Influence of Environmental Factors on Seed Germination and Seedling Emergence of Eclipta (Eclipta prostrata) in a Tropical Environment

Weed Science ◽  
2008 ◽  
Vol 56 (3) ◽  
pp. 383-388 ◽  
Author(s):  
Bhagirath S. Chauhan ◽  
David E. Johnson
Keyword(s):  
Seed Germination ◽  
Environmental Factors ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Humid Tropics ◽  
Plant Residue ◽  
Eclipta Prostrata ◽  
Exposure Temperature ◽  
Highly Sensitive ◽  
Ph Range

Experiments were conducted to determine the influence of various environmental factors on seed germination and seedling emergence of eclipta. Seed germination was completely inhibited in the dark, whereas in the light/dark it was 76, 93, and 87% at 25/15, 30/20, and 35/25 C alternating day/night temperatures, respectively. Germination was greater than 80% up to a temperature of 140 C, when seed were placed in an oven for 5 min followed by incubation at 30/20 C for 14 d, but declined progressively with a further increase in exposure temperature with no germination at 200 C. Seed germination was tolerant of salt stress but highly sensitive to water stress. Seed germinated (87 to 93%) over a pH range of 4 to 10. Seedling emergence was greatest (83%) for the seed placed on the soil surface but declined thereafter, and no seedlings emerged from a depth of 0.5 cm. Seedling emergence was slower and lower with the addition of 4 to 6 t ha−1of plant residue. The information gained from this study identifies some of the factors facilitating eclipta becoming a widespread weed in the humid tropics and might contribute to its control.

scholarly journals Impact of Environmental Factors on Seed Germination and Seedling Emergence of White Clover (Trifolium repens L.)

Agronomy ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 190
Author(s):  
Lei Chu ◽  
Yiping Gao ◽  
Lingling Chen ◽  
Patrick E. McCullough ◽  
David Jespersen ◽  
...  
Keyword(s):  
Seed Germination ◽  
Environmental Factors ◽  
White Clover ◽  
Trifolium Repens ◽  
Germination Rate ◽  
Seedling Emergence ◽  
Soil Surface ◽  
High Sensitivity ◽  
Series Of Experiments ◽  
Trifolium Repens L

White clover (Trifolium repens L.) is cultivated as a forage crop and planted in various landscapes for soil conservation. There are numerous reports of failed white clover stands each year. A good understanding of the seed germination biology of white clover in relation to environmental factors is essential to achieve successful stand establishment. A series of experiments were conducted to investigate the impacts of light, temperature, planting depth, drought, and salt stress on seed germination and the emergence of white clover. White clover is negatively photoblastic, and seed germination averaged 63 and 66% under light and complete dark conditions 4 weeks after planting (WAP), respectively. Temperature affected the seed germination speed and rate. At 1 WAP, seeds incubated at 15 to 25 °C demonstrated a significantly higher germination rate than the low temperatures at 5 and 10 °C; however, the germination rate did not differ among the temperature treatments at 4 WAP. The results suggest that white clover germination decreases with increasing sowing depths, and the seeds should be sown on the soil surface or shallowly buried at a depth ≤1 cm to achieve an optimal emergence. White clover seeds exhibited high sensitivity to drought and salinity stress. The osmotic potential and NaCl concentration required to inhibit 50% seed germination were −0.19 MPa and 62.4 mM, respectively. Overall, these findings provide quantifiable explanations for inconsistent establishment observed in field conditions. The results obtained in this research can be used to develop effective planting strategies and support the successful establishment of white clover stands.

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.

Factors affecting seed germination, seedling emergence, and survival of texasweed (Caperonia palustris)

Weed Science ◽  
2004 ◽  
Vol 52 (6) ◽  
pp. 989-995 ◽  
Author(s):  
Clifford H. Koger ◽  
Krishna N. Reddy ◽  
Daniel H. Poston
Keyword(s):  
Seed Germination ◽  
Osmotic Potential ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Production Potential ◽  
Factors Affecting ◽  
Edaphic Conditions ◽  
Percent Germination ◽  
Ph Range ◽  
Constant Dark

Field, laboratory, and greenhouse experiments were conducted to determine the seed production potential and effect of environmental factors on germination, emergence, and survival of texasweed. Texasweed produced an average of 893 seed per plant, and 90% were viable. Seed exhibited dormancy, and prechilling did not release dormancy. Percent germination ranged from 56% for seed subjected to no prechilling to 1% for seed prechilled at 5 C for 140 d. Seed remained viable during extended prechilling conditions, with 80% of seed viable after 140 d of prechilling. Texasweed seed germinated over a range of 20 to 40 C, with optimum germination (54%) occurring with a fluctuating 40/30 C temperature regime. Seed germinated with fluctuating 12-h light/dark and constant dark conditions. Texasweed seed germinated over a broad range of pH, osmotic potential, and salt concentrations. Seed germination was 31 to 62% over a pH range from 4 to 10. Germination of texasweed ranged from 9 to 56% as osmotic potential decreased from − 0.8 MPa to 0 (distilled water). Germination was greater than 52% at less than 40 mM NaCl concentrations and lowest (27%) at 160 mM NaCl. Texasweed seedlings emerged from soil depths as deep as 7.5 cm (7% emergence), but emergence was > 67% for seed placed on the soil surface or at a 1-cm depth. Texasweed seed did not germinate under saturated or flooded conditions, but seed survived flooding and germinated (23 to 25%) after flood removal. Texasweed seedlings 2.5 to 15 cm tall were not affected by emersion in 10-cm-deep flood for up to 14 d. These results suggest that texasweed seed is capable of germinating and surviving in a variety of climatic and edaphic conditions, and that flooding is not a viable management option for emerged plants of texasweed.

Influence of Environmental Factors on Seed Germination and Emergence of Asia Minor Bluegrass (Polypogon fugax)

2016 ◽  
Vol 30 (2) ◽  
pp. 533-538 ◽  
Author(s):  
Lifeng Wang ◽  
Su Jin ◽  
Lamei Wu ◽  
Xiaomao Zhou ◽  
Xiangying Liu ◽  
...  
Keyword(s):  
Seed Germination ◽  
Environmental Factors ◽  
Light Exposure ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Dongting Lake ◽  
Asia Minor ◽  
Soil Conditions ◽  
Lake District ◽  
Dongting Lake District

Asia minor bluegrass (AmB) is a major weed impacting rapeseed production in Dongting Lake District, China. Growth chamber experiments were conducted to determine the influence of environmental factors on germination and emergence of AmB. The optimum constant temperature for germination was around 20 C. Seeds showed germination percentages above 60% under 22/15 and 24/19 C day/night temperature regimes. Seeds could germinate in the dark, but light exposure significantly enhanced the germination percentage. More than 50% of seeds germinated over a pH range between 4 and 10. Seeds were highly sensitive to osmotic stress, and germination was completely inhibited at an osmotic potential of −0.4 MPa, indicating that it was favored by a moist environment. Increasing salinity reduced germination of AmB seeds from 58% at 0 mM to 13% at 80 mM NaCl. The highest seedling emergence (62%) was observed when seeds were placed on the soil surface, and no seedlings emerged from seeds placed at a depth of 5 cm. This work shows that the climate and soil conditions in Dongting Lake District are suitable for AmB seed germination and that no-till fields, where seeds remain on the soil surface, promote the successful establishment of the weed.

Seed Germination Ecology of Junglerice (Echinochloa colona): A Major Weed of Rice

Weed Science ◽  
2009 ◽  
Vol 57 (3) ◽  
pp. 235-240 ◽  
Author(s):  
Bhagirath S. Chauhan ◽  
David E. Johnson
Keyword(s):  
Seed Germination ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Moisture Stress ◽  
The Philippines ◽  
Reduced Tillage ◽  
Burial Depth ◽  
Tillage Systems ◽  
Ph Range ◽  
The Tropics

Junglerice is one of the most serious grass weeds of rice in the tropics. Experiments were conducted in the laboratory and screenhouse to determine the influence of environmental factors on seed germination and seedling emergence of junglerice in the Philippines. In the laboratory, germination was stimulated by light, suggesting that seeds of this species are positively photoblastic. The tested temperatures (35/25, 30/20, and 25/15 C alternating day/night temperatures), however, did not influence germination. Germination in the laboratory was not affected by a soil pH range of 4 to 9, but was decreased by salinity (> 50 mM NaCl) and moisture stress (< −0.2 MPa osmotic potential). In the screenhouse, germination of junglerice was greatest (97%) for seeds at the soil surface, but emergence declined exponentially with increasing seed burial depth, and no seedlings emerged from seeds buried at 6 cm. In pots, seedling emergence declined markedly with the addition of rice residue to the soil surface at rates equivalent to 4 to 6 tonnes (t) ha−1. As germination of junglerice was strongly stimulated by light, and seedling emergence was optimal at shallow burial depths, this species is likely to be problematic in reduced tillage systems.

Seed Germination Ecology of Catchweed Bedstraw (Galium aparine)

Weed Science ◽  
2016 ◽  
Vol 64 (4) ◽  
pp. 634-641 ◽  
Author(s):  
Hongchun Wang ◽  
Bing Zhang ◽  
Liyao Dong ◽  
Yuanlai Lou
Keyword(s):  
Salt Stress ◽  
Seed Germination ◽  
Osmotic Potential ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Burial Depth ◽  
Continuous Darkness ◽  
Solution Ph ◽  
Galium Aparine ◽  
Ph Range

The influence of temperature, light, solution pH, water stress, salt stress, and burial depth on seed germination and seedling emergence of catchweed bedstraw and the sensitivity of that weed to commonly available herbicides in China were studied in laboratory and greenhouse. Germination occurred at day/night temperatures from 5/0 C to 30/25 C, with optimum germination at 15/10 C. Catchweed bedstraw germinated equally well under a 12-h photoperiod and continuous darkness; however, a 24-h photoperiod inhibited seed germination. Catchweed bedstraw seed is moderately sensitive to osmotic potential and salt stress, with 15 and 3% germination rates at an osmotic potential of −0.5 Mpa and salinity level of 120 mM, respectively. Maximum seed germination was observed in near neutral pH; germination was greater than 80% over a broad pH range from 5 to 8. Seedling emergence of the seeds buried at a depth of 1 cm was higher (74%) than those placed on the soil surface (20%), but declined with burial depth increasing. Few (10%) seedlings emerged when seeds were placed at a depth of 5 cm. Bensulfuron-methyl, and ethametsulfuron-methyl applied PRE and tribenuron-methyl, fluroxypyr, and florasulam applied POST can be used to provide greater than 80% control of catchweed bedstraw. The results of this study have contributed to more complete understanding of the germination and emergence of catchweed bedstraw.

scholarly journals Impacts of environmental factors on seed germination and seedling emergence of white clover (Trifolium repens L.)

2020 ◽  
Author(s):  
Lei Chu ◽  
Yiping Gao ◽  
Lingling Chen ◽  
Patrick E. McCullough ◽  
David Jespersen ◽  
...  
Keyword(s):  
Seed Germination ◽  
Environmental Factors ◽  
White Clover ◽  
Trifolium Repens ◽  
Germination Rate ◽  
Seedling Emergence ◽  
Soil Surface ◽  
High Sensitivity ◽  
Drought And Salt Stress ◽  
Series Of Experiments

AbstractWhite clover (Trifolium repens L.) is cultivated as a forage crop and planted in various landscapes for soil conservation. There are numerous reports of failed white clover stands each year. A good understanding of seed germination biology of white clover in relation to environmental factors is essential to achieve successful stand establishment. A series of experiments were conducted to investigate the impacts of light, temperature, planting depth, drought, and salt stress on seed germination and emergence of white clover. White clover is negatively photoblastic, and seed germination averaged 63 and 66% under light and complete dark conditions at 4 weeks after planting (WAP), respectively. Temperature affected seed germination speed and rate. At 1 WAP, seeds incubated at 15 to 25 °C demonstrated significantly higher germination rate than the low temperatures at 5 and 10 °C; however, the germination rate did not differ among the temperature treatments at 4 WAP. Results suggest that white clover germination decreases with increasing sowing depths and the seeds should be sown on the soil surface or shallowly buried at a depth ≤1 cm to achieve an optimal emergence. White clover seeds exhibited high sensitivity to drought and salinity stress. The osmotic potential and NaCl concentration required to inhibit 50% seed germination was −0.19 MPa and 62.4 mM, respectively. Overall, these findings provide quantifiable explanations for inconsistent establishment observed in field conditions. The findings obtained in this research can be used to develop effective planting strategies and support the successful establishment of white clover stands.

Influence of Environmental Factors on Seed Germination and Seedling Emergence of American Sloughgrass (Beckmannia syzigachne)

Weed Science ◽  
2008 ◽  
Vol 56 (4) ◽  
pp. 529-533 ◽  
Author(s):  
Na Rao ◽  
Liyao Dong ◽  
Jun Li ◽  
Hongjun Zhang
Keyword(s):  
Seed Germination ◽  
Environmental Factors ◽  
Osmotic Potential ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Burial Depth ◽  
Optimum Temperature ◽  
Ph Values

The influence of environmental factors on seed germination and seedling emergence of American sloughgrass was studied in laboratory and greenhouse conditions. The optimum temperature for seed germination was 10 C and light was not necessary. Seed germination was sensitive to osmotic potential and completely inhibited at an osmotic potential of −0.6 MPa, but it was quite tolerant to salinity: germination occurred even at 160 mM NaCl (36%). More than 80% of seeds germinated at pH values ranging between 4 and 10. Seedling emergence was highest when seeds were placed on the soil surface (91%) but declined with burial depth. Few (3%) seedlings emerged when seeds were planted at a depth of 5 cm. Information gained in this study will lead to a better understanding of the requirements for American sloughgrass germination and emergence.

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.

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.

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