Seed Biology and Ecology of Natalgrass (Melinis repens)

Weed Science ◽  
2011 ◽  
Vol 59 (4) ◽  
pp. 527-532 ◽  
Author(s):  
Courtney A. Stokes ◽  
Gregory E. MacDonald ◽  
Carrie Reinhardt Adams ◽  
Kenneth A. Langeland ◽  
Deborah L. Miller
Keyword(s):  
Water Stress ◽  
Seed Germination ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Field Conditions ◽  
Tropical Regions ◽  
Seed Biology ◽  
The World ◽  
Depth Of Burial ◽  
Osmotic Potentials

Natalgrass is an invasive species that has become increasingly problematic in natural areas in Florida and other subtropical and tropical regions around the world. Natalgrass is a prolific seed producer, but little information is available regarding its seed biology and ecology. Research was conducted to determine levels of seed dormancy and to examine the effects of light, temperature, pH, water stress, and depth of burial on natalgrass seed germination. In addition, seed persistence under field conditions was examined both on the soil surface and while buried. Seeds appeared to undergo afterripening. Seed germination was not light dependent and occurred from 15 to 35 C, with optimum germination occurring at 20 to 35 C. Germination occurred at pH levels of 6 and 8 and was affected by water stress; no germination was observed at osmotic potentials less than −0.2 MPa. Seeds emerged from depths of at least 5 cm. Under field conditions, germination was reduced after burial; however, burial lengths of 3 to 15 mo did not result in differences in germination levels. Seedling numbers from seed deposits on the soil surface were greatly reduced after 1 mo, and no seedling emergence was observed after 4 mo.

Germination and Seedling Development of Fringed Sagebrush (Artemisia frigida)

Weed Science ◽  
1982 ◽  
Vol 30 (1) ◽  
pp. 102-105 ◽  
Author(s):  
Robert G. Wilson
Keyword(s):  
Seed Germination ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Seedling Development ◽  
Plant Water ◽  
Artemisia Frigida ◽  
Water Potentials ◽  
Optimum Ph ◽  
Average Plant ◽  
Osmotic Potentials

Optimum germination of fringed sagebrush (Artemisia frigidaWilld.) occurred at alternating temperatures of 10 to 20 C. Seeds were able to germinate (15%) in NaCl concentrations of 5000 ppmw. Light was important in seed germination; however, its absence could be overcome by adding 30 ppmw GA3(gibberellic acid) to the germination medium. Optimum pH for germination was between 5.8 and 7.0. Depth of planting influenced seedling emergence; the greatest emergence occurred when seeds were planted on the soil surface; emergence was lower when seeds were buried at any depth in the soil. Osmotic potentials of −13 bars and greater reduced germination, but 6% of the seeds germinated at −15 bars. Fringed sagebrush seedlings tolerated average plant water potentials of −10 to −19 bars and died when water potentials were decreased to −22 bars. Mature fringed sagebrush plants were capable of producing from 16500 to 190000 seeds/plant.

Germination, and Seedling and Rosette Development of Flodman Thistle (Cirsium flodmanii)

Weed Science ◽  
1984 ◽  
Vol 32 (6) ◽  
pp. 768-773 ◽  
Author(s):  
Robert G. Wilson ◽  
Melvin K. McCarty
Keyword(s):  
Seed Germination ◽  
Gibberellic Acid ◽  
Water Potential ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Plant Water ◽  
Germination Medium ◽  
Water Potentials ◽  
Average Plant ◽  
Osmotic Potentials

Maximum germination of flodman thistle [Cirsium flodmanii(Rydb.) Arthur ♯3CIRFL] occurred at alternating temperatures of 10 to 20 and 20 to 30 C. Seeds germinated (20%) in 1.7 M NaCl. Light was important in seed germination; however, its absence could be overcome by adding 8.6 × 10-5M GA3(gibberellic acid) to the germination medium. The greatest seedling emergence occurred when seeds were planted on the soil surface and was lower when seeds were buried at any depth in the soil. Osmotic potentials at −0.5 MPa and greater reduced germination, but 3% of the seeds germinated at −1.3 MPa. Flodman thistle seedlings tolerated average plant water potentials of −0.9 and −1.1 MPa, but they died when the water potential was decreased to −1.5 MPa. Flodman thistle seedlings 43 days old and with four true leaves resprouted after topgrowth removal. Regrowth was evident on 75% of the clipped plants 13 days after initial topgrowth removal. Flodman thistle rosettes spread more rapidly and rosette survival was enhanced more in a weed-free nursery than in a weedy pasture.

Seed Germination and Seedling Emergence of Synedrella (Synedrella nodiflora) in a Tropical Environment

Weed Science ◽  
2009 ◽  
Vol 57 (1) ◽  
pp. 36-42 ◽  
Author(s):  
Bhagirath S. Chauhan ◽  
David E. Johnson
Keyword(s):  
Seed Germination ◽  
Crop Residue ◽  
Seedling Emergence ◽  
Management Strategies ◽  
Soil Surface ◽  
Burial Depth ◽  
The Family ◽  
Synedrella Nodiflora ◽  
Annual Plant Species ◽  
Osmotic Potentials

Synedrella is a tropical annual plant species of the family Asteraceae that is widely distributed in many crops in nearly 50 countries. Experiments were conducted to determine the influence of various environmental factors on seed germination and seedling emergence of synedrella. Germination response was greater at 30/20 C and 35/25 C than at 25/15 C fluctuating day/night temperatures. Light stimulated germination; however, a small proportion of after-ripened seeds germinated in the dark. Seedling emergence was greatest (96%) for seeds placed on the soil surface but declined with increased seed burial depth. No seedlings emerged from a depth of 4 cm. Seedling emergence and seedling dry matter declined with the addition of crop residue to the soil surface; however, higher quantities of residue than those normally found in low-yield systems were required to result in substantial reductions in emergence. Seed germination was tolerant of moderate salt concentrations (40 to 100 mM sodium chloride) and a broad range of pH (4 to 10) but was sensitive to low osmotic potentials (< −0.8 MPa). The information gained from this study could help predict the invasion potential of this species and could lead to improved management strategies.

Factors Affecting Seed Germination of Perennial Wall Rocket (Diplotaxis tenuifolia) in Southern Australia

Weed Science ◽  
2007 ◽  
Vol 55 (5) ◽  
pp. 481-485 ◽  
Author(s):  
Samuel G. L. Kleemann ◽  
Bhagirath S. Chauhan ◽  
Gurjeet S. Gill
Keyword(s):  
Osmotic Potential ◽  
Seedling Recruitment ◽  
Seedling Emergence ◽  
South Australia ◽  
Soil Surface ◽  
Burial Depth ◽  
Optimal Conditions ◽  
Factors Affecting ◽  
Depth Of Burial ◽  
Osmotic Potentials

Germination response of perennial wall rocket to temperature, light, osmotic potential, and depth of burial emergence was evaluated under controlled environmental conditions. The effect of seed burial depth on seedling recruitment in the field was also investigated at Roseworthy, South Australia. Under optimal conditions (30 C, light/dark) germination of perennial wall rocket was rapid, with 90% of seeds germinating within 48 h of imbibition. Germination was reduced (20%) at lower, suboptimal temperatures (10 to 20 C) when seeds of perennial wall rocket were exposed to light. Germination declined with increasing osmotic potential and was completely inhibited at osmotic potentials of −1.5 MPa. Perennial wall rocket emergence was greatest from seeds placed on the soil surface, but some seedlings (< 10%) emerged from a depth of 0.5 to 2 cm. Under both field and growth-cabinet conditions, the greatest seedling emergence of perennial wall rocket occurred from seed present on the soil surface; however, the level of absolute recruitment from the seed bank was much lower (< 5%). Information gained from this study will further improve our understanding of the germination behavior of perennial wall rocket and contribute to developing sustainable strategies for its control.

Growth, Development, and Seed Biology of Feather Fingergrass (Chloris virgata) in Southern Australia

Weed Science ◽  
2017 ◽  
Vol 65 (3) ◽  
pp. 413-425 ◽  
Author(s):  
The D. Ngo ◽  
Peter Boutsalis ◽  
Christopher Preston ◽  
Gurjeet Gill
Keyword(s):  
Seedling Emergence ◽  
Soil Surface ◽  
Summer Rainfall ◽  
Management Program ◽  
Field Conditions ◽  
Shoot Biomass ◽  
Base Temperature ◽  
Weed Species ◽  
Seed Biology ◽  
Growth Development

Feather fingergrass is a major weed in agricultural systems in northern Australia and has now spread to southern Australia. To better understand the biology of this emerging weed species, its growth, development, and seed biology were examined. Under field conditions in South Australia, seedlings that emerged after summer rainfall events required 1,200 growing degree days from emergence to mature seed production and produced 700 g m−2shoot biomass. Plants produced up to 1,000 seeds panicle−1and more than 40,000 seeds plant−1, with seed weight ranging from 0.36 to 0.46 mg. Harvested seeds were dormant for a period of about 2 mo and required 5 mo of after-ripening to reach 50% germination. Freshly harvested seed could be released from dormancy by pretreatment with 564 mM sodium hypochlorite for 30 min. Light significantly increased germination. Seed could germinate over a wide temperature range (10 to 40 C), with maximum germination at 15 to 25 C. At 20 to 25 C, 50% germination was reached within 2.7 to 3.3 d, and the predicted base temperature to germinate was 2.1 to 3.0 C. The osmotic potential and NaCl concentration required to inhibit germination by 50% were −0.16 to −0.20 MPa and 90 to 124 mM, respectively. Seedling emergence was highest (76%) for seeds present on soil surface and was significantly reduced by burial at 1 (57%), 2 (49%), and 5 cm (9%). Under field conditions, seeds buried in the soil persisted longer than those left on the soil surface, and low spring–summer rainfall increased seed persistence. This study provides important information on growth, development, and seed biology of feather fingergrass that will contribute to the development of a more effective management program for this weed species in Australia.

scholarly journals Cranberry Germination and Emergence Response to Environmental Factors and Seeding Depth

HortScience ◽  
2021 ◽  
pp. 1-8
Author(s):  
Thierry E. Besançon
Keyword(s):  
Water Stress ◽  
Seed Germination ◽  
Seedling Emergence ◽  
Red Light ◽  
Soil Surface ◽  
Average Maximum ◽  
Fruit Productivity ◽  
Diurnal Temperatures ◽  
Residual Herbicide ◽  
Over Time

Cranberry (Vaccinium macrocarpon Ait.) cultivars are clonally propagated. Germination of cranberry seeds produces off-type varieties that are generally characterized by lower fruit productivity and higher vegetative vigor. Over time, the productivity of cranberry beds decreases as off-type frequency increases over time. Improved knowledge of cranberry germination biology would facilitate the use of targeted agronomic practices to reduce the emergence and growth of less productive off-types. The influences of light, temperature regime, pH, and water potential on cranberry seed germination were assessed in a growth chamber, whereas the effect of seeding depth on seedling emergence was evaluated in a greenhouse. Seeds stratified for 6 months at 3 °C were used for these experiments. Cranberry germination was influenced by light quality, with maximum germination reaching 95% after 15 minutes of exposure to red light but decreasing to 89% under far-red light. However, light was not required for inducing germination. Cranberry seeds germinated over a range of alternating diurnal/nocturnal temperatures between 5 and 30 °C, with an average maximum germination of 97% occurring for diurnal temperatures of 20 to 25 °C. The length of emerged seedlings was reduced by an average of 75% for pH 6 to 8 compared with pH 3 to 5. Seedlings that emerged at pH greater than 5 showed increasing chlorotic and necrotic injuries and were not considered viable at pH 7 or 8. Germination at 15 °C was reduced when seeds were subjected to water stress as low as −0.2 MPa, and no germination occurred below −0.4 MPa. Seeds incubated at 25 °C were more tolerant to water stress, with at least 70% maximum germination for osmotic potential (ψS) −0.6 MPa or greater. The average seedling emergence was 91% for seeds left on the soil surface or buried at a maximum depth of 1 cm; however, it was null at a burying depth of 4 cm. These results indicate that germination of cranberry seeds in cultivated beds in the northeastern United States likely occurs during the summer months, when temperatures are optimal and the moisture requirement is supported by irrigation. However, timely application of residual herbicide or sanding (a traditional cranberry agronomic practice) of open areas in cranberry beds could help prevent seed germination and reduce minimizing the onset of off-type varieties.

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.

scholarly journals Germination Ecology of Brachiaria eruciformis in Australia and Its Implications for Weed Management

Agronomy ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 30
Author(s):  
Ahmadreza Mobli ◽  
Mahboobeh Mollaee ◽  
Sudheesh Manalil ◽  
Bhagirath Singh Chauhan
Keyword(s):  
Sodium Chloride ◽  
Seed Germination ◽  
Weed Management ◽  
Cropping Systems ◽  
Germination Rate ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Burial Depth ◽  
The World ◽  
Noxious Weed

Brachiaria eruciformis (Sm.) Griseb. is a noxious weed of Australia and other parts of the world. The effects of different environmental conditions on the seed germination and seedling emergence of three biotypes sourced from different cropping systems (mungbean field, sorghum field, and fenceline) of this weed were evaluated. There were no differences in the response of biotypes to the evaluated factors; therefore, the data was pooled across the biotypes. The highest germination rate was observed at 30/20 °C, and seeds germinated both in light and dark conditions. Seed germination was influenced by different sodium chloride (NaCl) concentrations and water potentials, and no seeds germinated at 200 mM NaCl and −0.8 MPa water potential. Seeds germinated (>70%) at a broad range of pH, from 4 to 10. Compared with seeds sown on the soil surface, a burial depth of 4 cm reduced the seedling emergence by 84%. Similarly, a sorghum residue amount of 4 t ha−1 on the soil surface reduced the seedling emergence by 65%, compared with no sorghum residue cover. No seedlings emerged from seeds buried at 8 cm depth and >4 t ha−1 sorghum residue. This study suggests that burying seeds deep into the soil through tillage or employing a residue cover on the soil surface can reduce B. eruciformis emergence.

Seed-germination responses of Calotropis procera (Asclepiadaceae) to temperature and water stress in northern Australia

2016 ◽  
Vol 64 (5) ◽  
pp. 441 ◽  
Author(s):  
E. O. Menge ◽  
S. M. Bellairs ◽  
M. J. Lawes
Keyword(s):  
Water Stress ◽  
Seed Germination ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Seed Mass ◽  
Calotropis Procera ◽  
Northern Australia ◽  
Germination Time ◽  
Seed Biology ◽  
Mean Germination Time

Understanding the seed biology of the introduced weed rubber bush (Calotropis procera (Aiton, W.T.Aiton)) is critical to its management in northern Australia. We examined the numbers of seeds produced and the effects of environmental temperature and water stress on germination performance (germinability G; mean germination time MGT) of rubber bush seeds from across northern Australia. Germination trials were conducted using seeds from wild populations monitored for 3 years. Seed numbers per fruit did not vary significantly among the six populations studied (mean ± s.e. = 433.2 ± 19.0), but seed mass did (range from 8.32 ± 0.24 to 5.24 ± 0.06 mg), with no negative correlation between the measures. Maximum seed germination (68–100%) occurred at 30°C, associated with a mean germination time of 2.58 days. Under water stress, the proportion of germinated seeds declined significantly with increasing temperature from 92.5 ± 1.1% at 20°C and 0 MPa to 2.8 ± 1.7% at 40°C and –0.4 MPa respectively. Seeds were unable to germinate at ambient temperatures ≥40°C, but remained quiescent and hence viable. Planting depth influenced seedling emergence, with minimal germination of seeds on the surface (5.8%) but 88.5% germination at 3-cm depth. The effect of water stress was dependent on temperature, with water stress inducing a reduction in optimum germination temperature from 30°C to 20°C. Phenotypic plasticity in G and MGT did not show clear patterns among populations or years. Short MGTs increase seedling survival by rapid transition from endosperm resources to photosynthesis, whereas seed quiescence (cf. dormancy) optimises germination opportunities in a semiarid environment. Thus, the germination traits reported in the present study are likely to promote seedling survival and potential spread of rubber bush in semiarid Australia.

scholarly journals Factors affecting Cyperus difformis seed germination and seedling emergence

2013 ◽  
Vol 31 (4) ◽  
pp. 823-832 ◽  
Author(s):  
A. Derakhshan ◽  
J. Gherekhloo
Keyword(s):  
Seed Germination ◽  
Integrated Management ◽  
Germination Rate ◽  
Seedling Emergence ◽  
Management Strategies ◽  
Soil Surface ◽  
Weed Species ◽  
Factors Affecting ◽  
Cyperus Difformis ◽  
Emergence Patterns

Specific knowledge about the dormancy, germination, and emergence patterns of weed species aids the development of integrated management strategies. Laboratory studies were conducted to determine the effect of several environmental factors on seed germination and seedling emergence of Cyperus difformis. Germination of freshly harvested seeds was inhibited by darkness; however, when seeds were subsequently transferred to complete light they germinated readily. Our results showed that 2 wk of cold stratification overcome the light requirement for germination. Seeds of C. difformis were able to germinate over a broad range of temperatures (25/15, 30/20, 35/25, and 40/30 ºC day/night). The response of germination rate to temperature was described as a non-linear function. Based on model outputs, the base, the optimum and the ceiling temperatures were estimated as 14.81, 37.72 and 45 ºC, respectively. A temperature of 120 ºC for a 5 min was required to inhibit 50% of maximum germination. The osmotic potential and salinity required for 50% inhibition of maximum germination were -0.47 MPa and 135.57 mM, respectively. High percentage of seed germination (89%) was observed at pH=6 and decreased to 12% at alkaline medium (pH 9) pH. Seeds sown on the soil surface gave the greatest percentage of seedling emergence, and no seedlings emerged from seeds buried in soil at depths of 1 cm.

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