mostafa oveisi

In order to investigate the effectiveness of random, zigzag and diagonal sampling methods in seven sampling levels in estimating the weed population of corn fields under drip, furrow and sprinkler irrigation systems, a research was conducted in 2020 year in six corn fields. In order to estimate the accuracy of the sampling methods, first, the studied area was gridded with the standard grid sampling method of 5 m × 5 m and at the intersection of the lines using a square quadrat an area equal to one meter. The data related to the species number and density of weed seedlings by species were recorded in one stage. The results showed that increasing the sampling levels increased the accuracy in estimating the number of weed species in different sampling methods. At low sampling levels, the random sampling method estimated weed density with less error, but with increasing sampling levels, the accuracy of diagonal and zigzag systematic sampling methods increased and with 20 and 21 sampling units, respectively, they estimated the density of seedlings of the weed population with acceptable accuracy. With the increase of sampling levels, the amount of error in estimating the density of C. album species decreased so that the lowest error was in levels IV , VI (with 24 samples in random and diagonal methods and 25 sample in zigzag method) and VII (with 28 samples in random and diagonal methods and 29 samples in zigzag method) were observed with 0.04, 0.02 and -0.06 respectively.

Grapevine production encounters significant challenges due to competition from Cynodon dactylon. We conducted a three-year study in a Red Yaghuti vineyard using a randomized complete block design. Our experiment included treatments with Clethodim, Sethoxydim, Fluazifop-p-butyl, and Haloxyfop R-methyl ester, as well as the application of polyethylene mulch (PM) for one, two, or three consecutive years. A control group with no weed control measures was also included, resulting in a total of eight experimental treatments. Even the least effective herbicide, Sethoxydim, reduced the dry weight of both above-ground and underground parts of C. dactylon by at least 60%, underscoring the efficacy of the herbicides for controlling C. dactylon. However, among the herbicides tested, Clethodim was the most effective in reducing the dry weight of both above-ground and underground parts of C. dactylon. Keeping C. dactylon plants under PM for two consecutive seasons virtually eliminated measurable dry weight in both above-ground and underground parts. The treatment of three consecutive years of soil under PM produced similar results to two consecutive years, resulting in zero dry weight for both above-ground and underground parts of C. dactylon. In comparison, the control and one-year PM treatments consistently yielded less than the herbicide treatments. The highest yield was achieved with consecutive years of PM use, producing approximately 13,000 kilograms per hectare. The economic and environmental costs of Clethodim use versus PM in vineyards differ significantly. While herbicides like Clethodim involve recurring costs and potential.

Keeping and returning plant residues to the soil not only improve the physical and chemical structure of the soil, but the presence of chemical compounds of the residues can also reduce the germination and growth of weeds. In this regard, a factorial experiment based on randomized complete blocks design with three replications was conducted at the experimental greenhouse of agricultural research station of the college of agriculture and natural resources, university of Tehran in 2019-2020. Treatments included three levels of plant residues (no-residues, residues of Brassica napus and Hordeum vulgare), two types of soil (no-sterile and sterile), three levels of soil temperature (25, 35 and 45oC) and two types of weed (Amaranthus retroflexus and Hordeum spontaneum). By increasing the temperature from 25 to 45oc, the final emergence percentage and emergence rate of weed seedling in the no-residues increased and in the treatments with Brassica and Hordeum residues decreased. In both sterile and no-sterile soils, the highest final emergence percentage (76.1 and 66.1%) and emergence rate of weed seedling (0.12 and 0.11 h-1) were observed in the no-residues. In addition, in sterile soil, the mentioned treatment was very different from the treatments of Brassica and Hordeum residues. Although the allelopathic effect of Brassica napus residues for controlling the emergence of the H. spontaneum and A. retroflexus compared to H. vulgare was greater; however, both crops were able to disrupt the emergence of the weeds. Therefore, preserving soil plant residues by strengthening the population of soil microorganisms and the relative control of the weed population can be important in reducing the amount and cost of application herbicides, environmental protection, and maintaining the stability of agricultural systems.

The first and most important step in weed management planning is to know the weed population. The proper sampling method is necessary to get a real and accurate knowledge of weed contamination in the fields. To investigate the effectiveness of grid sampling methods in estimating the weed population of corn fields under drip, furrow and sprinkler irrigation systems, a research was conducted in 2020 in six corn (Zea mays L.) fields. The fields were gridded with nine methods (three square methods, a rectangle along the field and a rectangle across the field each in three sizes). At the intersection of the lines, using square (100×100 cm) and rectangular (80×125 cm) squares perpendicular to the planting lines, data on the density and diversity of weed seedlings were recorded by species and at the four-leaf stage of corn. The results showed that in weed species such as A. belitoides, which had a wide distribution range, in drip and furrow irrigation systems, the square quadrat showed a more accurate estimate, and in the rain irrigation system, the rectangular quadrat showed a more accurate estimate. This was affected by the different wetting patterns of the soil in different irrigation methods, which somehow affected the emergence of weeds in the field. In other weed species, such as A. retroflexus, which had a more limited distribution range, the square quadrat in all three irrigation systems estimated weed density with less error than the rectangular quadrat. Examining the accuracy of grid sampling methods in weed population estimation showed that rectangular grid methods by increasing the grid dimensions along the length or width of the land had a more accurate estimate of species diversity and population density, as well as the density of single weed species compared to square grid methods with larger dimensions. By using these networking methods, along with the appropriate estimation of species diversity and weed population density, the status of weed species in the field can be investigated by reducing the sampling points with greater ease and less human effort.

In order to investigate the effectiveness of grid methods in estimating the spatial distribution of weed populations in corn fields under drip, furrow and sprinkler irrigation systems, a research was conducted in 2020 year in three corn fields. The fields were gridded with two methods of 5 m × 5 m and 5 m × 10 m. At the intersection of the lines, using square (100×100 cm) and rectangular (80×125 cm) squares perpendicular to the planting lines, data on the density and diversity of weed seedlings were recorded by species. In general, the spatial distribution maps confirmed the distribution of weed patches and the effect of the irrigation system on the appearance of patches, which was affected by the biological characteristics and wetting pattern of the field soil. The variogram of the studied species showed that in the furrow irrigation system, the range of influence of the species increased compared to other irrigation systems, The distribution range of the studied species was smaller in the drip irrigation system. The output maps showed a higher number of dense patches of weed species in the sprinkler irrigation system, possibly due to the uniform wetting pattern of the field. Sampling methods of the studied species showed differences in the estimation of spatial distribution maps. The rectangular grid sampling method of 5 m × 10 m mainly showed the size of the weed patches to be slightly larger than the square grid method of 5 m × 5 m,

This research was carried out to estimate the cardinal temperatures of Ambrosia psilostachya seed germination and evaluation of some nonlinear regression models. The experiment was performed at Tehran University Weed laboratory in 2022. In this experiment, the seeds were exposed to 8 temperature treatments (5, 10, 15, 20, 25, 30, 35, and 40ºC) with 3 replications in a completely randomized design. The germination rate, seed germination percentage and mean germination time of seeds were measured. Cardinal temperatures of seed germination were estimated using four regression models including segmented, dent-like and beta (four and five parameters) models. The performance of models and statistical indices was compared by RMSE (root mean squared of error), R2 (coefficient of determination) and AICc (corrected Akaike Information Criterion). Highest germination percentage was obtained at 15, 20 and 25°C (60.3%, 63.7% and 63%, respectively). The Highest germination rate (0.13d-1) and the lowest mean germination time (7.48d) were obtained at 25°C. Due to lower AICc and RMSE, the beta model (five parameters) was the best model for predicting the response of germination percentage to temperature in A psilostachya. Generally, base, optimal and ceiling temperatures were estimated 5, 25.5 and 42.13°C respectively by beta five-parameter model.

In weed management planning, the most important step is to know the weed population, which starts with sampling. In order to investigate the effectiveness of random, zigzag and diagonal sampling methods with 28, 29, and 28 sampling units, respectively, the shape (square and rectangle) and the size of the square (0.25 square meters and one square meter) for estimating the weed population of corn fields under drip, Furrow, and sprinkler irrigation systems, a research was conducted in 2020 in six corn (Zea mays L.) fields. In order to estimate the accuracy of the sampling methods, first, the studied area was gridded with the standard grid sampling method of 5 m × 5 m (171 sampling points) and at the intersection of the lines using a square quadrat (100 × 100 cm), an area equal to one square meter. The data related to the species density and diversity of weed seedlings by species were recorded at the four-leaf stage of corn and before herbicide application in one stage. The results showed that regardless of the quadrat shape and sampling methods, one square meter quadrats had a better estimate of species diversity and weed population density in corn fields under three irrigation systems. But when only weed density is considered, the use of a rectangular square of 0.25 m2 (100 × 25 cm) was able to estimate weed density with acceptable accuracy. Due to the different pattern of soil wetting in different irrigation systems and consequently the appearance of weeds and the way of navigation in each sampling method, the sampling methods showed different estimates of the population density of weeds; so that the diagonal sampling method in the drip irrigation system and the sampling methods Zigzag and random in sprinkler and furrow irrigation systems showed less error compared to standard grid sampling method. Meanwhile, in the investigation of single weed species, the diagonal systematic sampling method in all three irrigation systems showed the least error in the accuracy of the density estimation of the studied species compared to the standard grid method.

Modern intensive agriculture has boosted crop yields through chemical inputs. However, this approach has caused decreased biodiversity, harm to human health, and environmental degradation. Developing sustainable agricultural practices that increase productivity while minimizing negative effects, especially in arid and semi-arid regions, requires strategies like deficit irrigation and environmentally compatible weed control methods such as intercropping. This study aims to assess the performance of an intercropping system comprising buckwheat and cowpea under deficit irrigation and minimal weeding. The research seeks to provide insights into the viability of this approach for sustainable agriculture in water-limited environments.

A field experiment was conducted in 2022 at the Agriculture and Natural Resources campus of the University of Tehran research farm in a randomized complete block design with split-split plot arrangements. The main plot factor included three levels of irrigation: 100% of the plant's water requirement (control), 85% of the water requirement and 70% of the water requirement compared to the control. The subplot factor consisted of five planting patterns: sole cultivation of buckwheat, sole cultivation of cowpea, and three intercropping patterns of buckwheat and cowpea with different row ratios (1:1, 3:1, and 1:3). Timing of weed removal, as the sub-subplot factor, was implemented at five levels: no weeding (control), weeding until the second, fourth, sixth, and eighth weeks after cultivation.

The highest grain yield of buckwheat (2436.9 kg ha-1) and cowpea (2495.5 kg ha-1) was observed in the sole cultivation plot with eight weeks of post-planting weeding under full irrigation. These results are attributed to higher planting densities in sole cultivation compared to intercropping. The 1:1 intercropping pattern with eight weeks of post-planting, exhibited the best cowpea leaf area index (3.36), and buckwheat (4.1) and similarly, this intercropping pattern with six weeks of post-planting resulted in the highest number of branches per plant (16). Sole cowpea plot under 85% deficit irrigation exhibited the highest weed dry weight (145.7 g m-2). The highest Land Equivalent Ratio (1.08), was observed in the 1:1 intercropping pattern with two weeks of post-planting weeding under full irrigation. Interestingly, the 1:1 intercropping pattern also showed the lowest weed biomass (12.1 g m-2) without specific weed management under 70% irrigation.

Most intercropping treatments achieved a land equivalent ratio greater than one, highlighting the superior efficiency of this planting method compared to sole cultivation. Specifically, the 1:1 intercropping pattern successfully controlled weed biomass, increased grain yields under deficit irrigation, and some for both crops. Therefore, intercropping offers a promising strategy to reduce reliance on herbicides and improve overall land use efficiency.

Pinto bean (Phaseolus vulgaris) is being sown in Iran from April to July. To investigate the effect of acetylsalicylic acid (ASA) and Bacillus velezensis bacteria on pinto bean yield and yield component, an experiment was conducted as a split-split plots experiment in a randomized complete block design with four replicates in the research farm of the college of Agriculture and Natural Resources, University of Tehran in 2021 on separate planting dates (mid May and late June). The treatments included two irrigation levels (irrigation 70% and 100% of the plant's water requirement) as the main plot, foliar spraying (ASA hormone at 0.5 mM level and control) as a secondary plot and inoculation with Bacillus velezensis bacteria and no inoculation as a secondary subplot. Results of the analysis of variance showed that the interactions of sowing date, irrigation, foliar spraying, and inoculation with bacteria on the traits measured in pinto beans was significant. The maximum plant height (154 cm), number of sub-branches (7), leaf area index (7.3), seed yield (3045 kg/ha), and harvest index (43%), 100 seed weight (37 g), pod number (24) were obtained in mid-May planting date, along with salicylic acid foliar spraying and bacterial inoculation without water stress. The highest biological yield (7997 kg/ha) was obtained under water deficit stress (70% of plant water requirement) and foliar spraying with ASA hormone and inoculation with bacteria, in late June sowing date. Overall, hormone spraying and inoculation with bacteria improved the yield characteristics of pinto bean under drought-stress conditions in both sowing dates.

In order to investigate the changes in weed flora in the irrigated wheat fields of Isfahan county over a 15-year period (from 2019 to 2004), a systematic sampling of weeds was conducted in 100 farms with W pattern during wheat tillering to stem elongation stages. In 2004, the dominant weed species was winter wild oat (Avena ludoviciana) with a abundance index of 76.1; however, in 2019 three weed species, including winter wild oat, wild barley (Hordeum spontaneum), and littleseed canarygrass (Phalaris minor) were recognized as the dominant species with abundance indices of 70.1, 42.3, and 28.6, respectively. In 2004, the dominant broadleaf weed species were lambsquarters (Chenopodium album) with a dominance index of 67.9 and prostrate knotweed (Polygonum aviculare) with a dominance index of 31.96. However, in 2019, the highest dominance indices were observed in lambsquarters, prostrate knotweed, and Flixweed (Descurainia Sophia) with abundance indices of 78.4, 38.5, and 39.04, respectively. The correlation between weed distribution and soil factors (nitrogen, phosphorus, potassium, soil texture, and electrical conductivity), crop rotation, and herbicides was examined using canonical correspondence analysis (CCA). Littleseed canarygrass, wild barley, field brome (Bromus commutatus), licorice (Glycyrrhiza glabra), hoary cress (Cardaria draba), and yellow sweet clover (Melilotus officinalis) showed the highest correlation with soil nitrogen levels.

The duration of vegetation restoration in the skid trails after logging operations is crucial and fundamental for preserving forests. The purpose of this research is to evaluate the long-term vegetation restoration of the skid trails in Kheyrud forest after logging operations. Therefore, 54 sample plots (1×1 m) were randomly positioned. This included 27 plots on the skid trails with ages of 5, 10, and 15 years at three traffic intensities (low, medium, and high). Additionally, 27 sample plots served as controls with a distance of 10 m from the skid trails parallel to these trails. All the plants in the plots were identified, their abundance was counted, and their species and families were identified. The results of the current research showed that among the three investigated treatments, traffic intensity alone had a significant effect on the recovery of vegetation along the skid trails. However, the age after harvesting and the interaction of traffic intensity and age after harvesting did not have a significant effect. The results also showed that traffic intensity significantly affected the abundance of species. Furthermore, in all three factors (traffic intensity, age after harvesting, and the interaction of traffic intensity × age after harvesting), tree species were more affected by soil changes compared to herbaceous species. Therefore, traffic intensity can significantly affect the variety of species and number of plants in the skid trails, with a greater effect on tree species than herbaceous species.

Conservative tillage and drought resistant crops can be efficient solution to alleviate climate change impacts. We evaluated tillage effect, water deficit and nitrogen level on sorghum in a split-split plot experiment with three replications. Main plots were conventional tillage and no tillage, sub plots were 30, 60, and 90% of sorghum water requirement, and sub-sub plots were consisted of 0, 50, and 100% of recommended nitrogen. Results showed that the highest forage yield (12263 kg ha-1) was obtained with no till and 100% nitrogen. Also, the yield of sorghum in no till with moderate water stress was equal to the yield in conventional tillage with partial water stress. Under partial water stress, qualitative traits including crude fiber, acid detergent fiber and neutral detergent fiber in no till had lower values than conventional tillage. In addition, qualitative traits including digestible dry matter and water-soluble carbohydrates in no till treatment with 100% nitrogen were higher than conventional tillage. The highest percentage of crude protein in conventional tillage was obtained by using 100% nitrogen. It seems that conservation tillage can achieve acceptable yield and quality in sorghum with less water than conventional tillage, but it requires long-term and additional research.

To evaluate the effect of crop rotation and chemical management on weed seed bank in wheat fields, a three-year experiment was conducted in split-plot design with three replications in Khuzestan province. Main plots were crop rotation (wheat-wheat-wheat, wheat-rapeseed-wheat and wheat-sugar beet-wheat) and subplots were chemical management (Untreated Control (UTC), chemical rotation and no chemical rotation (farmer program)). The results showed the change in crop rotation reduced the frequency ratio of weeds seed bank population in both evaluated depths (0 to 10 and 10 to 20 cm). Also, the combination of chemical management along with crop rotation significantly reduced weeds seed bank population. In the absence of herbicide application in the three years of experiment, the frequency ratio of winter wild oat weed seed bank population on the soil surface decreased from 2.20 to 1.48 with rapeseed and from 2.73 to 0.63 with sugar beet planting, however, in the case of non-crop rotation, the frequency of wild oat seeds in the seed bank increased. This trend was also evident in the total weed seed bank population.

To investigate the effect of different levels of irrigation and nitrogen fertilizer on yield and yield components of some safflower cultivars, an experiment was conducted as a split-split plot in a randomized complete blocks design with three replications in the research farms of the University of Tehran, Karaj during 2018-2019. Main plots were irrigation (normal irrigation, irrigation until at middle of flowering stage and irrigation until the beginning of seed filling), sub plots were nitrogen (supply of 100 % and 50 % of nitrogen needs) and sub-sub plots were safflower cultivars (Goldasht, Golmehr, Padideh and Parnian). The effect of irrigation, nitrogen, and cultivar factors on number of heads per plant, number of seeds per head, 1000-seed weight, grain yield, and biomass were significant. According to the results, cut-off of irrigation at the beginning of seed filling and middle of flowering stages leads to a reduction of 16.2 % and 68.1 % of seed yield compared to normal irrigation, respectively. Reducing the amount of nitrogen by 50 % compared to 100 % supply decreases seed yield 8.5 % and biomass by 12 %. The triple interaction of irrigation, fertilizer and cultivar was significant in stem diameter and head diameter. The interaction of irrigation and nitrogen levels showed that with decreasing irrigation levels, nitrogen uptake also decreased and reduced the number of seed per head. However, providing 100 % of the nitrogen requirement under drought stress conditions prevents a more severe decline in the number of grains per head.

Swallow-wort (Cynanchum acutum L.) is a perennial and invasive weed that infested many sugarcane fields in Khuzestan. Field experiment was conducted to find out an efficient method for C. acutum control in sugarcane during 2018 and 2019. The experiment was split-split plots in a randomized complete block design with three replications. Main plots were pre-emergence application of metribuzin, metazachlor + qinmerac, pendimethalin, indaziflam and acetochlor; Sub plots were one time hand hoeing (four weeks after pre-emergence application), two-times hand hoeing (four and eight weeks after pre-emergence application), and without hand hoeing and sub-sub plots were post emergence application of 2,4-D+MCPA, mixture of 2,4-D+MCPA and metribuzin, and bromoxynil + MCPA herbicides. Results showed that individual application of Pendimethalin, and indaziflam herbicides, two-times if hand hoeing, and then post emergence application of 2,4-D+MCPA and metribuzin as a had the highest efficiency with an average of 96% in reducing mass dry weight. The application of mentioned treatments increased cane yield 104.7 and 102.9 t/ha respectively compared to the control (without weeding, with 110 t. ha-1). However, the experimental treatments did not show a significant effect on quality traits of sugarcane.

Quinoa is a pseudo cereal from Amaranthaceae family, which is currently considered as a suitable alternative for plants with high water consumption due to its high nutritional value and stresses tolerance, especially drought and salinity. Meanwhile, reduction in crop yield caused by weeds competing for water, light and nutrients is well known. Hence, a study was conducted in Karaj to investigate the competitive capacity of quinoa with weeds under normal irrigation and drought stress and also to determine the required time for weed control. The experiment was arranged in split plot randomized complete block design with four replications consisted of irrigation levels (60, 80 and 100 mm evaporation from the evaporation pan) as main plots and weed control levels (0, 7, 14, 28 days of control and control in all seasons) as subplots. The highest quinoa grain (331 g/m2) and biological yields (1262 g/m2) were obtained under normal irrigation in weeds free treatment. Also, the lowest grain and biological yields were 139 and 723 g/m2, respectively that obtained under high drought stress in weeds infestation during growing season. In one month weeds free treatment under medium drought stress, grain and biological yields were 290 and 1010.25 g/m2, which show that despite the competitive potency of summer weeds, quinoa has good competitiveness in drought stress, and with one month of weed control, can achieve performance close to full control. In logistic model fitting to the grain yield, the maximum and minimum values of y0 and a, i.e. upper and lower limits, were observed in normal irrigation and high drought stress, respectively; although, the maximum and minimum values of GDD50 were obtained in high drought stress and normal irrigation, respectively.

The first factor limiting plant yield in many crop ecosystems is drought stress, and plant productivity under these conditions depends on the distribution of dry matter between plant organs and the spatial distribution of roots in the soil. Knowledge of root length conditions and its distribution in soil profile, which is an indicator of the ability of plants to absorb water from deeper layers and better root permeability in the soil, as well as understanding the shape of the root system, is important (Wasson et al., 2012). In general, the size, morphology, and architecture of the root system determine the plant's ability to absorb water and nutrients, as well as the relative size and growth rate of the shoot (Vamerali et al., 2003). Root growth is determined by the genetic characteristics of the plant as well as the physical and chemical characteristics of the soil. Even in wet areas in response to drought stress, root growth is limited to the topsoil, and when the soil dries, its infiltration resistance increases rapidly, resulting in a combination of drought stresses. Soil and its infiltration resistance (He et al., 2017). Reduction of root dry weight in rice (Nasiri et al., 2015), fresh weight of root in rapeseed (Razaviezadeh and Amoubeigi, 2013) indicate the negative effect of drought stress on root characteristics in Different plants. Tillage is the only crop method by which humans can directly affect soil properties. Moisture storage and aeration to the roots, depending on the desired or unfavorable application of tillage, affects the growth and development of plant roots and ultimately its yield (Bronick and Lal, 2005).

This experiment was conducted in split -split plots based on randomized complete block design with three replications. Tillage systems as the main -plot in two factors was including no tillage and conventional tillage, Water stress as the subplot in three levels by 30, 60 and 90 Percent of moisture requirement and nitrogen urea as the sub-sub plot at three levels by 0, 50 and 100 percent of the recommended rate.

The combined variance analyses indicated that the maximum root length (4147 cm per plant), root volume (158.13 cm3 per plant), root area (3055.7 cm2 per plant), root length density (0.44 cm2. cm-3), root dry weight (24.32 gr pl-1) and plant fresh weight (6732.6 gr. m-2) was obtained from the interaction of conventional tillage in mild drought stress (90% of the plant's water requirement) in 100% of the plant's nitrogen fertilizer requirement. Also, the interaction effect of severe drought stress (30% of plant water requirement) in 100% of plant nitrogen fertilizer requirement led to a sharp decrease in studied traits in both studied tillage systems. Although the conventional tillage system in this study ultimately increased the root growth characteristics and fresh weight of the forage maize plant, but because no significant difference in wet forage yield was observed in both studied tillage systems, the system no tillage is recommended because it can improve the physical and chemical properties of the soil in the long turn.

In order to evaluate the efficacy of mesosulfuron + iodosulfuron + diflufenican (Othello OD( herbicide doses under temperature and soil moisture conditions in the control of wheat weeds, field experiments were carried out in Fars and Alborz provinces during 2017 to 2018. Treatments included spraying at different times after irrigation (different soil moisture conditions) as main plots in three levels (2 and 7 days after irrigation and 1 day before next irrigation), dose of herbicide as a subplot at 6 levels (0, 25, 50, 75, 100 and 125% of recommended dose), and spraying day time as sub-sub plots at two levels (7-8 am, and 11-12am). The results showed that in the condition that moisture had provided after spraying, reduced doses of these herbicides were more effective in reducing the dry weight of broad leaves weeds than other conditions. 33, 66 and 99 g ai/ha herbicide doses (25, 50 and 75% of recommended concentration), especially in 2 days after irrigation and 1 day before irrigation tratments, weed dry weight of grass weeds had more difference than 7 days after irrigation conditions, compared to control treatment. Under normal moisture conditions (field capacity), the reduced concentrations were more efficient in controlling the weeds and the higher moisture stress resulted in the lower efficiency of the reduced concentrations.

The efficacy of pretilachlor from chloroacetamide herbicides inhibiting lipid synthesis and bensulfuron from sulfonylureas urea inhibiting the synthesis of enzyme acetolactate synthase in the control of barnyardgrass and bulrush were investigated in sole and mixed applications at 0, 25, 50, 75, 100 and 125% of the recommended doses. The results showed that weed control in response to different doses of two herbicides could be expressed by logistic dose-response model (R2≥95%). The required dose for 50% reduction of barnyard grass biomass (ED50) in the treatment with pretilachlor and bensulfuron was 17.1% and 24.7% of the recommended dose, respectively, and 32.3% and 26.4% of the recommended dose for bulrush respectively, indicating higher efficiency of pretilachlor in barnyardgrass and bensulfuron in bulrush controls. While pretilachler provided complete control of barnyardgrass, none of the herbicides were able to completely control bulrush up to 125% of the recommended dose. According to the fitted dose response logistic model (R2≥95%), mixing the recommended doses of bensulfuron with 75% of recommended dose of pretilachlor or the recommended dose of pretilachlor with 25% of recommended dose of bensulfuron resulted in 100% control of bulrush. Today, sedges are the most abundant and diverse weeds in rice fields, and according to the results of this study, to control the most prevalent weed of this group, bulrush, mixing of herbicides is necessary. By mixing the pretilachlor and bensulfuron herbicides, it is possible to control bulrush and barnyardgrass, the two key weeds of paddy, with lower doses of these herbicides, which require further studies in field conditions to determine the appropriate dose.

To investigate the effect of sowing date on yield and qualitative traits of canola cultivars and cope ‎with late-season drought stress, an experiment was carried out for two planting years in Karaj (Iran). ‎Sowing dates in six levels including three fall and three winter sowing dates were considered as the ‎main factor and five canola cultivars (RGS003, Dalgan, Zabol10, Hyola401 and Hyola4815) as the ‎sub-factors. The results showed that except for palmitic acid, the simple effect of sowing date on all ‎the studied traits was significant in winter. The simple effect of cultivar on all traits in fall was ‎significant and in winter, it was only significant on the seed yield and seed oil yield. The interaction ‎between sowing date and cultivar in fall is the reason of significant effect of seed oil yield, linoleic ‎acid, linolenic acid, erucic acid and glucosinolate and in winter, it is the reason for the significance of ‎seed yield, oil content, oil yield and erucic acid. Dalgan cultivar had the highest seed yield and oil ‎yield on sowing date of October 7, and had the highest levels of oleic, linoleic and palmitic fatty ‎acids. In addition, with low and standard erucic acid and glucosinolate, this cultivar is recommended ‎based on the results of this study.‎

Swallow-wort (Cynanchum acutum) in recent years has aggressively infested sugarcane fields. Understanding seed germination behavior of this weed will save time to control it. In this investigation, germination of seeds was studied at five fruit cutting time with two weeks intervals at 14 to 70 days after fruiting (DAF) at five temperature levels 10, 20, 30, 40 and 50°C in Sugarcane research and training institute in 2017. The results showed that swallow-wort seeds were not able to germinate by the 14 DAF. From the 42 DAF thereafter, germination rate showed increasing trend and reached its highest value at 56 DAF, with 19.70 seeds per day. At the same time, the highest germination of swallow-wort seeds was 97% at temperature of approximately 30°C. By fitting the segmented model to the germination rate data, the minimum, optimum and maximum germination of mature seeds were 18.1, 32.6, and 57°C, respectively. Seeds from fruit at the 28 and 42 DAF required higher germination temperatures and showed decreasing trend with increasing the days from formation to complete ripened fruit. Based on the results of this study, it is necessary to plan for utilizing different methods of control such as removal the above ground organs as a management strategy and at maximum the second week after swallow-wort fruiting, to prevent production of seeds with ability of germination.

Due to the existence of environmental hazards and the herbicide resistance, it is necessary to investigate the integration of herbicides with other non-chemical methods such as stale seedbed (SSB) in weed control of the potato field. This experiment was conducted as a split-plot based on randomized complete block design by three replications in at the Research Farm of Agriculture and the Natural Resources University of Tehran in 2013 and 2014. The main plots were in three levels: 1- conventional seedbed preparation, 2- SSB + Paraquat, and 3- SSB + glyphosate. Sub-plots were four treatments included the application of rimsulfuron, metribuzin, pendimethalin, and rimsulfuron + nicosulfuron herbicides. The results of interaction showed that according to the total weed control, the best treatment was SSB + paraquat and application of metribuzin, reducing 95.4% of density and 83.3% dry weight of total weeds and it had a tuber yield of 31.8 T ha-1. Therefore, this treatment was the most cost-effective of weed control in potato, because, it showed a better control of weeds, and cause of less injury to potato, so it produced the higher yield.

To evaluate the effects of plant density and reduced herbicide concentrations on the vertical distribution pattern of leaf area in red bean canopy profile in mixed bean cultivars, an experiment was conducted in a double-cropping plot design with 3 replications in the research farm of Tehran University in 2016. In this experiment, the reduced concentrations of herbicide at 5 levels (0%, 25%, 50%, 75% and 100% of recommended concentration with hand weeding treatment) were the main plots, bean plant density at three levels (40, 50 and 60 plants). M / s) were sub plots and pure cultivation system of standing cultivar and 50%-50% mixed cultivation in row of standing and creeping cultivars were sub-plot. The results showed that herbicide concentration increase resulted in the bean biomasses increase in different layers and the highest bean biomass (228 g/m2) was observed in the intercropping system and 60 plants/m2 density f in the hand weeding treatment in 30-40 cm layer and the lowest (123 g/m2) was obtained in pure planting system and 40 plants/m2 density at 0% of herbicide concentration in 50-40 cm layer. The interactions of herbicide application and cultivation system and also herbicide application and planting density were significant on bean yield and with increasing the herbicide concentration and plant density, bean seed yield increased. Based on the results of weed biomass analysis, imazapapir alone was able to reduce weed biomass up to 65%, and this was increased up to 75% under mixed cropping system and increase in density conditions. This suggests that increasing crop competitiveness by increasing plant density and using a mixed crop system instead of a single-crop system, can reduce weed biomass through faster and greater crop formation.

To study the effect of nitrogen fertilizer and irrigation regimes on yield and some qualitative traits of forage maize cultivated under traditional and conservational tillage systems, an experiment was conducted in 2018 in split-split plot on randomized complete block design with three replications in University of Tehran. The effects of tillage as main factor in two levels (traditional and no-till), water stress as the sub-factor in three levels (30%, 60% and 90% of moisture requirement) and nitrogen fertilizer as a sub sub-factor at three levels (0%, 50% and 100% of the recommended rate) were studied on qualitative traits (DMD, WSC, CP, ADF, NDF, CF and Ash) and dry matter of maize plant. The results showed that the highest dry matter of maize (18.3 t ha-1) was obtained from no-water stress treatment under traditional tillage which was and the lowest (7.2 t ha-1) was observed in severe water stress under no-till condition. 100% nitrogen fertilizer treatment with no-water stress under traditional tillage produced the highest percentage of crude protein (12.22%)and non-nitrogen fertilizer and moderate water stress treatment under no-till resulted in the lowest crude protein (6.11%) . The highest (25.43%) and lowest (13.27%) percentage of acid detergent fiber in corn forage was obtained from 100% nitrogen fertilizer with severe water stress under conservation tillage and 100% nitrogen fertilizer with moderate water stress under no-till conditions, respectively. Agronomically, it seems that it is not possible to achieve the aims of no-till in short-term. In other words, conservation tillage will be effective after the transition stage. Also, increasing nitrogen content under water stress did not have a positive effect on forage quality.

Rapeseed duo to having genotypes spring and autumn and adaptation to weather conditions as the point hope for provide edible oil of country is the required. Two separate experiments were set up as split-plot in a RCBD design with three replications in two fall and winter seasons during two years (2014-2015 and 2015-2016) at the research field of Seed and Plant Improvement Institute to investigate the effect of sowing season and date on the quantitative and qualitative yields of rapeseed genotypes in Karaj, Iran. In this study, the main plots were sowing dates of 7, 17, and 27 October in fall sowing and sowing dates of 9 and 19 February, and 1 March in winter sowing and sub-plots consisted of genotypes of RGS003, Dalgan, Zabol10, Hyola401, and Hyola4815. Grain and oil yields of rapeseed genotypes were 4330 and 1840 kg ha-1 in fall sowing, respectively, while these traits were decreased by 43.3 and 46.6% when rapeseed genotypes were planted in winter season, respectively. The highest grain and oil yields (5033 and 2202 kg ha-1) belonged to 7 October in fall sowing, while 9 February had the highest grain and oil yields (2996 and 1248 kg ha-1) in winter sowing. In general, the Dalgan genotype is recommended for cultivation due to suitable agronomic traits such as number of silique per plant, number of grain per silique, silique length, 1000-grain weight, as well as high grain and oil yields in cold temperate regions with arid and semi-arid climates such as Karaj, Iran.