نشریه بوم شناسی کشاورزی
سال ششم شماره 2 (تابستان 1393)

Optimum uses of water and nitrogen resources are the most important factors in agricultural systems due to limitations of agricultural inputs especially water. In order to investigate the effect of different levels of nitrogen fertilizer and irrigation on efficiency and productivity of water consumption in three crop (sugar beet, corn and sesame) an experiment was carried out as strip split plot based on randomized complete block design with three replications at the Agricultural Research Station, Ferdowsi University of Mashhad during growing season of 2008-2009. The main, sub and strip factors were three species (sugar beet, corn and sesame), three irrigation levels (100, 75 and 50% of water requirement of each crop) and four nitrogen levels (0, 50, 100 and 150 kg.ha-1), respectively. The result showed that the highest water use efficiency was observed as 2.4, 1.8 and 1.5 kg DM.m-3 in corn, sugar beet and sesame, respectively. The maximum water use productivity was obtained for sugar beet (4200 Rails.m-3), sesame (2123 Rails.m-3) and then for corn (1768 Rails.m-3). Interaction effect between water and nitrogen was significant on water use efficiency and productivity for all three studied crops. Water use efficiency declined up to 19% by decreasing 25% of water requirement. Water use productivity decreased in all three studied crops by increasing nitrogen consumption. It seems that high nitrogen level could not be affect on reducing drought stress effects.

Biodiversity refers to all forms of living animals, plants and microorganisms and agro-biodiversity is a component of biodiversity that represents diversity in arable lands. The aim of this study was to determine the biodiversity status of agro-ecosystems of Shahr-e-Rey city located in south of Tehran, through calculating species richness index using rarefaction method. To the collect required data, eight villages (Dorsun Abad, Kaiser Abad, Azim Abad, Deh Kheir, Taleb Abad, Qomi Abad, Ibrahim Abad and Khanlouq) of three district (Kahrizak, Ghaleno and Fashafuyeh), were selected as experimental samples. The results showed that the three villages of Ghaleno district (DehKheir, Qomi Abad and Taleb Abad) with species richness index of 14.85, 14.68 and 13.11 respectively, had the highest value of biodiversity in their agro ecosystems, while Azim Abad in Kahrizak district and Khanlouq in Fashafouyeh district with the value of 12.06 and 12.25 species richness index has the lowest levels of biodiversity. Rarefaction method application for calculating species richness diversity indicated that due to low surface area of arable lands, Taleb Abad and Ghomi Abad villages has the lowest number of species in their agro ecosystems. However, these villages had the highest value of equiponderated of species richness index between targeted villages.

In order to study the effect of different types and rates of animal manure and spent mushroom compost on controlling Egyptian broomrape (Orobanche aegyptiaca Perss.) in tomato (Mill. Lycopersicon esculentum), two studies were conducted on randomized complete block design with three replications at Research green house, College of Agriculture, Ferdowsi University of Mashhad and Nemooneh field of Astane Ghods Razavi during two years of 2009 and 2010. Greenhouse study treatments were consist of poultry, cow, sheep manure and spent mushroom compost, which each one applied at four rates (10, 20, 30 and 40 t.ha-1). Field experiment treatments were included of poultry, cow and sheep manure that each one applied at two rates (20 and 40 t.ha-1). Result of the greenhouse study indicated that poultry manure significantly reduced orobanch infestation and increase tomato dry weight compared to control. But in the field experiment, the maximum fruit yield (68 t.ha-1) with the minimum orobanch dry weight were obtained with sheep manure. The effect of cow manure was similar to poultry manure in all measured traits. In the field study, rates of manure application had no significant effect on orobanch fresh and dry weights. The findings indicated that all treatments of animal manure reduced orobanch infestation. But the mechanism of orobanch growth suppression due to animal manures application is unknown. It seems fermentation of different organic matters can produced heat and the resulting toxic compounds such as certain organic acids, ammonia and ammonium salts that may reduce orobanch growth at proper concentrations.

Shallot (Allium altissimum Regel.) is a medicinal, industrial and perennial plant that has underground tubers. It is one of the most important Allium species in Iran, which normally grows in semi-cold to very cold highlands. Because of being a wild plant, shallot is encounter with water deficit during its growth season. Therefore evaluation of water requirement of shallot is important. In order to assess the effects of different irrigation regimes and planting depth, a factorial experiment based on randomized complete block design with three replications was conducted at Agricultural Research Station Ferdowsi University of Mashhad, faculty of Agriculture. Treatments were five irrigation levels: no irrigation (I1), irrigation after 80±5 mm evaporation from pan evaporation (I2), irrigation after 60±5 mm evaporation from pan evaporation (I3), irrigation after 40±5 mm evaporation from pan evaporation (I4) and irrigation after 20±5 mm evaporation from pan evaporation (I5, control) and two levels of sowing depth of 5 cm (D1) and 10 cm (D2). Results showed that dry bulb yield, biological yield, harvest index and plant height were reduced by increasing irrigation intervals. Sowing depth had no significant effect on the parameters studied. Also the interaction between irrigation levels and sowing depth reduced plant height, dry bulb yield and harvest index. The interaction between irrigation and sowing depth was significant in leaf area index and crop growth rate. Shallot reacts to the amount of available water positively, but sowing depth of 10 cm has no effect on the bulb.

In order to evaluate the effects of plant density and planting pattern on quantitative and qualitative characteristics of Balangu (Lallemantia royleana Benth.) as a medicinal plant, an experiment was conducted at Research station of Faculty of Agriculture, Ferdowsi University of Mashhad, Iran, during growing season of 2011-2012. A factorial layout based on a randomized complete block design with nine treatments and three replications was used. The treatments comprised three levels of planting density (60, 70 and 80 plants.m-2) and three levels of planting pattern (row planting, mixed row planting and flat planting). Studied criteria of Balangu were quantitative characteristics (such as number of lateral stems, plant height, 1000-seed weight, biological and seed yield and harvest index) and qualitative characteristics (including mucilage content and yield; and swelling factor). Results showed that all quantitative characteristics of Balangu except 1000-seed weight were significantly increased by plant density. Qualitative characteristics were not significantly affected by plant density except mucilage yield but the maximum quantitative and qualitative characteristics were obtained by row planting. Interactions between plant density and planting pattern showed that the maximum of seed and mucilage yield were obtained by row planting and plant density of 80 plants.m-2. Non significantly affected by planting pattern and plant density showed that Balangu can tolerates the environmental effects and this is the important property for plants selection and development.

Estimating and determining of rice water requirement, being the main cultivate of Rasht region, is crucial for devoting water to this region. Equations which are used to calculate the reference evapotranspiration (ET0) are not match to all climatic conditions, due to their empirical bases. So, it is necessary to clarify proper methods for each region. Crop coefficient (Kc) is also the main parameter for determining each plant’s potential evapotranspiration and subsequently plant water requirement. Hence in this study, evapotranspiration data for grass and rice i.e. Binam and Khazar cultivars were collected in Rice Research Institute of Rash, by using drainable lysimeter at ten-day periods during three consecutive crop seasons. The reference evapotranspiration were calculated and compared with 16 empirical equations results included in Ref-ET software. Significant differences of them have been evaluated using SPSS software. Also, the crop coefficient values were calculated for each variety of rice. In all three equations i.e. Hargreaves, Priestley-Taylor and Penman (FAO 24) have not shown any significant differences. Among three methods, Hargreaves equation is recommended for Rasht region because, this equation as compared with others is a temperature-based method and would consider global warming phenomenon. Also, the average of crop coefficient (Kc) for Khazar and Binam in three consecutive crop seasons were 1.10 and 1.09, respectively.

In the last decades, pesticides have been used extensively, in order to control pests and plant diseases, but negative impacts of pesticides caused several environmental problems and put human health in danger. In order to decrease environmental hazards of pesticide, risk of pesticide application should be measured briefly and precisely. In this study environmental impacts of registered insecticides in Iran which applied in 2001-2002, 2003-2004, 2004-2005, are considered using environmental impact quotient (EIQ) index. Results showed that among considered insecticides, Imidacloprid, Fipronil and Tiodicarb, potentially (EIQ) were the most hazardous insecticides, respectively. Taking rate of application and active ingredient of insecticide in to account, environmental impact (practical toxicity) per cultivated hectare (EIQ Field) of each provinces were investigated. In this regard, among different province of Iran, Kerman, Mazandaran and Golestan were in danger more than the others, respectively. Besides, considering the amount of agricultural production in provinces, environmental impact per ton of production were calculated for each provinces which three northern provinces of Mazandaran, Golestan and Guilan, respectively endure the most environmental impact per ton of production. Eventually based on environmental impact quotient, results demonstrated that majority of environmental impacts of insecticide in Iran were due to inadequate knowledge and also overuse of a few number of insecticides. Therefore, by improving knowledge about environmental impact of pesticides and also developing environmental friendly and ecological based methods, negative environmental impacts of insecticides will be reduced significantly.

In order to investigate the response of coneflower to applying chemical fertilizer and incorporation with municipal solid waste compost (MSWC), a pot experiment was conducted as completely randomized design with six treatments included: control (without applying chemical fertilizer and compost), chemical fertilizer (150 kg N, 120 kg P2O5 and 250 kg K2O per hectare from urea, triple super phosphate and potassium sulphate source, respectively) (CF), 30 t.ha-1 MSWC, 15 t.ha-1 MSWC + 1 4 CF, 15 t.ha-1 MSWC+2 4 CF, and 15 t.ha-1 MSWC + 3 4 CF with three replications during 2012 in Sari Agricultural Sciences and Natural Resources University. Results indicated that growth and yield indices such as the number of flowers per plant, number of lateral branches, number of petals, main flower’s diameter, receptacle’s diameter, main stem’s diameter, fresh weight of flower, dry weight of flower and concentration of chlorophyll a and b in flowering stage were affected by application of chemical fertilizer and MSWC. The incorporation 15t.ha-1 MSWC + 1 4 CF also enhanced the diameter of receptacle, main stem’s diameter, the number of petals, 30%, 30% and 50%, respectively. Meanwhile, applying 15 t.ha-1 MSWC + 1 4 CF/ha increased the concentration of chlorophyll a, chlorophyll b, number of flowers per plant, total fresh and dry matter of flower about 80%.

The caster bean oil is high value in industry around of world. Plant nutrition and plant growth promoting rhizobacteria (PGPR) are important for crop production. An experiment was set up to investigate the effect of nitrogen (N), sulfur (S) fertilizers and PGPR on seed yield production of Ricinus commines L. This experiment was carry out in factorial layout based on complete randomize block design with three replicates at Research Center of University of Zabol during growing season of 2011-2012. The treatments were PGPR with three types of bacteria (control, Nitroxin, and Super Nitroplas 2 L.ha-1), three levels of nitrogen (0, 150 and 200 kg.ha-1) and two levels of sulfur fertilizer (0 and 300 kg.ha-1). The results showed that grain weight, 1000-seed weight, number of capsule and number of seed per plant were not affected by studied treatments. The highest effect of PGPR was on dry weight of capsule, plant height, number of leaf per plant, oil percentage and amount of seed protein. Number of inflorescence just affected by sulfur treatments and most of studied plant characters affected by N fertilizers. The highest and the lowest oil percentage were related to Nitroxin and Super Nitroplas 51.89 and 47.85, respectively. Also the highest and the lowest plant height were related to Nitroxin and control treatments 82.29 and 53.33, respectively.

In order to study the effect of different N fertilizer on berseem forage in an intercropping with basil, this experiment was conducted in Research Farm of College of Agriculture, University of Tehran during growing season 2011. Experimental treatments were arranged as split plots based on a randomized complete block design with three replications. Different fertilizers consisted of control (no N fertilizer), 100% chemical fertilizer, biological fertilizer, and integrated fertilizer (biological fertilizer + 50% N fertilizer) were assigned to the main plots while different additive intercropping patterns of basil mono cropping (weed free), basil mono cropping (weed infested), berseem clover mono cropping (weed free), berseem clover mono cropping (weed contaminated), berseem clover + %25 basil, berseem clover + %50 basil, berseem clover + %75 basil, berseem clover + %100 basil were assigned to the sub plots. The biological fertilizer comprised of Rhizobium (Rhizobium trefoli) + Azotobacter (Azotobacter sp.) + Azosprilium (Azosprilium sp.) + Bacillus (Bacillus sp.) + Mycorrihza (Mycorrihza sp.). The results showed that the highest basil forage yield (two harvests) (4223 kg.ha-1) was obtained from basil mono cropping (weed free) treatment when received integrated fertilizer. The highest forage yield (4833 kg.ha-1) for berseem clover was obtained from clover mono cropping (weed free) at 100% chemical fertilizing treatment. The highest total forage yield (berseem clover + basil) (5983 kg.ha-1) was obtained from berseem clover + %50 basil and berseem clover + %75 basil at integrated N fertilizer treatment. The best Land Equivalent Ratio and Relative Competition ratio were obtained at berseem clover + %75 basil and berseem clover + %100 basil treatments. Our results suggested that integrated fertilizer could be considered as the best fertilizing system to substitute for chemical N fertilizer (Urea) in additive intercropping of berseem clover and basil.

Climate change is a phenomenon that has made the most concern in communities and decision making centers. This phenomenon has important effects on different aspects of human life. One of the most important crops that are affected by climate change is wheat. Accordingly, data and information of Northern Khorasan have been used to study the effects of climate change on rain-fed wheat yield. For this reason, climatic data of Bojnourd synoptic station from 1984 to 2010 and economic data of Northern Khorasan rain-fed wheat available in Jihad Keshavarzi administration were used to analyze previous situation and detecting climate change and determine a relationship between economic yield and climatic variables. To determine relationship between economy of rain-fed wheat and regional climate, maximum and minimum temperature, annual precipitation and also cost of wheat production, price of wheat and barley, and cropping area have been selected as independent variables and yield and income of wheat have been selected as dependent variables. In addition, for prediction of the amount of climatic elements in future, numerical climatic meso scale models HADCM and LARS-WG have been used. The results showed that climate change occurred in 30 past years and there is significant relation between logarithm of maximum and minimum temperature and annual precipitation, and wheat yield. Using resulted equation for yield and income of wheat and the results from numerical climatic model showing 0.5 degree Celsius increasing of minimum and maximum temperature and decreasing 25 mm of precipitation from 2010 to 2039 in the region, increasing in wheat yield (10 kg.ha-1) and income (250000 t. thousand Rial-1) have been predicted in this region.

In order to study the sowing system, row distance and weeding effect on yield and yield components of intercropped maize with peanut, this experiment was conducted, as factorial based on a RCBD with three replications at the research farm of agriculture center of Zabol University (Iran) during growing season 2011- 2012. Sowing system were four levels including sole maize, sole peanut, 50% maize + 50% peanut, 100% maize + 100% peanut as the first factor and row distance as the second factor in two levels 40 and 50 cm and weeding as third factor in three levels of non-weeding, once weeding, twice weeding. The results showed that effect of the sowing system was significant on plant height, stem diameter, Number of kernel/ear-1, Number of kernel/row-1, Number of ear/plant-1, 1000-grain weight, biological yield, economical yield and harvest index of maize. Effect of weeding was significant on studied characteristics excluding of biological yield, economical yield and harvest index. The highest economical yield was obtained from sole maize, twice weeding and density of 50 cm. The highest LER was observed from 100% maize + 100% peanut.

This study was performed for evaluation of the qualitative traits of safflower (Carthamus tinctorius L.) as affected by Azotobacter and mycorrhizal symbiosis (host plant root symbiosis with the Glomus fungi) as factorial experiment based on randomized complete block design with three replications in research farm of college of Arak Islamic Azad University during growing season of 2011-2012. Treatments including of inoculated with Azotobacter in three levels (Non-inoculated, inoculation with Azotobacter-5 and inoculation with Azotobacter-12) and Glomus fungi treatment in four levels (Non-inoculated, inoculation with Glomus intraradices, inoculation with Glomus mosseae and inoculation with mixed G. intraradices and G. mossae). Results showed that interaction effect of Azotobacter and Glomus fungi (the combined use of the two combinations) had significant effect on seed phosphorous percent mycorrhizal dependency and seed nitrogen percent of safflower. The highest seed phosphorus (0.58%) was observed from inoculation with Azotobacter-5 and inoculation with mixed G. intraradices and G. mosseae (A1M3) and the lowest (0.37%) from treatment of inoculation with Azotobacter-5 and inoculation with G. mosseae (A1M2). Highest (3.14%) and lowest (2.46%) seed nitrogen were obtained with inoculation with Azotobacter-12 and inoculation with mixed G. intraradices and G. mosseae (A2M3) and non-inoculated with Azotobacter and inoculation with G. intraradices (A0M1), respectively. The main effect of Azotobacter and Glomus fungi inoculation was on seed oil percent, seed oil yield, seed phosphorous percent, root colonization percent and mycorrhizal dependency of safflower. The highest seed oil percent, seed oil yield, seed phosphorus percent, root colonization percent and mycorrhizal dependency of inoculation with Azotobacter-12 than those obtained from non-inoculated.

Salinity tolerance is one of the most important affecting factors on agricultural production in arid and semi-arid areas. In order to study the effects of saline and fresh water irrigation with application of organic and NPK fertilizers on cumin, a split plot experiment based on randomized complete block design was carried out with three replications during 2011 and 2012, at the research farm of Zabol University. Main factor was irrigation regimes (fresh water, and saline water EC: 4.180 dS.m-1) and the sub factor were including individual and combining treatments of manure and NPK fertilizer and control. Results indicated that increasing soluble salts in water irrigation until 4.180 dS.m-1 range, plant height, seed weight, and number of umbel per plant, number of seeds per umbel and plant, and yield decreased but the percentage and yield of essence was increased. Increasing the concentration of sodium ions lead to decrease concentrations of potassium, phosphorus, calcium and magnesium of cumin seed. Among the different fertilizer treatments, separate application of organic and chemical fertilizers have little advantage, but integrated chemical fertilizer and manure was more effective to improve the most investigated characters. Interaction of water and fertilizer regimes was significant on yield, seed weight, plant height, oil percentage and sodium content. In general, in order to reduce pollution of chemical fertilizers and the compensation lack of soil organic matter in arid and semi-arid areas, NPK fertilizer (40:20:15 kg.ha-1 ratio with 20 t.ha-1 manure) in area is recommended.

In order to study impacts of organic manure levels and inoculation with mycorrhiza fungi on growth, quantitative and qualitative yield of hyssop (Hyssopus officinalis L.), a field experiment was conducted as factorial based on a randomized complete block design with three replications at the Agricultural Research Station, Ferdowsi University of Mashhad, during two growing seasons of 2009-2010 and 2010-2011. Mycorhiza inoculation (with and without inoculation) and five levels of organic manure as decomposed cow manure (zero, 10, 20, 30 and 40 t.ha-1) were considered as treatments. Plant height, canopy diameter, leaf to shoot ratio, shoot dry weight, essential oil content and essential oil yield of hyssop were measured and calculated accordingly. The results showed that the simple and interaction effects between organic manure and mycorrhiza were significant (p≤0.01) on plant height, canopy diameter, leaf to stem ratio, shoot dry weight and essential oil content and yield of hyssop. By increasing organic manure level from zero to 30 t.ha-1 enhanced shoot dry weight and essential oil yield of hyssop up to 127 and 43%, respectively. Whereas by increasing organic manure level up to 40 t.ha-1 improved these traits up to 12 and 24%, respectively. Mycorrhiza inoculation enhanced shoot dry weight and essential oil yield up to 19 and 14%, respectively. The second year, growth of hyssop plants due to suitable establishment and more availability of nutrients were higher than the first year. Organic manure enhanced growth and yield of hyssop due to availability of nutrients and improvement in soil characteristics. Mycorrhiza inoculation promoted growth and yield of this valuable medicinal plant because of root development and nutrient availability particularly phosphorus.

To evaluate the effect of different sources of P fertilizer on grain yield and yield components of two barely varieties, this experiment was conducted in Research Farm, College of Agriculture, University of Tehran in 2010. The experimental treatments were arranged as factorial based on randomized complete block design with three replications. The treatments consisted of two barely varieties (Bahman and Fasieh) and 7 levels of P fertilizer viz: 1. Control (no fertilizer application), 2. Chemical P fertilizer (based on the soil test), 3. Biological P fertilizer (P solubilizing bacteria), 4. Biological P fertilizer + 100% chemical P fertilizer, 5. Biological P fertilizer + 75% chemical P fertilizer, 6. Biological P fertilizer + 50% chemical P fertilizer, 7. Biological P fertilizer + 25% chemical P fertilizer. The results indicated that the ash percentage in Fasieh was significantly higher than Bahman at Chemical P fertilizer, integrated and Biological P fertilizer + 50% chemical P fertilizer. Except for Biological P fertilizer, DMD percentage was significantly higher in Fasieh compared to Bahman. The highest crude protein percentage was obtained for Fasieh in Biological P fertilizer + 50% chemical P fertilizer for Bahman in Biological P fertilizer + 75% chemical P fertilizer, respectively. The water soluble carbohydrate content was significantly higher in Fasieh at Chemical P fertilizer and integrated fertilizer treatments compared to Bahman variety. The highest NDF in Bahman was observed when received Biological P fertilizer + 50% chemical P fertilizer treatment, while the same results was obtained for Fasieh when received Biological P fertilizer + 100% chemical P fertilizer and Biological P fertilizer + 75% chemical P fertilizer.

Agricultural activities have always been partly responsible for the emission of greenhouse gases and other environmental contaminants in the atmosphere. Thus, studying on the environmental effects of agricultural activities and proposing appropriate strategies to mitigate these adverse effects can be paramount importance. In this study, in order to determine the environmental impacts of peanut production in Guilan province, the life cycle assessment method was used. These effects in six groups; the global warming, acidification, terrestrial eutrophication, the depletion of fossil resources, the depletion of potassium and the depletion of phosphate were investigated. In this research, the nitrogen, phosphorus and potassium fertilizers and diesel fuel for one-ton production and drying of peanut were set as the input to production system that cause the environmental impacts. Dada analysis revealed that the final indicators for one-ton production of peanut for the global warming, acidity, the depletion of fossil resources, eutrophication, the deplete of potassium resources and the depletion of phosphate resources were calculated 0.036, 0.194, 3.64, 0.316, 0.0243 and 0.266, respectively. It suggests that in one-ton production of peanut in Guialn province, the depletion of fossil resources has the most severe environmental effect followed by the eutrophication. In this study, the environmental index (ECOX) and resources depletion index (RDI) for one-ton production of peanut were obtained 0.55, 3.93, respectively. Also, final indicators for the global warming, acidification, the depletion of fossil resources, eutrophication, the depletion of phosphate resources and the depletion of potassium resources were 0.0015, 0.0082, 0.153, 0.0112 and 0.0010 respectively, for generating 1000 MJ energy.

To study the effects of planting date and planting density on quantitative traits of medicinal plant, Schneider squash (Cucurbita pepo L.), an experiment was conducted at research field of Ferdowsi University of Mashhad, in year 2012. A split plot arrangement based on Randomized Complete Block Design with three replications was used. Treatments consisted of three planting date levels (1 May, 11 May and 21 May) and two density levels (2.5 and 4 Plants per m-2) which were allocated to main plots and sub plots, respectively. At the end of the growing season, the seed yield, fruit yield, number of fruits (per ha-1), number of seed (per m-2), number of seed per fruit, seed weight per fruit, 1000- seed weight and harvest index were measured. Results showed that the second planting date (11 May) results in highest amount of the quantitative study traits. The density of 2.5 plants per m-2, compared to the density of 4 plants per m-2, could result in highest yield and yield components. The interactions of planting date and density were not significant in terms of fruit and seed yield but among the other yield components, significantly affect the number of seed (per m-2), the number of seed per fruit and the seed weight per fruit at the probability level of 5%. Overall this study showed that the optimum planting date and suitable density can play an important role in increasing fruit and seed yield of the pumpkin plant, considering the usefulness of this plant in the food, cosmetics, and medicinal industry.

To investigate the factors affecting the population density of weeds and yield loss of them in wheat, a non systematic survey experiment was conducted in 45 fields in the township of Bandar-gaz (Sarmahaleh village) in 2012. Sampling of wheat and weeds were taken in two stages (Heading and Harvest maturity) by randomized to the five points of each field using quadrate size 1m*1m. In this study all information about crop management including Land area, farmers experience, the seed bed preparation, sowing date, cultivar and site preparation of them, sowing ways, seed rate, weeds control ways, kind, amount and time of herbicide, fungicide use and wheat harvest time were collected during a growing season by preparing questionnaire and complete them with farmers. At the end of the growing season, the actual yield harvested by farmers’ recorded. Among the various parameters, Wheat plant and raceme density, farmer experience, Kind of variety and use of Tapic+Geranestar herbicide had significant effects on weed population. With increased wheat plant density, weed density decreased. Also there was less weed density in field of high experience farmer. Weed density was lesser in N8118 variety than N8019 variety and not use Tapic+granestar herbicide due to increased of weeds density. Among weed different species, Avena sp, Phalaris minor and Sinapis arvense had highest negative effect on wheat yield. Model study showed if wheat plant density was optimum and there were weeds, yield will be 2713kg/ha and if weeds remove yield will increase to 2877kg/ha (yield gap equal164kg/ha). Amaong weed, Phalaris minor (12 plant per m-2), Sinapis arvensis (3plant per m-2) and Avena sp (2 plant per m-2) with 65, 18 and 17% yield loss respectively, were the strongest competitor with wheat.