The Experts below are selected from a list of 24255 Experts worldwide ranked by ideXlab platform
Bhagirath S. Chauhan - One of the best experts on this subject based on the ideXlab platform.
-
Effect of narrow row-spacing and weed crop Competition duration on cotton productivity
Archives of Agronomy and Soil Science, 2020Co-Authors: Nadeem Iqbal, Sudheesh Manalil, Bhagirath S. Chauhan, Steve W. AdkinsAbstract:Amongst all biotic factors, weeds pose the most serious threat to successful cotton production. Adoption of conservation agriculture, the evolution of herbicide-resistant weed populations, and the ...
-
Glyphosate-induced hormesis: impact on seedling growth and reproductive potential of common sowthistle (Sonchus oleraceus)
Weed Science, 2020Co-Authors: Ahmadreza Mobli, Amar Matloob, Bhagirath S. ChauhanAbstract:AbstractIn Australia, glyphosate is widely used in glyphosate-tolerant crops and fallows to control weeds such as common sowthistle (Sonchus oleraceus L.). It has been hypothesized that glyphosate at sublethal doses, as a consequence of herbicide drift, may have a stimulatory effect on S. oleraceus growth. In 2017, pot trials were conducted to evaluate the effect of low doses of glyphosate on growth and seed production of this weed at the Weed Science Screenhouse Facility at the University of Queensland, Australia. At the 4- to 5-leaf stage (3-wk-old rosette), plants were treated with low doses of glyphosate (0 [control], 5, 10, 20, 40, 80, and 800 g ae ha−1), and their responses were recorded until plant maturity. The study was repeated after completion of the first experimental run. An additional glyphosate dose (2.5 g ha−1) was added in the second run. The low doses of glyphosate (<40 g ha−1) caused a significant increase in S. oleraceus plant height and number of leaves compared with the no-glyphosate treatment. The highest stimulatory effect was observed at 5 g ha−1. At 5 g ha−1 glyphosate, S. oleraceus seed production increased by 154% and 101% in the first and second experimental runs, respectively, compared with the no-glyphosate treatment. The results of this study suggest that the sublethal doses of glyphosate produced hormetic effects on growth and seed production of S. oleraceus that changed the dynamics of weed–crop Competition.
-
Enhanced weed‐crop Competition effects on growth and seed production of herbicide‐resistant and herbicide‐susceptible annual sowthistle (Sonchus oleraceus)
Weed Biology and Management, 2020Co-Authors: Ahmadreza Mobli, Sahil, Rajpaul Yadav, Bhagirath S. ChauhanAbstract:Enhanced crop Competition could aid in the management of annual sowthistle (Sonchus oleraceus L.), a dominant weed of Australian cropping systems. A two-year pot study was conducted to evaluate the effect of wheat (Triticum aestivum L.) planting densities (0, 82, and 164 wheat plants/m) on growth and seed production of glyphosate-resistant (GR) and glyphosate-susceptible (GS) biotypes of annual sowthistle. Without Competition, both biotypes produced a similar number of leaves and biomass, but the GS biotype produced 80% more seeds (46,050 per plant) than the GR biotype. In Competition with 164 wheat plants/m, the number of leaves in the GR and GS biotypes was reduced by 62 and 61%, respectively, in comparison with the no-Competition treatment, and similarly, weed biomass was reduced by 78 and 77%, respectively. Compared to no-Competition treatment, the seed production of GR and GS biotypes was reduced by 33 and 69%, respectively, when grown with 82 wheat plants/m, but increasing wheat density from 82 to 164 plants/m reduced the number of seeds only in the GS biotype (81%). Both biotypes produced greater than 6,000 seeds per plant when grown in Competition with 164 plants/m, suggesting that increased crop density should be integrated with other weed management strategies for efficient control of annual sowthistle.
-
Parthenium weed (Parthenium hysterophorus) Competition with grain sorghum under arid conditions
Experimental Agriculture, 2020Co-Authors: Ali Ahsan Bajwa, Bhagirath S. Chauhan, Ahmad Nawaz, Muhammad Farooq, Steve W. AdkinsAbstract:Parthenium weed is an invasive species in a growing number of countries where it infests numerous crop fields, including sorghum. Two field studies were conducted to quantify the effect of parthenium weed on the performance of grain sorghum at different weed densities (0, 5, 10, 15 and 20 plants m) and durations of Weed-Crop Competition (season-long weed-free, weed-free after 2, 4, 6 or 8 weeks, and season-long weedy). Our aim was to identify the density threshold and ideal duration to control parthenium weed in sorghum fields. Both field experiments were planned in a randomised complete block design each with three replications in 2016 and were repeated in 2017. Parthenium weed biomass increased significantly with increasing density and Competition duration. The increasing parthenium weed density had a linear negative effect on sorghum growth, yield and yield-contributing traits. The highest yield loss, of up to 66%, was recorded at the highest parthenium weed density of 20 plants m when compared to weed-free treatment. In addition, the season-long Competition of this weed with sorghum caused 81% reduction in grain yield over weed-free treatment. According to our results, parthenium weed should be managed below a density of 5 plants m and throughout the crop growth duration in grain sorghum fields as it can cause serious yield losses even at low densities and through strong Competition at early as well as late growth stages of the crop.
-
Effect of parthenium weed on maize yield at different Competition durations in Ethiopia
2018Co-Authors: Ali Ahsan Bajwa, Bhagirath S. Chauhan, Tamado Tana, Steve W. AdkinsAbstract:Parthenium weed (Parthenium hysterophorus L.) is an invasive weed species in more than 40 countries, including Australia. It infests several major crops and causes substantial yield losses. It is important to determine its critical Competition duration in different crops to devise a suitable management strategy. A field study was conducted to evaluate the effect of parthenium weed on maize at different Weed-Crop Competition durations in Ethiopia. Six treatments applied included: season-long weed-free; weed-free after 2, 4, 6 and 8 weeks of crop emergence; and seasonlong weedy. Parthenium weed biomass increased with increasing Competition duration. Parthenium weed negatively affected the growth, yield and yield related traits of maize at all Competition durations; however, more reductions in all these parameters were observed at longer parthenium weed Competition durations. The highest and lowest values for leaf area index, ears per plant, thousand grain weight, grain yield and biological yield were observed in season-long weedfree and season-long weedy treatments, respectively. Parthenium weed Competition for 2, 4, 6 and 8 weeks after crop emergence caused 3, 6, 8 and 15% losses in maize grain yield, respectively, when compared with the season-long weed-free treatment. It is important to note that the yield reductions in plots which were kept weed-free after 8 weeks were similar as in those kept weedy throughout the season. The results suggest that management strategies should be devised to control parthenium weed in maize during the critical Competition period of 4–8 weeks after crop emergence.
Rukhsana Bajwa - One of the best experts on this subject based on the ideXlab platform.
-
The effect of sunflower leaf extracts on Chenopodium album in wheat fields in Pakistan
Crop Protection, 2007Co-Authors: Tehmina Anjum, Rukhsana BajwaAbstract:Abstract In search of natural alternatives for weed management against Chenopodium album L., extracts of sunflower leaves (var. Suncross-42) were tested in two aqueous concentrations. The activity of a crude aqueous extract was evaluated taking MCPA as internal reference. Sunflower leaf extracts allelochemicals showed substantial potential to be used as natural herbicide for broadleaved weeds such as C. album. In comparison with synthetic herbicides the crude extract failed to eradicate this weed completely, but the highest tested concentration successfully killed the weed and overcame weed crop Competition and consequently increased wheat yield significantly.
-
Field appraisal of herbicide potential of sunflower leaf extract against Rumex dentatus
Field Crops Research, 2006Co-Authors: Tehmina Anjum, Rukhsana BajwaAbstract:Abstract Comparative evaluation of sunflower aqueous extracts and commercially available synthetic herbicides was carried out in field trials. Crude aqueous extract was tested in 80 and 100% concentrations in plots where wheat was grown with Rumex dentatus in a 1:1 mix. In comparison with the synthetic herbicides (Buctril-Super ® and Chwastox ® ) the aqueous extract failed to kill 100% of selected weeds, but the highest tested extract concentration completely overcame weed crop Competition by reducing the weed biomass and increasing wheat yield significantly. The trial confirmed the herbicidal potential of sunflower allelochemicals against broad leaf weeds.
Tehmina Anjum - One of the best experts on this subject based on the ideXlab platform.
-
The effect of sunflower leaf extracts on Chenopodium album in wheat fields in Pakistan
Crop Protection, 2007Co-Authors: Tehmina Anjum, Rukhsana BajwaAbstract:Abstract In search of natural alternatives for weed management against Chenopodium album L., extracts of sunflower leaves (var. Suncross-42) were tested in two aqueous concentrations. The activity of a crude aqueous extract was evaluated taking MCPA as internal reference. Sunflower leaf extracts allelochemicals showed substantial potential to be used as natural herbicide for broadleaved weeds such as C. album. In comparison with synthetic herbicides the crude extract failed to eradicate this weed completely, but the highest tested concentration successfully killed the weed and overcame weed crop Competition and consequently increased wheat yield significantly.
-
Field appraisal of herbicide potential of sunflower leaf extract against Rumex dentatus
Field Crops Research, 2006Co-Authors: Tehmina Anjum, Rukhsana BajwaAbstract:Abstract Comparative evaluation of sunflower aqueous extracts and commercially available synthetic herbicides was carried out in field trials. Crude aqueous extract was tested in 80 and 100% concentrations in plots where wheat was grown with Rumex dentatus in a 1:1 mix. In comparison with the synthetic herbicides (Buctril-Super ® and Chwastox ® ) the aqueous extract failed to kill 100% of selected weeds, but the highest tested extract concentration completely overcame weed crop Competition by reducing the weed biomass and increasing wheat yield significantly. The trial confirmed the herbicidal potential of sunflower allelochemicals against broad leaf weeds.
Amar Matloob - One of the best experts on this subject based on the ideXlab platform.
-
Glyphosate-induced hormesis: impact on seedling growth and reproductive potential of common sowthistle (Sonchus oleraceus)
Weed Science, 2020Co-Authors: Ahmadreza Mobli, Amar Matloob, Bhagirath S. ChauhanAbstract:AbstractIn Australia, glyphosate is widely used in glyphosate-tolerant crops and fallows to control weeds such as common sowthistle (Sonchus oleraceus L.). It has been hypothesized that glyphosate at sublethal doses, as a consequence of herbicide drift, may have a stimulatory effect on S. oleraceus growth. In 2017, pot trials were conducted to evaluate the effect of low doses of glyphosate on growth and seed production of this weed at the Weed Science Screenhouse Facility at the University of Queensland, Australia. At the 4- to 5-leaf stage (3-wk-old rosette), plants were treated with low doses of glyphosate (0 [control], 5, 10, 20, 40, 80, and 800 g ae ha−1), and their responses were recorded until plant maturity. The study was repeated after completion of the first experimental run. An additional glyphosate dose (2.5 g ha−1) was added in the second run. The low doses of glyphosate (<40 g ha−1) caused a significant increase in S. oleraceus plant height and number of leaves compared with the no-glyphosate treatment. The highest stimulatory effect was observed at 5 g ha−1. At 5 g ha−1 glyphosate, S. oleraceus seed production increased by 154% and 101% in the first and second experimental runs, respectively, compared with the no-glyphosate treatment. The results of this study suggest that the sublethal doses of glyphosate produced hormetic effects on growth and seed production of S. oleraceus that changed the dynamics of weed–crop Competition.
-
Weeds of Direct-Seeded Rice in Asia: Problems and Opportunities
Advances in Agronomy, 2015Co-Authors: Amar Matloob, Abdul Khaliq, Bhagirath S. ChauhanAbstract:Rice production symbolizes the single largest land use for food production on the Earth. The significance of this cereal as a source of energy and income seems overwhelming for millions of people in Asia, representing 90% of global rice production and consumption. Estimates indicate that the burgeoning population will need 25% more rice by 2025 than today's consumption. As the demand for rice is increasing, its production in Asia is threatened by a dwindling natural resource base, socioeconomic limitations, and uncertainty of climatic optima. Transplanting in puddled soil with continuous flooding is a common method of rice crop establishment in Asia. There is a dire need to look for rice production technologies that not only cope with existing limitations of transplanted rice but also are viable, economical, and secure for future food demand.Direct seeding of rice has evolved as a potential alternative to the current detrimental practice of puddling and nursery transplanting. The associated benefits include higher water productivity, less labor and energy inputs, less methane emissions, elimination of time and edaphic conflicts in the rice-wheat cropping system, and early crop maturity. Realization of the yield potential and sustainability of this resource-conserving rice production technique lies primarily in sustainable weed management, since weeds have been recognized as the single largest biological constraint in direct-seeded rice (DSR). Weed Competition can reduce DSR yield by 30-80% and even complete crop failure can occur under specific conditions. Understanding the dynamics and outcomes of Weed-Crop Competition in DSR requires sound knowledge of weed ecology, besides production factors that influence both rice and weeds, as well as their association. Successful adoption of direct seeding at the farmers' level in Asia will largely depend on whether farmers can control weeds and prevent shifts in weed populations from intractable weeds to more difficult-to-control weeds as a consequence of direct seeding. Sustainable weed management in DSR comprises all the factors that give DSR a competitive edge over weeds regarding acquisition and use of growth resources. This warrants the need to integrate various cultural practices with weed control measures in order to broaden the spectrum of activity against weed flora. A weed control program focusing entirely on herbicides is no longer ecologically sound, economically feasible, and effective against diverse weed flora and may result in the evolution of herbicide-resistant weed biotypes. Rotation of herbicides with contrasting modes of action in conjunction with cultural measures such as the use of weed-competitive rice cultivars, sowing time, stale seedbed technique, seeding rate, crop row spacing, fertilizer and water inputs and their application method/timing, and manual and mechanical hoeing can prove more effective and need to be optimized keeping in view the type and intensity of weed infestation. This chapter tries to unravel the dynamics of Weed-Crop Competition in DSR. Technological issues, limitations associated with DSR, and opportunities to combat the weed menace are also discussed as a pragmatic approach for sustainable DSR production. A realistic approach to secure yield targets against weed Competition will combine the abovementioned strategies and tactics in a coordinated manner. This chapter further suggests the need of multifaceted and interdisciplinary research into ecologically based weed management, as DSR seems inevitable in the near future.
-
Weed-Crop Competition period in three fine rice cultivars under direct-seeded rice culture.
Pakistan Journal of Weed Science Research, 2011Co-Authors: Abdul Khaliq, Amar MatloobAbstract:Weeds are a serious biological constraint to rice production. The establishment of critical period of weed Competition is central in the development of an effective weed management program. A field study was carried out to determine the critical period of weed Competition in three cultivars of fine direct-seeded rice viz. Super Basmati, Basmati 2000 and Shaheen Basmati. Weeds were allowed to initially grow and compete with rice for 10, 20, 30, 40, 50 days after sowing (DAS) and a season long Competition plot was also maintained. Weed flora of the experimental site comprised of Echinochloa crus-galli, E. colona, Dactyloctenium aegyptium, Leptochloa chinensis, Eleusine indica, Cyperus rotundus and C. iria and Trianthema portulacastrum, Ipomoea aquatica and Portulaca oleracea. The highest weed density was recorded between 20 and 30 DAS for all cultivars while maximum weed biomass was recorded at 50 DAS. Yield losses due to Weed-Crop Competition were most pronounced during the period from 30 to 50 DAS. Rice yield continued to decline as the duration of weed Competition increased. Weed Competition beyond 20 DAS resulted in drastic reduction in the number of panicles m -2 and grains panicle -1 that accounted for lower rice yield. Broadleaved weeds represent >50% of total weed dry biomass in Super and Shaheen Basmati during early season while grasses and sedges contributed over 80% at harvest, with grasses alone contributing by ca. 65%. The period within 20 to 50 DAS appeared to be an important factor in crop weed Competition in dry direct-seeded rice.
Laura Armengot - One of the best experts on this subject based on the ideXlab platform.
-
Tillage as a driver of change in weed communities: a functional perspective
Agriculture Ecosystems & Environment, 2016Co-Authors: Laura Armengot, J.m. Blanco-moreno, Paolo Bàrberi, Gionata Bocci, Stefano Carlesi, R. Aendekerk, Alfred Berner, Florian Celette, Meike Grosse, H.f. HuitingAbstract:Abstract The adoption of non-inversion tillage practices has been widely promoted due to their potential benefits in reducing energy consumption and greenhouse emissions as well as improving soil fertility. However, the lack of soil inversion usually increases weed infestations and changes the composition of the weed community. Weed management is still a main drawback for the wider adoption of reduced tillage practices. However, it is not entirely clear whether these changes in weed communities are a consequence of non-random filters on the functional attributes of weed species and may thus affect the potential Weed-Crop Competition relationship. Here, we analyse the changes in weed diversity, community composition, and the functional attributes of weed communities under reduced (non-inversion) and conventional (inversion) tillage. We discuss their potential effects on the competitiveness against crop production using data from two crops of seven on-going organic and low-input field trials in different climatic regions across Europe. Weeds were evaluated after post-emergence weed control methods. We used the community weighted mean values of the life form (annuals versus perennials), specific leaf area, seed weight, canopy height, seed bank longevity, soil nutrient conditions affinity, beginning of flowering and flowering span. Moreover, the effect of the crop type on the functional attributes was also evaluated. Overall, the tillage system affected the composition and functional attributes of the weed communities. Weed community changes may imply a reduction in Weed-Crop Competition under both tillage systems. For instance, weed communities under reduced tillage were potentially less competitive because they were shorter and had less affinity to nutrients. On the other hand, weed communities under conventional tillage had potentially less seed production and a lower abundance of perennial species. Our study thus supports tillage as an important driver of the functional attributes of weed communities, but both tillage systems can have their downside. However, the crop type was overall more relevant than the tillage in determining most of the trait values of the weed communities.
-
Weed harrowing in organically grown cereal crops avoids yield losses without reducing weed diversity
Agronomy for Sustainable Development, 2013Co-Authors: Laura Armengot, Laura José-maría, Lourdes Chamorro, Francesc SansAbstract:This report shows that weed harrowing in organic cereal fields is an efficient alternative to herbicides since weed harrowing does not reduce yields compared to weed-free plots. Arable weeds provide resources and habitat to many organisms. However, weeds are the most important constraint to crop production. Indeed, the potential crop losses of the eight major crops due to weed–crop Competition amount to about 30 %. New ways of food production are needed due to the current severe biodiversity decline, about 1,000 times higher than the natural rate of species loss, and the growing food demands. Herbicides are highly efficient at reducing crop losses due to weed–crop Competition, but at the expense of declining biodiversity. Studies have shown a poor efficiency of weed harrows in terms of weed reduction in organic farming systems. Here, we evaluated the feasibility of weed harrows in organic fields to reduce weeds to a threshold that does not limit crop production, while maintaining a rich flora. The results were compared to results obtained using herbicides in conventionally managed fields. Eleven organic and conventional cereal field pairs in Catalonia, Spain, were evaluated for one season in 2006–2007. Three different weed control treatments were applied: weed-free plots; weed-controlled plots, using herbicide in conventional fields and weed harrowing in organic ones and non-weeded plots. Crop yield and the abundance, richness and composition of the weed flora, which was dominated by ryegrass and poppies, were evaluated. Our results show that weed harrowing prevents weeds from being a limiting factor of crop productivity in organic cereal fields, since weed-controlled plots did not reduce yields compared to weed-free plots. A similar trend was observed in herbicide-controlled plots. However, herbicides diminished weed species richness in approximately 47 % and changed the species composition whereas harrowing allowed the maintenance of high levels of weed diversity in the organic fields.
