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This study is to understand the fate and ecological consequences of pyroxasulfone in aridisols of Punjab, a detailed dissipation study in soil, its influence on soil enzymes, microbial count and succeeding crops was evaluated. Half-lives (DT50) increased with an increase in the application rate of pyroxasulfone. Dissipation of pyroxasulfone decreased with increase in organic matter content of soil and was slower in clay loam soil (DT50 12.50 to 24.89) followed by sandy loam (DT50 8.91 to 17.78) and loamy sand soil (DT50 6.45 to 14.89). Faster dissipation was observed under submerged conditions (DT50 2.9 to 20.99 days) than under field capacity conditions (DT50 6.45 to 24.89 days). Dissipation increased with increase in temperature with DT50 varying from 6.46 to 24.88, 4.87 to 22.89 and 2.97 to 20.99 days at 25 ± 2, 35 ± 2 and 45 ± 2 °C, respectively. Dissipation was slower under sterile conditions and about 23.87- to 33.74-fold increase in DT50 was observed under sterile conditions as compared to non-sterile conditions. The application of pyroxasulfone showed short-lived transitory effect on dehydrogenase, alkaline phosphatase and soil microbial activity while herbicide has non-significant effect on soil urease activity. PCA suggested that dehydrogenase and bacteria were most sensitive among enzymatic and microbial activities. In efficacy study, pyroxasulfone effectively controlled Phalaris minor germination, with higher efficacy in loamy sand soil (GR50 2.46 µg mL−1) as compared to clay loam soil (GR50 5.19 µg mL−1). [ABSTRACT FROM AUTHOR]

Field experiments were carried out during Rabi season 2020–21 and 2021–22 at Agronomy Research Farm, CCS HAU, Hisar, for the management of multiple herbicide-resistant Phalaris minor in wheat. Experiment was performed using randomized block design and replicated thrice with a total number of 15 treatment consisting of different combination of pre (PRE) and post-emergence (POST) herbicides. Herbicides selected in this study have different modes of action, i.e. clodinafop and pinoxaden are acetyl-CoA carboxylase (ACCase) inhibitors, sulfosulfuron, mesosulfuron, iodosulfuron and metsulfuron belongs to acetolactate synthase (ALS)/Acetohydroxy acid synthase (AHS) inhibitor group, pendimethalin and pyraxosulfone inhibits the microtubule assembly and long chain fatty acids synthesis, respectively, while metribuzin is Photosystem-II (PS-II) inhibitor and flumioxazin is from protoporphyrinogen oxidase (PPO) inhibitor group. Among different treatments, application of flumioxazin + pendimethalin fb clodinafop propargyl + metribuzin (RM) resulted in significantly lower density and dry weight of P. minor and broadleaved weeds and maximum weed control efficiency at 60 DAS. It was statistically comparable to application of flumioxazin, flumioxazin + pendimethalin, pyroxasulfone + pendimethalin fb mesosulfuron + iodosulfuron (RM), or pinoxaden + metsulfuron (TM) or clodinafop propargyl + metribuzin. Sequential application of pyroxasulfone + pendimethalin (TM) fb mesosulfuron + iodosulfuron (RM) resulted in significantly higher grain yield (5847 and 5369 kg/ha) when compared to rest of the treatments. It was statistically comparable to PRE pyroxasulfone + pendimethalin (TM) fb POST pinoxaden + metsulfuron (TM) or clodinafop propargyl + metribuzin (RM). In conclusion, pre-emergence application of pyroxasulfone + pendimethalin (TM) followed by post-emergence application of either mesosulfuron + iodosulfuron (RM), pinoxaden + metsulfuron (TM) or clodinafop propargyl + metribuzin resulted in better control of resistant P. minor and broadleaved weeds along with higher grain yield. [ABSTRACT FROM AUTHOR]

Agriculture is an important part of the India's economy. India ranks first in net cropland area in the world with 179.8 mha which is 9.6% of global net cropland area and India's agriculture sector makes up 16% of the country's economy, while accounting for 49% of employment (FAOSTAT, 2020). The rice-wheat cropping system (RWCS) is extensive in the subtropical areas of the Indo-Gangetic Plains of India while maize-wheat is widespread in tropical, sub-tropical and warm temperate regions. In north India, rice is grown in the summer season (June/July to September/October) whereas wheat is grown in the winter season (October/November to February/March). The area under wheat in India was 30.59 mha with an annual production of 99.78 mt and average productivity of 3.22 t ha-1 (Anonymous, 2019). The weeds are accounting as a major factor in yield reduction of wheat. The mechanical weed control is not so much effective in controlling weeds in wheat because of narrow inter row spacing. Further, the manual weeding is not much feasible because of mimicry weeds like Phalaris minor which are very much similar to wheat during initial stages. Therefore, the role of herbicides cannot be neglected. But the continuous application of herbicides with same mode of action year by year has resulted in evolution of herbicide resistance in weed species. The management of herbicide resistant weeds in crop production is a major challenge. This review mainly focuses on the current status of herbicide resistant weeds in India associated with wheat along with their management strategies. [ABSTRACT FROM AUTHOR]

Background: The seedling stage is the most vulnerable period of growth and development for annual weeds and an important target for weed management operations. To address this, several weed emergence models have been developed, but none are commercially available. Therefore, this study aims to develop a web application that implements predictive weed emergence models for eight different weed species, utilizing weather data sourced from public weather stations. Results: Lolium rigidum Gaudin presented a mean root mean squared error (RMSE) value of 8.9, achieving an RMSE value below 15 (success rate) in 84.5% of cases. This result may be attributed to the use of a water potential base, set at −0.4 MPa, to evaluate water availability. Centaurea diluta Aiton achieved an RMSE value below 15 in all situations, with an average value of 9.0. This weed showed higher accuracy at southern sites than northern sites. Conversely, Avena sterilis ssp. ludoviciana (Durieu) Gillet & Magne achieved higher precision at northern sites where no dry periods occurred. The newly developed model for Bromus diandrus Roth. achieved an average RMSE value of 7.7 and a 100% success rate. Papaver rhoeas L. and the three Phalaris species exhibited lower accuracy in this study than in previous ones. Nonetheless, the success rates for Papaver rhoeas and Phalaris paradoxa L. were still above 70%. Conclusion: Models for C. diluta, B. diandrus, L. rigidum, Papaver rhoeas and Phalaris paradoxa have demonstrated potential for adoption in commercial production, while Phalaris minor and Phalaris brachystachys models require refinement. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Field and pot investigations were conducted to determine the effectiveness of pyroxasulfone alone and its combinations with other herbicides against diverse weed flora of wheat (Triticum aestivum L.) including multiple herbicide‐resistant (MHR) littleseed canarygrass (Phalaris minor Retz.). Applications of pyroxasulfone 100–127.5 g/ha as pre‐emergence (PE) or early post‐emergence (EPOE) @ 63.75 g/ha at 21–23 days after sowing (1 day before irrigation) were highly effective for control of grass weeds namely P. minor and wild oat (Avena ludoviciana Dur.). It was poor for control of broad‐leaved weeds (Medicago denticulata Willd. and Rumex dentatus L.). However, pyroxasulfone in tank‐mix combination with metsulfuron 4 g/ha, triasulfuron 20 g/ha, and pyroxsulam 18 g/ha effectively controlled (96.5%–99.8%) the diverse weed flora and improved the wheat grain yield (69.5%–285.9%) over untreated weedy control. Also, the pre‐mix of pyroxasulfone + pendimethalin applied as PE was superior to either of these applied alone for weed control and grain yield. Pyroxasulfone 100–127.5 g/ha had yield gain of 119.6%–125.4% and 10.1%–26% over untreated control and pendimethalin 800–1250 g/ha, respectively. In pot studies, straw burnt ash drastically reduced the pyroxasulfone efficacy against P. minor and A. ludoviciana. Pyroxasulfone was also effective in pot studies for control of MHR P. minor having resistance against acetyl‐coA carboxylase (ACCase), acetolactate synthase (ALS), and photosynthesis at the photosystem‐II site‐A (PS‐II) inhibitor herbicides (clodinafop, sulfosulfuron, and isoproturon, respectively). The studies indicate that pyroxasulfone as PE or EPOE can be an alternative grass weed control herbicide in wheat in particular for the control of MHR P. minor. [ABSTRACT FROM AUTHOR]

The introduction and large scale cultivation of wheat cultivars which are semi-dwarf and high yielding in the north-western Indo-Gangetic Plains (IGPs) of India has led to the dominance of wheat mimicking weed, Phalaris minor Retz. Over the period, this weed has become a highly competitive and pernicious weed of wheat in rice–wheat cropping system resulting in huge yield losses. In 1978, the herbicide isoproturon was adopted on large scale to control P. minor in wheat fields and remained as most feasible option for its chemical control. However, P. minor populations have developed resistance over time as a result of continuos application of same herbicide. This herbicide resistance started from isoproturon with 0.8 m ha area to several herbicides like sulfosulfuron, clodinafop, metribuzin, fenoxaprop, pinoxaden, mesosulfuron + iodosulfuron and clodinafop + metribuzin in 7.5 m ha today. Out of 7.5 m ha, 3 m ha was observed under multiple herbicide resistance. To check the herbicide resistant P. minor populations, farmers adopted mixing post-emergence (POE) herbicides with metribuzin as well as its early POE application through fertilizer dust 2–3 days after first irrigation of wheat, and sequential application of pre-emergence (PRE) pyroxasulfone / pendimethalin / metribuzin followed by POE application of pinoxaden / clodinafop / mesosulfuron + iodosulfuron / clodinafop + metribuzin (low dose) in rice–wheat cropping zone of the IGPs of India. Therefore, considering the importance of herbicide resistance and its alarming situation in the region, this review presents the history of evolution of herbicide resistance in P. minor, its present status, management strategies and severity that causes a dent in the sustainability of wheat production under the rice–wheat cropping system of IGPs. In addition, for long-term management of resistance and maintenance of the sustainability of wheat yields, herbicides should be supplemented with integrated weed management strategies like soil solarization, crop rotation, use of crop residue management practices, growing of wheat cultivars with early crop vigour, timely application of herbicides with optimum dose, optimum seed rate, closer row spacing, use of microbial herbicides, exploring the potential use of allelochemicals and correct spray techniques are some of viable options for farmers to avoid losses from this troublesome weed and increasing wheat productivity. [ABSTRACT FROM AUTHOR]

Uncontrolled growth of Phalaris minor in the wheat (Triticum aestivum) crop has remained a problem, leading to a massive reduction in wheat grain production. Herbicides have been used to control the weed, which leads to the development of frequent resistance in P. minor and mutant biotypes were also reported (Trp2027Cys and Ile2041Asn). Development of resistance enforced agro researchers to analyses the action of herbicide on P. minor. In this study, the sequence and structure of P. minor and T. aestivum Acetyl CoA Carboxylase (ACCase) have been analysed to locate the differences in their sequence and structure and to formulate a plausible explanation of the selectivity of herbicides which may help in the rationale discovery of noble herbicides. The sequence and 3D structure analysis of weed and wheat ACCase indicate minute differences in the distantly located amino acid residues. However, proteins are conserved at the binding site of herbicides with no mutation at the catalytic site. Analysis indicates that herbicides selectively target P. minor ACCase might be due to unknown other reasons, but not due to differences in their protein sequence and structure. [ABSTRACT FROM AUTHOR]

The present study was planned to identify the phenolic compounds and allelopathic effect of Glycyrrhiza glabra on germination and seedling growth Phalaris minor at Weed Science Laboratory, Department of Agronomy, University of Agriculture, Faisalabad during winter 2018. The experiments were laid out under a completely randomized design (CRD), having three replicates. In this study seven different concentrations of Glycyrrhiza glabra aqueous extracts (0%, 0.25%, 0.5%, 10%, 20%, 40% and 80%) applied on winter weed P. minor. Data on regarding germination percentage (%), mean Germination time (days), time to 50% germination, root length (mm), shoot length (mm), root fresh weight (mg), shoot fresh weight was recorded following standard procedures. Data were analyzed using Fishers Analysis of Variance. The differences among treatments were separated using a least significant difference test (LSD). Results of the experiment revealed that maximum germination percentage (%), Mean Germination time (Days), Time to 50% germination and minimum, root length (mm), shoot length (mm), root fresh weight (mg), shoot fresh weight of P. minor was recorded at 80% concentration of G. glabra. From the present study, it is concluded that there are phenolic compounds in the wood extract of G. glabra which cause allelopathic effects on P. minor. [ABSTRACT FROM AUTHOR]

Chemical weed regulator process may source ecological hazards and produce residual effects in crops as well as in soil. Another method to switch weeds is accomplishment special treatment in bearable production scheme. Practice of liquid residue of produces is receiving systematic consideration as environmental substitute to copied weed-killer specifically below rapid scheme of growing herbicide refusal in the production of weeds. Therefore, current research was directed at Science Laboratory of weed, Department of Agronomy, University of Agriculture, Faisalabad during winter 2018 to determine the phytotoxic impact proceeding Glycyrrhiza glabra on winter vegetable crop Pisum sativum. The trials were placed out further down an entirely randomized plan, showing three replicates. Some experiments comprised of seven treatments with different concentrations of extract. The wood of G. glabra extracts comprised 0%, 0.25%, 0.5%, 10%, 20%, 40%, and 80% concentration applied on P. sativum. Data on seed sprouting, the measurement of shoot and original mass of weed and pea was recorded following standard procedures. Data stayed investigated through Fishers Study of Variance. The differences among treatments were divided with the action of a least significant difference test (LSD). Results revealed that aqueous extracts were possessed phytotoxic chemicals that cause phytotoxic effect to P. sativum and result in maximum propagation ratio (%), Mean Sprouting period (Days), Period to 50% germination and minimum, the length of root (mm), shoot dimension (mm), root fresh weight (mg), shoot fresh weight was recorded at 80 % concentration of G. glabra. It is concluded that there are phenolic compounds in the wood extract of G. glabra which cause allelopathic effects on P. sativum. [ABSTRACT FROM AUTHOR]

Phalaris minor is a major weed of wheat crop which has evolved resistance against herbicides. Isoproturon is the most accepted herbicide developed resistance in 1992. Later, introduced herbicides also developed resistance and cross-resistance to their respective binding sites. Isoproturon binds at the QB binding site of the D1 protein of photosystem-II (PS-II), which blocks the electron transfer in photosynthesis. In this work, we have carried out a series of computational studies to prioritize the promising herbicides against D1 protein of P. minor. Through the computational studies, twenty-four lead molecules are prioritized which have shown a higher binding affinity and inhibition constant than the reference ligand molecule. The binding and conformational stability of docked complexes was evaluated by molecular dynamics simulations and binding free energy calculations i.e., MM/PBSA. A list of amino acids such as Ala225, Ser226, Phe227, and Asn229 present in the binding site of protein is obtained to be playing an important role in the stability of the protein-lead complex via hydrogen bond and π-π interactions. Binding free energy calculation revealed that the selected lead molecule binding is energetically favorable and driven by electrostatic interactions. Among 24 leads, computational results have uncovered eight promising compounds as potential herbicides which have shown comparable physiochemical profile, better docking scores, system stability, H-bond occupancy, and binding free energy than terbutryn, a reference molecule. These prioritized molecules were custom synthesized and evaluated for their herbicidal activity and specificity through whole plant assay under laboratory-controlled conditions. The lead molecule ELC5 (6-ethoxy-4-N-(2-morpholin-4-ylethyl)-2-N-propan-2-yl-1,3,5-triazine-2,4-diamine) has shown comparable activity to the reference herbicide(isoproturon) against P. minor. [ABSTRACT FROM AUTHOR]

Essential oil (EO) of Tagetes minuta L. extracted from aerial parts of plant through hydro-distillation was tested for its chemical composition by GC-MS. In order to explore the allelopathic potential of the oil, it was tested under laboratory conditions on a common agricultural weed Phalaris minor. The modes of oil application were volatile form (VB), solution form (SB) and oil mixed with agar-agar (AAB). Bioassay studies revealed a dose-dependent inhibitory effect of EO of T. minuta on growth of P. minor. Most effective mode of treatment was VB followed by AAB and minimum effect was observed in SB. Thus, volatile form of EO is best suitable for managing P. minor in agroecosystems. [ABSTRACT FROM AUTHOR]

Foliar blights of graminaceous host are one of the important fungal diseases causing considerable losses to the crops. Under Punjab conditions, foliar blight/spot blotch of wheat and barley (Bipolaris sorokiniana) and leaf spot of oats (Drechslera avenae) are one of the devastating fungal diseases causing considerable reduction in the grain yield. Fifty leaf samples showing typical disease symptoms of foliar blight were collected from different barley, wheat and oats growing areas of Punjab. Samples were also collected from the commonly found weed in the wheat fields i.e. Phalaris minor. Considering the pathogenic behaviour of different isolates on their respective susceptible checks viz., PL426 (barley), HD2329 (wheat), OL-9 (oats) and P. minor, the most virulent isolate from each host i.e. Bsb1, Bsb32, Bsp46 and Da46 from barley, wheat, P. minor and oats, respectively were selected to check their cross-infectivity on different graminaceous hosts including weed hosts under pot house conditions. It was observed that isolate Bsb1 and Bsw32 from barley and wheat, respectively were more aggressive exhibiting moderately resistant to susceptible reaction on different hosts, followed by Bsp34 from P. minor. Isolate Da46 from oats was least aggressive thus exhibiting resistant to moderate reaction on the different tested hosts. Hence, for B. sorokiniana, wheat, barley and oats can serve as collateral hosts. The test isolates developed moderately resistant and resistant reaction on rice also, hence, it can also help in the perpetuation of the pathogen. [ABSTRACT FROM AUTHOR]

Phalaris minor Retz. is a major issue in wheat growing areas of Pakistan because it has evolved resistance to ACCase inhibitors herbicides like fenoxaprop due to enhanced metabolic activity to detoxify herbicides. Cytochrome P450 inhibitors such as 1- aminobenzotriazole (ABT) and malathion are expected to increase the toxicity of herbicides against ACCase resistant weeds. In this regard, a wire house experiment was carried to explore the effect of cytochrome P450 inhibitors on ACCase resistant P. minor biotypes. Seeds of nine ACCase resistant P. minor biotypes and susceptibility were sown in pots (5 seeds per pot). After seedling establishment (at 3-4 leaf stage), different doses of cytochrome P450 inhibitors (ABT at 50, 100 and 150 μM and malathion at 500, 1000 and 1500 g a.i. ha-1) were applied 30 minutes before spray of fenoxaprop at 67.5 g a.i. ha-1. Outcomes exhibited that cytochrome P450 inhibitors improved the herbicidal activity of fenoxaprop, significant decrease in fresh and dry weight of resistant biotypes were achieved. Maximum decrease in weight (fresh and dry) was noted for ABT at 50 μM, 100 μM and 150 μM+ fenoxaprop at 67.5 g a.i ha-1. Similarly, percent decrease in dry weight and mortality was also maximum when ABT at 50 μM, 100 μM and150 μM+ fenoxaprop at 67.5 g a.i ha-1 was used. Results conferred the resistance potential of P. Minor biotypes against fenoxaprop and P450inhibitors could be used to synergize the activity of fenoxaprop. [ABSTRACT FROM AUTHOR]

Copyright of Gesunde Pflanzen is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wheat is the staple cereal crop of Pakistan but its growth is rigorously affected by associated weeds. Present study evaluated the synergistic effect of plant antagonistic rhizobacteria and fungi on growth, yield and suppression of wheat-associated weeds. Wheat associated weeds Phalaris minor and Avena fatua were grown in pots containing wheat as well. Pseudomonas aeruginosa strain PAO1 and Trichoderma harzianum T-MN6 were used as amendments to check their effect on two major weeds of wheat. The combined application of PAO1 and T-MN6 reduced the shoot length of Phalaris minor up to 30% and Avena fatua 40%, root length 22% and 28%, fresh biomass 29% and 31% respectively over their sole application. Similarly, inoculation of PAO1 and T-MN6 alone and in combination considerably enhanced growth, yield and physiological parameters of wheat. It was inferred from this study that the synergistic application of PGPR and fungi is a promising option to suppress major weeds of wheat and to enhance growth and yield of wheat. [ABSTRACT FROM AUTHOR]

The experiment was designed to study allelopathic effect of Rhazya stricta Decne. against selected weeds of wheat crop by using aqueous, hexane and methanolic extracts on filter paper and soil. The germination percentage, radicle length and plumule length were observed. The results revealed that R. stricta methanolic extract showed the highest degree of seed germination percentage inhibition of C. album, P. minor and R. dentatus with 47%, 43% and 42%, respectively in soil, and minimum germination for C. album (53%). The same extract caused significant radical length reduction of R. dentatus and A. fatua measuring 51% and 50%, respectively. The highest degree of inhibition in plumule length was measured for A. fatua and R. dentatus with 55% and 34%, respectively by R. stricta methanolic extract. Based on the results, it can be concluded that R. stricta showed good allelopathic activity that may be used in future herbicide screening program to launch in the market. [ABSTRACT FROM AUTHOR]

Phalaris minor is a problematic weed of wheat (Triticum aestivum L.). Repeated application of herbicides to control this weed causes environmental pollution and some of the weeds even develop herbicide resistance. Recently, phytohormones and allelochemicals produced by rhizosphere microorganisms have been found to suppress the growth of different weeds. Therefore, 32 bacterial isolates obtained from the rhizosphere of wheat were screened for the production of phytohormones indole-3-acetic acid (IAA) and 5-aminolevulinic acid (ALA). Rhizobacterial isolates, having variation in IAA and ALA production ability, were tested for their effect on seedling growth of P. minor on 0.8% water agar plates and four rhizobacterial isolates i. e. HWM 7, HWM 11, HWM 17 and CP 43 caused significant retardation of P. minor seedling growth on 5th and 10th day of seed germination. Under pot house conditions, seed inoculation with Bacillus subtilis strain SYB 101 caused 70.8 and 80.7% decrease in root and shoot dry weight of P. minor and its inoculation showed 136.8 and 316.6% increase in root and shoot dry weight of wheat at 75 days of wheat growth. P. minor growth was also suppressed in the pot house by inoculation of Providentia rettgeri strain CPS 67 and Pseudomonas isolate HWM 11. Maximum growth stimulation of wheat was observed by inoculation with rhizobacterial isolates SYB 101 and HWM 11. Maximum growth retardation of weed was observed by inoculation of B. subtilis strain SYB 101 having moderate level of IAA and ALA production, followed by high IAA and ALA producing P. rettgeri strain CPS 67, suggesting that besides phytohormones, some other metabolite was also involved in growth retardation of P. minor. These rhizobacterial isolates could be further tested for suppression of weed growth under field conditions for their subsequent application as bioherbicide. [ABSTRACT FROM AUTHOR]

Experimental studies were carried out under invitro conditions to examine the effect of Callistemon viminalis essential oil (EO) against the Echinochloa crus-galli L., Amaranthus viridis and Phalaris minor. EO composition was analysed by gas chromatography/mass spectrometry, revealing that EO was rich in monoterpenes and sesquiterpenes like eucalyptol, D-limonene, α-terpineol and caryophyllene oxide. EO applied in the concentration range of 0.5, 1, 2 and 4 μl against Amaranthus viridis, Echinochloa crus-galli L. and Phalaris minor drastically affected the germination of all test plants and inhibited root and shoot development. Also, not only seedling growth, even the chlorophyll content also reduced appreciably. This led to the demonstration that Callistemon viminalis EO was negatively affecting the photosynthetic process. Upregulation of antioxidant enzymes activities indicated that these enzymes were providing protection against Callistemon viminalis EO induced stress. Amaranthus viridis was reported to be more sensitive in comparison to Echinochloa crus-galli L. and Phalaris minor. [ABSTRACT FROM AUTHOR]

Repeated use of herbicides with similar modes of action for weed control in wheat has resulted in evolution of multiple herbicide resistance in Phalaris minor, which could threaten the sustainability of the rice-wheat cropping system in north-western India. Herbicide resistance could also become a problem in direct seeded rice and soybean crops, which rely heavily on acetolactate synthase (ALS) and acetyl coenzyme A carboxylase (ACCase) inhibiting herbicides. As discovery of new herbicide modes of action has slowed dramatically, all effort should be made to increase the effective life of existing herbicides and make weed management cost-effective and efficient. Early detection of resistance can facilitate timely adoption of alternative tactics and minimise the financial impact on farmers. Structured surveys of resistance affected areas can provide required information for site-specific recommendations as expression of herbicide resistance tends to be highly site-specific. Greater emphasis is needed on weed management systems based on sound knowledge of weed ecology. Refinement is needed in seeding machinery for high residues systems, improvements in equipment for inter-row cultivation and application technology of herbicides. Farmer-participatory research and adoption of improved agronomy could delay evolution of resistance in weeds and enhance the sustainability of Indian cropping systems. This paper has reviewed and discussed herbicide resistance in weeds in Indian context. [ABSTRACT FROM AUTHOR]

Copyright of Jordan Journal of Agricultural Sciences is the property of University of Jordan and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Littleseed canarygrass (Phalaris minorRetz.) is a most dominant weed of wheat (Triticum aestivumL.) in the north-western states of India. Little information is available on germination of littleseed canarygrass and wheat under similar ecological conditions. The present study was conducted under controlled conditions to study germination ecology of littleseed canarygrass population possessing multiple-herbicide resistance, along with wheat. Germination of littleseed canarygrass and wheat was independent of light. Optimum temperature for germination of littleseed canarygrass and wheat was 20°C. Germination of both species was completely inhibited at osmotic potentials lower than −0.4 MPa. Seeds of littleseed canarygrass and wheat were able to germinate even at NaCl concentration of 200 mM, with complete inhibition at 300 mM. Germination of both species was favored in a pH range of 5–8. Moisture, salinity, and pH stresses significantly reduced the speed of germination, with a concomitant increase in mean germination time, thus exposing seedlings to longer periods of less favorable conditions. This information should help in predicting potential distribution of littleseed canarygrass to new areas and also assist in formulating effective weed-management strategies for the future. [ABSTRACT FROM PUBLISHER]

Littleseed canarygrass ( Phalaris minor Retz.) is one of the most common and troublesome weeds infesting wheat crop in India. Repeated use during the last two decades of the ACCase-inhibiting herbicide (clodinafop) to control this weed has resulted in the occurrence of resistance. Fifty-three P. minor populations were collected from wheat fields in Haryana and Punjab states of India. The dose-response assays indicated that 29 populations were resistant, 23 populations were susceptible and one population was moderately resistant to clodinafop. Sequence analysis of the CT domain of ACCase gene among resistant and susceptible populations revealed two non-synonymous mutations, Trp to Cys and Ile to Asn in the resistant populations. Allele-specific PCR markers were developed to differentiate between wild-type and resistant codons at positions 2027 and 2041 of ACCase in P. minor which enables molecular assays for rapid detection and resistance diagnosis for efficient weed management in wheat. This is the first report from India of a target site mutation corresponding to resistance to clodinafop in P. minor. [ABSTRACT FROM AUTHOR]

Little seed canary grass ( Phalaris minor Retz.) populations resistant to herbicides that inhibit acetyl-CoA carboxylase (ACCase) represent an increasingly important weed control problem in northern India. The objective of this study was to develop DNA-based markers to differentiate herbicide-resistant and herbicide-susceptible population of P. minor. Primers were designed to amplify the conserved region carrying two reported mutations Trp to Cys and Ile to Asn conferring ACCase inhibitor resistance in several grass weeds and subjected to single-strand conformational polymorphism (SSCP) to detect the mutations. Five distinctive electrophoretic patterns on non-denaturing PAGE were observed, and four patterns were found to be associated with ACCase herbicide resistance in P. minor. The PCR-SSCP test developed in this study confirmed 17 resistant populations to contain mutations in CT domain of ACCase gene. This is the first report of rapid and easy molecular diagnosis of ACCase herbicide-resistant and herbicide-sensitive population of P. minor through PCR-SSCP analysis. [ABSTRACT FROM AUTHOR]

Littleseed canarygrass (∼canarygrass) evolved populations that are resistant to isoproturon during the early 1990s in north-western India. Clodinafop-propargyl (∼clodinafop) was recommended for controlling these populations. It has been used extensively in wheat for the last several years. Recently, poor or no control of canarygrass by clodinafop has been observed in large areas, which could be related to cross-resistance or multiple resistance. This study was designed to test whether resistance has evolved in canarygrass populations against clodinafop and to explore control of the resistant populations with sulfosulfuron and pinoxaden. Among the 311 canarygrass populations that were tested, 86, 55 and 34 showed variable phytotoxicity (0-99%) due to 0.030, 0.060 and 0.120 kg ha−1 clodinafop, respectively. Based on the resistance index, 11 populations were 'highly resistant', 60 were 'resistant' and the rest (240) were 'susceptible' to clodinafop. Five and six clodinafop-resistant populations showed slight resistance to 0.0125 kg ha−1 sulfosulfuron and 0.025 kg ha−1 pinoxaden, respectively. But, sulfosulfuron at 0.025 and 0.050 kg ha−1 and pinoxaden at 0.050 and 0.100 kg ha−1 controlled all the canarygrass populations. Clodinafop used for 4 years increased the chance of resistance evolving, whereas its rotation with sulfosulfuron reduced the chance of resistance evolving. This study showed that considerable canarygrass populations have evolved a low-to-high degree of resistance against clodinafop. The further use of clodinafop would lead to the spread of resistance in larger areas through the dispersal of resistant seeds. Clodinafop should be replaced with 0.025 kg ha−1 sulfosulfuron or 0.050 kg ha−1 pinoxaden. Besides, where canarygrass has not evolved resistance, the yearly rotation of sulfosulfuron with clodanafop or pinoxaden might delay the evolution of resistance. [ABSTRACT FROM AUTHOR]

Wheat is one of the important cereals contributing approximately 30-35 % to total food grain basket of the country. Wheat infested by multifarious weed flora comprising both grassy as well as broad leaf weeds causing yield reduction of 15-40 % depending upon type and intensity of their infestation. Herbicides continue to be the most powerful, economically effective and reliable way to control weeds in wheat. Over the years, the efficacy of herbicides has started declining and there is possibility of development of cross resistance. An integrated approach, where herbicide plays a pivotal role is the only way ahead for effective weed management. Use of weed free seed, use of well rotten farm yard manure, method of sowing, seed rate, sowing time, varietal selection, amount of fertilizer application, proper herbicide selection, proper dose, time and method of herbicide application, herbicide rotation and mixture, use of adjuvant, mechanical weeding and crop rotation are the major constituents of integrated weed management. Thus, integrated weed management practices should be location and time specific by considering the weeds in a broader ecological and management context. [ABSTRACT FROM AUTHOR]

Bioinoculants contribute to soil environment through their versatile role. Whereas weeds are a limitation and herbicide carryover can also be injurious to subsequent crops. The residual/carryover herbicides may influence sowing decisions for the next crop due to reduced herbicide breakdown. The present study aimed at exploring the contribution of bio-fertilizer microbes (Azospirillum) to mitigate the inhibitory effect of herbicide residue in soil, and their inhibitory effect on weed seeds. The crops studied under laboratory conditions were Brassica spp. and Zea mays while Phalaris minor was the test weed. In first experiment, Brassica and maize, grown in soils having residues of either Triasulfuron+Terbutryn (Logran) or Sulfosulfuron (Leader), were found to significantly mitigate (% increase in root length, shoot length, fresh weight and dry weight) the inhibitory effect of residues, when inoculated with Azospirillum A4. In second experiment two Azospirillum (B2 and B3) and two Azorhizobium (3.6ksk and srsn2k4) isolates reduced seed germination of Phalaris minor by 95%. The results imply that biofertilizer microbes can mitigate the carryover effect of the two sulfonylureas; they can also inhibit Phalaris minor. Therefore, the use of bio-inoculants, weed seed germination and residual effect of weedicide can be manipulated for the betterment of the crops and these microbes can be used for a positive interaction of maintaining a threshold of weeds in a crop field. [ABSTRACT FROM AUTHOR]

The germination of a population of seeds was modelled using the concept of hydrotime or hydrothermal time. Typically, a Normal distribution for base water potential ( Ψ b( g)) was used within these models to relate variation in Ψ b( g) to the variation in time to germination of a given fraction of seeds. We sought to examine empirically the validity of this assumption, to compare the fit of alternative distributions and make recommendations for improved germination modelling procedures. Eight statistical distributions ( Gumbel, Weibull, Normal, Log-Normal, Logistic, Loglogistic, Inverse Normal and Gamma) were fitted to data for four weed species Hordeum spontaneum, Phalaris minor, Heliotropium europaeum and Raphanus raphanistrum. Methods for incorporating each of these distributions into hydrotime are presented. For three species ( H. spontaneum, P. minor and H. europaeum), the Normal distribution gave the worst fit (with AIC values: −124.2, −296.9 and −264.5, respectively) and would lead to biased predictions, whereas the Loglogistic distribution consistently provided the best explanation of Ψ b( g) variation in these species (with AIC values: −188.6, −326.2 and −272.1 respectively). All distributions failed to provide an unbiased description of the observed distribution of Ψ b( g) in R. raphanistrum. The Normal distribution is not necessarily the best function for base water potential in hydrothermal models and, indeed, may give much more biased predictions than alternative functions. The 'best' distribution may vary with species. The distribution of Ψ b( g) within a seed sample should therefore be examined and an appropriate equation selected, before using a model to make predictions. [ABSTRACT FROM AUTHOR]

Abstract: The effect of cold and hot aqueous leaf extracts of Lantana camara L. on the germination and seedling growth of Phalaris minor Retz. and Sorghum bicolor L. (Moench) was evaluated. Bioassays indicated that the inhibitory effect of the allelopathic plant on the germination percentage (GP), inhibition percentage (IP) and seed germination index (SGI) of the two recipient weed species was proportional to the concentration of the extract. High concentrations had stronger inhibitory effect than low concentrations that showed no stimulatory effect on both species. Both plumule (PL) and radicle (RL) lengths of the recipient species were affected negatively due to the addition of L. camara extracts and this effect was directly proportional to the concentration and more significant in the case of the radicle of P. minor compared with S. bicolor. Our results suggested that L. camara aqueous extract could be used as a potential allelopathic substance for some weed bio-control. [Copyright &y& Elsevier]

Isoproturon is the only herbicide that can control Phalaris minor, a competitive weed of wheat that developed resistance in 1992. Resistance against isoproturon was reported to be due to a mutation in the psbA gene that encodes the isoproturon-binding D1 protein. Previously in our laboratory, a triazole derivative of isoproturon (TDI) was synthesized and found to be active against both susceptible and resistant biotypes at 0.5 kg/ha but has shown poor specificity. In the present study, both susceptible D1, resistant D1 and D2 proteins of the PS-II reaction center of P. minor have been modeled and simulated, selecting the crystal structure of PS-II from Thermosynechococcus elongatus (2AXT.pdb) as template. Loop regions were refined, and the complete reaction center D1/D2 was simulated with GROMACS in lipid (1-palmitoyl-2-oleoylglycero-3-phosphoglycerol, POPG) environment along with ligands and cofactor. Both S and R models were energy minimized using steepest decent equilibrated with isotropic pressure coupling and temperature coupling using a Berendsen protocol, and subjected to 1,000 ps of MD simulation. As a result of MD simulation, the best model obtained in lipid environment had five chlorophylls, two plastoquinones, two phenophytins and a bicarbonate ion along with cofactor Fe and oxygen evolving center (OEC). The triazole derivative of isoproturon was used as lead molecule for docking. The best worked out conformation of TDI was chosen for receptor-based de novo ligand design. In silico designed molecules were screened and, as a result, only those molecules that show higher docking and binding energies in comparison to isoproturon and its triazole derivative were proposed for synthesis in order to get more potent, non-resistant and more selective TDI analogs. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Isoproturon, 3-p-cumenyl-1 dimethylurea was the only herbicide controlling Phalaris minor, a major weed growing in wheat fields till the early 1980s. Since it has acquired resistance against isoproturon, like other substituted urea herbicides, where the identified target site for isoproturon is in the photosynthetic apparatus at D1 protein of Photosystem-II (PS-II). Nucleotide sequence of susceptible and resistant psbA gene of P. minor has been reported to have four point mutations. During the present work D1 protein of both susceptible and resistant biotypes of P Minor has been modeled. Transmembrane segments of amino acids were predicted by comparing with the nearest homolog of bacterial D1 protein. Volume and area of active site of both susceptible and resistant biotypes has been simulated. Isoproturon was docked at the active site of both, susceptible and resistant D1 proteins. Modeling and simulation of resistance D1 protein indicates that the resistance is due to alteration in secondary structure near the binding site, resulting in loss in cavity area, volume and change in binding position, loss of hydrogen bonds, hydrophobic interaction and complete loss of hydrophobic sites. To regain sensitivity in resistant biotype new derivatives of isoproturon molecules have been proposed, synthesized and tested. Among the 17 derivatives we found that the N-methyl triazole substituted isoproturon is a potential substitute for isoproturon. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Phalaris minor (littleseed canary grass) is a major weed in wheat fields in some parts of Iran. Diclofop-methyl, fenoxaprop-P-ethyl, and clodinafop-propargyl are three acetyl coenzyme A carboxylase (ACCase)-inhibiting herbicides that are commonly used to control this grass in wheat fields. Thirty-four P. minor populations with suspected resistance to ACCase-inhibiting herbicides were sampled from wheat fields in the provinces of Fars and Golestan in Iran. The dose-response assays that were conducted under controlled greenhouse conditions indicated that 14 populations were resistant to fenoxaprop-P-ethyl, seven populations were resistant to both fenoxaprop-P-ethyl and diclofop-methyl, and three populations were resistant to fenoxaprop-P-ethyl, diclofop-methyl, and clodinafop-propargyl. These populations showed different levels of resistance to the applied herbicides, compared to the susceptible population. These results suggest that different mechanisms of resistance could be involved. The enzyme assay revealed that the existence of modified ACCase in the three most-resistant populations (AR, MR4, and SR3) is responsible for the resistance of these populations. [ABSTRACT FROM AUTHOR]

Herbicidal activity of Withania somnifera (L.) Dunal. was studied against Phalaris minor Retz., one of the most problematic weeds of wheat in Pakistan. In laboratory bioassays the aqueous, methanol and n-hexane extracts of 5, 10 and 15% w/v (fresh weight basis) of the roots and shoots of W. somnifera were applied. Extracts in the different solvents exhibited markedly variable herbicidal activities against germination and seedling growth of the target weed species. The methanol extracts showed the highest toxicity. Different concentrations of methanol shoot and root extracts declined the germination of P. minor by 21-71%, its shoot length by 40-72%, its root length by 50-99% and the plant biomass by 32-83%. The aqueous extracts proved to be comparatively less toxic than the methanol extracts, where generally the highest concentration of 15% exhibited pronounced toxicity against the target weed species. There was up to 48, 51, 99 and 55% suppression of the weed's germination, shoot length, root length and plant biomass, respectively, due to the 15% aqueous root and shoot extracts. Generally, the n-hexane extracts of both roots and shoots exhibited insignificant or stimulatory effects against weed shoot length and plant biomass. In a foliar spray bioassay, aqueous and methanol shoot extracts of 10% w/v (dry weight basis) concentration were sprayed on one- and two-week old pot grown P. minor seedlings. Two subsequent sprays were carried out at five day intervals each. The aqueous extract significantly reduced the shoot and root dry biomass of one-week old P. minor plants. In a residue incorporation bioassay, crushed shoots of W. somnifera were incorporated in the soil at 1, 2, ... 5% w/w. Phalaris minor seeds were sown one week after residue incorporation and plants were harvested 45 days after sowing. The lower concentrations of 2 and 3% significantly reduced, while higher concentrations of 4 and 5% of residue incorporation completely arrested, the germination of P. minor. The present study concludes that both roots and shoots of W. somnifera contain herbicidal constituents against P. minor. [ABSTRACT FROM AUTHOR]

Present study was designed to evaluate the herbicidal activity of metabolites of four Drechslera species viz. D. australiensis, D. hawaiiensis, D. biseptata and D. holmii (prepared in malt extract broth) against some problematic weeds of wheat namely Rumex dentatus, Phalaris minor and Avena fatua in 2009. Metabolites of Drechslera spp. were employed in 100% (original) and 50% concentrations. These metabolites wrought appreciable reduction in the germination of test weed's seeds by 3-72%. Original metabolites of all the fungal species significantly reduced shoot length and biomass by 39-72% and 30-70%, respectively. Metabolites of D. australiensis D. hawaiiensis and D. biseptata showed pronounced phytotoxic activity against all tested weeds, D. holmii appeared to be least effective. Root growth was more susceptible to metabolites than shoot growth. The metabolites of Drechslera spp. reduced 56-97% and 27-92% in root and shoot biomass, respectively. The present study concludes that metabolites of all the tested Drechslera spp. contain phytotoxic constituents that can be used as benign method of weed control alternative to synthetic chemical herbicides for management of some weeds of wheat. Further studies regarding the isolation of effective ingredients are in progress. [ABSTRACT FROM AUTHOR]

The increasing concern about the toxicity of synthetic herbicides has boosted the search for eco-friendly and sustainable weed management practices. Allelopathic control of weeds has received great attention in recent years as a possible alternative for weed management. Here, a two-year field study was conducted to explore the herbicidal potential of sorghum water extract alone and in combination with water extracts of other allelopathic plants: eucalyptus, sesame, sunflower, tobacco and brassica, against wild oat ( Avena fatua) and canary grass ( Phalaris minor), two noxious weeds of wheat fields. Water extracts were applied twice 30 and 40 days after sowing. Our results show that application of sorghum and sunflower extracts at 12 L ha each was more effective than other combinations. This treatment reduced wild oat dry matter by 42-62%, and canary grass by 36-55%. Application of sorghum and sunflower at 6 L ha each increased the wheat grain yield by 89% during the first year, and by 35% during the second year. Application of the synthetic herbicide isoproturon at 1000 g active ingredient ha was more effective for weed inhibition and yield increase than allelopathic water extracts. Nevertheless, application of sorghum and sunflower at 6 L ha was economically more viable than the other treatments, with the highest marginal rate of return of 2824%. [ABSTRACT FROM AUTHOR]

The increasing concern about the toxicity of synthetic herbicides has boosted the search for eco-friendly and sustainable weed management practices. Allelopathic control of weeds has received great attention in recent years as a possible alternative for weed management. Here, a two-year field study was conducted to explore the herbicidal potential of sorghum water extract alone and in combination with water extracts of other allelopathic plants: eucalyptus, sesame, sunflower, tobacco and brassica, against wild oat (Avena fatua) and canary grass (Phalaris minor), two noxious weeds of wheat fields. Water extracts were applied twice 30 and 40 days after sowing. Our results show that application of sorghum and sunflower extracts at 12 L ha-1 each was more effective than other combinations. This treatment reduced wild oat dry matter by 42-62%, and canary grass by 36-55%. Application of sorghum and sunflower at 6 L ha-1 each increased the wheat grain yield by 89% during the first year, and by 35% during the second year. Application of the synthetic herbicide isoproturon at 1000 g active ingredient ha-1 was more effective for weed inhibition and yield increase than allelopathic water extracts. Nevertheless, application of sorghum and sunflower at 6 L ha-1 was economically more viable than the other treatments, with the highest marginal rate of return of 2824%. [ABSTRACT FROM AUTHOR]

Littleseed canarygrass ( Phalaris minor Retz.), a troublesome weed of wheat in India, has evolved multiple herbicide resistance across three modes of action: photosynthesis at the photosystem II site A, acetyl-coA carboxylase (ACCase), and acetolactate synthase inhibition. The multiple herbicide-resistant (MHR) populations had a low level of sulfosulfuron resistance but a high level of resistance to clodinafop and fenoxaprop (ACCase inhibitors). Some of the populations had GR50 (50% growth reduction) values for clodinafop that were 11.7-fold greater than that of the most susceptible population. The clodinafop-resistant populations also showed a higher level of cross-resistance to fenoxaprop (fop group) but a low level of cross-resistance to pinoxaden (den group). Although clodinafop and pinoxaden are from two different chemical families (fop and den groups), their same site of action is responsible for cross-resistance behavior. The populations that were resistant to four groups of herbicides (phenylureas, sulfonylurea, aryloxyphenoxypropionate, and phenylpyrazolin) were susceptible to the triazine (metribuzin and terbutryn) and dinitroaniline (pendimethalin) herbicides. The P. minor populations that were resistant to the aryloxyphenoxypropionate and phenylurea herbicides were effectively controlled by the sulfonylurea herbicide, sulfosulfuron. In the fields infested with P. minor that was resistant to clodinafop, a sulfosulfuron application (25 g ha−1) increased the wheat yield by 99.2% over that achieved using the recommended rate of clodinafop (60 g ha−1). However, the evolution of multiple resistance against the four groups is a threat to wheat production. To prevent the spread of MHR P. minor populations, as well as the extension of multiple resistance to new chemicals, concerted efforts in developing and implementing a sound, integrated weed management program are needed. The integrated approach, consisting of crop and herbicide rotation with cultural and mechanical weed control tactics, should be considered as a long-term resistance management strategy that will help to sustain wheat productivity and farmers' income. [ABSTRACT FROM AUTHOR]

Intra- and inter-sample similarities for four populations of the annual grass weed Phalaris minor from Haryana state, India, were examined using inter-simple sequence repeat (ISSR) DNA markers. Levels of polymorphism within and between populations were low in comparison with values reported from other grassy weed species. Analysis of inter-population similarities allowed a partial differentiation of the four populations and of pairs of populations classified by cropping system. Analysis of the intra-population similarity data showed a weak but consistent and statistically significant negative correlation between the molecular similarity of seedlings and the physical distance between their mother plants over distances up to 40 m (the maximum separation tested) in all four populations. The consistency of the observed relationship between molecular similarity and physical separation, and the differences in cultivation practices at the four sites, suggested that the relationship may be a result of localized out-crossing, rather than an effect of localized seed rain. The results of the analyses are discussed in relation to the potential for evolution of multiple traits in the weed in response to changes in the wheat production system in the region. [ABSTRACT FROM AUTHOR]

Phalaris minorRetz. is a major exotic annual weed in the wheat ( Triticum aestivum L.) crop. Unharvested rice ( Oryza sativa L.) straw, unburned and burned, is often incorporated in the field prior to cultivating wheat. Isoxaflutole (Balance), a pre-emergent systemic soil applied herbicide, has potential to control P. minor. Glasshouse experiments were conducted to determine the phytotoxicity of isoxaflutole defined by reductions in relation to shoot length of P. minor when grown in unamended soil or soil amended with unburned or burned rice straw. A 120 g soil was amended with 0, 1, 2 and 4 g of unburned or burned rice straw, and placed in 150 mL styrofoam pots. Appropriate amount of isoxaflutole (75% active ingredient, ai) was added to pots to get final concentration of 0, 7.5, 30, 60 and 120 μg ai/pot. Unamended soil and soil amended with unburned or burned rice straw were analyzed for pH and organic matter; two important determinants of isoxaflutole activity. Results indicate a significant reduction in shoot length of P. minor when grown in soil treated with isoxaflutole at 30, 60 or 120 μg ai/pot. Inhibition in the shoot length of P. minor was observed when soil amended with unburned straw was treated with isoxaflutole at 7.5 and 30 μg ai/pot compared with unamended soil treated with similar amounts of isoxaflutole. No significant change in isoxaflutole toxicity was observed when soil amended with unburned straw was treated with isoxaflutole at 60 and 120 lg ai/pot compared with unamended soil treated with similar amounts of isoxaflutole. Isoxaflutole phytotoxicity to P. minor shoot length was eliminated when soil amended with burned straw was treated with isoxaflutole at 7.5 and 30 μg ai/pot. P. minor shoot length was greater when soil amended with burned straw was treated with isoxaflutole at 60 and 120 μg ai/pot relative to herbicide-treated unamended soils. We conclude that incorporation of burned rice straw greatly reduces the phytotoxicity of isoxaflutole to P. minor. [ABSTRACT FROM AUTHOR]

OmH, KumarS&DhimanSD (2005) Dormancy and viability ofPhalaris minorseed in a rice–wheat cropping system.Weed Research45, 140–148.Seed placement, soil temperature and soil moisture content influenced the process of after-ripening inPhalaris minorseeds. Seeds ofP. minorcollected from the soil just after wheat harvesting exhibited higher germination than seeds fromP. minorthreshed directly. There was a pronounced impact of periodic inhabitation of seed into the soil on germination after its dispersal. Germination was strongly inhibited when the seed was kept in soil at more than field capacity (FC) or in water. Maximum germination of seed incubated in soil at FC occurred at 30°C while a temperature of 40°C favoured after-ripening of seed when mixed with dry soil or kept dry without any medium. Release from conditional dormancy was quicker in the seed retrieved from the soil kept at 20°C than at 10°C. Seed release from conditional dormancy and germination increased with a rise in temperature from 30 to 40°C when the seed was retrieved from incubation in soil at FC for 70 days. The seed kept immersed in water was least responsive to a rise in temperature. Seed recovered from dry soil, or kept without any medium, responded quickly at both temperatures. Light enhanced the germination ofPhalaris minorseed. The seedbank subjected to rice (Oryza sativa) field management conditions lost vigour in comparison with the seed stored in laboratory. There was significant variability in seed viability when exposed to differential water management conditions in rice. [ABSTRACT FROM AUTHOR]

Littleseed canarygrass (Phalaris minor Retz.) is a major weed in wheat fields, and has developed resistance to the commonly used herbicide isoproturon. This study explores the potential use of isoxaflutole, a pre-emergence herbicide, to control littleseed canarygrass. Greenhouse studies were carried out to determine the phytotoxicity of isoxaflutole in relation to shoot height, fresh shoot biomass and leaf chlorophyll concentration of wheat and littleseed canarygrass. Electron microscopy was used to examine any damage to leaf chloroplast at ultrastructural level. Results indicate that isoxaflutole (0.5 mg/L) significantly reduced the shoot height of littleseed canarygrass (39.6%), but no significant reduction in the shoot height of wheat was observed (9.6%) when compared to control. None of the concentrations (0.05, 0.1, 0.5 and 1 mg/L) of isoxaflutole altered soil chemistry in relation to pH, organic matter, macro or micro inorganic ions. While untreated littleseed canarygrass leaves had elongated chloroplast, starch grains and small number of plastoglobuli; treated littleseed canarygrass leaves had swollen chloroplast, large number of plastoglobuli, and a lack of starch grains. We conclude that isoxaflutole can be an effective herbicide for controlling littleseed canarygrass. [ABSTRACT FROM AUTHOR]

Field experiments were conducted in northern Greece during 1994, 1995, and 1996 to study the effect of nitrogen fertilization on competition between littleseed canaryglass ( Phalaris minor Retz.) and wheat ( Triticum aestivum L.), barley ( Hordeum vulgare = distichum L.) or triticale ( Triticosecale). The presence of 400 P. minor plants per square meter until early March did not have an adverse effect on dry weight of any crop. However, their further presence significantly reduced dry weight of wheat and triticale, but not that of barley. Grain yield of wheat and triticale was reduced 48% and 47%, respectively, by season-long competition of P. minor, whereas the corresponding reduction for barley was only 8%. Crop yield reduction due to P. minor competition resulted mainly from reduction in ear number and less from reduction in 1000-grain weight. Nitrogen fertilization (150 kg N ha−1), compared with control (0 kg N), slightly increased yield of all crops grown without weed competition. The same treatment also increased dry weight and competitive ability of P. minor against wheat and triticale, compared with that of control (0 kg N); the split application of nitrogen (50 kg N ha−1 before crop sowing and 100 kg N ha−1 in early March) caused a slightly greater increase in P. minor dry weight than did 150 kg N ha−1 applied once before crop sowing. Dry weight of P. minor grown with barley was not affected by nitrogen fertilization, but it was severely reduced compared with that of P. minor grown with wheat or triticale. [ABSTRACT FROM AUTHOR]

The Phalaris genus includes annual weed species such as short-spiked canarygrass (Phalaris brachystachys Link.), little-seed canarygrass (Phalaris minor Retz.) and hood canarygrass (Phalaris paradoxa L.), which are especially problematic in Spain; as such, there is a need to develop models to predict the timing of their emergence. Field experiments were conducted at two different locations during two (2006/07 and 2007/08) and three (from 2005/06 to 2007/08) growing seasons. In both locations, 500 seeds of each Phalaris species were sown each growing season, simulating rain-fed cereal field conditions. In addition, the models were validated with three, four and eight independent experiments for P. brachystachys, P. minor and P. paradoxa, respectively. The emergence period of the three Phalaris species lasted between 31 and 48 days after sowing (DAS), showing two main flushes. The three cardinal points for parametric and non-parametric models were established to be between −1 °C and 1 °C for base temperature, between 9.8 °C and 11.8 °C for optimal temperature and between 21.2 °C and 23.4 °C for ceiling temperature; base water potential was estimated to be between −1 and −1.1 MPa. Both parametric and non-parametric models obtained similar results and were successfully validated in 12 out of 15 independent experiments. [ABSTRACT FROM AUTHOR]

Because cropping systems can greatly affect the establishment and spread of alien species populations, the design of cropping systems to control invasive weeds is an important approach for invasive species management in agro-ecosystems to avoid excessive increases in other control measures such as herbicides. The annual weed Phalaris minor Retz. (P. minor) is one of the most troublesome invasive weed species of winter crops in Yunnan Province, China, but the development of cropping systems for ecological control of this weed have received limited research attention. Here, we studied seed dormancy, germination characteristics and reproductive responses of P. minor to various cropping systems to show how cropping systems could be better designed to control P. minor in China. Our research showed that cropping systems significantly affected seed dormancy in submerged paddy fields. Phalarisminor seed remained dormant and the germination rates (less than 10%) were significantly lower (p < 0.05) than in maize fields and dry, bare soil conditions. Wheat, faba bean and rapeseed crops had no significant influence (p < 0.05) on the seed germination rate of P. minor, but increasing soil depth significantly decreased (p < 0.05) the germination rate and germination index of this weed. Total biomass, spike biomass, spike number and seed number of P. minor were significantly reduced (p < 0.05) with increasing proportions of the three crops (wheat, faba bean and rapeseed), with rapeseed having the strongest inhibition effects among the three crops. The reproductive allocation and reproductive investment of P. minor were also significantly reduced (p < 0.05) in mixed culture with wheat and rapeseed. With increasing proportions of wheat or rapeseed, the specific leaf area of P. minor significantly increased (p < 0.05), but the reverse was true for leaf area and specific leaf weight. Moreover, the net photosynthetic rate, stomatal conductance and transpiration rate for P. minor also decreased significantly (p < 0.05) when grown with wheat or rapeseed. These results suggest that optimal cropping systems design could involve planting rapeseed in conjunction with deep plowing and planting rice (continuous submergence underwater) in summer. Such a system could reduce the field populations and seed bank of P. minor, thus providing a sustainable and environmentally friendly means of suppressing P. minor. [ABSTRACT FROM AUTHOR]

Background: Faba bean weeds are considered as serious pests that lead to pronounced damages to its agricultural production since they consume water and nutrients from the soil, reducing not only the yield but also the quality of the crops. So, the aim of this investigation is to control the weeds associated with faba bean plants. Materials/methods: Two pot experiments were carried out during two successive winter seasons of 2016/2017 and 2017/2018 in the greenhouse of the National Research Centre, Dokki, Giza, Egypt. Treatments were applied by incorporating the dry leaf powder of Ficus nitida to the soil surface of pots at the rate of (0, 10, 20, 30, 40, 50, and 60 g/kg soil). Results: All concentrations used pronouncedly decreased the fresh and dry weight of both Phalaris minor and Malva parviflora. On the other hand, Vicia faba growth as well as its yield and yield components were increased with most concentrations used as compared to their mixed controls. Treatments of 20, 30, and 40 g/kg soil, from F. nitida leaf powder, respectively recorded the highest increases in the most growth characters of V. faba with both weeds (P. minor and M. parviflora) at the two growth ages when compared to the healthy control. Also, the best results in all V. faba yield components were recorded with 20 g/kg soil of F. nitida treatment. Conclusion: The results of the present study indicate the possibility of using the allelopathic activity of the leaf powder of Ficus nitida as a selective bioherbicide for controlling annual weeds accompanied Vicia faba plants. [ABSTRACT FROM AUTHOR]