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Chloris virgata is a problematic weed in mungbean crops due to its high seed production, resistance to glyphosate and high dispersal ability. Pot and field experiments were conducted in 2020 and 2021 to evaluate a range of preemergent (PRE) herbicides for C. virgata control in mungbean. In the field and pot studies, isoxaflutole 75 g ai ha−1 caused crop injury, and in the field experiment, it reduced mungbean yield by 61% compared with the best treatment (pyroxasulfone 100 g ai ha−1). In the field and pot experiments, dimethenamid-P 720 g ai ha−1, pyroxasulfone 100 g ai ha−1 and S-metolachlor 1400 g ai ha−1 provided >88% control of C. virgata (for reduced biomass) and in the field experiment, these herbicides resulted in improved yield by 230%, 270% and 170%, respectively, compared with nontreated control (250 kg ha−1). Similarly, pendimethalin 1000 g ai ha−1 and trifluralin 600 g ai ha−1 provided >89% control (biomass) of C. virgata, and in the field experiment, these resulted in improved yields of 230% and 160%, respectively, compared with the nontreated control. PRE herbicides such as diuron 750 g ai ha−1, linuron 1100 g ai ha−1, metribuzin 360 g ha−1, terbuthylazine 750 g ai ha−1, imazapic 48 g ai ha−1 and imazethapyr 70 g ha−1 although did not cause crop injury; however, these herbicides did not control C. virgata. Flumioxazin 90 g ai ha−1 caused reduced biomass of C. virgata by 80% compared with the nontreated control, and in the field experiment, it resulted in improved yield by 140% compared with the nontreated control. This study suggests the potential use of herbicides, such as dimethenamid-P, pyroxasulfone and S-metolachlor in addition to pendimethalin and trifluralin, for C. virgata control in mungbean. Further studies are needed to determine the efficacy of dimethenamid-P, S-metolachlor and pyroxasulfone for controlling other troublesome weeds in mungbean.
Gulshan Mahajan; Bhagirath Chauhan. Evaluation of Preemergent Herbicides for Chloris virgata Control in Mungbean. Plants 2021, 10, 1632 .
AMA StyleGulshan Mahajan, Bhagirath Chauhan. Evaluation of Preemergent Herbicides for Chloris virgata Control in Mungbean. Plants. 2021; 10 (8):1632.
Chicago/Turabian StyleGulshan Mahajan; Bhagirath Chauhan. 2021. "Evaluation of Preemergent Herbicides for Chloris virgata Control in Mungbean." Plants 10, no. 8: 1632.
Navua sedge (Cyperus aromaticus) is a hard to control C4 perennial weed species in tropical regions of Australia. Knowledge of its seed biology could help to develop integrated weed management programs for this species. This study was conducted in laboratory and screenhouse conditions to evaluate the effect of alternating day/night temperatures, light, pretreatment high temperatures, burial depth, and flooding depth on the germination and emergence of two populations (Ingham and Tablelands) of C. aromaticus. Both populations germinated at temperatures ranging from 20/10 to 35/25 C; however, the Ingham population germination (76%) was greater than the Tablelands population (42%) at the highest temperature regime (35/25 C). None of the populations germinated at 15/5 C. Darkness completely inhibited germination in both populations, suggesting that the seeds are positively photoblastic. Seeds (dry and wet) of both populations germinated after exposure to pretreatment temperatures of up to 100 C for 5 min. After pretreatment at 150 C, only the Ingham population germinated, and the germination of dry seeds (62%) was greater than wet seeds (1%). None of the populations germinated after the exposure to 200 C. For both populations, maximum germination was observed for seeds at 0 cm, and a burial depth of 0.5 cm completely inhibited emergence of the Tablelands population and 2.0 cm inhibited germination of the Ingham population. A flooding depth of 10 cm greatly reduced emergence in both populations compared with 0 cm (62 and 78%) but 12 to 14% of seedlings still emerged, suggesting the need to integrate flooding with other management tools. The results also suggest that the Ingham population may have a greater potential to spread into new areas or become more invasive than the Tablelands population. Knowledge gained from this study can be used to manage C. aromaticus by fire/burning, tillage, and flooding.
Bhagirath S. Chauhan. Differential germination response of Navua sedge (Cyperus aromaticus) populations to environmental factors. Weed Science 2021, 1 -24.
AMA StyleBhagirath S. Chauhan. Differential germination response of Navua sedge (Cyperus aromaticus) populations to environmental factors. Weed Science. 2021; ():1-24.
Chicago/Turabian StyleBhagirath S. Chauhan. 2021. "Differential germination response of Navua sedge (Cyperus aromaticus) populations to environmental factors." Weed Science , no. : 1-24.
Summer weed species, including Echinochloa colona, are becoming problematic in the eastern grain region of Australia, but cover crops can be useful to suppress weeds during the summer fallow period. The present study evaluated the growth and seed production of E. colona grown alone or with four and eight cover crop plants per pot (i.e., 80 and 160 plants m-2). Four legume (cowpea, lablab, pigeonpea, and soybean) and two grass (forage sorghum and Japanese millet) cover crops were used. Interference by cover crops reduced the height, the number of leaves and tillers, inflorescence number, seed production, and biomass of this weed than when it was grown alone. Cover crops differed in their ability to suppress the growth and seed production of E. colona. The effect of cover crop density on the studied attributes was non-significant in most cases. Pigeonpea as a cover crop was the least effective in suppressing the growth and seed production of E. colona. In general, leguminous cover crops exhibited less suppression of E. colona than grasses. Forage sorghum was most efficient in reducing the growth of this weed. Forage sorghum and Japanese millet reduced E. colona leaf and tiller numbers per plant by 90 and 87%, respectively. These cover crops reduced E. colona leaf number to only 17 per plant as against 160 per plant recorded without cover crops. Inflorescence number per E. colona plant growing alone was as high as 48. However, it was reduced by 20–92% when this weed was grown with cover crop plants. E. colona’s seed production was significantly suppressed by all the cover crops, except pigeonpea. Biomass of E. colona was suppressed largely by forage sorghum and Japanese millet compared to other cover crops. Among the cover crops, pigeonpea produced the lowest biomass of 11 g pot-1, and the highest biomass (114 g pot-1) was produced by forage sorghum. The study demonstrated the usefulness of cover crops, especially forage sorghum and Japanese millet, to suppress the growth and seed output of E. colona.
Amar Matloob; Bhagirath Singh Chauhan. Utilization of the neighborhood design to evaluate suitable cover crops and their density for Echinochloa colona management. PLOS ONE 2021, 16, e0254584 .
AMA StyleAmar Matloob, Bhagirath Singh Chauhan. Utilization of the neighborhood design to evaluate suitable cover crops and their density for Echinochloa colona management. PLOS ONE. 2021; 16 (7):e0254584.
Chicago/Turabian StyleAmar Matloob; Bhagirath Singh Chauhan. 2021. "Utilization of the neighborhood design to evaluate suitable cover crops and their density for Echinochloa colona management." PLOS ONE 16, no. 7: e0254584.
Thorough knowledge of the germination behavior of weed species could aid in the development of effective weed control practices, especially when glyphosate resistance is involved. A study was conducted using two glyphosate-resistant (GR) (SGW2 and CP2) and two glyphosate-susceptible (GS) (Ch and SGM2) populations of Chloris virgata, an emerging and troublesome weed species of Australian farming systems, to evaluate their germination response to different alternating temperature (15/5, 25/15 and 35/25°C with 12 h/12 h light/dark photoperiod) and moisture stress regimes (0, -0.1, -0.2, -0.4, -0.8 and -1.6 MPa). These temperature regimes represent temperatures occurring throughout the year in the eastern grain region of Australia. Seeds germinated in all the temperature regimes with no clear indication of optimum thermal conditions for the GR and GS populations. All populations exhibited considerable germination at the lowest alternating temperature regime 15/5°C (61%, 87%, 49%, and 47% for Ch, SGM2, SGW2, and CP2, respectively), demonstrating the ability of C. virgata to germinate in winter months despite being a summer annual. Seed germination of all populations was inhibited at -0.8 and -1.6 MPa osmotic potential at two alternating temperature regimes (15/5 and 35/25°C); however, some seeds germinated at 25/15°C at -0.8 MPa osmotic potential, indicating the ability of C. virgata to germinate in arid regions and drought conditions. Three biological parameters (T10: incubation period required to reach 10% germination; T50: incubation period required to reach 50% germination; and T90: incubation period required to reach 90% germination) suggested late water imbibition with increasing moisture stress levels. The GR population SGW2 exhibited a distinctive pattern in T10, T50, and T90, possessing delayed germination behaviour and thus demonstrating an escape mechanism against pre-plating weed management practices. Knowledge gained from this study will help in developing site-specific and multi-tactic weed control protocols.
Het Samir Desai; Bhagirath Singh Chauhan. Differential germination characteristics of glyphosate-resistant and glyphosate-susceptible Chloris virgata populations under different temperature and moisture stress regimes. PLOS ONE 2021, 16, e0253346 .
AMA StyleHet Samir Desai, Bhagirath Singh Chauhan. Differential germination characteristics of glyphosate-resistant and glyphosate-susceptible Chloris virgata populations under different temperature and moisture stress regimes. PLOS ONE. 2021; 16 (6):e0253346.
Chicago/Turabian StyleHet Samir Desai; Bhagirath Singh Chauhan. 2021. "Differential germination characteristics of glyphosate-resistant and glyphosate-susceptible Chloris virgata populations under different temperature and moisture stress regimes." PLOS ONE 16, no. 6: e0253346.
Calotropis procera (Aiton) Dryand. (commonly known as the apple of sodom, calotrope, and giant milkweed) is an evergreen, perennial shrub of the family Apocynaceae, mainly found in arid and semi-arid regions. It is a multipurpose plant, which can be utilized for medicine, fodder, and fuel purposes, timber and fiber production, phytoremediation, and synthesis of nanoparticles. It has been widely used in traditional medicinal systems across North Africa, Middle East Asia, and South-East Asia. At present, it is being extensively explored for its potential pharmacological applications. Several reports also suggest its prospects in the food, textile, and paper industries. Besides, C. procera has also been acknowledged as an ornamental species. High pharmacological potential and socio-economic value have led to the pantropical introduction of the plant. Morpho-physiological adaptations and the ability to tolerate various abiotic stresses enabled its naturalization beyond the introduced areas. Now, it is recognized as an obnoxious environmental weed in several parts of the world. Its unnatural expansion has been witnessed in the regions of South America, the Caribbean Islands, Australia, the Hawaiian Islands, Mexico, Seychelles, and several Pacific Islands. In Australia, nearly 3.7 million hectares of drier areas, including rangelands and Savannahs, have been invaded by the plant. In this review, multiple aspects of C. procera have been discussed including its general characteristics, current and potential uses, and invasive tendencies. The objectives of this review are a) to compile the information available in the literature on C. procera, to make it accessible for future research, b) to enlist together its potential applications being investigated in different fields, and c) to acknowledge C. procera as an emerging invasive species of arid and semi-arid regions.
Amarpreet Kaur; Daizy R. Batish; Shalinder Kaur; Bhagirath S. Chauhan. An Overview of the Characteristics and Potential of Calotropis procera From Botanical, Ecological, and Economic Perspectives. Frontiers in Plant Science 2021, 12, 1 .
AMA StyleAmarpreet Kaur, Daizy R. Batish, Shalinder Kaur, Bhagirath S. Chauhan. An Overview of the Characteristics and Potential of Calotropis procera From Botanical, Ecological, and Economic Perspectives. Frontiers in Plant Science. 2021; 12 ():1.
Chicago/Turabian StyleAmarpreet Kaur; Daizy R. Batish; Shalinder Kaur; Bhagirath S. Chauhan. 2021. "An Overview of the Characteristics and Potential of Calotropis procera From Botanical, Ecological, and Economic Perspectives." Frontiers in Plant Science 12, no. : 1.
An elevated atmospheric carbon dioxide (CO2) concentration and frequent droughts are two anticipated climate change scenarios in which certain invasive weeds may develop competitive advantages over crops and adversely impact productivity and herbicide efficacy. Hence, a study was conducted to explore the effect of different climatic scenarios on the growth and management of Sesbania cannabina (Retz.) Pers with glyphosate. The variables investigated were two CO2 concentrations (400 and 700 ppm), two soil moisture levels (100% and 50% of field capacity (FC)), and three glyphosate rates (0 (control), 517 (50% of recommended rate), and 1034 g ae ha−1 (recommended rate)). CO2 concentrations and soil moisture levels had different effects on the growth and management of S. cannabina. Overall, 100% FC and elevated [CO2] of 700 ppm recorded the maximum plant height (38 cm), leaves per plant (20), growth index (60), chlorophyll content (SPAD value 37), and dry biomass (3 g) in comparison with ambient [CO2] of 400 ppm and 50% FC treatment. The recommended glyphosate application gave 100% weed biomass reduction; however, efficacy was reduced (63%) when applied at 50% of the recommended rate under elevated [CO2] of 700 ppm and 50% FC conditions.
Nadeem Iqbal; Sudheesh Manalil; Bhagirath Chauhan; Steve Adkins. Effect of Different Climate Change Variables on the Ecology and Management of Sesbania cannabina through Glyphosate. Plants 2021, 10, 910 .
AMA StyleNadeem Iqbal, Sudheesh Manalil, Bhagirath Chauhan, Steve Adkins. Effect of Different Climate Change Variables on the Ecology and Management of Sesbania cannabina through Glyphosate. Plants. 2021; 10 (5):910.
Chicago/Turabian StyleNadeem Iqbal; Sudheesh Manalil; Bhagirath Chauhan; Steve Adkins. 2021. "Effect of Different Climate Change Variables on the Ecology and Management of Sesbania cannabina through Glyphosate." Plants 10, no. 5: 910.
Amaranthus retroflexus L. (Amaranthaceae), Redroot pigweed, is native to North America, but has become a weed of agriculture worldwide. Previous research into competition with food crops found it significantly reduces yields. Additionally, taxonomy, biomass allocation, physiological responses to light intensity, water stress, elevated CO2, and herbicide resistance have been investigated. To extend other research findings, we investigated growth and biomass yield in response to (i) soil moisture stress, and (ii) drought and elevated CO2. Additionally, we investigated seed germination rates following exposure to three elevated temperatures for two different time periods. Overall, moisture stress reduced plant height, stem diameter, and number of leaves. Elevated CO2 (700 ppm) appeared to reduce negative impacts of drought on biomass productivity. Heating seeds at 120 °C and above for either 180 or 300 s significantly reduced germination rate. These results inform an understanding of potential responses of A. retroflexus to future climate change and will be used to predict future occurrence of this weed. The finding that exposing seeds to high temperatures retards germination suggests fire could be used to prevent seed germination from soil seed banks, particularly in no-till situations, and therefore may be used to address infestations or prevent further spread of this weed.
Sandra Weller; Singarayer Florentine; Muhammad Javaid; Amali Welgama; Aakansha Chadha; Bhagirath Chauhan; Christopher Turville. Amaranthus retroflexus L. (Redroot Pigweed): Effects of Elevated CO2 and Soil Moisture on Growth and Biomass and the Effect of Radiant Heat on Seed Germination. Agronomy 2021, 11, 728 .
AMA StyleSandra Weller, Singarayer Florentine, Muhammad Javaid, Amali Welgama, Aakansha Chadha, Bhagirath Chauhan, Christopher Turville. Amaranthus retroflexus L. (Redroot Pigweed): Effects of Elevated CO2 and Soil Moisture on Growth and Biomass and the Effect of Radiant Heat on Seed Germination. Agronomy. 2021; 11 (4):728.
Chicago/Turabian StyleSandra Weller; Singarayer Florentine; Muhammad Javaid; Amali Welgama; Aakansha Chadha; Bhagirath Chauhan; Christopher Turville. 2021. "Amaranthus retroflexus L. (Redroot Pigweed): Effects of Elevated CO2 and Soil Moisture on Growth and Biomass and the Effect of Radiant Heat on Seed Germination." Agronomy 11, no. 4: 728.
Dry direct seeded rice (DSR) has emerged as an economically viable alternative to puddled transplanted rice to address emerging constraints of labor and water scarcity and the rising cost of cultivation. However, wide adoption of DSR is seriously constrained by weed management trade-off. Therefore, the availability of effective weed control options is critical for the success and wide-scale adoption of DSR. A field study was conducted at ICAR-National Rice Research Institute, Cuttack, India, in the dry seasons of 2015 and 2016 to evaluate the performance of three crop establishment methods and five weed control practices on weed management, productivity, profitability and energetics of dry DSR. The results demonstrated that weed density and weed dry weight was lower in drill seeding than broadcast seeding by 26–36% and manual line-seeding by 16–24%, respectively, at 30 and 60 days after crop emergence (DAE). Among herbicides, post-emergence application (17 DAE) of azimsulfuron was most effective in controlling weeds compared to early post application of bispyribac-sodium and bensulfuron-methyl+pretilachlor. Weed competition in the weedy check treatment resulted 58% reduction in rice yield. Among establishment methods, drill-seeding was most profitable with US $ 685 ha−1 higher net income than broadcast seeding primarily due to higher yield. Among weed control treatments, azimsulfuron was most profitable resulting in US $ 160 and 736 ha−1 higher net income than weed free and weedy check, respectively. The specific energy was lowest for drill seeding among establishment method and azimsulfuron among weed control practices, suggesting lowest energy consumed in producing per unit of grain yield.
Sanjoy Saha; Sushmita Munda; Sudhanshu Singh; Virender Kumar; Hemant Jangde; Ashirbachan Mahapatra; Bhagirath Chauhan. Crop Establishment and Weed Control Options for Sustaining Dry Direct Seeded Rice Production in Eastern India. Agronomy 2021, 11, 389 .
AMA StyleSanjoy Saha, Sushmita Munda, Sudhanshu Singh, Virender Kumar, Hemant Jangde, Ashirbachan Mahapatra, Bhagirath Chauhan. Crop Establishment and Weed Control Options for Sustaining Dry Direct Seeded Rice Production in Eastern India. Agronomy. 2021; 11 (2):389.
Chicago/Turabian StyleSanjoy Saha; Sushmita Munda; Sudhanshu Singh; Virender Kumar; Hemant Jangde; Ashirbachan Mahapatra; Bhagirath Chauhan. 2021. "Crop Establishment and Weed Control Options for Sustaining Dry Direct Seeded Rice Production in Eastern India." Agronomy 11, no. 2: 389.
Redroot pigweed (Amaranthus retroflexus L.) and slender amaranth (Amaranthus viridis L.) are considered emerging problematic weeds in summer crops in Australia. An outdoor pot experiment was conducted to examine the effects of planting time on two populations of A. retroflexus and A. viridis at the research farm of the University of Queensland, Australia. Both species were planted every month from October to January (2017 to 2018 and 2018 to 2019), and their growth and seed production were recorded. Although both weeds matured at a similar number of growing degree days (GDD), they required a different number of days to complete their life cycles depending on planting date. The growth period was reduced and flowering occurred sooner as both species experienced cooler temperatures and shorter daylight hours. Both species exhibited increased height, biomass, and seed production for the October-sown plants compared with other planting times, and these parameters were reduced by delaying the planting time. The shoot and root biomass of A. retroflexus and A. viridis (averaged over both populations) was reduced by more than 70% and 65%, respectively, when planted in January, in comparison to planting in October. When planted in October, A. retroflexus and A. viridis produced 11,350 and 5,780 seeds plant−1, but these were reduced to 770 and 365 seeds plant−1 for the January planting date, respectively. Although the growth and fecundity of these species were dependent on planting time, these weeds could emerge throughout the late spring to summer growing season (October to March) in southeast Australia and could produce a significant number of seeds. The results showed that when these species emerged in the late spring (October), they grew vigorously and produced more biomass in comparison with the other planting dates. Therefore, any early weed management practice for these species could be beneficial for minimizing the subsequent cost and energy inputs toward their control.
Asad M. Khan; Ahmadreza Mobli; Jeff A. Werth; Bhagirath S. Chauhan. Effect of emergence time on growth and fecundity of redroot pigweed (Amaranthus retroflexus) and slender amaranth (Amaranthus viridis): emerging problem weeds in Australian summer crops. Weed Science 2021, 69, 333 -340.
AMA StyleAsad M. Khan, Ahmadreza Mobli, Jeff A. Werth, Bhagirath S. Chauhan. Effect of emergence time on growth and fecundity of redroot pigweed (Amaranthus retroflexus) and slender amaranth (Amaranthus viridis): emerging problem weeds in Australian summer crops. Weed Science. 2021; 69 (3):333-340.
Chicago/Turabian StyleAsad M. Khan; Ahmadreza Mobli; Jeff A. Werth; Bhagirath S. Chauhan. 2021. "Effect of emergence time on growth and fecundity of redroot pigweed (Amaranthus retroflexus) and slender amaranth (Amaranthus viridis): emerging problem weeds in Australian summer crops." Weed Science 69, no. 3: 333-340.
Slender amaranth (Amaranthus viridis L.) and redroot pigweed (Amaranthus retroflexus L.) are increasingly problematic weeds of summer crops in Australia. Water is considered the most limiting factor in an agroecosystem, and water stress adversely impacts the growth and reproduction of plant species. The primary objective of this study was to determine the growth and fecundity of two Australian biotypes (Goondiwindi and Gatton) of A. viridis and A. retroflexus under water-stress conditions. Four water-stress treatments (100%, 75%, 50%, and 25% field capacity [FC]) at a 4-d irrigation interval were chosen. No difference was observed for growth and seed production between the two biotypes of both species when grown under varying soil moisture regimes. At 100% FC, A. viridis produced 44 g plant−1 aboveground biomass and 1,740 seeds plant−1. The maximum growth (46 g plant−1) and seed production (3,070 seeds plant−1) of A. retroflexus were observed at 100% FC. The growth and seed production of both species were reduced with increased water-stress levels. Both weeds responded to water stress by decreasing the shoot:root biomass ratio. However, A. viridis (290 seeds plant−1) and A. retroflexus (370 seeds plant−1) were able to produce a significant number of seeds per plant even at 25% FC. Results suggest that both weeds will produce seeds under water-limiting conditions. Therefore, management strategies are required to minimize the growth and survival of weeds in water-deficit conditions.
Asad M. Khan; Ahmadreza Mobli; Jeff A Werth; Bhagirath S. Chauhan. Effect of soil moisture regimes on the growth and fecundity of slender amaranth (Amaranthus viridis) and redroot pigweed (Amaranthus retroflexus). Weed Science 2020, 69, 82 -87.
AMA StyleAsad M. Khan, Ahmadreza Mobli, Jeff A Werth, Bhagirath S. Chauhan. Effect of soil moisture regimes on the growth and fecundity of slender amaranth (Amaranthus viridis) and redroot pigweed (Amaranthus retroflexus). Weed Science. 2020; 69 (1):82-87.
Chicago/Turabian StyleAsad M. Khan; Ahmadreza Mobli; Jeff A Werth; Bhagirath S. Chauhan. 2020. "Effect of soil moisture regimes on the growth and fecundity of slender amaranth (Amaranthus viridis) and redroot pigweed (Amaranthus retroflexus)." Weed Science 69, no. 1: 82-87.
Nadeem Iqbal; Sudheesh Manalil; Bhagirath S. Chauhan; Steve W. Adkins. Effect of narrow row-spacing and weed crop competition duration on cotton productivity. Archives of Agronomy and Soil Science 2020, 1 -13.
AMA StyleNadeem Iqbal, Sudheesh Manalil, Bhagirath S. Chauhan, Steve W. Adkins. Effect of narrow row-spacing and weed crop competition duration on cotton productivity. Archives of Agronomy and Soil Science. 2020; ():1-13.
Chicago/Turabian StyleNadeem Iqbal; Sudheesh Manalil; Bhagirath S. Chauhan; Steve W. Adkins. 2020. "Effect of narrow row-spacing and weed crop competition duration on cotton productivity." Archives of Agronomy and Soil Science , no. : 1-13.
Sonchus oleraceus is becoming a hard-to-control weed in Australian cropping systems, especially in glyphosate-tolerant cotton and during summer fallows. Several biotypes of this weed have developed resistance to glyphosate as a result of common management practices under conservation agriculture systems in the country. A series of pot experiments were conducted to evaluate the effect of temperature on glyphosate efficacy and performance of several post-emergence and pre-emergence herbicides on a glyphosate-resistant (GR) and a glyphosate-susceptible (GS) biotype of S. oleraceus. At low temperatures (19–24 °C), no plants of the GS biotype survived glyphosate application at 570 g/ha; however, in the high-temperature regime (28–30 °C), 83% of the plants survived this rate of glyphosate. Similarly, for the GR biotype, up to 58% of the plants survived at 2280 g/ha of glyphosate when applied during the high-temperature regime and no plants survived this rate during the low-temperature regime. A number of post-emergence herbicides were found to be effective for S. oleraceus control. However, herbicide application delayed to the six-leaf stage compared with the four-leaf stage reduced control, especially for bromoxynil and saflufenacil herbicides. Glufosinate and paraquat were the most effective herbicides for S. oleraceus control, resulting in no seedling survival for both biotypes. Isoxaflutole, pendimethalin or s-metolachlor efficacy was not reduced by the presence of crop residue, suggesting that these herbicides could be used to control S. oleraceus in conservation agriculture systems. The results of this study suggest that growers will need to reduce over-reliance on glyphosate for weed control in summer fallows and use alternative post-emergence herbicides.
Bhagirath Chauhan; Prashant Jha. Glyphosate Resistance in Sonchus oleraceus and Alternative Herbicide Options for Its Control in Southeast Australia. Sustainability 2020, 12, 8311 .
AMA StyleBhagirath Chauhan, Prashant Jha. Glyphosate Resistance in Sonchus oleraceus and Alternative Herbicide Options for Its Control in Southeast Australia. Sustainability. 2020; 12 (20):8311.
Chicago/Turabian StyleBhagirath Chauhan; Prashant Jha. 2020. "Glyphosate Resistance in Sonchus oleraceus and Alternative Herbicide Options for Its Control in Southeast Australia." Sustainability 12, no. 20: 8311.
Tillage has been used as a major weed management tool for several decades in conventional agricultural systems; however, it has also presented problems, such as degradation of soil health and high production costs. Therefore, a trend towards the adoption of no-till (NT) systems has emerged over recent decades. With the adoption of NT systems has come the elimination of a key component (tillage) of weed management strategies, resulting in a shift in weed dynamics across agricultural systems. Weed management is a challenging component of a successful NT system wherein the use of herbicides have become the most prevalent control method. This over-reliance on chemicals is not a sustainable long-term strategy as it imposes a high selection pressure on weeds, drives the problematic evolution of herbicide-resistant weeds, pollutes the environment, and causes health hazards. The use of biotechnology to develop herbicide-tolerant crops, such as those tolerant to glyphosate, has undoubtedly revolutionized the adoption of NT systems. However, many issues concerning human health and the development of weeds resistant to herbicides are arising as a result of the use of these crops. A recent ban on the use of glyphosate in a few countries may lead to further restrictions on the use of herbicide-tolerant crops, potentially resulting in a reverse in course from NT production systems to more conventional tillage systems. Therefore, the task of evaluating alternative weed management strategies with respect to NT systems presents challenges. Techniques designed to reduce competitiveness in weeds or enhance competitiveness in crop plants while reducing dependency on herbicides, such as modifying row spacing and orientation, adjusting planting density and sowing time, and use of competitive cultivars, mulching and cover cropping have been developed by agricultural scientists. Modified or strategic tillage and crop diversification are other potential strategies which can be used for weed management in NT systems. Potential non-conventional weed management strategies such as harvest weed seed control, allelopathy and precision weed management using remote sensing and robotics require further evaluation for their feasibility, efficiency and viability in these systems. This chapter highlights possible combinations of non-chemical, non-conventional and chemical weed management tools that can be used in an integrated weed management approach, presenting the potential for a favorable shift in the crop-weed balance in NT systems.
Vivek Kumar; Gulshan Mahajan; Sahil Dahiya; Bhagirath S. Chauhan. Challenges and Opportunities for Weed Management in No-Till Farming Systems. No-till Farming Systems for Sustainable Agriculture 2020, 107 -125.
AMA StyleVivek Kumar, Gulshan Mahajan, Sahil Dahiya, Bhagirath S. Chauhan. Challenges and Opportunities for Weed Management in No-Till Farming Systems. No-till Farming Systems for Sustainable Agriculture. 2020; ():107-125.
Chicago/Turabian StyleVivek Kumar; Gulshan Mahajan; Sahil Dahiya; Bhagirath S. Chauhan. 2020. "Challenges and Opportunities for Weed Management in No-Till Farming Systems." No-till Farming Systems for Sustainable Agriculture , no. : 107-125.
Due to the overdependence on glyphosate to manage weeds in fallow conditions, glyphosate resistance has developed in various biotypes of several grass weeds, including Chloris virgata Sw. The first case of glyphosate resistance in C. virgata was found in 2015 in Australia, and since then several cases have been confirmed in several biotypes across Australia. Pot studies were conducted with 10 biotypes of C. virgata to determine glyphosate resistance levels. The biotypes were identified as either susceptible, moderately resistant or highly resistant based on the glyphosate dose required to kill 50% of plants. Two glyphosate-susceptible (GS) and two glyphosate-resistant (GR) biotypes were identified by the dose-response study and analyzed for the presence of target-site mutation in the 5–enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene. Performance of alternative herbicides to glyphosate as well as the double-knock herbicide approach was evaluated on the two GS (Ch and SGM2) and two GR (SGW2 and CP2) biotypes. Three herbicides, clethodim, haloxyfop and paraquat, were found to be effective (100% control) against all four biotypes when applied at the 4–5 leaf stage. All the sequential herbicide treatments, such as glyphosate followed by paraquat and glufosinate-ammonium followed by paraquat, provided 100% control of all four biotypes of C. virgata. This study identified effective herbicide options for the control of GR C. virgata and showed that target-site mutations were involved in the resistance of two biotypes to glyphosate (SGW2 and CP2). Results could aid farmers in selecting herbicides to manage C. virgata in their fields.
Het Samir Desai; Michael Thompson; Bhagirath Singh Chauhan. Target-Site Resistance to Glyphosate in Chloris Virgata Biotypes and Alternative Herbicide Options for its Control. Agronomy 2020, 10, 1266 .
AMA StyleHet Samir Desai, Michael Thompson, Bhagirath Singh Chauhan. Target-Site Resistance to Glyphosate in Chloris Virgata Biotypes and Alternative Herbicide Options for its Control. Agronomy. 2020; 10 (9):1266.
Chicago/Turabian StyleHet Samir Desai; Michael Thompson; Bhagirath Singh Chauhan. 2020. "Target-Site Resistance to Glyphosate in Chloris Virgata Biotypes and Alternative Herbicide Options for its Control." Agronomy 10, no. 9: 1266.
The growth response of annual sowthistle (Sonchus oleraceus L.) to anticipated future climate conditions is currently unknown, and thus two parallel studies were conducted dealing with glyphosate-resistant (GR) and glyphosate-susceptible (GS) biotypes of S. oleraceus. The glyphosate efficacy study was conducted using different doses of glyphosate (0 [control], 180, 360, 720 [recommended dose], and 1,440 g ae ha−1) at two different moisture levels (well-watered and water-stressed conditions). In the second study, the growth and seed production of these biotypes were studied under different atmospheric carbon dioxide (CO2) concentrations (450 and 750 ppm) and under well-watered (100% field capacity) and water-stressed (50% field capacity) conditions. Results showed that the GR biotype survived (>68%) at 1,440 g ha−1, but for the GS biotype, no plant survived, and both biotypes were slightly (2 condition, the GS biotype plants were >38% taller and produced >44%, >18%, and >21% more leaves, buds, and seeds, respectively, compared with the ambient CO2 concentration under both moisture regimes. The biomass also increased by 27% in comparison with the ambient CO2 concentration. For the GR biotype, plants at the elevated CO2 level, while they also grew 38% taller in comparison with the ambient CO2 concentration, the numbers of leaves, buds, and seeds and biomass were not affected by this increase in CO2. Results showed that there were minimal changes in response to glyphosate for GR and GS biotypes of S. oleraceus with or without moisture stress. Our study suggests that future climate change with elevated CO2 levels can affect the response of S. oleraceus to glyphosate, and such knowledge will be helpful for weed management in the future.
Ahmadreza Mobli; Singarayer K Florentine; Prashant Jha; Bhagirath Singh Chauhan. Response of glyphosate-resistant and glyphosate-susceptible biotypes of annual sowthistle (Sonchus oleraceus) to increased carbon dioxide and variable soil moisture. Weed Science 2020, 1 -7.
AMA StyleAhmadreza Mobli, Singarayer K Florentine, Prashant Jha, Bhagirath Singh Chauhan. Response of glyphosate-resistant and glyphosate-susceptible biotypes of annual sowthistle (Sonchus oleraceus) to increased carbon dioxide and variable soil moisture. Weed Science. 2020; ():1-7.
Chicago/Turabian StyleAhmadreza Mobli; Singarayer K Florentine; Prashant Jha; Bhagirath Singh Chauhan. 2020. "Response of glyphosate-resistant and glyphosate-susceptible biotypes of annual sowthistle (Sonchus oleraceus) to increased carbon dioxide and variable soil moisture." Weed Science , no. : 1-7.
Rice cultivation always remains significant for food and livelihood security. The predictions of increasing water deficiency under a changing climate and escalating labor shortages in agriculture have brought a paradigm swing in rice cultivation from conventionally flooded transplanting to direct-seeded rice (DSR). DSR cultivation can potentially address the concerns of diminishing natural resources and mounting production costs in the establishment of transplanted rice. The transition towards DSR saves water, reduces duration to maturity as well as labor required, and reduces negative environmental footprints. Despite all these recompenses, the potential yield losses through enormous weed menaces under DSR remains a challenge and may reduce yield by up to 50%. In this review, we examine the extent of weed infestation, weed shift and the losses in dry DSR (DDSR). Various regional and global scientific efforts made under DDSR have been assessed in the present and the smart weed-management strategies suggested can be adopted after scrutiny. Integration of different weed management approaches, namely prevention, cultural, mechanical, and chemical, have been discussed, which can pave the way for worldwide adoption of DDSR, especially in South Asia. In Asia, 22% of the acreage of total rice cultivation is under DSR and the region-specific integration of these weed-management approaches might reduce herbicide use in these areas by up to 50%.
Kapila Shekhawat; Sanjay Singh Rathore; Bhagirath S. Chauhan. Weed Management in Dry Direct-Seeded Rice: A Review on Challenges and Opportunities for Sustainable Rice Production. Agronomy 2020, 10, 1264 .
AMA StyleKapila Shekhawat, Sanjay Singh Rathore, Bhagirath S. Chauhan. Weed Management in Dry Direct-Seeded Rice: A Review on Challenges and Opportunities for Sustainable Rice Production. Agronomy. 2020; 10 (9):1264.
Chicago/Turabian StyleKapila Shekhawat; Sanjay Singh Rathore; Bhagirath S. Chauhan. 2020. "Weed Management in Dry Direct-Seeded Rice: A Review on Challenges and Opportunities for Sustainable Rice Production." Agronomy 10, no. 9: 1264.
Agricultural practice, which includes well-established systems of cropping, pasture and forestry, represents a continual and essential dependence on healthy arable land across the globe and requires safeguarding with sustainable fertilization and pest control measures. This natural resource system must be continually protected from deliberate and inadvertent damage, in order to provide a suitable source of current and future amenities for all inhabitants of the planet. In this respect, it is morally and ethically necessary that we strive to manage the productivity and well-being of agricultural land in a way that will fulfil the necessities of the present generations and do not compromise needs of the future generations (Bruntland et al. 2012).
Singarayer Florentine; Bhagirath Singh Chauhan; Khawar Jabran. Agriculture and Crop Protection; Its Global Importance and Relationship with Climate Change. Crop Protection Under Changing Climate 2020, 1 -16.
AMA StyleSingarayer Florentine, Bhagirath Singh Chauhan, Khawar Jabran. Agriculture and Crop Protection; Its Global Importance and Relationship with Climate Change. Crop Protection Under Changing Climate. 2020; ():1-16.
Chicago/Turabian StyleSingarayer Florentine; Bhagirath Singh Chauhan; Khawar Jabran. 2020. "Agriculture and Crop Protection; Its Global Importance and Relationship with Climate Change." Crop Protection Under Changing Climate , no. : 1-16.
The impacts of weeds in cropping systems are diverse and costly. Direct expenditure on control and biosecurity measures costs society billions each year. Even with such heavy investment in prevention and control, weeds continue to reduce the quality and quantity of agricultural produce and represent a significant threat to global food production. The challenge of managing weeds in cropping systems is rendered increasingly complex given the diverse and unpredictable impacts of climate change on both weeds and crops. Atmospheric CO2, temperature and precipitation are key drivers of plant growth, and weeds, like all other plant species, will need to respond to climate change in order to survive. Weed species are by their very nature survivors, able to relocate, acclimate or adapt to changing environmental conditions, with genetic diversity that could confer a natural competitive advantage over crop species. Conversely, modern crops are the result of extensive and highly sophisticated breeding to improve their genetic potential to survive in challenging conditions, including herbicide application, limited soil moisture and high temperatures. Moreover, agricultural weeds evolve in highly managed environments, and management intervention through crop selection, crop planting strategies and weed control measures may exert stronger selection pressures on weed species relative to climate change. It is, however, reasonable to assert that evolution driven by management pressures could occur simultaneously to climate-driven adaptation. For this reason, even given the rapid advancement of increasingly sophisticated weed control technology, weed management now and in the future should be guided a sound understanding of evolutionary biology.
Annie Ruttledge; Bhagirath S. Chauhan. Climate Change and Weeds of Cropping Systems. Crop Protection Under Changing Climate 2020, 57 -84.
AMA StyleAnnie Ruttledge, Bhagirath S. Chauhan. Climate Change and Weeds of Cropping Systems. Crop Protection Under Changing Climate. 2020; ():57-84.
Chicago/Turabian StyleAnnie Ruttledge; Bhagirath S. Chauhan. 2020. "Climate Change and Weeds of Cropping Systems." Crop Protection Under Changing Climate , no. : 57-84.
The prevention and management of weeds have been difficult throughout the history of food production. We are now entering into a new era where new challenges are arising more rapidly due in part to the rapid population growth, which places an unprecedented demand upon both natural and agricultural ecosystems to fulfil food, fibre, and feed for at least another two billion people by 2050. Climatic change is associated with a higher frequency of extreme weather events, and it is generally agreed that this will have a drastic impact on ecosystem productivity and biodiversity. The present world atmospheric temperature has increased by 1.0 °C since 1900 with half of this rise coming in the past 30 years. Crop production is directly affected by the direct effects of climate change (temperature and water stress) and indirect effects of increased competition from weeds and other pest species. In a field situation, crop plants are inevitably surrounded by an assemblage of C3 and C4 plants, and a considerable variation in the growth response of weeds to climate change have been reported. In this chapter, we present an overview of the impact of temperature rise, carbon dioxide increase, and changed rainfall patterns on weed composition, distribution, abundance, and our current approaches to weed management. There is a high risk that some weed species will shift their range with the change in temperature and precipitation patterns. The efficacy of chemical weed control depends on the environmental conditions before, during and after the herbicide application. The changes in physiology, morphology, and anatomy of plants will result in altered weed growth, crop-weed competition, and herbicide efficacy under elevated temperature and/or carbon dioxide. Global warming may increase the risk of evolution of nontarget site resistance mechanisms against herbicides in the weed plants and thus decrease herbicide efficacy. The anticipated actions in these areas are also discussed in the end which may enhance our understanding of the impact of climate change on the practice and future of weed management and crop production.
Simerjeet Kaur; Khawar Jabran; Singarayer Florentine; Bhagirath S. Chauhan. Assuring Crop Protection in the Face of Climate Change Through an Understanding of Herbicide Metabolisms and Enhanced Weed Control Strategies. Crop Protection Under Changing Climate 2020, 17 -56.
AMA StyleSimerjeet Kaur, Khawar Jabran, Singarayer Florentine, Bhagirath S. Chauhan. Assuring Crop Protection in the Face of Climate Change Through an Understanding of Herbicide Metabolisms and Enhanced Weed Control Strategies. Crop Protection Under Changing Climate. 2020; ():17-56.
Chicago/Turabian StyleSimerjeet Kaur; Khawar Jabran; Singarayer Florentine; Bhagirath S. Chauhan. 2020. "Assuring Crop Protection in the Face of Climate Change Through an Understanding of Herbicide Metabolisms and Enhanced Weed Control Strategies." Crop Protection Under Changing Climate , no. : 17-56.
Plant hormones influence various physiological processes during the growth and development of plants, but their critical roles in influencing yield and antioxidant activities in dry-seeded rice (DSR) have not been adequately explored. This study aims to analyze the performance and antioxidant activity of contrasting genotypes of DSR in response to soil moisture regimes and foliar-applied hormones. The study comprised sixteen treatments that were evaluated under field conditions as per split-plot design in three replications. Treatments comprised combinations of two soil moisture tension regimes (10 kPa and 20 kPa) and two genotypes (PR-111, non-stay-green type and PR-123, stay-green type) applied to the main plots and foliar application of three hormones (gibberellic acid (GA3) 40 mg kg−1, abscisic acid (ABA) 20 mg kg−1, and cytokinin (CK) 40 mg kg−1)) and a control (unsprayed) to subplots. The non-stay-green genotype (PR-111) resulted in 34.6% more grain yield (6.48 t ha−1) than the stay-green genotype (PR-123) at the lower soil moisture tension regime (SMTR) (10 kPa) due to the increased number of filled grains per panicle and improvement in harvest index (HI). At the higher SMTR (20 kPa), the stay-green genotype (PR-123) produced 26.4% more grain yield (5.21 t ha−1) than non-stay green genotype (4.12 t ha−1) and showed enhanced superoxide dismutase (SOD) and peroxide dismutase (POD) activity that may have contributed in maintaining sink size through improved chlorophyll content. Grain yield (6.35 t ha−1) with foliar-applied GA3 (40 mg kg−1) at SMTR of 10 kPa was higher by 12.2% and 24.0% than with foliar-applied ABA (20 mg kg−1) and unsprayed treatments, respectively. Irrigation application at SMTR of 20 kPa and foliar application of ABA gave 24.1% higher grain yield (5.15 t ha−1) than the unsprayed treatment, but it was similar to foliar-applied GA3 and CK. This study implied that the stay-green genotype (PR-123) was more suitable under moisture stress conditions (20 kPa) in DSR, as it maintained sink size even under moisture stress conditions by improving dry matter translocation and enhancing SOD and POD activity. The study suggests the need to find out the endogenous level of these plant hormones in rice genotypes under a range of water regimes to develop high yielding and water use efficient genotypes of DSR.
Rajinder Pal; Gulshan Mahajan; Virender Sardana; Bavita Asthir; Bhagirath Singh Chauhan. Performance of Dry-Seeded Rice Genotypes under Varied Soil Moisture Regimes and Foliar-Applied Hormones. Plants 2020, 9, 539 .
AMA StyleRajinder Pal, Gulshan Mahajan, Virender Sardana, Bavita Asthir, Bhagirath Singh Chauhan. Performance of Dry-Seeded Rice Genotypes under Varied Soil Moisture Regimes and Foliar-Applied Hormones. Plants. 2020; 9 (4):539.
Chicago/Turabian StyleRajinder Pal; Gulshan Mahajan; Virender Sardana; Bavita Asthir; Bhagirath Singh Chauhan. 2020. "Performance of Dry-Seeded Rice Genotypes under Varied Soil Moisture Regimes and Foliar-Applied Hormones." Plants 9, no. 4: 539.