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In order to meet the dietary requirements of the rising human population with diminishing water resources, there is the need to adopt techniques that optimize crop yield under reduced water conditi...

Chemical weed control method creates environmental hazards and residual effects in crops and soil. Alternate approach to control weeds is getting attentions in sustainable production system. Aqueous extract of crop is an important technique to control weed and also environment friendly and cheap. To investigate the herbicidal potential of aqueous extract of winter crop Carthamus tinctorius (safflower) on summer weed Oryza punctata (red rice) seed germination and initial seedling growth, a study was planned in Weed Science Laboratory. In this study, seeds of C. tinctorius were incubated in seven concentrations (0, 0.25, 0.50, 1, 2, 4, and 8%) of different parts i.e. leaves, stem, flower of C. tinctorius. All the tested concentrations of various plant parts of C. tinctorius significantly inhibited the mean emergence time, germination index, germination percentage (%), time taken to 50% germination as well as growth of O. punctata weed. However, maximum mean emergence time (4.73 days), time taken to 50% germination (4.19 days) was noted at 8% concentration and germination index of O. punctata was noted at 0.25% concentration when flower extract was applied. Leaf aqueous extract at the concentration 8% caused the lowest root length (1.53 cm), shoot length (4.51 cm) and fresh weight (54.72 g) of O. punctata. Results suggested leaf and flower extract of C. tinctorius at concentration (8%) can be used potential bio-herbicide for the control of red rice. Key words: Allelopathy, seedling growth, inhibitory, weed growth, plant parts, promotor

Plant growth-promoting rhizobacteria are known to associate with several cereal crops. The rhizobacterium exerts its function by synthesizing diverse arrays of phytohormones, such as cytokinin (Ck). However, it is difficult to determine the plant growth promotion when a bacterium produces many different kinds of phytohormones. Therefore, to assess the involvement of Ck in growth promotion and activation of antioxidant and physiological systems, we set up this experiment. Wheat seeds (

Annual sowthistle (Sonchus oleraceus L.) is a broadleaf weed that is increasing in prevalence in the northern cropping regions of Australia. Being a member of Asteraceae family, this weed possesses many biological attributes needed to thrive in varying environments and weed management pressure. Interference of this weed was examined in a wheat (Triticum aestivum L.) crop through field studies in 2016 and 2017. Different densities of S. oleraceus were evaluated for their potential to cause yield loss in wheat: 0.0 (weed free), low (9 to 15 plants m−2), medium (29 to 38 plants m−2), and high (62 to 63 plants m−2). Based on the exponential decay model, 43 and 52 plants m−2 caused a yield reduction of 50% in 2016 and 2017, respectively. Yield components such as panicles m−2 and grains per panicles were affected by weed density. At the high weed infestation level, S. oleraceus produced a maximum of 182,940 and 192,657 seeds m−2 in 2016 and 2017, respectively. Sonchus oleraceus exhibited poor seed retention at harvest as more than 95% of seeds were blown away by wind. Adverse effects on crop, high seed production and wind-blown dispersal may lead to an increased prevalence of this weed in the absence of an integrated weed management strategy utilizing both herbicides and non-chemical options.

Sonchus oleraceus and Rapistrum rugosum are two rapidly emerging weeds of the northern grain region of Australia. To understand the ability of these weeds regarding their germination response to temperature and different soil moisture regimes, experiments were undertaken on the germination of these weeds at varying osmotic potential and temperature regimes. The experiment was conducted as a split-plot design with alternating day/night temperature regimes (15/5, 20/10, 25/15 and 30/20 degrees C) as a main plot and osmotic potential regimes (0.0, -0.1, -0.2, -0.4, -0.6, -0.8 and -1 MPa) as a subplot. At different temperature regimes, there was 65-91% germination of S. oleraceus in water (0 MPa). There was 0-4% germination at -0.8 MPa and no germination at -1.0 MPa. Osmotic potential values that can cause 50% reduction in germination of S. oleraceus based on a sigmoid regression model ranged from -0.38 to -0.48 MPa. There was 33-81% germination of R. rugosum in distilled water (0 MPa), 1-3% germination at -0.8 MPa and no germination at -1.0 MPa. Osmotic potential values that can cause 50% reduction in germination of R. rugosum based on a sigmoid model ranged from -0.26 to -0.54 MPa. Results of the study were related to the emergence pattern of weeds during field survey and soil moisture profiles estimated by the Australian Landscape Water Balance Model and explain the emergence of these weeds outside the normal seasonal window of prevalence as a response to changes in weather.

In a field experiment, various strengths of Hoagland’s nutrient solutions were sprayed to mitigate the deleterious effects of nutrient stresses at different growth stages on mash bean cultivars. Ho...

Due to increased industrialization, arsenic (As) in the soil has become a serious issue for wheat production since past few decades. We investigated the role of Azospirillum brasilense and trans-zeatin riboside (tZR) in the mitigation of arsenic toxicity in wheat for 2 years (2018-2019 and 2019-2020) in pot experiments. Wheat plants grown in soil artificially spiked with arsenic (50, 70, and 100 μM) was left alone or amended with A. brasilense, tZR, or their combination as mitigation strategies. A treatment without arsenic or amendments was maintained as control. Arsenic-induced physiological damages were noticed in the wheat plants. Detrimental effects on the plant physiological functions, such as disruption of cell membrane stability, reduced water uptake, and stomatal functions, were noticed with increase in As toxicity. Application of biological amendments reversed the effects of As toxicity by increasing wheat plant growth rate, leaf area, and photosynthesis and also yield. Therefore, application of tZR and wheat seed inoculation with A. brasilense could be a sustainable and environmentally friendly strategy to mitigate arsenic-induced crop physiological damages.

Exotic plant invasion, a global issue, has a tremendous impact on ecology, economy, human, and animal health. Alligator weed (the world’s first aquatic weed) is a serious invasive weed in 32 different countries of South America, Australia, Asia, and North America. Recently, it has been recorded as a threat weed of rice, maize, soybean, vegetables, fruit trees, and pastures, causing 19–45% yield losses in these crops in addition to its infestation in canals, lakes, and ditches. Alligator weed has the potential to ruin agricultural and natural ecosystems and recreational areas. Ability to propagate via vegetative fragmentation, water-borne dispersal of vegetative propagules, and allelopathic potential contribute towards its success as an invasive weed species of terrestrial, semi-aquatic, and aquatic environments. Application of glyphosate, metsulfuron-methyl, dichlobenil, fluridone, hexazinone, triclopyr amine, dimethylamine, imazapyr, diuron, and amitrole herbicides have been found most effective in controlling this weed in different habitats. Agasicles hygrophila, Vogtia malloi pastana, Amynothrips andersoni, and Nimbya alternanthera have been reported as bio-agents for the control of alligator weed. We present a comprehensive review of the biology, interference, and management options of an extremely dangerous invasive weed species. Although management of alligator weed through chemical, biological, and mechanical means are often effective, there is need for well-planned, long-term field experiments to evaluate the role of different factors that are stated to be responsible for its increasing infestation and distribution (e.g., regeneration after damage caused by herbicides, high soil fertility levels, soil disturbances, shallow vs. deep ploughing and grazing management). It is recommended that future research should focus more on the integration of different management approaches in both aquatic and terrestrial ecosystems, and in various ecological regions.

Widespread resistance in Phalaris minor is a major challenge for sustainable wheat production. Recently, multiple resistance and cross resistance in this weed increased the concerns of wheat growers. The use of potential integrated resistance management strategies including allelopathic crop mulches and herbicide mixtures is crucial in assuring sustainable production. A two-year field trial was conducted during 2014–15 and 2015–16 in wheat to evaluate the efficacy of allelopathic mulches of sunflower, rice, maize, and sorghum alone and in combination with three types of herbicide mixtures. Post-emergence herbicide mixtures used in this study were clodinafop –propargyl plus metribuzin, sulfosulfuron plus clodinafop-propargyl, and pinoxaden plus sulfosulfuron at 50% of recommended doses. Integrated use of allelopathic crop mulches and herbicide mixtures provided effective control of P. minor in wheat. However, application of allelopathic mulches and herbicide mixtures alone did not provide a satisfactory control of P. minor. In addition, the application of allelopathic mulches caused a significant decay (23–52%) of soil weed seed bank. The integrated use of mulches and herbicide mixtures consistently enhanced the wheat yield by 23–39% and 24–35% during 2014–15 and 2015–16, respectively. These findings, as the first indication of the potential integration of allelopathic mulches and post-emergence herbicide mixtures to manage P. minor in wheat fields, would help control resistant P. minor and delay further herbicide resistance in this weed.

Information relating to germination and seedling emergence of a plant aids in determining the species potential distribution and also helps in designing appropriate plant management strategies within an agroecosystem. Salsola foetida Del. ex Spreng, a naturally occurring perennial shrub, is traditionally used as a medicinal plant and a promising camel fodder in the hypersaline, semiarid, and arid areas across the globe. A series of laboratory and greenhouse experiments were conducted to determine the effect of various environmental factors such as temperature, light, salinity, osmotic stress, pH, and seed burial depth on seed germination and seedling emergence of S. foetida. A decline in germination was observed with increases in temperature. The maximum germination of 95% was observed at 25/15°C followed by 83% at 30/20°C; however, minimum germination (35%) was observed at 40/30°C. Maximum seed germination (95%) was observed under 24-h darkness while a decrease in germination (72%) was recorded when seeds were kept in 24-h light. Under saline conditions, 67% of seeds germinated at 100 mM sodium chloride (NaCl) and germination decreased to 12% with an increase in salinity to 500 mM NaCl. The optimum pH for seed germination of S. foetida was 7 (97% germination), although 36% and 75% of seeds germinated at the pH levels of 5 and 10, respectively. About 5% of seeds germinated at an osmotic potential of — 0.8 MPa compared with 40% at — 0.2 MPa. However, seeds of S. foetida were found sensitive to increased burial depth. The maximum germination was observed at the soil surface, and emergence inhibited completely from the seeds buried at the 5-cm depth. The high germination ability of S. foetida over a wide range of environmental factors suggests that this species is likely to thrive easily under harsh arid conditions. Therefore, it is used as a potential candidate for the rehabilitation of rangelands and will be helpful in mitigating the adverse effect of climatic changes on humans and livestock in the degraded areas.

Avena fatua and Avena ludoviciana are closely related grass weed species infesting a large number of crops around the world. These species are widely distributed in diverse agro-ecosystems from temperate to sub-tropical regions due to their unique seed traits, successful germination ecology, high competitive ability, and allelopathic potential. A. fatua is more widespread, adaptable, and problematic than A. ludoviciana. Both these species infest major winter and spring crops, including wheat, oat, barley, canola, maize, alfalfa, and sunflower, causing up to 70% yield losses depending on crop species and weed density. Chemical control has been challenged by large-scale herbicide resistance evolution in these weed species. A. fatua is the most widespread herbicide-resistant weed in the world, infesting about 5 million hectares in 13 countries. The use of alternative herbicides with different modes of action has proved effective. Several cultural practices, including diverse crop rotations, cover crops, improved crop competition (using competitive cultivars, high seed rates, narrow row spacing, altered crop geometry), and allelopathic suppression, have shown promise for controlling A. fatua and A. ludoviciana. The integrated use of these cultural methods can reduce the herbicide dose required, and lower dependency on herbicides to control these grasses. Moreover, integrated management may successfully control herbicide-resistant populations of these weed species. The use of integrated approaches based on the knowledge of biology and ecology of A. fatua and A. ludoviciana may help to manage them sustainably in the future.

The food security of many developing countries relies on sorghum production due to its low input requirements and ability to endure extreme climatic stresses. This C4 grass species is widely cultivated for grain, feed/fodder, and bio-fuel uses in tropical and semi-arid areas of the world. A high efficiency water utilization mechanism and tolerance to drought and high temperatures favours it as an alternative crop to maize in areas with marginal water availability. Despite of its potential, this crop is underutilized given few weed management options. In addition to other biotic and abiotic factors, weeds are considered to be a major constraint, causing 15–97% losses for sorghum growth and yield under different climatic conditions. Previous studies where the crop spacing, seeding rate, and selection of competitive cultivars were altered, highlighted the importance of weed management through cultural practices or crop competition. Narrowing the crop rows and increasing plant densities were found effective in reducing the growth, biomass, and competitive ability of several weed species in sorghum. In addition, selection of competitive and allelopathic sorghum cultivars affected the weed seedling emergence by decreasing light interception and by releasing numerous allelochemicals. However, a review of the literature directed our attention towards some neglected points of weed management through crop competition in sorghum. For instance, crop row orientation has not been studied yet to investigate its influences on weed competitiveness against sorghum around the world. There is a dire need to diversify cultural practices in agro-ecosystems as much as possible to provide competitive advantage for the sorghum crop. Future research should be planned to evaluate the effectiveness of different sowing rates, dates, and directions on the crop yield and weed suppression under different cropping systems. Furthermore, cultural practices should be integrated with other weed management techniques for the development of a more reliable and sustainable weed control program in sorghum.

Agriculture occupies an important place in improving the living standards of farmers in Pakistan. About 90% of farm earnings rely on the cultivation of sugar, fibre, cereals and legumes. Due to lack of essential resources and technical expertise, every year thousands of farmers fail to reach maximum yield potential. Over 70% of farmers own less than 5 ha in Pakistan; therefore, it is uneconomic to employ costly mechanical and chemical strategies for the control of pests in their crops. Among these pests, we eds are considered to be the major obstacle to crop production, and can ultimately result in crop failure. Traditionally, manipulation of cropping techniques was employed for the control of weeds; later on, development of synthetic chemical herbicides made it easier to control weeds in a very short time period. However, over time the increased use of herbicides has led to the development of herbicide resistant weeds. Furthermore, increasing environmental concerns, weed population shifts, and increased managerial costs have made it difficult for farmers to control these weed species within their limited economic resources. Nowadays, scientists and research organizations are being urged to provide innovative weed management solutions, with minimal ecological impacts. Studies have revealed the importance of cultural strategies for the management of weeds in different cropping systems. Research has proved that alternation of cultural practices, and selection of competitive crop cultivars, could be a possible strategy to minimize the competitiveness of weeds. Increased crop densities, narrower row spacing, intercropping and alternation in row directions are among the weed control strategies gaining rapid attention in many countries. Unfortunately, limited information is available about weed management using crop competition in Pakistan. This review article focusses on the importance of these agronomic practices in reducing the competitive potential of weeds, for their effective and appropriate management in major crops of Pakistan. It is intended to assist researchers in the design of economically viable and eco-friendly weed management strategies, which will aid in eliminating the burden of herbicides and mechanical cultivation from farmer’s production costs.

It is now widely recognized that Bidens pilosa has become a problematic broadleaf weed in many ecosystems across the world and, particularly in the light of recent climate change conditions, closer management strategies are required to curtail its impact on agricultural cropping. In this investigation, experiments were conducted to evaluate the effect of environmental factors on the germination and emergence of B. pilosa, and also on the response of this weed to commonly available post-emergence herbicides in Australia. The environmental factors of particular interest to this current work were the effect of light and temperature, salinity, burial depth and moisture on B. pilosa since these are key management issues in Australian agriculture. In addition, the effects of a number of commonly used herbicides were examined, because of concerns regarding emerging herbicide resistance. In the tested light/dark regimes, germination was found to be higher at fluctuating day/night temperatures of 25/15 °C and 30/20 °C (92–93%) than at 35/25 °C (79%), whilst across the different temperature ranges, germination was higher in the light/dark regime (79–93%) than in complete darkness (22–38%). The standard five-minute temperature pretreatment required for 50% inhibition of maximum germination was found to be 160 °C, and it was further shown that no seeds germinated at temperatures higher than 240 °C. With regard to salinity, some B. pilosa seeds germinated (3%) in 200 mM sodium chloride (NaCl) but all failed to germinate at 250 mM NaCl. Germination declined from 89% to 2% as the external osmotic potential decreased from 0 to −0.6 MPa, and germination ceased at −0.8 MPa. Seeding emergence of B. pilosa was maximum (71%) for seeds placed on the soil surface and it was found that no seedlings emerged from a depth of 8 cm or greater. A depth of 3.75 cm was required to inhibit the seeds to 50% of the maximum emergence. In this study, application of glufosinate, glyphosate and paraquat provided commercially acceptable control levels (generally accepted as >90%) when applied at the four-leaf stage of B. pilosa. However, none of the herbicide treatments involved in this study provided this level of control when applied at the six-leaf stage. In summary, B. pilosa germination has been clearly shown to be stimulated by light and thus its emergence was greatest from the soil surface. This suggests that infestation from this weed will remain as a problem in no-till conservation agriculture systems, the use of which is increasing now throughout the world. It is intended that information generated from this study be used to develop more effective integrated management programs for B. pilosa and similar weeds in commercial agricultural environments which are tending toward conservation approaches.

The species Euphorbia dracunculoides and Astragalus are problematic weeds of arid chickpea in the chickpea mono-cropping system in Pakistan. The influence of various ecological factors on germination and seedling emergence characteristics of these weeds was determined under laboratory conditions. The results suggested that seed germination of both species was 50% at 15 oC under light conditions, and germination decreased when the temperature was increased. The increase in drought stress from 2.5 to 15% significantly decreased germination of E. dracunculoides and Astragalus spp. Both species failed to germinate at the osmotic potential of -3.02 MPa. The increase in field capacity from 25 to 100% increased emergence percentage and emergence index of both weeds. A pH range of 6 to 9 did not influence seed germination of both species and they were able to germinate at a wide range of pH conditions. Both weeds were very sensitive to salinity; however, a few seeds (10%) of Astragalusspp. germinated even at a 150 mM sodium chloride concentration. To check the effect of burial depth, seeds were placed in pots under seeding depths of 0 to 6 cm at an interval of 1 cm, respectively. Maximum emergence was attained at the soil surface and emergence declined with increasing depths. Seedling emergence of E. dracunculoides was higher than that of Astragalusspp. at all burial depths. Studies on germination ecology of these two weeds will offer insights into their behavior under different environmental conditions. Their germination responses and growth patterns under different ecological factors will help us to design an efficient management strategy to control these two troublesome weeds. RESUMO: As espécies Euphorbia dracunculoides e Astragalus são plantas daninhas problemáticas do grão-de-bico no sistema monocultivo desta cultura no Paquistão. Em condições de laboratório, determinou-se a influência de vários fatores ecológicos nas características de germinação e emergência de plântulas dessas plantas daninhas. Os resultados sugeriram que a germinação de sementes de ambas as espécies foi de 50% a 15 oC sob condições de luz, e a germinação diminuiu com o aumento da temperatura. O aumento do estresse hídrico de 2,5 para 15% causou a diminuição significativa da germinação de E. dracunculoides e Astragalus spp. Ambas as espécies não germinaram no potencial osmótico de -3,02 MPa. O aumento na capacidade de campo de 25 para 100% aumentou a porcentagem de emergência e o índice de emergência de ambas as plantas daninhas. A variação do pH de 6 a 9 não influenciou a germinação de sementes de ambas as espécies, que foram capazes de germinar em uma ampla gama de condições de pH. Ambas as plantas daninhas foram muito sensíveis à salinidade; no entanto, algumas sementes (10%) de Astragalusspp. germinaram mesmo em uma concentração de cloreto de sódio de 150 mM. Para verificar o efeito da profundidade de semeadura, as sementes foram colocadas em vasos com profundidades de semeadura de 0 a 6 cm, em um intervalo de 1 cm, respectivamente. Foi obtida máxima emergência na superfície do solo e houve diminuição da emergência com o aumento da profundidade. A emergência de plântulas de E. dracunculoides foi maior que a de Astragalusspp. em todas as profundidades de semeadura. Estudos sobre a ecologia da germinação dessas duas plantas daninhas poderão elucidar seu comportamento sob diferentes condições ambientais. As respostas de germinação e os padrões de crescimento dessas espécies sob diferentes fatores ecológicos serão úteis para a elaboração de uma estratégia de gerenciamento eficiente para controlar essas duas plantas daninhas problemáticas.

Resistance evolution in weeds against all major herbicide groups demand investigations to identify various factors responsible for resistance development. Herbicide hormesis has not yet been included in the list of factors promoting the evolution of resistance. Studies were conducted to evaluate the degree of hormesis in fenoxaprop-p-ethyl susceptible and resistant Phalaris minor to provide a first indication of whether hormesis is a potential factor in the development of resistance. In the first experiment, a wide range of doses up to 160% of the recommended field rate was used to identify potential hormetic doses for resistant and susceptible P. minor populations. Doses below 40% have been designated as potential hormetic doses. In the second experiment, ten different doses of fenoxaprop below 40% (0, 2, 4, 8, 12, 16, 20, 24, 28 and 32% of the recommended rate) were sprayed at the 4-5 leaf stage of both resistant and susceptible P. minor populations. At fifteen days after spraying, dose range of 2-12% and 2-20% caused a significant increase (up to 22% and 24%) in growth traits of susceptible and resistant populations, respectively. At maturity, dose range of 2-12% for susceptible and 2-24% for resistant populations caused a significant increase (up to 20% and 57%) in growth and seed production potential (13% and 17%), respectively. The upper limit of the hormetic dose range (16 to 24%) for the resistant population was inhibitory for the susceptible populations. These results indicate that fenoxaprop hormesis could play a vital role in the evolution of fenoxaprop resistance in P. minor.

Evolution of herbicide resistance in weeds is among the serious challenges that agriculture face today. In Pakistan herbicide use over last 6 decades has enabled earlier planting of short-season crops and improved weed control in wheat as well as other cropping systems. This has greatly favored the use of more and more herbicides. Conversely, this exercise increased the evolution of resistant biotypes. Wheat being Pakistan's number one staple crop faces daunting weeds problem. In order to understand the status of herbicide resistant weeds in wheat fields, survey was conducted for two consecutive years (2015-2017) in different regions of Pakistan. A questionnaire was designed to collect data from three hundred farmers randomly selected in all four provinces of Pakistan on herbicides used in wheat, history of crop cultivation regimes and weed species that have seized to respond to field rates of herbicides. Seed of suspected biotypes were collected from the survey sites and preserved in our gene pool for the confirmation of the resistance in the laboratory by bioassay and molecular level in future. Farmers (96%) perceived that Phalaris minor Retz. was the most important annual weed of wheat crop followed by Avena fatua L. (94%). Customarily, three aryloxyphenoxy propionate herbicides, clodinafop-propargyl, fenoxaprop-P-ethyl and diclofop-methyl were used to control different grass weeds such as P. minor, A. sativa L. and A. fatua. In farmers' opinion, high yield of wheat was associated with the continuous use of these herbicides. Resistance-suspicious weeds were reported from all studied areas (Punjab, KPK, Sindh, and Baluchistan provinces) in fields with the herbicide use history of five to seven years or more. This study suggests that for long-term avoidance of herbicide resistance, in our wheat growing systems we will require embracing practices that decrease selection pressures favoring resistant weeds. Achieving these goals requires an understanding of the evolution and dynamics of resistant populations. It is recommended that for the effective management of resistant populations of P. minor and A. fatua, farmers' education on ecologically sustainable weed management is critically important. This study will provide a basis for examining the questions that are relevant to understanding herbicide resistance evolution in Pakistan and that may help determine appropriate weed management strategies.

A field survey was conducted for the sampling of Acetyl-CoA carboxylase (ACCase) inhibitor resistance littleseed canarygrass, a major weed of wheat, from Punjab, Pakistan in 2014 for confirmation of resistance. The surveyed regions encompassed four different cropping systems including rice–wheat, maize–wheat, cotton–wheat and mixed cropping. Dose–response assay was conducted for confirmation of resistance. Efficacy of herbicide mixtures including clodinafop–propargyl, metribuzin, pinoxaden and sulfosulfuron at a range of doses was investigated to manage littleseed canarygrass. Results revealed that all populations were resistant to fenoxaprop except PM-BWL-2. The higher level resistance (6.5) was found in populations collected from rice–wheat cropping system. The tested herbicide mixtures at 75% and 100% of the recommended dose of each mixture component provided the effective control of resistant littleseed canarygrass. Mixtures at 50% provided more than 80% control and reduced growth and seed production potential of surviving plants. The confirmation of ACCase inhibitor resistance as the first case of herbicide resistance in Pakistan, leads us to discourage use of ACCase inhibitor herbicides alone. However, herbicide mixtures at 75% and 100% of the recommended dose are suggested to manage this weed for sustainable wheat production in the surveyed cropping systems.

Echinochloa colona (L.) Link. is one of the most problematic weeds across the world. It is an annual C4 summer grass, native to tropical and subtropical Asia, emerged as a serious and persistent threat in 35 cropping systems in more than 60 countries. E. colona is reported as an important associated weed species in transplanted and direct-seeded rice. Diverse ecotypes, high seed production, short seed dormancy, rapid growth, competitive potential, allelopathic interaction, and resistance against several herbicides makes it a more adaptable and persistent challenge in various agro-ecosystems. Development of resistance to recommended or higher doses of numerous herbicides, including ametryn, atrazine, bispyribac-sodium, clefoxidym, cyhalofop-butyl, fenoxaprop-p-ethyl, glyphosate, metribuzin, propanil, and triazine, is a serious concern for the farming and scientific community. Crop infestation with resistant E. colona biotypes may ultimately increase the weed control cost. Unfortunately, investigations on seed dormancy release, genetic diversity, allelopathic interference, and competitive ability of this weed are inadequate in accomplishing its appropriate control in different environments. Therefore, a comprehensive review is presented here to gather the existing information, to pin point key findings, and to highlight the research gaps in the biology, interference, and management of E. colona. Different management options have been discussed in relation with eco-biology of this noxious weed. The potential research endeavours have also been highlighted in order to provide an insight of its existing scenario and to facilitate the future management strategies.

To assess the phytotoxic potential of Achyranthes aspera, Alternanthera philoxeroides, Datura metel and Rumex dentatus against Parthenium hysterophorus, 5% (w/v on dry weight basis) aqueous extracts from root, stem, leaf, flower and whole plant were tested through a Petri plate-based germination and pot-cultured seedling bioassays. Achyranthes aspera and A. philoxeroides inhibited parthenium weed germination more than extracts from other species. Whole plant, leaf and fruit extracts of A. aspera reduced the germination percentage (5%); leaf extract from A. philoxeroides caused lower germination index (0.4), higher mean germination time (14 d) and longer time to 50% germination (13.5 d) of parthenium weed. In the foliar spray bioassay, A. aspera reduced parthenium weed shoot growth more than the other species whereas R. dentatus caused more reduction in root growth. Whole plant extract from A. aspera caused maximum reduction in parthenium weed seedling vigor index (98%) and seedling biomass (96%). The aqueous extracts of A. aspera and A. philoxeroides contained higher concentrations of phenolics viz. gallic (16.9 mg L-1), caffeic (7.4 mg L-1), chromatotropic (63.8 mg L-1), p-coumaric (10.5 mg L-1), m-coumaric (3.1 mg L-1), syringic (9.21 mg L-1) and 4 hydroxy-3-methoxy benzoic (118.6 mg L-1) acids compared with extracts of the other two species tested.