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Takele Negewo

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Born at Jarsso, Cheliya, West Shewa, Oromia. Live in Ambo town and work as senior researcher at Ambo Agricultural Research Center.
Phone: +251911892875
Address: Plant Protection Research Center, Ambo-Ethiopia

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Yaakov Goldwasser

The Hebrew University of Jerusalem

Agricultural Research Organization of Israel

Sylvestre Habimana

Andrea C. Rinaldi

University of Cagliari

Dr. Satbir Singh Punia

ساميه عثمان يعقوب علي

Sudan university of Science and technology

Ahmed M E Rugheim

Omdurman Islamic University

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Papers by Takele Negewo

Challenges and management of parasitic weeds in Ethiopia

Background Unlike regular weeds, parasitic weeds parasitize their host crop for sustenance, and c... more Background Unlike regular weeds, parasitic weeds parasitize their host crop for sustenance, and critically reduce growth and productivity of the host plants. Main body The parasitic weeds or heterotrophic plants are conveniently divided into different groups; hemi/partialor holo/total-parasites, facultative or obligate parasites, root or stem parasites and annual or perennial parasites. Out of about 4000 parasitic plant species, certain species under few plant families; (Orobancheaceae, Convolvulaceae, Loranthaceae and Viscaceae) are considered to be among the most serious agricultural pests of economic importance. They can incur up to 100% yield reduction on host crops depending on the levels of infestation, crop susceptibility and environmental conditions. Their dense occurrence strongly hampers host-crops cultivation. Ample management practices have been tried using many control methods, but so far no economical, feasible or universally dependable means in controlling any of the parasitic weed species. There is inadequate knowledge on parasitic weeds. Conclusion This manuscript developed to provide information, knowledge and technology on biology, harmful effects and management of parasitic weeds all over the world particularly in Ethiopia.

Corrigendum: Biological characteristics, impacts, and management of crenate broomrape (Orobanche crenata) in faba bean (Vicia faba): a review

Weed science research achievements on maize in Ethiopia: a review

F1000Research

Recent research into assessing and combatting maize weeds was reviewed based on scientific and wo... more Recent research into assessing and combatting maize weeds was reviewed based on scientific and working reports from the year 2011 onwards in Ethiopia. This review paper covered two main topics: assessment of major weed types and their impacts, and research results of weed management in the maize cropping system of the country. More than 80 major weed floras dominated by broad leaved weeds were found infesting maize fields in different localities. By competing, toxifying and/or parasitizing maize plants, they reduce the crop germination, growth and productivity. Several experiments indicated that maize yield loss due to uncontrolled weed growth varied from 35 to 87.5%, indicating that weed management is a critical factor for maize production in the country. Hoeing, hand weeding and pre-emergence herbicides application have been the most frequently used weed control practices to minimize the competition effect of weeds. So far, there has been no effective and sustainable individual we...

Biological Characteristics, Impacts, and Management of Crenate Broomrape (Orobanche crenata) in Faba Bean (Vicia faba): A Review

Frontiers in Agronomy

Crenate broomrape, Orobanche crenata Forskal belongs to the family Orobanchaceae. It is a root ho... more Crenate broomrape, Orobanche crenata Forskal belongs to the family Orobanchaceae. It is a root holoparasitic weed devoid of chlorophyll and entirely dependent on host plants for its growth requirement. This parasite considerably infects plant species of the families Leguminosae, Apiaceae, and Asteraceae in highly infested drier and warmer areas of the world. It is well-known for its devastating effects on cool-season food legumes especially on faba bean (Vicia faba L.) and for threatening the livelihood of subsistence farmers. Yield losses of infected crops reach up to 100% depending on the level of infection by the parasitic weed. The long-term impact of the parasite is even more serious than its short-term effects as its numerous minute seeds are easily spread using different mechanisms and persist in the soil for up to 20 years. Besides, its management is difficult as no single method proved to be effective, economical, and complete in managing the weed. This review article gives...

Barley Research and Development in Ethiopia

Ethiopian Institute of Agricultural Research(EIAR) International Center for Agricultural Research... more

Distribution and Importance of Euphorbia schimperiana in Highlands of West Shewa Zone of EthiopiaDistribution and importance of euphorbia unpublished

In Ethiopia, Euphorbia schimperiana Scheele problem localized to certain highland areas and no an... more In Ethiopia, Euphorbia schimperiana Scheele problem localized to certain highland areas and no any research effort so far made on it. A survey was carried out in 17 highland districts of West Shewa Zone in main rainy season to determine the distribution, infestation level, and biological and socio-economic impact of the weed. It is an important annual broad leaved weed that belongs to the family of Euphorbiaceae, locally called “Annano”. The weed plant shoot count per square meter was collected using an “X” shaped five sampling points on a grazing land at an interval of 5 km along car road. The infestation of the weed varied among the surveyed districts. Ten of the districts were found free of E. schimperiana infestation while the rest districts i.e., Tikur-Inchiny, Chelia, Jibat, Mida-Kegn, Toke-Kutaye, Ambo and Wonchi scored a frequency of 33 to 85% across the districts. On average, greater than 50 weed plants m-2 were recorded in Toke-Kutaye, Jibat and Chela districts. The weed plant grows vigorous reaching more than 50 cm height in Toke-Kutaye, Jibat, Tikur-Inchiny and Wonchi districts. It becomes serious problem in these districts and some other districts like Chelia and Mida-Kegn. Impact assessment also revealed that the weed was seriously affecting animal production and productivity, and human health in the districts especially following seasonally occurring prolonged dry season. Most of the farmers in the surveyed areas have recognized its demerit causing rangeland intrusion, animal death and human irritation. The existing farmers’ sole management option is hand weeding, though it has its own limitations. The weed is toxic up on contact and occur densely creating difficulties up on hand pulling. Therefore, an effort must be putted in place to investigate the weed biology and ecology, and to develop an effective integrated management strategy to avoid the negative impact of the weed in the area.

Allelopathic effect of aqueous extracts of major weed species plant parts on germination and growth of wheat

by Takele Negewo and Dessalegne Gella

A laboratory experiment was conducted at Plant Protection Research Center, Ambo to assess allelop... more A laboratory experiment was conducted at Plant Protection Research Center, Ambo to assess allelopathic effect of aqueous extracts of Amaranthus hybridus, Parthenium hysterophorus, Datura stramonium and Argemone mexicana leaf, stem and root parts on seed germination, seedlings growth and biomass production of wheat cultivars; HAR-1685 and Durum wheat. Aqueous extracts at 1 g/ml ratio concentrations were prepared for each weed species plant parts uniformly and applied to seeds placed sparsely in petri dish. Highest wheat seed germination reduction (22%) was caused by leaf extract of P. hysterophorus. Uniformly more inhibition on radicle length of wheat seedlings was observed with leaf extracts of the test weed species than the other plant part extracts. Plumule length of the wheat seedlings were reduced by 60 and 40% due to leaf extracts of P. hysterophorus and A. hybridus. In general, the investigation showed that P. hysterophorus and A. hybridus plant leaf and stem extracts consiste...

Assessment of Weeds and Farmers adopted Weed Control Methods in Wheat Grown Fields of West Shewa Zone, Ethiopia

International Journal of Current Research and Academic Review

Article Info Studies on assessment of weeds and farmers adopted weed control method in wheat fiel... more Article Info Studies on assessment of weeds and farmers adopted weed control method in wheat fields was carried out at west shewa zone. The aim wasto determine the status of weed problems and to gather information on existing farmer's indigenous knowledge regarding in wheat weed management at Ambo, Dandi, Toke Kutaye and Cheliya districts of West Shewa Zone, Ethiopia. Survey on weed problems of wheat based farming systems and farmers practices was carried out in Ambo, Dandi, Toke Kutaye and Cheliya districts of West Shewa Zone during the main rainy season of 2014/2015. Stratified random sampling technique and structured questioners were used to collect information on major weeds of the wheat.Grass weeds infestation and associated grain yield reduction problems were found most serious in wheat farms in the study area. Phalaris paradoxa, Avena fatua, Bromus pectinatus and Snowdenia polystachya have been found common weed species in wheat fields in the study areas. Polypogon monospeliensis and Convolvulus arvensis found to be specifically problematic weed in Ambo and Dandi area, and Chrysanthemum segetum, Raphanus raphanistrum and Veronica sp. in Cheliya district. Weed as main constraint and its infestation increase in the last five years having high impact on wheat production. Large proportion of the respondents (> 65%) blamed weeds as major constraint on wheat production Survey results indicated that about 100, 60, 97 and 30% of respondents were practicing application of herbicide, supplementary hand weeding, and crop rotation and fallowing, respectively to manage weeds of wheat in the studied districts.

Assessment of Weeds and Farmers adopted Weed Control Methods in Wheat Grown Fields of West Shewa Zone, Ethiopia

International Journal of Current Research and Academic Review

Article Info Studies on assessment of weeds and farmers adopted weed control method in wheat fiel... more Article Info Studies on assessment of weeds and farmers adopted weed control method in wheat fields was carried out at west shewa zone. The aim wasto determine the status of weed problems and to gather information on existing farmer's indigenous knowledge regarding in wheat weed management at Ambo, Dandi, Toke Kutaye and Cheliya districts of West Shewa Zone, Ethiopia. Survey on weed problems of wheat based farming systems and farmers practices was carried out in Ambo, Dandi, Toke Kutaye and Cheliya districts of West Shewa Zone during the main rainy season of 2014/2015. Stratified random sampling technique and structured questioners were used to collect information on major weeds of the wheat.Grass weeds infestation and associated grain yield reduction problems were found most serious in wheat farms in the study area. Phalaris paradoxa, Avena fatua, Bromus pectinatus and Snowdenia polystachya have been found common weed species in wheat fields in the study areas. Polypogon monospeliensis and Convolvulus arvensis found to be specifically problematic weed in Ambo and Dandi area, and Chrysanthemum segetum, Raphanus raphanistrum and Veronica sp. in Cheliya district. Weed as main constraint and its infestation increase in the last five years having high impact on wheat production. Large proportion of the respondents (> 65%) blamed weeds as major constraint on wheat production Survey results indicated that about 100, 60, 97 and 30% of respondents were practicing application of herbicide, supplementary hand weeding, and crop rotation and fallowing, respectively to manage weeds of wheat in the studied districts.

Relative Competitiveness of Major Weed Species at Various Densities in Barley (Hordeum vulgare L.) Field of West Shewa Zone Takele Negewo Plant Protection Research Center, P. O. Box 37, Ambo, Ethiopia, [email protected]

Abstract Competitive interaction of four dominant weed species: Avena fatua L., Erucastrum arabi... more Abstract

Competitive interaction of four dominant weed species: Avena fatua L., Erucastrum arabicum Fisch. & May., Guizotia scabra (Vis.) Chiov. and Snowdenia polystachya (Fresen.) Pilg. at different density levels (0, 10, 20, 40, 80, 160 and 320 plants m-2) with food barley cultivar HB-42 was studied at Ambo Plant Protection Research Center during 2000, 2002 and 2003 main cropping seasons. The relative competitiveness of the major weed species at various densities in respect to their effect on yield of barley was determined. Barley grain yield data were fitted to rectangular hyperbola model to facilitate the prediction of yield losses and to derive relative competitiveness of the weed species. Accordingly, at higher weed density levels percentage grain yield loss found to be greatest due to S. polystachya (66.73) followed by A. fatua (57.24), G. scabra (41.59) and E. arabicum (12.26). Whereas, at lower weed density levels the reverse hold true: E. arabicum (0.64) > G. scabra (0.50) > A. fatua (0.47) > S. polystachya (0.30). This revealed the more competitiveness of broad leaved weed species at lower densities unlike grass weed species that become more competitive at higher densities.

Key words: barley, relative competitiveness,weed density and weed species.

Relative Competitiveness of Major Weed Species at Various Densities in Barley (Hordeum vulgare L.) Field of West Shewa Zone

Competitive interaction of four dominant weed species: Avena fatua L., Erucastrum arabicum Fisch.... more Competitive interaction of four dominant weed species: Avena fatua L., Erucastrum arabicum Fisch. & May., Guizotia scabra (Vis.) Chiov. and Snowdenia polystachya (Fresen.) Pilg. at different density levels (0, 10, 20, 40, 80, 160 and 320 plants m-2) with food barley cultivar HB-42 was studied at Ambo Plant Protection Research Center during 2000, 2002 and 2003 main cropping seasons. The relative competitiveness of the major weed species at various densities in respect to their effect on yield of barley was determined. Barley grain yield data were fitted to rectangular hyperbola model to facilitate the prediction of yield losses and to derive relative competitiveness of the weed species. Accordingly, at higher weed density levels percentage grain yield loss found to be greatest due to S. polystachya (66.73) followed by A. fatua (57.24), G. scabra (41.59) and E. arabicum (12.26). Whereas, at lower weed density levels the reverse hold true: E. arabicum (0.64) > G. scabra (0.50) > A. fatua (0.47) > S. polystachya (0.30). This revealed the more competitiveness of broad leaved weed species at lower densities unlike grass weed species that become more competitive at higher densities.

Key words: barley, relative competitiveness,weed density and weed species.

Challenges and management of parasitic weeds in Ethiopia

Background Unlike regular weeds, parasitic weeds parasitize their host crop for sustenance, and c... more Background Unlike regular weeds, parasitic weeds parasitize their host crop for sustenance, and critically reduce growth and productivity of the host plants. Main body The parasitic weeds or heterotrophic plants are conveniently divided into different groups; hemi/partialor holo/total-parasites, facultative or obligate parasites, root or stem parasites and annual or perennial parasites. Out of about 4000 parasitic plant species, certain species under few plant families; (Orobancheaceae, Convolvulaceae, Loranthaceae and Viscaceae) are considered to be among the most serious agricultural pests of economic importance. They can incur up to 100% yield reduction on host crops depending on the levels of infestation, crop susceptibility and environmental conditions. Their dense occurrence strongly hampers host-crops cultivation. Ample management practices have been tried using many control methods, but so far no economical, feasible or universally dependable means in controlling any of the parasitic weed species. There is inadequate knowledge on parasitic weeds. Conclusion This manuscript developed to provide information, knowledge and technology on biology, harmful effects and management of parasitic weeds all over the world particularly in Ethiopia.

Corrigendum: Biological characteristics, impacts, and management of crenate broomrape (Orobanche crenata) in faba bean (Vicia faba): a review

Weed science research achievements on maize in Ethiopia: a review

F1000Research

Recent research into assessing and combatting maize weeds was reviewed based on scientific and wo... more Recent research into assessing and combatting maize weeds was reviewed based on scientific and working reports from the year 2011 onwards in Ethiopia. This review paper covered two main topics: assessment of major weed types and their impacts, and research results of weed management in the maize cropping system of the country. More than 80 major weed floras dominated by broad leaved weeds were found infesting maize fields in different localities. By competing, toxifying and/or parasitizing maize plants, they reduce the crop germination, growth and productivity. Several experiments indicated that maize yield loss due to uncontrolled weed growth varied from 35 to 87.5%, indicating that weed management is a critical factor for maize production in the country. Hoeing, hand weeding and pre-emergence herbicides application have been the most frequently used weed control practices to minimize the competition effect of weeds. So far, there has been no effective and sustainable individual we...

Biological Characteristics, Impacts, and Management of Crenate Broomrape (Orobanche crenata) in Faba Bean (Vicia faba): A Review

Frontiers in Agronomy

Crenate broomrape, Orobanche crenata Forskal belongs to the family Orobanchaceae. It is a root ho... more Crenate broomrape, Orobanche crenata Forskal belongs to the family Orobanchaceae. It is a root holoparasitic weed devoid of chlorophyll and entirely dependent on host plants for its growth requirement. This parasite considerably infects plant species of the families Leguminosae, Apiaceae, and Asteraceae in highly infested drier and warmer areas of the world. It is well-known for its devastating effects on cool-season food legumes especially on faba bean (Vicia faba L.) and for threatening the livelihood of subsistence farmers. Yield losses of infected crops reach up to 100% depending on the level of infection by the parasitic weed. The long-term impact of the parasite is even more serious than its short-term effects as its numerous minute seeds are easily spread using different mechanisms and persist in the soil for up to 20 years. Besides, its management is difficult as no single method proved to be effective, economical, and complete in managing the weed. This review article gives...

Barley Research and Development in Ethiopia

Ethiopian Institute of Agricultural Research(EIAR) International Center for Agricultural Research... more

Distribution and Importance of Euphorbia schimperiana in Highlands of West Shewa Zone of EthiopiaDistribution and importance of euphorbia unpublished

In Ethiopia, Euphorbia schimperiana Scheele problem localized to certain highland areas and no an... more In Ethiopia, Euphorbia schimperiana Scheele problem localized to certain highland areas and no any research effort so far made on it. A survey was carried out in 17 highland districts of West Shewa Zone in main rainy season to determine the distribution, infestation level, and biological and socio-economic impact of the weed. It is an important annual broad leaved weed that belongs to the family of Euphorbiaceae, locally called “Annano”. The weed plant shoot count per square meter was collected using an “X” shaped five sampling points on a grazing land at an interval of 5 km along car road. The infestation of the weed varied among the surveyed districts. Ten of the districts were found free of E. schimperiana infestation while the rest districts i.e., Tikur-Inchiny, Chelia, Jibat, Mida-Kegn, Toke-Kutaye, Ambo and Wonchi scored a frequency of 33 to 85% across the districts. On average, greater than 50 weed plants m-2 were recorded in Toke-Kutaye, Jibat and Chela districts. The weed plant grows vigorous reaching more than 50 cm height in Toke-Kutaye, Jibat, Tikur-Inchiny and Wonchi districts. It becomes serious problem in these districts and some other districts like Chelia and Mida-Kegn. Impact assessment also revealed that the weed was seriously affecting animal production and productivity, and human health in the districts especially following seasonally occurring prolonged dry season. Most of the farmers in the surveyed areas have recognized its demerit causing rangeland intrusion, animal death and human irritation. The existing farmers’ sole management option is hand weeding, though it has its own limitations. The weed is toxic up on contact and occur densely creating difficulties up on hand pulling. Therefore, an effort must be putted in place to investigate the weed biology and ecology, and to develop an effective integrated management strategy to avoid the negative impact of the weed in the area.

Allelopathic effect of aqueous extracts of major weed species plant parts on germination and growth of wheat

by Takele Negewo and Dessalegne Gella

A laboratory experiment was conducted at Plant Protection Research Center, Ambo to assess allelop... more A laboratory experiment was conducted at Plant Protection Research Center, Ambo to assess allelopathic effect of aqueous extracts of Amaranthus hybridus, Parthenium hysterophorus, Datura stramonium and Argemone mexicana leaf, stem and root parts on seed germination, seedlings growth and biomass production of wheat cultivars; HAR-1685 and Durum wheat. Aqueous extracts at 1 g/ml ratio concentrations were prepared for each weed species plant parts uniformly and applied to seeds placed sparsely in petri dish. Highest wheat seed germination reduction (22%) was caused by leaf extract of P. hysterophorus. Uniformly more inhibition on radicle length of wheat seedlings was observed with leaf extracts of the test weed species than the other plant part extracts. Plumule length of the wheat seedlings were reduced by 60 and 40% due to leaf extracts of P. hysterophorus and A. hybridus. In general, the investigation showed that P. hysterophorus and A. hybridus plant leaf and stem extracts consiste...

Assessment of Weeds and Farmers adopted Weed Control Methods in Wheat Grown Fields of West Shewa Zone, Ethiopia

International Journal of Current Research and Academic Review

Article Info Studies on assessment of weeds and farmers adopted weed control method in wheat fiel... more Article Info Studies on assessment of weeds and farmers adopted weed control method in wheat fields was carried out at west shewa zone. The aim wasto determine the status of weed problems and to gather information on existing farmer's indigenous knowledge regarding in wheat weed management at Ambo, Dandi, Toke Kutaye and Cheliya districts of West Shewa Zone, Ethiopia. Survey on weed problems of wheat based farming systems and farmers practices was carried out in Ambo, Dandi, Toke Kutaye and Cheliya districts of West Shewa Zone during the main rainy season of 2014/2015. Stratified random sampling technique and structured questioners were used to collect information on major weeds of the wheat.Grass weeds infestation and associated grain yield reduction problems were found most serious in wheat farms in the study area. Phalaris paradoxa, Avena fatua, Bromus pectinatus and Snowdenia polystachya have been found common weed species in wheat fields in the study areas. Polypogon monospeliensis and Convolvulus arvensis found to be specifically problematic weed in Ambo and Dandi area, and Chrysanthemum segetum, Raphanus raphanistrum and Veronica sp. in Cheliya district. Weed as main constraint and its infestation increase in the last five years having high impact on wheat production. Large proportion of the respondents (> 65%) blamed weeds as major constraint on wheat production Survey results indicated that about 100, 60, 97 and 30% of respondents were practicing application of herbicide, supplementary hand weeding, and crop rotation and fallowing, respectively to manage weeds of wheat in the studied districts.

Assessment of Weeds and Farmers adopted Weed Control Methods in Wheat Grown Fields of West Shewa Zone, Ethiopia

International Journal of Current Research and Academic Review

Article Info Studies on assessment of weeds and farmers adopted weed control method in wheat fiel... more Article Info Studies on assessment of weeds and farmers adopted weed control method in wheat fields was carried out at west shewa zone. The aim wasto determine the status of weed problems and to gather information on existing farmer's indigenous knowledge regarding in wheat weed management at Ambo, Dandi, Toke Kutaye and Cheliya districts of West Shewa Zone, Ethiopia. Survey on weed problems of wheat based farming systems and farmers practices was carried out in Ambo, Dandi, Toke Kutaye and Cheliya districts of West Shewa Zone during the main rainy season of 2014/2015. Stratified random sampling technique and structured questioners were used to collect information on major weeds of the wheat.Grass weeds infestation and associated grain yield reduction problems were found most serious in wheat farms in the study area. Phalaris paradoxa, Avena fatua, Bromus pectinatus and Snowdenia polystachya have been found common weed species in wheat fields in the study areas. Polypogon monospeliensis and Convolvulus arvensis found to be specifically problematic weed in Ambo and Dandi area, and Chrysanthemum segetum, Raphanus raphanistrum and Veronica sp. in Cheliya district. Weed as main constraint and its infestation increase in the last five years having high impact on wheat production. Large proportion of the respondents (> 65%) blamed weeds as major constraint on wheat production Survey results indicated that about 100, 60, 97 and 30% of respondents were practicing application of herbicide, supplementary hand weeding, and crop rotation and fallowing, respectively to manage weeds of wheat in the studied districts.

Relative Competitiveness of Major Weed Species at Various Densities in Barley (Hordeum vulgare L.) Field of West Shewa Zone Takele Negewo Plant Protection Research Center, P. O. Box 37, Ambo, Ethiopia, [email protected]

Abstract Competitive interaction of four dominant weed species: Avena fatua L., Erucastrum arabi... more Abstract

Competitive interaction of four dominant weed species: Avena fatua L., Erucastrum arabicum Fisch. & May., Guizotia scabra (Vis.) Chiov. and Snowdenia polystachya (Fresen.) Pilg. at different density levels (0, 10, 20, 40, 80, 160 and 320 plants m-2) with food barley cultivar HB-42 was studied at Ambo Plant Protection Research Center during 2000, 2002 and 2003 main cropping seasons. The relative competitiveness of the major weed species at various densities in respect to their effect on yield of barley was determined. Barley grain yield data were fitted to rectangular hyperbola model to facilitate the prediction of yield losses and to derive relative competitiveness of the weed species. Accordingly, at higher weed density levels percentage grain yield loss found to be greatest due to S. polystachya (66.73) followed by A. fatua (57.24), G. scabra (41.59) and E. arabicum (12.26). Whereas, at lower weed density levels the reverse hold true: E. arabicum (0.64) > G. scabra (0.50) > A. fatua (0.47) > S. polystachya (0.30). This revealed the more competitiveness of broad leaved weed species at lower densities unlike grass weed species that become more competitive at higher densities.

Key words: barley, relative competitiveness,weed density and weed species.

Relative Competitiveness of Major Weed Species at Various Densities in Barley (Hordeum vulgare L.) Field of West Shewa Zone

Competitive interaction of four dominant weed species: Avena fatua L., Erucastrum arabicum Fisch.... more Competitive interaction of four dominant weed species: Avena fatua L., Erucastrum arabicum Fisch. & May., Guizotia scabra (Vis.) Chiov. and Snowdenia polystachya (Fresen.) Pilg. at different density levels (0, 10, 20, 40, 80, 160 and 320 plants m-2) with food barley cultivar HB-42 was studied at Ambo Plant Protection Research Center during 2000, 2002 and 2003 main cropping seasons. The relative competitiveness of the major weed species at various densities in respect to their effect on yield of barley was determined. Barley grain yield data were fitted to rectangular hyperbola model to facilitate the prediction of yield losses and to derive relative competitiveness of the weed species. Accordingly, at higher weed density levels percentage grain yield loss found to be greatest due to S. polystachya (66.73) followed by A. fatua (57.24), G. scabra (41.59) and E. arabicum (12.26). Whereas, at lower weed density levels the reverse hold true: E. arabicum (0.64) > G. scabra (0.50) > A. fatua (0.47) > S. polystachya (0.30). This revealed the more competitiveness of broad leaved weed species at lower densities unlike grass weed species that become more competitive at higher densities.

Key words: barley, relative competitiveness,weed density and weed species.