Bhagirath S Chauhan

University of Queensland | UQ · Queensland Alliance for Agriculture and Food Innovation (QAAFI)

Feathertop Rhodes grass (Chloris virgata Sw.) is a problematic weed in Australian summer crop fields that has recently expanded its presence into colder seasons. In this study, the phenology, growth, and seed production of four C. virgata populations were investigated across six different planting dates every other month from May to March between 2...

Sonchus asper and S. oleraceus are among the most problematic broadleaf weeds in eastern cropping systems of Australia. This study investigated the seed germination ecology of S. asper and S. oleraceus. The study hypothesized that S. asper may have greater ecological advantages under adverse environmental conditions compared to S. oleraceus. Result...

Herbicides have been placed in global Herbicide Resistance Action Committee (HRAC) herbicide groups based on their sites of action (e.g., acetolactate synthase–inhibiting herbicides are grouped in HRAC Group 2). A major driving force for this classification system is that growers have been encouraged to rotate or mix herbicides from different HRAC...

Annual ryegrass (Lolium rigidum) is a problematic weed in winter crops and fallows in the southeastern cropping region (SCR) of Australia. This weed has evolved resistance to multiple herbicide groups, globally. In Australia, L. rigidum is more prevalent in the western and southern regions than in SCR. To assess the herbicide resistance status of L...

Utilizing the potential of crops to suppress weeds is an important strategy for sustainable management. Feathertop Rhodes grass (FTR) (Chloris virgata Sw.) is a problematic warm-season weed in Australia that has recently expanded into colder seasons. This study investigated the growth and seed production of FTR at two planting times (May and July)...

COVID-19 has caused a deep economic impact on the lives of small and marginal farmers due to travel restrictions, market closures, and social distancing requirements. Due to COVID-induced labor scarcity and water shortage in India, direct-seeded rice (DSR) has emerged as a viable alternative to puddled transplanted rice (PTR). However, there was pl...

A study assessed the potential for using cumulative growing degree days (CGDD) to predict the weed emergence periodicity of three weed species: Argemone mexicana, Brassica tournefortii, and Rapistrum rugosum. Weed emergence was monitored regularly by placing 200 fresh seeds of each weed species on the soil surface. Weed emergence data was fit using...

Tropical ageratum (Ageratum conyzoides L.) is a problematic weed frequently observed in association with commercially important crops in Australian agroecosystems. Knowledge of the germination response of A. conyzoides is crucial for proactively managing this weed species, especially when herbicide resistance is involved. Herbicide screening and me...

This research was carried out to evaluate the effect of (1) different methods of breaking seed dormancy (physical and chemical scarification, high temperature, hot water and after-ripening), and (2) environmental factors (temperature, salinity and water stress) on seed germination of Trifolium angustifolium , T. arvense , T. fragiferum , T. fucatum...

Parthenium weed (Parthenium hysterophorus L.) is an emerging production constraint in many summer crops including sorghum (Sorghum bicolor L. Moench), but limited control options are available. In this field study, the efficacy of sole and sequential applications of a pre-emergence (pendimethalin) and a post-emergence (bromoxynil) herbicide was eva...

Information regarding the relative importance of elevated day/night-time temperatures combined with water stress on mungbean yield is limited. This study aimed to investigate the yield response of mungbean cultivars to different water stress and temperature regimes under controlled glasshouse conditions. Two mungbean cultivars, Celera II-AU and Jad...

African mustard ( Brassica tournefortii Gouan), turnipweed [ Rapistrum rugosum (L.) All.], and African turnipweed ( Sisymbrium thellungii O.E. Schulz) are common broadleaf weeds in chickpea ( Cicer arietinum L.) crops, particularly under dryland regions of eastern Australia. Information on crop yield losses and the seed production potential for the...

Knowledge of the germination pattern and seed longevity of Echinochloa colona under field conditions could play a crucial role in effective weed management. Germination patterns of four populations (B17/12, B17/13, B17/7, and B17/25) of E. colona collected from eastern Australia were studied under field conditions for two years. Each population had...

Avena sterilis ssp. ludoviciana (Durieu) is a problematic weed in the wheat crop of Australia. Pinoxaden is an effective herbicide for the control of this weed. However, late cohorts of A. ludoviciana escape from the early application of pinoxaden and produce seeds. This research investigated the integrated effect of tillage systems (no-tillage and...

Proper weed management strategies are very essential for sustainable agriculture crop production. Chenopodium murale L. is one of the most problematic weed all over the world. It’s an annual herbaceous plant weed found in Pakistan, India as well as other subtropical and tropical parts of Asia. In approximately fifteen Asian countries, C. murale is...

Leptochloa chinensis (L.) Nees (Chinese sprangletop) is a weed that is becoming a serious threat in upland and lowland rice. A field study was conducted at the Agronomic Research Farm, University of Sargodha, Punjab, Pakistan, during the summer seasons of 2018 and 2019 to evaluate the effect of L. chinensis density on the yield of direct-seeded fin...

Ageratum conyzoides L. (Billy goat weed; Asteraceae) is an annual herbaceous plant of American origin with a pantropical distribution. The plant has unique biological attributes and a raft of miscellaneous chemical compounds that render it a pharmacologically important herb. Despite its high medicinal value, the constant spread of the weed is notic...

Context Knowledge gaps exist for the interference of Avena ludoviciana and Argemone mexicana in chickpea grown in eastern Australia. Aims This research aimed to examine the effect of different interference levels of A. ludoviciana and A. mexicana for their potential to cause yield loss in chickpea. Methods Experiments were conducted in a randomised...

In Australia, wheat planting is preferred in June compared with May to kill early cohorts of weeds before planting, particularly in fields with a history of high weed infestation. However, wheat grain yield is often reduced for June planting. This study aimed to investigate the integrated effect of planting dates (May 7, i.e., early‐planted, and Ju...

Increased planting density can provide crops a competitive advantage over weeds. This study appraised the growth and seed production of two noxious grassy weeds, i.e. feather fingergrass (Chloris virgata SW.) and junglerice [Echinochloa colona (L.) Link] in response to different mungbean [Vigna radiata (L.) R. Wilczek] densities (0, 82, 164, 242, a...

Sterile oat (Avena sterilis subsp. ludoviciana) and turnipweed (Rapistrum rugosum (L.) All.) are two important weed species in wheat fields, and their chemical control is affected by low temperatures at the time of spray. Both weed species were exposed to a freezing treatment (−4 °C) before and after spraying for three nights from 7:00 PM to 5:00 A...

Vipergrass [ Dinebra retroflex a (Vahl) Panzer] is an annual weed of the Poaceae family distributed in several parts of Australia, Asia, and Europe. Very limited information is available on its germination response to different environmental conditions. Knowledge of its seed ecology and biology could help in formulating better weed management decis...

Plant genetic resources (PGRs) are the total hereditary material, which includes all the alleles of various genes, present in a crop species and its wild relatives. They are a major resource that humans depend on to increase farming resilience and profit. Hence, the demand for genetic resources will increase as the world population increases. There...

Chloris virgata is one of the most problematic summer grass species in southeastern Australia. A total of 40 populations of C. virgata were evaluated in the spring–summer season of 2021–2022 in an open environment at the Gatton Farms of the University of Queensland, Queensland, Australia, for their response to two acetyl-coenzyme-A carboxylase (ACC...

Australian grain growers are showing interest in winter-planted sorghum to avoid heat and water stress during the grain-filling stage. Winter-planted sorghum may face competition from winter weeds, including sterile oats, and there are no herbicides registered for controlling winter weeds in winter-planted sorghum. The objectives of this study were...

Wild oat (Avena spp.) is one of the most serious weeds in Australian winter season crops such as wheat, barley, chickpea, etc. Avena fatua and A. ludoviciana are the dominant species of wild oat in cropping regions of Australia. Propagation of wild oat can occur through seeds. Dissemination of wild oat occurs by agricultural machinery, use of the c...

Glyphosate alone or a tank mixture of glyphosate and 2,4-D is commonly used for broad-spectrum weed control under fallow conditions in Australia. Air temperature or mixing glyphosate with 2,4-D, may influence the efficacy of glyphosate on feather fingergrass (Chloris virgata Sw.), a problematic summer-season weed of Australia. Dose–response studies...

Navua sedge is a difficult-to-control perennial sedge in north Australian farming systems, including fallow fields, pastures, and along roadsides and fencelines. A set of pot trials were conducted to evaluate the performance of different herbicides when used alone or in mixtures on different sizes of Navua sedge plants, and the performance of diffe...

The occurrence of freezing stress around herbicides application is one of the most important factors influencing their performance. This experiment was performed to evaluate the efficacy of clodinafop-propargyl and 2,4-D plus MCPA (2,4-Dichlorophenoxyacetic acid plus 2-methyl-4-chlorophenoxyacetic acid), the most important herbicides used in wheat...

Hood canarygrass (Phalaris paradoxa L.) is a problematic weed in winter crops of Australia. Experiments were conducted to determine the effects of environmental factors on seed germination of P. paradoxa and wheat (Triticum aestivum L.) and herbicide options for P. paradoxa control. Results revealed that P. paradoxa had higher germination (> 89%) a...

Rigid ryegrass is a problematic weed species in winter crops and winter fallow; however, recently, this weed species has been observed in summer crops and fallow. These observations warrant the evaluation of different postemergence herbicides for its control. Outdoor pot studies were conducted during the spring-summer of 2021-22 to determine the pe...

Chickpea growers in Australia have no post-emergent (POST) herbicides labeled for broadleaf weed control and they rely on pre-emergent herbicides for control of broadleaf weeds. The objective of this study was to evaluate chickpea tolerance to POST application of paraquat (0, 90, 180, 360, and 540 g ai ha ⁻¹ ) in a randomized complete block design....

An in-depth understanding of the germination response of troublesome weed species, such as feather fingergrass ( Chloris virgata Sw.), to environmental factors (temperature, soil moisture, etc.) could play an essential role in the development of sustainable site-specific weed control programs. A laboratory experiment was conducted to understand the...

Different herbicides are currently required for sustainable weed management in aerobic rice. Three pot experiments were conducted using different herbicides to evaluate rice safety and for the control of Echinochloa colona, a major weed of aerobic rice. Among the pre-emergence (PRE) herbicides, it was found that pendimethalin (594 g ai ha−1) and fl...

Junglerice [ Echinochloa colona (L.) Link] is increasing its prevalence in eastern Australia by adapting to Australia’s changing climatic conditions and conservation agricultural systems and by evolving resistance to glyphosate. Information is limited on the growth and seed production dynamics of E. colona when it interferes with mungbean, a major...

Leucaena leucocephala (Lam.) de Wit (commonly known as leucaena) is a leguminous species of the family Fabaceae and a native of Mexico and Central America. It is often addressed as a “miracle tree” for offering a wide variety of ecosystem services and possessing strong ecological attributes. The multiple uses of leucaena in agroforestry, livestock,...

Leucaena [ Leucaena leucocephala (Lam.) de Wit] is a perennial weed in over 25 countries, including Australia. Knowledge regarding the seed biology of L. leucocephala could help in making weed management decisions. Experiments were conducted to study the effect of hot water (scarification), alternating temperatures, heat stress, salt stress, water...

Basmati rice grown in Pakistan has a world over importance owing to its fragrant long grains and premium cooking quality. Further, the rice plays a significant role in fetching high foreign exchange and feeding nearly 200 million people in the country. The conventional rice system of Pakistan is characterized with puddling, enormous water supplies,...

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Weeds pose a serious threat in achieving sustainable and profitable crop production. South Asia, as both a major food-producing and consuming region, needs a linear increase in food grain production. Among the several methods of weed management practice, herbicides are the most cost-effective and timely solution. Rice and wheat are the major staple...

Echinochloa species is the most competitive and difficult to control weed in agricultural crops. It causes significant economical crop yield losses across the world. Echinochloa ecotypes possess great variability and thereby significantly reduce the efficacy of different herbicides. For effective control and reducing the competition for nutrients a...

The rice–wheat cropping system (RWCS) is the backbone of Indian farming, especially in the north-western region. But continuous adoption of the RWCS in northwest India has resulted in major challenges and stagnation in the productivity of this system. Additionally, the Indo-Gangetic Plains of Pakistan, Nepal, and Bangladesh are also facing similar...

Redroot pigweed (Amaranthus retroflexus L.) and slender amaranth (Amaranthus viridis L.) are becoming problematic weeds in summer crops, including cotton in Australia. A series of laboratory and field experiments were performed to examine the germination ecology, and seed persistence of two populations of A. retroflexus and A. viridis collected fro...

Control of glyphosate-resistant (GR) junglerice is quite a challenging task in eastern Australia. There is limited information on the efficacy and reliability of alternate herbicides for GR populations of junglerice, especially when targeting large plants and when temperatures are high. A series of experiments were conducted to confirm the level of...

Summer grass weed species are a particular problem in the northeast cropping region of Australia because they are prolific seeders and favor no-till systems. Information on weed seed persistence levels can be used for the development of effective and sustainable integrated weed management programs. A field study was conducted over 42 months to eval...

The rice-wheat cropping system is the backbone for food security in all South Asian countries on 13.5 million hectares, except in Sri Lanka, where the rice-rice cropping system is mainly followed. A large proportion of rice and wheat crops is produced as well as consumed in South Asia. Weeds are one of the major biotic factors constraining crop pro...

Chloris virgata has become one of the most difficult glyphosate-resistant (GR) grass weeds in summer fallows in the eastern region of Australia. It germinates in several cohorts following rainfall events; therefore, growers are often tempted to wait for most of the weeds to emerge before herbicide application. However, by that time, some seedlings...

High weed infestation and low nitrogen (N) recovery are among the major causes of lower yield in dry-seeded rice (DSR) compared with transplanted rice. The effects of N rate and planting density dynamics on rice productivity and N-use efficiency (NUE) have been extensively studied in transplanted rice. However, information on the combined impact of...

Wild mustard ( Sinapis arvensis L.) is a widespread weed of the southeastern cropping region of Australia. Seed germination ecology of S. arvensis populations selected from different climatic regions may differ due to adaptative traits. Experiments were conducted to evaluate the effects of temperature, light, radiant heat, soil moisture, salt conce...

Sweet summer grass is a problematic weed in the central Queensland region of Australia. This study found glyphosate resistance in two biotypes (R1 and R2) of sweet summer grass. The level of resistance in these biotypes was greater than 8-fold. The glyphosate dose required to reduce dry matter by 50% (GR50) for the resistant populations varied from...

A thorough understanding of the emergence pattern and persistence of weed seeds is a prerequisite in framing appropriate weed management options for noxious weeds. In a study conducted at the University of Queensland, Australia, the emergence and seed persistence behavior of three major weeds Sonchus oleraceous, Rapistrum rugosum, and Argemone mexi...

ABSTRACT Echinochloa crus-galli (L.) Beauv. is a stronger competitor of rice for resources than other weeds. An adequate knowledge of the biology, ecology and critical period of competition of E. crus-galli with dry-seeded rice (DSR) is fundamental in designing effective, sustainable and integrated weed management programs. Experiments were conduct...

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...

Sumatran fleabane [ Conyza sumatrensis (Retz.) Walker] is an emerging weed in the Australian cropping region. Populations resistant to glyphosate have evolved in Australia, creating the demand for information regarding the seed germination ecology of glyphosate-resistant (R) and glyphosate-susceptible (S) populations of C. sumatrensis . A study was...

Junglerice and feather fingergrass are major problematic weeds in the summer sorghum cropping areas of Australia. The objectives of this study were to investigate the growth and seed production of junglerice and feather fingergrass in crop-free (fallow) and under competition with sorghum planted in 50 cm and 100 cm row spacings at three sorghum pla...

XtendFlex TM cotton with resistance to glyphosate, glufosinate and dicamba may become available in Australia. Resistance to these herbicides enables two additional modes of action to be applied in crop. The double knock strategy, typically glyphosate followed by paraquat, has been a successful tactic for control of glyphosate-resistant in fallow si...

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...

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...

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...

Phalaris minor Retz., P. paradoxa L. and P. brachystachys Link. are prolific and competitive and considered as winter crops weeds. All three Phalaris species. The objective of the study was to obtain information about germination responses of P. minor, P. paradoxa and P. brachystachys to constant temperatures, drought and salt stresses, pH and seed...

Herbicide resistance is an increasing issue in many weed species, including rigid ryegrass ( Lolium rigidum Gaudin); a major weed of winter cropping systems in southern Australia. Recently, this weed has also been found in summer crops in the south eastern region of Australia. Effective control of this herbicide resistant weed across south eastern...

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 th...

Evolution in the seed dormancy depends on the presence of heritable variation in weed populations. This genetic variation in weeds arises because of abundant, grow rapidly, and produce large numbers of off springs. Compared with other plant species, populations of weed species frequently show limited genetic variation in seed dormancy due to coloni...

African mustard ( Brassica tournefortii Gouan) is a problematic winter annual weed in Australia. Germination ecology of B. tournefortii may change in response to the maternal environments or habitats in which they grow. A study was conducted to evaluate the effect of environmental factors on germination and emergence of four populations of B. tourn...

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 herb...