scholarly journals Response of Barley Genotypes to Weed Interference in Australia

Agronomy ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 99 ◽  
Author(s):  
Gulshan Mahajan ◽  
Lee Hickey ◽  
Bhagirath Singh Chauhan
Keyword(s):  
Negative Correlation ◽  
Weed Management ◽  
Field Experiments ◽  
Yield Loss ◽  
Production Systems ◽  
Relative Yield ◽  
Organic Production ◽  
Integrated Weed Management ◽  
Weed Interference ◽  
Barley Genotypes

Weed-competitive genotypes could be an important tool in integrated weed management (IWM) practices. However, weed competitiveness is often not considered a priority for breeding high-yielding cultivars. Weed-competitive ability is often evaluated based on weed-suppressive ability (WSA) and weed-tolerance ability (WTA) parameters; however, there is little information on these aspects for barley genotypes in Australia. In this study, the effects of weed interference on eight barley genotypes were assessed. Two years of field experiments were performed in a split-plot design with three replications. Yield loss due to weed interference ranged from 43% to 78%. The weed yield amongst genotypes varied from 0.5 to 1.7 Mg ha−1. Relative yield loss due to weed interference was negatively correlated with WTA and WSA. A negative correlation was also found between WSA and weed seed production (r = −0.72). Similarly, a negative correlation was found between WTA and barley yield in the weedy environment (r = −0.91). The results suggest that a high tillering ability and plant height are desirable attributes for weed competitiveness in the barley genotypes. These results also demonstrated that among the eight barley genotypes, Commander exhibited superior WSA and WTA parameters and therefore, could be used in both low- and high-production systems for weed management. Westminster had a superior WSA parameter. Therefore, it could be used for weed management in organic production systems. These results also implied that genotypic ranking on the basis of WSA and WTA could be used as an important tool in strengthening IWM programs for barley.

scholarly journals The Critical Period for Weed Control (CPWC) in Potato (Solanum tuberosum L.)

2015 ◽  
Vol 43 (2) ◽  
pp. 355-360 ◽  
Author(s):  
Dogan ISIK ◽  
Adem AKCA ◽  
Emine KAYA ALTOP ◽  
Nihat TURSUN ◽  
Husrev MENNAN
Keyword(s):  
Weed Control ◽  
Weed Management ◽  
Critical Period ◽  
Field Experiments ◽  
Yield Loss ◽  
Cropping Systems ◽  
Control Period ◽  
Relative Yield ◽  
Yield Data ◽  
Weed Interference

Accurate assessment of crop-weed control period is an essential part for planning an effective weed management for cropping systems. Field experiments were conducted during the seasonal growing periods of potato in 2012 and 2013 in Kayseri, Turkey to assess critical period for weed control (CPWC) in potato. A four parameter log-logistic model was used to assist in monitoring and analysing two sets of related, relative crop yield. Data was obtained during the periods of increased weed interference and as a comparison, during weed-free periods. In both years, the relative yield of potato decreased with a longer period of weed-interference whereas increased with increasing length of weed free period. In 2012, the CPWC ranged from 112 to 1014 GDD (Growing Degree Days) which corresponded to 8 to 66 days after crop emergence (DAE) and between 135-958 GDD (10 to 63 DAE) in the following year based on a 5% acceptable yield loss. Weed-free conditions needed to be established as early as the first week after crop emergence and maintained as late as ten weeks after crop emergence to avoid more than 5% yield loss in the potato. The results suggest that CPWC could well assist potato producers to significantly reduce the expense of their weed management programs as well as improving its efficacy.

Economics of integrated weed management in herbicide-resistant canola

Weed Science ◽  
2006 ◽  
Vol 54 (1) ◽  
pp. 138-147 ◽  
Author(s):  
Bharat M. Upadhyay ◽  
Elwin G. Smith ◽  
G. W. Clayton ◽  
K. N. Harker ◽  
R. E. Blackshaw
Keyword(s):  
Weed Control ◽  
Weed Management ◽  
Field Experiments ◽  
Production Systems ◽  
Statistical Significance ◽  
Integrated Weed Management ◽  
Seeding Rate ◽  
Herbicide Resistant ◽  
Leaf Stage ◽  
Weed Removal

Integrated weed management (IWM) decision strategies in herbicide-resistant canola-production systems were assessed for net returns and relative risk. Data from two field experiments conducted during 1998 to 2000 at two locations in Alberta, Canada, were evaluated. A herbicide-based experiment included combinations of herbicide system (glufosinate-, glyphosate-, and imazethapyr-resistant canola varieties), herbicide rate (50 and 100% of recommended dose), and time of weed removal (two-, four-, and six-leaf stages of canola). A seed-based experiment included canola variety (hybrid and open-pollinated), seeding rate (100, 150, and 200 seeds m−2), and time of weed removal (two-, four-, and six-leaf stages of canola). For the herbicide-based experiment, strategies with glyphosate were profitable at Lacombe, but both imazethapyr and glyphosate strategies were profitable at Lethbridge. Weed control at the four-leaf stage was at least as profitable as the two-leaf stage at both sites. For the seed-based experiment, the hybrid was more profitable than the open-pollinated cultivar, seed rates of 100 and 150 seeds m−2were more profitable than 200 seeds m−2, and weed control at the two- and four-leaf stages was more profitable than at the six-leaf stage. When risk of returns and statistical significance was considered, several strategies were included in the risk-efficient set for risk-averse and risk-neutral attitudes at each location. However, the glyphosate-resistant cultivar, the 50% herbicide rate, and weed control at four-leaf stage were more frequent in the risk-efficient IWM strategy set. The open-pollinated cultivar, 200 seeds m−2rate, and weed control at the six-leaf stage were less frequent in the set. The risk-efficient sets of IWM strategies were consistent across a range of canola prices.

Planting date influences critical period of weed control in sweet corn

Weed Science ◽  
2006 ◽  
Vol 54 (5) ◽  
pp. 928-933 ◽  
Author(s):  
Martin M. Williams
Keyword(s):  
Weed Control ◽  
Weed Management ◽  
Critical Period ◽  
Sweet Corn ◽  
Relative Yield ◽  
Planting Date ◽  
Integrated Weed Management ◽  
Yield Losses ◽  
Yield Data ◽  
Weed Interference

The critical period for weed control (CPWC) identifies the phase of the crop growth cycle when weed interference results in unacceptable yield losses; however, the effect of planting date on CPWC is not well understood. Field studies were conducted in 2004 and 2005 at Urbana, IL, to determine CPWC in sweet corn for early May (EARLY) and late-June (LATE) planting dates. A quantitative series of treatments of both increasing duration of interference and length of weed-free period were imposed within each planting-date main plot. The beginning and end of the CPWC, based on 5% loss of marketable ear mass, was determined by fitting logistic and Gompertz equations to the relative yield data representing increasing duration of weed interference and weed-free periods, respectively. Weed interference stressed the crop more quickly and to a greater extent in EARLY, relative to LATE. At a 5% yield-loss level, duration of weed interference for 160 and 662 growing-degree days (GDD) from crop emergence marked the beginning of the CPWC for EARLY and LATE, respectively. When maintained weed-free for 320 and 134 GDD, weeds emerging later caused yield losses of less than 5% for EARLY and LATE, respectively. Weed densities exceeded 85 plants m−2for the duration of the experiments and predominant species included barnyardgrass, common lambsquarters, common purslane, redroot pigweed, and velvetleaf. Weed canopy height and total aboveground weed biomass were 300% and 500% higher, respectively, for EARLY compared with LATE. Interactions between planting date and CPWC indicate the need to consider planting date in the optimization of integrated weed management systems for sweet corn. In this study, weed management in mid-June–planted sweet corn could have been less intensive than early May–planted corn, reducing herbicide use and risk of herbicide carryover to sensitive rotation crops.

scholarly journals Critical Period of Weed Control in Aerobic Rice

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
M. P. Anwar ◽  
A. S. Juraimi ◽  
B. Samedani ◽  
A. Puteh ◽  
A. Man
Keyword(s):  
Weed Control ◽  
Weed Management ◽  
Critical Period ◽  
Yield Loss ◽  
Field Trials ◽  
Integrated Weed Management ◽  
Aerobic Rice ◽  
View Point ◽  
Weed Interference ◽  
Economic View

Critical period of weed control is the foundation of integrated weed management and, hence, can be considered the first step to design weed control strategy. To determine critical period of weed control of aerobic rice, field trials were conducted during 2010/2011 at Universiti Putra Malaysia. A quantitative series of treatments comprising two components, (a) increasing duration of weed interference and (b) increasing length of weed-free period, were imposed. Critical period was determined through Logistic and Gompertz equations. Critical period varied between seasons; in main season, it started earlier and lasted longer, as compared to off-season. The onset of the critical period was found relatively stable between seasons, while the end was more variable. Critical period was determined as 7–49 days after seeding in off-season and 7–53 days in main season to achieve 95% of weed-free yield, and 23–40 days in off-season and 21–43 days in main season to achieve 90% of weed-free yield. Since 5% yield loss level is not practical from economic view point, a 10% yield loss may be considered excellent from economic view point. Therefore, aerobic rice should be kept weed-free during 21–43 days for better yield and higher economic return.

Influence of barnyardgrass (Echinochloa crus-galli) time of emergence and density on corn (Zea mays)

Weed Science ◽  
1997 ◽  
Vol 45 (2) ◽  
pp. 276-282 ◽  
Author(s):  
Aca C. Bosnic ◽  
Clarence J. Swanton
Keyword(s):  
Leaf Area ◽  
Seed Production ◽  
Weed Management ◽  
Field Experiments ◽  
Yield Loss ◽  
Seedling Emergence ◽  
Integrated Weed Management ◽  
Corn Yield ◽  
Area Index ◽  
Leaf Stage

Barnyardgrass is a serious weed problem in cornfields in Ontario. Field experiments were conducted at two locations in 1994 and 1995 to determine the influence of emergence time and barnyardgrass density on corn yield loss, leaf area at 50% silking, and barnyardgrass seed production. Selected barnyardgrass densities up to 200 plants m−1were established within 12.5 cm on either side of the corn row. Barnyardgrass seeds were planted concurrently with corn and at the 3- to 5- or 1- to 2-leaf stage of corn growth in 1994 and 1995, respectively. Barnyardgrass density and seedling emergence relative to corn influenced the magnitude of corn yield loss. Maximum corn grain yield loss ranged from 26 to 35% for early emerging barnyardgrass, and less than 6% yield loss occurred from barnyardgrass seedlings emerging later than the 4-leaf stage of corn growth. Changes in corn leaf area index at 50% silking reflected the level of barnyardgrass competition in corn. Maximum leaf area reduction ranged from 21 to 23%. Barnyardgrass seed production varied with time of seedling emergence and density. Ten barnyardgrass plants emerging up to the 3-leaf stage of corn growth produced 14,400 to 34,600 seeds m−2compared to only 1,200 to 2,800 seeds m−2from plants emerging after the 4-leaf corn stage. The results of this study are essential in the development of an integrated weed management strategy for corn.

Stability of Corn (Zea mays)-Velvetleaf (Abutilon theophrasti) Interference Relationships

Weed Science ◽  
1996 ◽  
Vol 44 (2) ◽  
pp. 309-313 ◽  
Author(s):  
John L. Lindquist ◽  
David A. Mortensen ◽  
Sharon A. Clay ◽  
Richard Schmenk ◽  
James J. Kells ◽  
...  
Keyword(s):  
Weed Management ◽  
Field Experiments ◽  
Yield Loss ◽  
Abutilon Theophrasti ◽  
Corn Yield ◽  
Critical Component ◽  
Coefficient Estimates ◽  
Data Set ◽  
Weed Interference ◽  
The Stability

The crop-weed interference relationship is a critical component of bioeconomic weed management models. Multi-year field experiments were conducted at five locations to determine the stability of corn-velvetleaf interference relationships across years and locations. Two coefficients (I and A) of a hyperbolic equation were estimated for each data set using nonlinear regression procedures. The I and A coefficients represent percent corn yield loss as velvetleaf density approaches zero, and maximum percent corn yield loss, respectively. The coefficient I was stable across years at two locations, but varied across years at one location. The coefficient A did not vary across years within locations. Both coefficients, however, varied among locations. Results do not support the use of common coefficient estimates for all locations within a region.

scholarly journals Tolerance and velvetleaf (Abutilon theophrasti) suppressive ability of two old and two modern corn (Zea mays) hybrids

Weed Science ◽  
1998 ◽  
Vol 46 (5) ◽  
pp. 569-574 ◽  
Author(s):  
John L. Lindquist ◽  
David A. Mortensen
Keyword(s):  
Weed Management ◽  
Field Experiments ◽  
Yield Loss ◽  
Maximum Yield ◽  
Management Program ◽  
Integrated Weed Management ◽  
Photon Flux ◽  
Corn Yield ◽  
Area Index ◽  
Capsule Production

Improved crop tolerance and weed suppressive ability are tactics that may reduce the negative effect of weeds on crop yield. Irrigated field experiments were conducted to compare leaf area index (LAI), intercepted photosynthetic photon flux (PPF), and relative tolerance and velvetleaf suppressive ability among two old (circa 1940) and two modern corn hybrids. Each hybrid was grown in monoculture and in mixture with velvetleaf at 1, 4, 16, and 40 plants m−1row. Plants were periodically harvested in monoculture plots to obtain estimates of corn LAI, and PPF interception was measured. Variation in hybrid tolerance to velvetleaf competition for light was evaluated by comparing among hybrids the coefficients of a regression of corn yield loss on velvetleaf density. Velvetleaf seed capsule production in the presence of each hybrid was compared to evaluate variation in velvetleaf suppressive ability among hybrids. Maximum corn yield loss was 32% lower for the two old hybrids, and velvetleaf capsule production was reduced by 62% at low velvetleaf densities in 1995 compared to the modern hybrids. In 1996, yield loss of the modern hybrid 3394 was 74% lower than that of the other three hybrids at low velvetleaf densities, whereas maximum yield loss of the old hybrid 336 was 44% lower at high densities. Velvetleaf capsule production did not vary among hybrids at any velvetleaf density in 1996. Hybrids with greater tolerance and velvetleaf suppressive ability also had greater LAI and PPF interception, suggesting optimized corn LAI and PPF interception may be useful in an integrated weed management program.

scholarly journals Weed economic thresholds : Useful agronomic tool or pipe dream?

2005 ◽  
Vol 77 (1) ◽  
pp. 13-28 ◽  
Author(s):  
J.T. O’Donovan
Keyword(s):  
Weed Management ◽  
Crop Production ◽  
Production Systems ◽  
Integrated Weed Management ◽  
Practical Implementation ◽  
Weed Interference ◽  
Research Activities ◽  
Sampling Procedures ◽  
The Impact

Interest in more rational and objective approaches to weed management has increased considerably in Canada and elsewhere. Cost/benefit issues, environmental concerns, and the development of weed resistance to herbicides have cast doubt on the rationality and sustainability of prophylactic herbicide use. The concept of an economic threshold for weeds and the broader concept of integrated weed management have considerable potential as practical agronomic tools in Canadian crop production Systems. A large number of experiments have been conducted to determine the impact of weeds on crop yield, but the models developed from these studies have been put to little practical use. Constraints to the practical implementation of these concepts include a lack of realistic sampling procedures to assess the impact of weeds on crops over large areas, and a lack of information on the long-term implications of seed production by uncontrolled weeds. Weed ecologists conducting weed interference experiments should define their objectives better, and should provide guidelines on how their findings can be used at the farm level. Emphasis should be placed on the effects of the crop on the weed rather than the weed on the crop. There is also a need for greater coordination of research activities among weed ecologists. The establishment of standard protocols for long-term studies across locations and years would enhance the relevance and precision of weed interference models, and lead to the development of user- friendly decision support Systems specifically adapted to aiding rational weed management decisions in Canadian crop production Systems. The development of such Systems will be essential to the implementation of weed thresholds and integrated weed management.

scholarly journals Preliminary Reports on Comparative Weed Competitiveness of Bangladeshi Monsoon and Winter Rice Varieties under Puddled Transplanted Conditions

2021 ◽  
Vol 13 (9) ◽  
pp. 5091
Author(s):  
A. K. M. Mominul Islam ◽  
Mohammad Nasir ◽  
Mahmuda Akter Mou ◽  
Sabina Yeasmin ◽  
Md. Shafiqul Islam ◽  
...  
Keyword(s):  
Weed Management ◽  
Field Experiments ◽  
Monsoon Season ◽  
Block Design ◽  
Winter Season ◽  
Relative Yield ◽  
Integrated Weed Management ◽  
Rice Varieties ◽  
Growing Seasons ◽  
Hybrid Variety

Weed-competitive rice cultivars, a viable tool for integrated weed management of rice-field weeds, may greatly reduce the weed pressure and excessive dependence on herbicide in controlling weeds. Based on this premise, field experiments were conducted in 2018 and 2019 during the monsoon and winter rice-growing seasons at the Agronomy Field Laboratory of Bangladesh Agricultural University, Bangladesh, to evaluate the weed competitiveness of the selected rice varieties. A total of 42 monsoon and 28 winter rice varieties from Bangladesh were evaluated under “weedy” and “weed-free” conditions in the puddled transplanted system of cultivation. The field experiments were designed with three replications in a randomized complete block design. The results revealed that weed competition greatly reduces the yield of rice, and relative yield loss was 15–68% and 20–50% in monsoon and winter season rice, respectively. The lowest relative yield losses were recorded in monsoon rice from the variety BU dhan 1 (18%) and from the winter rice BRRI hybrid dhan5 (23.7%), which exhibited high weed tolerance. The weed competitive index (WCI) greatly varied among the varieties in both seasons and the monsoon season, ranging from 0.4 to 2.8, and the highest value was recorded from the hybrid variety Dhani Gold followed by BU dhan 1. In winter season rice, the WCI varied 0.25 to 2.4 and the highest value was recorded from the variety BRRI hybrid dhan3, followed by hybrid variety Heera 6. In monsoon rice, hybrid Dhani Gold was the most productive, but BU dhan 1 was the most weed competitive variety. Among the winter-grown varieties, the hybrid Heera 6 was the most productive, and the most weed competitive. Our research confirmed a high degree of variability in weed competitiveness among the 70 Bangladeshi rice varieties tested.

Weed Problems in Uruguayan Agriculture: Evolution and Current Situation

2021 ◽  
Vol 32 (5) ◽  
pp. 203-207
Author(s):  
M. Alejandro Garcia ◽  
Lucia V. Meneses ◽  
Tiago Edu Kaspary
Keyword(s):  
Weed Management ◽  
Agricultural Production ◽  
Production Systems ◽  
Integrated Weed Management ◽  
Zero Tillage ◽  
Weed Species ◽  
Management Tools ◽  
Herbicide Resistant ◽  
Species Frequencies ◽  
Agricultural Production Systems

Uruguayan agriculture has undergone dramatic changes in the last 50 years driven by the adoption of new agricultural production systems that incorporate zero tillage and herbicide resistant crops. This has resulted in a shift in weed species frequencies and the dispersion of introduced herbicide resistant weed populations. Finally, integrated weed management tools are being developed by research and extension services to manage herbicide-resistant (HR) weeds better and to reduce environmental impact of herbicides.

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