The relative competitiveness of atrazine susceptible and resistant populations of Chenopodium album and C. strictum

1981 ◽  
Vol 59 (5) ◽  
pp. 689-693 ◽  
Author(s):  
S. I. Warwick ◽  
L. Black
Keyword(s):  
Biomass Production ◽  
Aboveground Biomass ◽  
Competitive Ability ◽  
Chenopodium Album ◽  
Dry Weight ◽  
Replacement Series ◽  
Susceptible Population ◽  
Resistant Population ◽  
Reproductive Biomass ◽  
Susceptible Populations

The total aboveground biomass and reproductive dry weight of one atrazine resistant and one susceptible population from southern Ontario of each of two species of Chenopodium, C. album and C. strictum, were compared. The comparison was made between plants grown under both noncompetitive and competitive conditions. Results from a spaced noncompetitive trial provided evidence for: (1) greater total and reproductive biomass production and earlier flowering of resistant and susceptible populations of C. album as compared with both populations of C. strictum, (2) greater aboveground total and reproductive biomass production of the susceptible population of C. album as compared with the resistant population, and (3) greater total aboveground biomass production (but similar reproductive biomass) of the susceptible population of C. strictum as compared with the resistant population. Results from the competition trials (i.e., plants grown in a de Wit replacement series), provided evidence for inter- and intra-specific differences in competitive ability: (1) the susceptible population of C. album was found to be more competitive than the susceptible population of C. strictum, (2) the susceptible population of C. album was a superior competitor to the resistant population, and (3) the resistant and susceptible populations of C. strictum appeared to be equally competitive.

A Waterhemp (Amaranthus tuberculatus) Population Resistant to 2,4-D

Weed Science ◽  
2012 ◽  
Vol 60 (3) ◽  
pp. 379-384 ◽  
Author(s):  
Mark L. Bernards ◽  
Roberto J. Crespo ◽  
Greg R. Kruger ◽  
Roch Gaussoin ◽  
Patrick J. Tranel
Keyword(s):  
Dose Response ◽  
Dry Weight ◽  
Population Based ◽  
Susceptible Population ◽  
Herbicide Resistant ◽  
Synthetic Auxins ◽  
Resistant Population ◽  
Amaranthus Tuberculatus ◽  
Susceptible Populations ◽  
Dose Response Study

A waterhemp population from a native-grass seed production field in Nebraska was no longer effectively controlled by 2,4-D. Seed was collected from the site, and dose-response studies were conducted to determine if this population was herbicide resistant. In the greenhouse, plants from the putative resistant and a susceptible waterhemp population were treated with 0, 18, 35, 70, 140, 280, 560, 1,120, or 2,240 g ae ha−12,4-D. Visual injury estimates (I) were made 28 d after treatment (DAT), and plants were harvested and dry weights (GR) measured. The putative resistant population was approximately 10-fold more resistant to 2,4-D (R:S ratio) than the susceptible population based on both I50(50% visual injury) and GR50(50% reduction in dry weight) values. The R:S ratio increased to 19 and 111 as the data were extrapolated to I90and GR90estimates, respectively. GR50doses of 995 g ha−1for the resistant and 109 g ha−1for the susceptible populations were estimated. A field dose-response study was conducted at the suspected resistant site with 2,4-D doses of 0, 140, 280, 560, 1,120, 2,240, 4,480, 8,960, 17,920, and 35,840 g ha−1. At 28 DAT, visual injury estimates were 44% in plots treated with 35,840 g ha−1. Some plants treated with the highest rate recovered and produced seed. Plants from the resistant and susceptible populations were also treated with 0, 9, 18, 35, 70, 140, 280, 560, or 1,120 g ae ha−1dicamba in greenhouse bioassays. The 2,4-D resistant population was threefold less sensitive to dicamba based on I50estimates but less than twofold less sensitive based on GR50estimates. The synthetic auxins are the sixth mechanism-of-action herbicide group to which waterhemp has evolved resistance.

Wild Mustard (Brassica kaber) Resistance to Ethametsulfuron But Not to Other Herbicides

1996 ◽  
Vol 10 (4) ◽  
pp. 847-850 ◽  
Author(s):  
G. Mark Jeffers ◽  
John T. O'Donovan ◽  
Linda M. Hall
Keyword(s):  
Dry Weight ◽  
The Other ◽  
Controlled Environment ◽  
Susceptible Population ◽  
Initial Frequency ◽  
Wild Mustard ◽  
Resistant Population ◽  
Imidazolinone Herbicides ◽  
Brassica Kaber ◽  
Very High

In 1993, a wild mustard population growing in a canola crop near Wetaskiwin, AB was poorly controlled by ethametsulfuron after only one previous use of the herbicide. Controlled environment experiments were conducted to compare the response of this suspected resistant population (R) with that of a known susceptible population (S) collected near Vegreville, AB to increasing rates of ethametsulfuron, metsulfuron, chlorsulfuron, thifensulfuron, HOE 075032, imazamethabenz, imazethapyr, metribuzin, and 2,4-D. The R wild mustard population was highly resistant to ethametsulfuron, slightly resistant to low rates of metsulfuron but not resistant to any of the other herbicides tested. This suggests that the mechanism of resistance may differ from that reported for other sulfonylurea and imidazolinone herbicides. Since resistance was documented after only 2 yr of ethametsulfuron use, the initial frequency of resistance to this herbicide in wild mustard populations may be very high. Dry weight of untreated plants did not differ significantly between the S and R populations suggesting little or no differences in competitiveness between them.

Nutrient cycling in a mixed-species plantation of Eucalyptus globulus and Acacia mearnsii

2005 ◽  
Vol 35 (12) ◽  
pp. 2942-2950 ◽  
Author(s):  
David I Forrester ◽  
Jürgen Bauhus ◽  
Annette L Cowie
Keyword(s):  
Nutrient Cycling ◽  
Biomass Production ◽  
Aboveground Biomass ◽  
Eucalyptus Globulus ◽  
N Availability ◽  
Species Replacement ◽  
Mixed Species ◽  
Acacia Mearnsii ◽  
Replacement Series ◽  
Silvicultural System

A doubling of aboveground biomass production has been observed in mixtures of Eucalyptus globulus Labill. and Acacia mearnsii de Wildeman when compared with monocultures after 11 years of growth. This study examined to what extent increased nitrogen (N) availability and accelerated rates of nutrient cycling may contribute to increased growth in mixtures. Monocultures of E. globulus (E) and A. mearnsii (A) and mixtures of these species were planted in a species replacement series: 100% E, 75% E + 25% A, 50% E + 50% A, 25% E + 75% A, and 100% A. Litterfall mass increased with aboveground biomass production and was highest in 50:50 mixtures and lowest in monocultures. Owing to higher N concentrations of A. mearnsii litter, N contents of annual litterfall were at least twice as high in stands containing A. mearnsii (32-49 kg·ha–1·year–1) as in E. globulus monocultures (14 kg·ha–1·year–1). Stands with A. mearnsii also cycled higher quantities of phosphorus (P) in annual litterfall than E. globulus monocultures. This study demonstrated that mixing A. mearnsii with E. globulus increased the quantity and rates of N and P cycled through aboveground litterfall when compared with E. globulus monocultures. Thus, mixed-species plantations appear to be a useful silvicultural system to improve nutrition of eucalypts without fertilization.

scholarly journals Competitive ability of Rhinanthus minor L. in relation to productivityin the Rengen Grassland Experiment

2011 ◽  
Vol 57 (No. 2) ◽  
pp. 45-51 ◽  
Author(s):  
M. Hejcman ◽  
J. Schellberg ◽  
V. Pavlů
Keyword(s):  
Biomass Production ◽  
Aboveground Biomass ◽  
Vascular Plants ◽  
Dry Matter ◽  
Competitive Ability ◽  
Standing Biomass ◽  
Viable Population ◽  
Rhinanthus Minor ◽  
Control Application ◽  
And Control

Rhinanthus minor (yellow-rattle) can be used for restoration of species-rich grasslands but is vulnerable to competitive exclusion from high total aboveground biomass production of vascular plants. We asked (1) whether there is a threshold limit for total annual aboveground biomass production of vascular plants above which R. minor cannot establish viable population in grasslands and (2) how is cover of R. minor in grassland related to standing biomass of bryophytes. Data were collected in the Rengen Grassland Experiment (RGE) established in Germany in 1941 with following fertilizer treatments: unfertilized control, application of Ca, CaN, CaNP, CaNPKCl and CaNPK<sub>2</sub>SO<sub>4</sub>. Cover of R. minor and total annual aboveground biomass production of vascular plants were determined from 2005 to 2009. Further relationship between standing biomass of bryophytes and cover of R. minor was analyzed in 2006. Mean cover of R. minor over five years ranged from 0.7% to 12.3% in CaNPK<sub>2</sub>SO<sub>4</sub> and control treatments, respectively. Cover of R. minor was significantly negatively related to total annual aboveground biomass production of vascular plants and cover of R. minor was below 3% in all plots with total annual aboveground dry matter biomass production of vascular plants higher than 5 t/ha. Although cover of R. minor was markedly reduced in highly productive plots in the RGE, high standing biomass of bryophytes (1.8 t/ha) in low productive control was not an obstacle for establishment of its viable population. We concluded, that viable population of R. minor can be established in grasslands only if total annual aboveground dry matter biomass production of vascular plants is below 5 t/ha regardless on standing biomass of bryophytes.

Differential Response of Fall Panicum (Panicum dichotomiflorum) Populations in Florida Sugarcane to Asulam

2018 ◽  
Vol 32 (6) ◽  
pp. 762-767 ◽  
Author(s):  
Jose V. Fernandez ◽  
D. Calvin Odero ◽  
Gregory E. MacDonald ◽  
Jason A. Ferrell ◽  
Brent A. Sellers ◽  
...  
Keyword(s):  
Weight Reduction ◽  
Aboveground Biomass ◽  
Dry Weight ◽  
Differential Response ◽  
Single Application ◽  
Susceptible Population ◽  
Sugarcane Production ◽  
Biomass Harvesting ◽  
Evolution Of Resistance ◽  
Panicum Dichotomiflorum

AbstractSugarcane growers in Florida have been reporting reduced control of fall panicum with asulam, the main herbicide used for POST grass control. Therefore, outside container experiments were conducted to determine the response of four fall panicum populations from Florida to asulam applied alone and to evaluate whether tank-mix combination with trifloxysulfuron enhances control. Asulam was applied at 230 to 7,400 g ai ha−1, corresponding to 1/16 to 2X the maximum labeled rate for a single application in sugarcane, with or without combination with trifloxysulfuron at 16 g ai ha−1. Three fall panicum populations were collected from fields in which reduced control had been reported, while one population was from a field not used for sugarcane production but adjacent to a sugarcane field. The potency of asulam based on ED50values (the rate required to cause 50% dry weight reduction at 28 d after treatment) ranged from 2,249 to 5,412 g ha−1for tolerant populations with reported reduced fall panicum control compared with 1,808 g ha−1for the susceptible population from the field not used for sugarcane production, showing that the latter was most sensitive to asulam. Addition of trifloxysulfuron to asulam increased potency on fall panicum by 5- to 15-fold, indicating that the tank mix enhanced dry weight reduction for all populations. The probability of fall panicum survival (regrowth after aboveground biomass harvesting) at the labeled rate of asulam ranged from 2% to 47% compared with 0% to 6% when trifloxysulfuron was added to the tank mix. Our results show differential response of fall panicum populations in Florida to asulam, which can be overcome by tank mixing with trifloxysulfuron even for populations that are difficult to control in sugarcane, but no evolution of resistance to asulam.

scholarly journals RELATIVE COMPETITIVENESS OF GOOSEGRASS BIOTYPES AND SOYBEAN CROPS

2017 ◽  
Vol 30 (2) ◽  
pp. 271-277 ◽  
Author(s):  
JADER JOB FRANCO ◽  
DIRCEU AGOSTINETTO ◽  
ANA CLAUDIA LANGARO ◽  
LAIS TESSARI PERBONI ◽  
LEANDRO VARGAS
Keyword(s):  
Competitive Ability ◽  
Total Population ◽  
Dry Weight ◽  
Replacement Series ◽  
Genetically Modified Soybean ◽  
Eleusine Indica ◽  
Soybean Crop ◽  
Shoot Dry Weight ◽  
Control Failure ◽  
Level Resistance

ABSTRACT The goosegrass (Eleusine indica (L.) Gaertn) is an annual plant that has a low-level resistance to glyphosate (LLRG), resulting in control failure in genetically modified soybean crops for resistance to this herbicide. Alleles related to resistance may cause changes in the plant biotype, such as inferior competitive ability. Thus, the objective of this work was to evaluated the competitive ability of soybean crops and susceptible and resistant (LLRG) goosegrass biotypes. Replacement series experiments were conducted with soybean crops and goosegrass biotypes. The ratios of soybean to susceptible or resistant (LLRG) goosegrass plants were 100:0, 75:25, 50:50, 25:75 and 0:100, with a total population of 481 plants m-2. The leaf area, plant height and shoot dry weight were evaluated at 40 days after emergence of the soybean crops and weeds. The soybean crop had superior competitive ability to the susceptible and resistant (LLRG) goosegrass biotypes. The soybean crop showed similar competitive ability in both competitions, either with the susceptible or resistant (LLRG) goosegrass biotypes. The intraspecific competition was more harmful to the soybean crop, while the interspecific competition caused greater damage to the goosegrass biotypes competing with the soybean crop.

scholarly journals KEMAMPUAN KOMPETISI RELATIVE TEBU-PRG EVENT-5 TERHADAP GULMA DAUN SEMPIT DAN DAUN LEBAR MELALUI PENDEKATAN REPLACEMENT SERIES (RELATIVE COMPETITIVE ABILITY OF SUGARCANE EVENT-5 AND ITS PRIMARY WEEDS USING REPLACEMENT SERIES APPROACH)

2016 ◽  
Vol 16 (1) ◽  
Author(s):  
Netty Ermawati ◽  
Nurmala Sari ◽  
Novita Cholifah Ida ◽  
Bambang Sugiharto
Keyword(s):  
Competitive Ability ◽  
Genetically Modified ◽  
Block Design ◽  
Dry Weight ◽  
Sucrose Phosphate Synthase ◽  
Security Requirements ◽  
Replacement Series ◽  
Ability Test ◽  
Transgenic Sugarcane ◽  
Combination Treatments

Event-5 is a genetically modified (GM) sugarcane that engineered by introducing the Sucrose-Phosphate Synthase (SPS) gene to enhance the sugar productivity. To fulfill the security requirements of genetically modified products in the safety agriculture and the enviroment, it is necessary to test the competitive ability to the primary weeds which grow in the sugarcane cultivation areas. This study aimed to determine whether the transgenic sugarcane (Event-5) potentially invasive to the weeds at the critical stage of growth, that could effect the environmental balances. This research was conducted at Screen House and Laboratory for Biosciences, State Polytechnic of Jember, designed using the replacement series method in a Randomized Complete Block Design without factorial treatment. The combination treatments were Event-5, Non-transgenic sugarcane (NT) and the weeds (Ciperus rotundus and Portulaca olecarea) densities which consists of thirty-three treatments. The competitive ability test was determined by the rate of vegetative growth and the relative dry weight biomass of Event-5, NT plant and the weeds. The results indicated that the growth rate of Event-5, as well as the accumulation of dry weight of transgenic sugarcane were highly decrease than those of the weeds. The relative crowding coefficient (RCC) value of Event-5 showed lower compared to the P. olecarea weed, and sligtly higher to the C. rotundus weed. The RCC value of weed (C. rotundus) was higher than the RCC value of Event-5, suggested that the weed was potentially invasive to the transgenic sugarcane, and the Event-5 was not potential as a weed. 

scholarly journals Aboveground Biomass Production and Nitrogen Content of Gliricidia Sepium under Different Pruning Regime- A Case Study at the Department of Agroforestry Farm (Kwame Nkrumah University of Science and Technology-KNUST)

2020 ◽  
Vol 5 (9) ◽  
pp. 149-153
Author(s):  
Christian Tettey Agbana ◽  
Elvis Wireko Boampong
Keyword(s):  
Nitrogen Content ◽  
Biomass Production ◽  
Aboveground Biomass ◽  
Nitrogen Concentration ◽  
Dry Weight ◽  
Nutrient Content ◽  
Gliricidia Sepium ◽  
Kwame Nkrumah ◽  
Matter Production ◽  
Pruning Regime

Gliricidia sepium is considered one of the commonly used multipurpose legume shade trees in Ghana. Different pruning regimes affect the nutrient content as the amount of biomass produced by many multipurpose trees. In this study, the aboveground biomass (both fresh and dry matter) production and nitrogen content in Gliricidia sepium under different pruning regimes (4, 8 and 12 weeks) was studied. The study was carried out in the demonstration farm of Department of Agroforestry in the Faculty of Renewable Natural Resources-KNUST. A total of nine (9) Gliricidia trees were selected. The pruning frequencies were assigned to the selected trees, after an initial pruning of 1.2m from the ground. The data collected include; new fresh weight, dry weight and nitrogen content at the various pruning time. Also, the amount of nitrogen (N) in the new biomass was estimated at each pruning time. The result shows that the aboveground biomass production increased from 4 weeks to 12 weeks regime. Overall nitrogen concentration increased from 2.61% to 3.58% upon reducing the pruning frequency from 4 to 12 weeks, and total nitrogen content was much higher in 12 weeks (36.01g) than in the other pruning frequencies, due to biomass production been larger. In conclusion, the study highlights the potential of Gliricidia biomass as a source of N and green manure for both agricultural and agroforestry purposes. Hence pruning regime of Gliricidia should be considered in managing it for nutrient and manure purposes.

Paraquat resistance in horseweed (Conyza canadensis) and Virginia pepperweed (Lepidium virginicum) from Essex County, Ontario

Weed Science ◽  
1998 ◽  
Vol 46 (2) ◽  
pp. 200-204 ◽  
Author(s):  
Alida Smisek ◽  
Colleen Doucet ◽  
Martha Jones ◽  
Susan Weaver
Keyword(s):  
Dose Response ◽  
Dry Weight ◽  
Repeated Exposure ◽  
Conyza Canadensis ◽  
Essex County ◽  
Shoot Dry Weight ◽  
Paraquat Resistance ◽  
Resistant Population ◽  
Susceptible Populations ◽  
Fruit Orchards

Populations of horseweed and Virginia pepperweed resistant to the herbicide paraquat were found in several fruit orchards in Essex County, Ontario, Canada, where paraquat had been applied four to five times per year for at least 10 yr. Dose–response experiments were conducted in the greenhouse for each species, using 2-to 4-mo-old plants from populations that had received repeated exposure to paraquat and those that had not. The paraquat dose that reduced shoot dry weight by 50% (ED50) was estimated for each population. Resistant populations of horseweed had ED50 values 25 to 35 times higher than susceptible populations. A resistant population of Virginia pepperweed had an ED50 10 times higher than susceptible populations.

scholarly journals Subirrigation of Quercus rubra Seedlings: Nursery Stock Quality, Media Chemistry, and Early Field Performance

HortScience ◽  
2008 ◽  
Vol 43 (7) ◽  
pp. 2179-2185 ◽  
Author(s):  
Mindy L. Bumgarner ◽  
K. Francis Salifu ◽  
Douglass F. Jacobs
Keyword(s):  
Biomass Production ◽  
Aboveground Biomass ◽  
Quercus Rubra ◽  
Field Performance ◽  
Dry Weight ◽  
Nutrient Content ◽  
Forest Tree ◽  
Red Oak ◽  
Tree Seedlings ◽  
Northern Red Oak

Container seedling production systems for forest tree nurseries are challenged by the need for judicious water consumption. Subirrigation systems may provide an alternative to overhead systems by mitigating water use, yet remain relatively untested for propagation of forest tree seedlings. We evaluated effects of overhead versus subirrigation under varying media (40:60, 60:40, and 80:20 peat:perlite) and fertilization (0 or 1.2 g nitrogen/plant) regimes on nursery development and first-year field performance of northern red oak (Quercus rubra L.) seedlings. Fertilization increased aboveground biomass production and nutrient content, but decreased root dry weight. Relative to overhead-irrigated seedlings, subirrigation increased red oak seedling aboveground biomass production as well as above- and belowground nitrogen content under fertilized conditions. Media had no effect on plant response. Subirrigation increased electrical conductivity (5 dS·m−1 greater) and decreased pH in the upper media zone (0 to 5 cm from top), whereas the opposite effect was found in the lower zone. Nursery fertilization was associated with reduced field survival and growth, which may have been the result of transplant stress resulting from higher shoot:root. Subirrigated seedlings had greater field diameter growth. Our results suggest that subirrigation could serve as a viable alternative to overhead systems in container propagation of hardwood seedlings.

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