WEEDS identification and distribution is one of the most important basics in their management, so the WEEDS of chickpea fields in rain-fed areas of Maragheh, North west Iran, were systematically sampled and the traits of species distribution, life cycle, canopy, species diversity and similarity indices were studied. Convolvulus arvensis, Cardaria draba, Sophora alopecuroides, Acroptilon repens, Tragopogon graminifolius, Euphorbia helioscopia, Geranium tuberosum and Falcaria vulgaris showed high frequencies among WEEDS. Also diversity, uniformity and dominance of weed population were evaluated via Shannon-Wiener index and similarities and differences between various regions based on species diversity were evaluated by using Sorensen and Jaccard indices. Among the studied areas, the highest and lowest richness index was belonged to Khodajo (44 species) and Khorma Zard (28 species), respectively, whereas, the regions had equal Shanon-Winener diversity index. Tragopogon graminifolius, Convolvulus arvensis and Galium tricornutum with relative dominance indices of 38.82, 32.92 and 28.39 respectively, were detected as dominant WEEDS in Maragheh chickpea fields.

Surveying WEEDS of irrigated barley fields is one of the most important practices in weed management. Based on cultivated areas irrigated barley in all counties of Ardabil province during six years (2000-2005), 46 sample barley fields were selected and weed species were counted in each sampling point and population indices were calculated with Thomas method. By using specific furmula the density, frequency and uniformity of each weed species in fields were calculated. In each field longitude, latitude and altitude were recorded by using GPS. These data were used for producing weed maps using GIS. Results showed that Galium tricurnatum, Fumaria vaillanti and Raphanus raphanistrum were dominante broadleaf species in irrigated barley fields of Ardabil province. The dominant grassy weed species in these fields were Avena fatua and Secale cereal. Convolvulus arvensis and Cirsium arvense were the most important troublesome plants prior to harvesting in irrigated barley fields of this province.

Weed species to various herbicides, show varying degrees of sensitivity or resistance. Therefore, to investigate the effect of herbicide application Trifuralin and Imazethapyr the composition and diversity of WEEDS a trial based on randomized complete block design with three replications was acheieved. Treatments were application of Trifuralin herbicide, Imazethapyr herbicide and not application of herbicide (control). The results showed that Trifuralin reduced 13.2% frequency of Lamb’s quarters (Chenopodium Black album) and 3.7% of barnyard grass (Echinochloa crus-galli) and Imazethapyr reduced 11.6% frequency of nightshade (Solanum nigrum) in final growth stage but non of the herbicides was not effect on Common Purslane (Portulaca oleracea). Dyer’s croton (Chrozophora tinctoria), Flower-of-an-Hour (Hibiscus trionum), Redroot Pigweed (Amaranthus retroflexus), Prostrate amaranth (Amaranthus blitoides), Flixweed (Descurainia Sophia) and Datura had low densities between herbicides treatment. In Imazethapyr treatment, Shannon–Wiener diversity index was more than control treatment in Almost growth stage and it was 0.97, 0.51 and 1.27 for Imazethapyr herbicide, Trifuralin herbicide and control treatments respectively in final growth stage.

In order to investigate species and functional diversity and COMMUNITY structure for WEEDS in wheat and sugar beet fields in different provinces of Iran, this study was conducted by using data from a previous projects on weed control conducted by Ministry of Jihad Keshavarzi. Total number of weed species were 72 and 52 species in wheat and sugar beet, respectively. In the wheat fields, Poaceae and Asteraceae showed the most diversity amongst monocotyledonous and dicotyledonous groups. In the sugar beet fields, Poaceae and Brassicaceae were the most diverse family amongst monocotyledonous and dicotyledonous groups. Provinces were grouped in three clusters for functional weed groups in wheat and sugar beet fields (similarity 75%). Tehran and East Azerbaijan had the highest similarity percentage (71%) amongst the provinces for weed diversity in wheat. In sugar beet fields, the highest similarity percentage was observed in Hamedan and Kohkiloyieh va boier-ahmad (71%), Ilam-Ardabil and Khoozestan-Ardabil provinces showed the lowest.

To study weed species diversity and COMMUNITY structure in pistachio (Pistacia vera L.) orchards in 33 orchards of 12 villages an investigation was conducted in Bardaskan County, Khorasan Razavi Province, Iran during 2008-2009. weed population sampling was conducted in a w shape method using 1m² quadrate. the results showed that the WEEDS of pistachio orchards were belonging to 15 families and 44 species.dicotyledons (31 species) were more than monocotyledons (13 species). Such as in this COMMUNITY, weed species of C3, C4, annual and perennial were 26, 18, 28 and 13, respectively. the majority of weed species were belonging to the plant families of chenopodiceae (9 species) and poaceae (12 species) amongst dicotyledons and monocotyledons, respectively. the most important species of monocotyledon annual WEEDS were including Echinochloa crus-gali, Digitaria sanguinlis, Setaria viridis and perennial WEEDS were including Cyperus routundus, Cynodon dactylon and convolvulus arvensis. weed species were grouped in seven clusters for density average, frequency and uniformity (similarity 75 percent) whereas in eight clusters for relative density average, relative frequency and relative uniformity (similarity 75 percent). amplitude changes of Shannon-winter diversity index were between 2.3 and 0.16 and of Simpson dominant index were between 0.97 and 0.17. the difference among indices of biodiversity and dominant clusters were relative to scale and type of management practices.

An experiment was conducted on clay soil at Lods Agronomy Research Center, McGill University to study the response of WEEDS communities and corn plants to nitrogen and herbicide application. The experiment was arranged as split plots design with 6 replications, in which application of herbicide (at 4 levels) and nitrogen (at 3 levels) were respectively the main- and sub-treatments. The herbicide Nicosulfuron (9 g ha-1) mixed with mineral oil (Agral 90, 25% v/v) was used to control grass WEEDS. The herbicide dicamba (590 g ha-1) was used for broadleaf control. Nicosulfuron mixed with Agral at the above mentioned rates, and dicamba at 295 g ha-1 were used to control both grass and broadleaf WEEDS. Weedy check also was considered as control. Nitrogen (ammonium nitrate) at 60, 120, and 250 kg ha-1 was applied twice; once at planting time and again 54 days after planting. The results indicated that the density of grass WEEDS was higher than that of broadleaf WEEDS. However, broadleaf WEEDS could grow vigorously and by the end of the season they showed strong growth in most weedy check. Nitrogen had a pronounced effect on corn growth and yield. Reducing the nitrogen supply resulted in pale green leaves in the corn. Increasing nitrogen application increased the corn biomass mainly during the rapid vegetative growth stage.

Application of intercropping systems is one of the ecological methods for controlling WEEDS due to maximization of soil cover and plant diversity. In order to study the effect of intercropping system of indigo (Indigofera tinctoria L. ) and roselle (Hibiscus sabdariffa L. ) on biodiversity, WEEDS population changes and plant yield an experiment was conducted based on randomized complete block design with three replications in the Research Farm of South Kerman Agricultural and Natural Resources Research and Education Center, Jiroft, Iran, during 2014-2015 growing season. Treatments were additive and replacement series of intercropping including: I100: H100, I100: H50, I50: H100, I50: H50 and monoculture of indigo and roselle. The results showed that the density and biomass of Amaranth, Cyprus and other WEEDS (Heliotropium europaeum L., Heliotropium europaeum L. and Portulaca oleracea L. ) were significant by intercropping of indigo and roselle. Amaranth weed density in I100: H100, I50: H100 and I100: H50 were 57. 44, 81. 5 and 70. 38%, respectively, lower than roselle monoculture. The highest of Cyprus weed density was in indigo and roselle monoculture and I50: H50 intercropping ratio. The density of other WEEDS in I50: H50, I50: H100, I100: H50 and I100: H100 ratio were 44. 4, 48. 2, 51. 8 and 77. 7 % lower than monoculture. Weed biomass in I100: H100, I10: H50 and I50: H100 ratio were decreased by 25. 44, 23. 38 and 15. 98 % in comparison to monoculture, respectively. The highest yield of roselle (1114. 2 kg/ha) and leaf dry weight (3016. 7 kg/ha) of indigo was observed in I100: H100 ratio. The values of the land equivalent ratio (LER) in all of intercropping treatments were greater than unit and the highest LER belonged to H100: I100 treatment, indicating that intercropping system outperforms the monoculture in terms of crop productivity and hence weed control.