mostafa oveisi

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.

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.

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.

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.

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.‎

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.

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 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.

Corn (Zea mays L.) for its high potential in the production of yield is critical. Given Iran's position in the arid and semiarid belt of the world, the issue of drought, salinity, and their effects on crops should be considered more than any other non-biological stress. Drought stress is a global problem that threatens the growth of crops and food security (Jaleel et al., 2009). Drought stress affects biomass and eventually, yield losses by affecting physiological processes, growth and development of plant tissues (Orfanou et al., 2019). Irrigation and nitrogen mismanagement have been considered as the most critical factors in reducing maize yield (Norwood, 2000). Although nitrogen is critical for the growth of plants, the negative growth response to the excess of nitrogen fertilizer under drought stress (Cabrera, 2004) must be considered. Conservation tillage due to improved water, carbon and nitrogen resources in the soil has the remarkable ability to optimize crop production in arid and semiarid regions of the world (Husnjak et al., 2002). Optimal leaf aria deployment is crucial for photosynthesis performance and dry matter production (Aslam et al., 2013). Decrease in leaf area index following drought stress (Karam, 2005) and a decrease in plant height and grain weight following reduction of nitrogen levels and increase in drought intensity (Kalamian et al., 2006) have been reported previously. It has been suggested that no-3tillage under drought stress and conventional tillage under normal water demand, will cause increased yield (Ruisi et al., 2014). The results of different researches on the application of tillage methods on maize crop varied, with no significant differences in plant traits (height, leaf area index and dry weight) as a result of long-term application of different tillage methods (Ram et al. 2010), no significant effect of tillage on plant growth and yield (Jat et al., 2006) and improved growth and yield enhancement in non-tillage under compacted soils due to improved aeration And increased seedling emergence (Morrison et al., 1990). This study was conducted to study the effects of different tillage methods, different nitrogen fertilizer levels and drought stress on forage maize yield.

This study was carried out to study the effect of irrigation and nitrogen fertilizer on crop yield of forage maize cultivated under conventional and conservation tillage systems, an experiment was conducted in 2018 and 2019 in split -split plots on randomized complete block design with three replications in farm of University of Tehran. Tillage systems as the main -plot in two factors was including conversation 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 highest stem diameter (19.8 mm) was obtained from the interaction of water slightly stress and conventional tillage. the highest leaf aria index (6.08), leaf dry weight (441.58 g m-2), stem dry weight (1478.2 g m-2), total dry weight (1919.93 -2) and total fresh weight (6732.6 -2) was obtained from the interaction of conventional tillage, 90 and 100 percent water and nitrogen demand, respectively. The effect of drought stress on stem diameter reduction in conservation tillage compared to conventional tillage can be due to decreased root penetration and consequently reduced nutrient uptake by the plant. Decrease of leaf area index due to drought stress (Ur-Rahman et al., 2004) and increase of leaf area index with increased irrigation levels and supply of required amounts of nitrogen fertilizer (Lack et al., 2008), previously has been reported. Loss of leaf dry weight following water stress can be attributed to decreased water uptake and, most likely disruption of plant photosynthetic processes and sap production.

According to the results of two years of study, it is concluded that the interaction between drought stress and nitrogen fertilizer in conventional tillage with severe drought stress will decrease yield. Nitrogen fertilizer management is critical under these conditions.

Prediction of weed emergence timing would help reduce herbicide use through the optimization of the timing of weed control. In order to predict the emergence of wild buckwheat (Polygonum convolyulus L.), alkafaun (Fumaria vaillantii Lois) and Field bindweed (Convolvulus arvensis L.) by using the temperature model, an experiment was conducted at wheat field research of university of Tehran, Karaj during 2012-13. Based on the results, 50 percent of cumulative emergence of wild buckwheat were obtained in 75.21, 71.48 and 75.21 growing degree day at inner margin, center and outer margin of wheat field, respectively. The presence of wheat was not impressed the emergence of wild buckwheat. It was for that this weed was not required light for germination. Alkafaun emergence was happened at higher growing degree day at inner margin of field. Of course alkafaun had lower emergence per received GDD at outer margin in comparison with other parts of the field. Although emergence had lower slope per growing degree day at this part, but it was achieved to 50 percent cumulative emergence with lower received GDD. It was this time that 50 percent cumulative emergence of alkafaun achieved with 49.11 and 45.90 GDD at center and outer margin of field, respectively. Field bindweed was achieved to 50 percent of cumulative emergence with 158.98 and 150.60 growing degree day at inner margin and center of field. but there was no direct correlation between the number of weeds in the wild buckwheat seed bank and the number of seedlings were emerged.

The present study was carried out to compare the phenology of annual ground cherry (Physalis divdricata L.) and its effect on maize yield ‎ ‎.

A field experiment was conducted in the Research Station of Mahidasht in Kermanshah Agricultural and Natural ‎Resources Research and Education Center, in 2017.‎ Different densities of annual ground cherry, including 0, 8 and 16 plants m-2 and corn were planted.  The competition‎ and their phenological stages ‎were recorded based on GDD (growing degree days) for each growing stage. ‎

The results of this study showed that ‎annual ground cherry ends its phenological stages later than corn. In order to complete its life cycle, ‎‎1262.7 growing degree days and 159 days were needed. Thus, complete life cycle of corn required ‎‎1890.7 GDD and 139 days.Both plants passes the early stages of growth and ‎germination concurrently, Maize, however, ‎comleted Vegetative growth and seed ‎ripening more earlier than annual ground cherry. ‎Also, the results of studying the effect of different densities of ‎annual ground cherry on yield and yield components of corn including 1000-seed weight, number of seeds per ear row, corn harvest index and leaf area index showed that all these traits decreased by increasing density of annual ground cherry. However, the number of seed rows per ear, which is genetically-control trait, was not affected by competition with annual ground cherry. In contrary to the above traits, the density of this weed increased with the effect of increasing the height of corn and as a result, increasing the biomass of corn compared to control. In general, weed densities of the 8 and 16 plants m-2 decreased maize yield by 10 and 14 percentages, respectively.

The results of this study suggest that if corn fields are infected with this weed and we do not ‎succeed in combating it in the early stages, earlier harvest of corn in the fall will allow it to be ‎harvested by cultivation methods or using a general herbicide of this weed before its seeds are fully ‎ripen.

 The experiment was conducted to evaluate soil applicant herbicides effects on controlling growth of Orobanche among 3 Sunflower cultivars (Prograss, Farrokhi & Confectionary (Ajili)) The location of the experiment was Khayraj village, Buin Zahra city, Qazvin province, which was conducted in the year 2017. The experiment was conducted in a completely randomized block design with 18 treatments, one waterlogging treatment and 17 other herbicide treatments with three concentrations (0%, 75% and 100% recommended) with three replications. The measured traits included density, Fresh weight, dry weight of Orobanche and biological indicators of sunflower. The results of the experiment showed that the best control of Orobanche was in the treatment of trifloxysulfuron (Envoke) WG 75%) 20g/ha (92.2%), Flooding method (90.1%), Butacchlor (Machete) 3L/ha (88.1%), cycloate (Ro-Neet EC 72%) 1.5L/ha (88%) and etal-fluoraline (Sonalan EC33. 3%) 4L/ha (87%). In this study, among the three sunflower cultivars, respectively Ajili, Farokhi and Progres were sensitive to Orobanche. The effect of herbicide on sunflower cultivars was not significant.

In order to evaluate the effect of planting density and application of reduced herbicide doses in optimizing weed control and management in intercropping of red bean cultivars, an experiment was conducted in 2016 at the University of Tehran Research Farm using reduced doses of Imaztapir herbicide at five levels (0, 25, 50, 75). And 100% of the recommended dose of herbicide with manual weeding (as the main plot and different bean planting densities (40, 50 and 60 plants per square meter) as a sub-plot and pure and mixed cultivation system of standing and climbing cultivar was performed as a sub-plot. The results showed that the interaction effects of herbicide application on cultivation system and herbicide application on planting density, dry weight and bean yield were significant and also with increasing herbicide dose and plant density bean dry weight and bean seed yield increased and weed dry weight and Weed density decreased. At low herbicide doses, the use of a mixed culture system was more involved in reducing weed density and increasing bean biomass than increasing density; However, in high doses of herbicides, the role of increasing density was superior to intercropping, so to preserve the environment and reduce the economic costs of spraying, reduced doses of herbicides can be used to reduce biomass and weed density, which reduces its competitiveness with the crop. Density and mixed culture system used.