures and higher germination percentages were observed between 20.3 ºC and 37.5 ºC. Tecoma stans seedlings did not germinate when planted at 40 and 80 mm depth. However, the seedlings placed on the soil surface had an emergence percentage of 72. At 20 mm depth, the emergence rate was 31%.

Germination Ecology of Southern Crabgrass (Digitaria ciliaris) and India Crabgrass (Digitaria longiflora): Two Important Weeds of Rice in Tropics

Weed Science ◽  
2008 ◽  
Vol 56 (5) ◽  
pp. 722-728 ◽  
Author(s):  
Bhagirath S. Chauhan ◽  
David E. Johnson
Keyword(s):  
Seed Germination ◽  
Environmental Factors ◽  
Weed Management ◽  
Small Proportion ◽  
Seedling Emergence ◽  
Management Strategies ◽  
Soil Surface ◽  
Integrated Weed Management ◽  
Burial Depth ◽  
Wide Range

Southern and India crabgrass are important grass weeds of rice in many tropical countries. Environmental factors influenced seed germination and seedling emergence of these weeds. Seeds of both species germinated at a range of alternating temperatures (25/15, 30/20, and 35/25 C day/night), though the germination of southern crabgrass was reduced at the lowest alternating temperatures (25/15 C). Light stimulated germination of both species; however, a small proportion of southern crabgrass seeds germinated in the dark. Germination of India crabgrass was influenced to a greater degree by increasing salt and water stresses than was southern crabgrass. Seeds of both species germinated over a wide range of pH between 5 and 10. Seedling emergence of both species (98% for southern crabgrass and 94% for India crabgrass) was greatest for seeds placed on the soil surface. Seed burial depth of 2 cm completely inhibited emergence of India crabgrass, whereas for southern crabgrass, this depth was 8 cm. Knowledge gained from this study is expected to contribute to developing components of integrated weed management strategies for these species.

Seed germination biology of sweet acacia (Vachellia farnesiana) and response of its seedlings to herbicides

Weed Science ◽  
2021 ◽  
pp. 1-19
Author(s):  
Bhagirath S. Chauhan ◽  
Shane Campbell ◽  
Victor J. Galea
Keyword(s):  
Sodium Chloride ◽  
Seed Germination ◽  
Development Stage ◽  
Hot Water ◽  
Control Treatment ◽  
Similar Species ◽  
Weed Species ◽  
Physical Dormancy ◽  
Seed Biology ◽  
Wide Range

Abstract Sweet acacia [Vachellia farnesiana (L.) Willd.]is a problematic thorny weed species in several parts of Australia. Knowledge of its seed biology could help to formulate weed management decisions for this and other similar species. Experiments were conducted to determine the effect of hot water (scarification), alternating temperatures, light, salt stress, and water stress on seed germination of two populations of V. farnesiana and to evaluate the response of its young seedlings (the most sensitive development stage) to commonly available POST herbicides in Australia. Both populations behaved similarly to all the environmental factors and herbicides; therefore, data were pooled over the populations. Seeds immersed in hot water at 90 C for 10 min provided the highest germination (88%), demonstrating physical dormancy in this species. Seeds germinated at a wide range of alternating day/night temperatures from 20/10 C (35%) to 35/25 C (90%) but no seeds germinated at 15/5 C. Germination was not affected by light, suggesting that seeds are nonphotoblastic and can germinate under a plant canopy or when buried in soil. Germination was not affected by sodium chloride concentrations up to 20 mM and about 50% of seeds could germinate at 160 mM sodium chloride, suggesting its high salt tolerance ability. Germination was only 13% at −0.2 MPa osmotic potential and no seeds germinated at −0.4 MPa, suggesting that V. farnesiana seeds may remain ungerminated until moisture conditions have become conducive for germination. A number of POST herbicides, including 2,4-D + picloram, glufosinate, paraquat and saflufenacil, provided >85% control of biomass of young seedlings compared with the nontreated control treatment. Knowledge gained from this study will help to predict the potential spread of V. farnesiana in other areas and help to integrate herbicide use with other management strategies.

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