Seed Germination and Seedling Emergence of Scotch Broom (Cytisus scoparius)

Weed Science ◽  
2009 ◽  
Vol 57 (6) ◽  
pp. 620-626 ◽  
Author(s):  
Timothy B. Harrington
Keyword(s):  
Seed Germination ◽  
Temperature Regime ◽  
Root Biomass ◽  
Seedling Emergence ◽  
Soil Drought ◽  
Dark Light ◽  
Scotch Broom ◽  
Effects Of Temperature ◽  
Chamber Studies ◽  
Growth Chamber Studies

Scotch broom is a large, leguminous shrub that has invaded 27 U.S. states. The species produces seeds with a hard coat that remain viable in the soil for years. Growth-chamber studies were conducted to determine effects of temperature regime and cold-stratification period on seed germination. Seedling emergence, mortality, and biomass also were studied in response to sulfometuron and metsulfuron herbicides and variation in soil texture and watering regime. Germination was greatest for a dark/light temperature regime of 15/20 C. Initial rates of germination increased as stratification period was varied from 0 to 60 d, but final germination after 90 d did not differ significantly among periods. Applied alone or in combination, sulfometuron and metsulfuron decreased biomass and increased mortality of seedlings. Mortality from simulated soil drought was greater in the presence versus absence of sulfometuron (20 and 6% mortality, respectively) probably because the herbicide reduced root biomass by 58 to 95%. Invasiveness of Scotch broom is facilitated by a prolonged period of germination across a broad temperature range. Increased control of Scotch broom seedlings with sulfometuron is likely if application is timed to expose recently emerged seedlings to developing conditions of soil drought.

Stimulation of Common Cocklebur (Xanthium pensylvanicum) and Redroot Pigweed (Amaranthus retroflexus) Seed Germination by Injections of Ethylene into Soil

Weed Science ◽  
1980 ◽  
Vol 28 (5) ◽  
pp. 510-514 ◽  
Author(s):  
G. H. Egley
Keyword(s):  
Seed Germination ◽  
Laboratory Tests ◽  
Seedling Emergence ◽  
Amaranthus Retroflexus ◽  
Redroot Pigweed ◽  
Plastic Bags ◽  
Viable Seeds ◽  
Chamber Studies ◽  
Growth Chamber Studies ◽  
Stimulation Of

The effects of ethylene upon germination of common cocklebur (Xanthium pensylvanicumWallr.) and redroot pigweed (Amaranthus retroflexusL.) seeds were studied. In laboratory tests with seeds in sealed flasks in the dark, 10 μl/L ethylene increased germination of redroot pigweed seeds from 7% to 52% at 30 C, and increased germination of large and small common cocklebur seeds from 30% and 0% to 100% and 90% respectively, at 25 C. At least 12 h of exposure to ethylene was necessary for appreciable stimulation of germination. In growth chamber studies with known numbers of seeds in pots of soil, ethylene at 11 kg/ha was injected into the soil, and the pots were enclosed in plastic bags for 24 h. One such injection at 2 weeks after planting, and successive injections at 2, 3, and 4 weeks, significantly increased redroot pigweed seedling emergence, and significantly decreased the numbers of dormant, viable seeds remaining in the soil. When pots were not enclosed, injections did not significantly effect redroot pigweed seeds, but significantly increased common cocklebur seedling emergence and decreased the number of viable common cocklebur seeds remaining in the soil.

Control of Kochia in Sugarbeets With Benzadox

Weed Science ◽  
1970 ◽  
Vol 18 (1) ◽  
pp. 183-185 ◽  
Author(s):  
D. M. Weatherspoon ◽  
E. E. Schweizer
Keyword(s):  
Acetic Acid ◽  
Beta Vulgaris ◽  
Temperature Regime ◽  
Environmental Conditions ◽  
Growth Chamber ◽  
Kochia Scoparia ◽  
Simulated Rain ◽  
Chamber Studies ◽  
Growth Chamber Studies

Benzadox [(benzamidooxy)acetic acid] applied at 1, 2, 3, and 4 lb/A as a postemergence treatment controlled kochia [Kochia scoparia(L.) Schrad.] selectively in sugarbeets (Beta vulgarisL.). Control increased as the rate of benzadox increased, but some kochia survived at the 4-lb/A rate. Competition from these plants reduced the yields of sugarbeet roots and sucrose. Where surviving kochia plants were removed by hand 7 weeks after emergence, all sugarbeets treated with benzadox yielded as well as the hand-weeded checks. In growth chamber studies, the activity of benzadox was increased by temperature and decreased by simulated rain which occurred within 4 hr following application. Under a temperature regime of 70 F day and 40 F night, if simulated rain was delayed for 8 hr, the control of kochia was identical to that obtained where no simulated rain followed treatment. The growth chamber studies confirmed our results with the performance of benzadox under different environmental conditions in the field.

scholarly journals Seed germination and seedling emergence of velvetleaf (Abutilon theophrasti) and Barnyardgrass (Echinochloa crus-galli)

2013 ◽  
Vol 31 (2) ◽  
pp. 259-266 ◽  
Author(s):  
A. Sadeghloo ◽  
J. Asghari ◽  
F. Ghaderi-Far
Keyword(s):  
Drought Stress ◽  
Seed Germination ◽  
Salinity Stress ◽  
Cropping Systems ◽  
Seedling Emergence ◽  
Abutilon Theophrasti ◽  
Medium Ph ◽  
Wide Range ◽  
Salinity Levels ◽  
Effects Of Temperature

Abutilon theophrasti and Barnyardgrass (Echinochloa crus-galli) are major weeds that affect cropping systems worldwide. Laboratory and greenhouse studies were conducted to determine the effects of temperature, pH, water and salinity stress, and planting depth on seed germination and seedling emergence of Velvetleaf and Barnyardgrass. For Velvetleaf, the base, optimum and ceiling germination temperatures were estimated as 5, 35 and 48 ºC, respectively. Seed germination was sensitive to drought stress and completely inhibited by a potential of -0.6 MPa, but it was tolerant to salinity. Salinity stress up to 45 mM had no effect on the germination of Velvetleaf, but germination decreased with increasing salt concentration. Drought and salinity levels for 50% inhibition of maximum germination were -0.3 MPa and 110 mM, respectively. Seed germination of Velvetleaf was tolerant to a wide range of pH levels. For Barnyardgrass, the base, optimum and ceiling germination temperatures were estimated as 5, 38 and 45 ºC, respectively. Seed germination was tolerant to drought stress and completely inhibited by a potential of -1.0 MPa. Salinity stress up to 250 mM had no effect on seed germination. Drought and salinity levels for 50% inhibition of maximum germination were -0.5 MPa and 307 mM, respectively. A high percentage of seed germination was observed at pH=5 and decreased to 61.5% at acidic medium (pH 4) and to 11% at alkaline medium (pH 9). Maximum seedling emergence of Velvetleaf and Barnyardgrass occurred when the seeds were placed on the surface of the soil or at a depth of 1 cm.

Modeling weed emergence as influenced by burial depth using the Fermi-Dirac distribution function

Weed Science ◽  
1997 ◽  
Vol 45 (2) ◽  
pp. 242-248 ◽  
Author(s):  
Eric P. Prostko ◽  
Hsin-I Wu ◽  
James M. Chandler ◽  
Scott A. Senseman
Keyword(s):  
Distribution Function ◽  
Abiotic Factors ◽  
Seedling Emergence ◽  
Model Parameters ◽  
Burial Depth ◽  
Data Sets ◽  
Downy Brome ◽  
Dirac Distribution ◽  
Chamber Studies ◽  
Growth Chamber Studies

Research was conducted to determine the suitability of the Fermi-Dirac distribution function for modeling the seedling emergence of downy brome, johnsongrass, and round-leaved mallow, as influenced by burial depth. Six sets of previously published emergence data were used to formulate the model and test its adequacy. Two independent johnsongrass emergence data sets were used to validate the model. Constant temperature growth chamber studies were conducted to evaluate the effects of temperature and moisture on the model parameters. The Fermi-Dirac distribution function was found to adequately describe the seedling emergence of downy brome, johnsongrass, and round-leaved mallow as indicated by a good visual data fit, narrow confidence intervals for the model parameters, and regression analysis of observed vs. modeled data. Although this function is a model used in physical science, its parameters can be related to abiotic factors such as soil texture, temperature, and moisture.

scholarly journals Inoculation Method, Temperature, and Relative Humidity Affect Leaf and Neck Anthracnose, a New Onion Disease in Michigan

2018 ◽  
Vol 19 (1) ◽  
pp. 64-68
Author(s):  
Lina M. Rodriguez-Salamanca ◽  
Rachel P. Naegele ◽  
Lina M. Quesada-Ocampo ◽  
Mary K. Hausbeck
Keyword(s):  
Relative Humidity ◽  
Disease Severity ◽  
Colletotrichum Coccodes ◽  
Conidial Suspension ◽  
New Disease ◽  
Inoculation Method ◽  
Millet Seed ◽  
Effects Of Temperature ◽  
Chamber Studies ◽  
Growth Chamber Studies

Leaf and neck anthracnose caused by Colletotrichum coccodes is a new disease of onion in Michigan. To test the effect of inoculation method, Prince onion seedlings were grown in the greenhouse and inoculated with either a conidial suspension of C. coccodes (alone or with an abrasive agent) or infested millet seed (dry or wet, 2 or 5 g). Foliar disease severity was greater when a conidial suspension (>39%) was used compared with infested millet seed (≤24.3%). Growth chamber studies were conducted using Infinity onion seedlings that were inoculated with a conidial suspension spray to determine the effects of temperature (15, 20, 25, or 30°C) and duration (0, 12, 24, 48, or 72 h) of high (95 ± 5%) relative humidity (RH) on disease severity (percentage of leaf area with C. coccodes lesions). Significant differences and interactions among temperature and RH were observed. The combination of high temperature (≥25°C) and extended (≥24 h) high RH resulted in >20% disease severity 28 days postinoculation. Results suggest that onion leaf and neck anthracnose symptoms are likely to be more severe when the environmental conditions are ≥25°C with ≥24 h of high RH.

scholarly journals Modeling the Effects of Temperature and Gibberellic Acid Concentration on Red Huckleberry Seed Germination

HortScience ◽  
2008 ◽  
Vol 43 (1) ◽  
pp. 223-228 ◽  
Author(s):  
Omar A. Lopez ◽  
Danny L. Barney ◽  
Bahman Shafii ◽  
William J. Price
Keyword(s):  
Logistic Regression ◽  
Seed Germination ◽  
Gibberellic Acid ◽  
Temperature Regime ◽  
Potassium Salt ◽  
Logistic Regression Model ◽  
Germination Percentage ◽  
Effects Of Temperature ◽  
Lag Times ◽  
Collection Sites

Low seed germination percentages have been reported for red huckleberry (Vaccinium parvifolium Smith). Attempts to improve germination percentages and the speed of germination for red huckleberry are described. Red huckleberry seeds from two collection sites were given gibberellic acid potassium salt (GA-K) treatments (0, 500, 1000, and 1500 mg·L−1) and were germinated under three temperature regimens [constant 22 °C, 22 °C day/5 °C night (22/5 °C), and 20 °C day/13 °C night (20/13 °C) with a 12-h photoperiod]. A logistic regression model was used to assess the effects of temperature regimens and GA-K treatments on the maximum cumulative germination percentages, rates of increase, and germination lag times. For seeds untreated with GA-K, the 20/13 °C temperature regime resulted in germination percentages ranging from 30% to 61% and lag times (i.e., time to reach one-half of the maximum cumulative germination percentage) of 29 to 35 d for the two accessions. In comparison, the 22/5 °C temperature regime produced germination percentages of 12% and 38% and lag times of 38 to 64 d. The 22 °C constant temperature produced germination percentages ≤1%. Maximum germination percentages of up to 75% were obtained with 1500 mg/L GA-K. Rates of germination were generally unaffected by GA-K treatments, and germination lag times were reduced by an average of 10 d when compared with without GA-K. Improved germination percentages and reduced lag times for red huckleberry seeds were obtained by using a 20/13 °C temperature regime and 1000 to 1500 mg·L −1 GA-K.

scholarly journals Seed germination and emergence of Eragrostis tenuifolia (A. Rich.) Hochst. ex Steud. in response to environmental factors

2016 ◽  
Vol 56 (1) ◽  
pp. 32-38 ◽  
Author(s):  
Henrique von Hertwig Bittencourt ◽  
Lisandro Tomas da Silva Bonome ◽  
Fortunato de Bortoli Pagnoncelli ◽  
Marcos Alberto Lana ◽  
Michelangelo Muzell Trezzi
Keyword(s):  
Seed Germination ◽  
Environmental Factors ◽  
Constant Temperature ◽  
Cover Crops ◽  
Temperature Regime ◽  
Seedling Emergence ◽  
No Tillage ◽  
Weed Species ◽  
Crop Fields ◽  
Positive Effect

AbstractEragrostis tenuifolia is a weed species that is gaining ground in Brazil. This weed occurs in pastures, grasslands, crop fields, and roadsides. The objective of this study was to examine the effects of different environmental factors on E. tenuifolia seed germination and seedling emergence. The optimum constant temperature for germination was around 35-30°C. It was also found that 85% of seeds germinated under a 30/20°C alternate temperature regime. Light appears to have a positive effect on seed germination. No seedlings emerged when seeds were buried 3 cm or deeper. The results suggested that E. tenuifolia has the potential to spread into pastures and in no-tillage crop systems in Brazil. Measures such as the use of cover crops and/or soil cultivation can be used to limit germination and seedling emergence, respectively.

Effects of placement of urea with a urease inhibitor on seedling emergence, N uptake and dry matter yield of wheat

1995 ◽  
Vol 75 (2) ◽  
pp. 449-452 ◽  
Author(s):  
Wang Xiaobin ◽  
Xin Jingfeng ◽  
C. A. Grant ◽  
L. D. Bailey
Keyword(s):  
N Uptake ◽  
Seedling Emergence ◽  
Wheat Seedling ◽  
Nitrogen Accumulation ◽  
N Availability ◽  
Urease Inhibitor ◽  
Hard Red Spring Wheat ◽  
Urea Fertilizer ◽  
Chamber Studies ◽  
Growth Chamber Studies

Growth chamber studies were conducted to determine the effect of seed-placed and surface dribble-banded urea fertilizer, with and without the addition of two levels of the urease inhibitor N-(n-butyl) thiophosphoric triamide (nBTPT) on seedling emergence, vegetative yield and nitrogen accumulation of hard red spring wheat. Seedling emergence was reduced with increasing applications of seed-placed urea, but nBTPT reduced the damage from seed-placed urea. The 0.15% inhibitor level was as effective as the 0.25% level in reducing seedling damage. Vegetative yield increased with application of urea fertilizer but no difference in vegetative yield resulted from varying fertilizer placement or additions of nBTPT. Nitrogen accumulation increased with increasing N application and with the use of the urease inhibitor, indicating an increase in N availability due to slowing of urea hydrolysis. Use of the urease inhibitor nBTPT shows promise in reducing seedling damage from seed-placed urea fertilizer and increasing the utilization of seed-placed and surface-applied urea fertilizer on a black Chernozemic soil. Further studies are in progress to assess the performance of nBTPT under field conditions. Key words: N-(n-butyl) thiophosphoric triamide

The Influence of Environmental Factors on Oryzalin Activity

Weed Science ◽  
1983 ◽  
Vol 31 (5) ◽  
pp. 752-758 ◽  
Author(s):  
James E. Nelson ◽  
William F. Meggitt ◽  
Donald Penner ◽  
James S. Ladlie
Keyword(s):  
Environmental Factors ◽  
Foxtail Millet ◽  
Grain Sorghum ◽  
Amaranthus Retroflexus ◽  
Surface Irrigation ◽  
Setaria Verticillata ◽  
Effects Of Temperature ◽  
Chamber Studies ◽  
Growth Chamber Studies ◽  
Smooth Pigweed

Effects of temperature, sunlight, soil incorporation and surface irrigation on the phytotoxicity of oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide) were studied. The activity of oryzalin applied 4 to 6 weeks prior to planting was enhanced by covering the soil with plastic as measured by the inhibition of grain sorghum [Sorghum bicolor(L.) Moench. 'Sexauer G-701′] root growth. Growth chamber studies demonstrated that oryzalin phytotoxicity to grain sorghum was greater at 20 and 25 C than at 30C. The control of foxtail millet[Setaria italica(L.) Beauv. #5SETIT] bristly foxtail[Setaria verticillata(L.) Beauv. # SETVE], redroot pigweed (Amaranthus retroflexusL. # AMARE), and smooth pigweed (Amarantbus hybridusL.), and injury to grain sorghum increased as the thoroughness of mechanical incorporation of oryzalin into soil increased. The phytotoxicity of surface-applied oryzalin increased with increasing amounts of irrigation water until it equaled the level of a preplant-incorporated treatment.

Environmental Effects on MSMA Phytotoxicity to Wild-Type and Arsenical Herbicide-Resistant Common Cocklebur (Xanthium strumarium)

1996 ◽  
Vol 10 (4) ◽  
pp. 809-814 ◽  
Author(s):  
Chandrashekhar I. Nimbal ◽  
David R. Shaw ◽  
Gene D. Wills ◽  
Stephen O. Duke
Keyword(s):  
Relative Humidity ◽  
Xanthium Strumarium ◽  
Wild Type ◽  
Fresh Weight ◽  
Low Light ◽  
Herbicide Resistant ◽  
Effects Of Temperature ◽  
Chamber Studies ◽  
Growth Chamber Studies ◽  
Weed Resistance

Effects of temperature, relative humidity, and light on MSMA phytotoxicity to wild-type and arsenical herbicide-resistant biotypes of common cocklebur grown from seed collected in Mississippi were evaluated. In growth chamber studies, 20-d-old plants were sprayed with 0.5 kg ai/ha of MSMA, and after 7 d, fresh weight and chlorophyll content were measured to estimate phytotoxicity. All three environmental factors influenced the level of weed resistance. In studies with day/night temperatures of 30/25 C and 500 μmol/m2/s PPFD light with a 14-h photoperiod, phytotoxicity of MSMA at 40% relative humidity was minimal, but was significantly greater at 60 and 90% relative humidities. The resistant (R) biotype was affected less than the susceptible (S) biotype at the higher relative humidities. The level of resistance estimated by fresh weight reduction was greatest at 30/25 C, but was most pronounced at 35/30 C using chlorophyll measurements. Resistance was lowest at 25/20 C by either measurement. MSMA phytotoxicity occurred at light intensities of 75, 500, and 750 μmol/m2/s PPFD; however, biotypic response was greatest at 500, followed by 750 μmol/m2/s PPFD. Resistance of the (R) biotype to MSMA was not significant at 75 μmol/m2/s, suggesting that differentiation between the biotypes for MSMA sensitivity would be difficult under low light.

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