فهرست مطالب seyed vahid eslami

Salinity stress is an important abiotic stress threatening the production of cotton in arid and semi-arid regions of the country and the world, which can be reduced by the proper use of organic materials. Cotton is the most important fiber product, which is widely cultivated for agricultural and industrial purposes in temperate and hot regions of more than 15 countries of the world. Although cotton is known as a salinity-tolerant plant, not only is the resistance to salinity limited in this plant, but different stages of development also show different reactions to salinity. One of the effects of stress is disturbing the nutritional balance in the plant. Proper nutrition during times of stress can partially help the plant deal with various environmental stresses. In this regard, by using fertilizers containing micronutrient elements, firstly, plant yield increases, secondly, increasing the concentration of these elements in agricultural products plays an important role in improving the quality of food consumption. Using organic fertilizers, especially organic and animal manure such as humic acid, can improve the performance and performance components of different products under stress conditions.

To study the effect of manure and humic acid on some of the physiological qualities of cotton under salt water salinity stress, an experiment was conducted as factorial split plots (factorial split plot) in which different levels of irrigation water salinity at three levels (2.5, 5.5 and 8.5 ds.m-1) as the main factor and two treatments of manure at two levels (0 and 20 t/h) and humic acid at two levels (0 and 200 gr/100 kg of seeds) as sub-factor in 4 replications in a farm located in Boshrouyeh city in 1398 years. The software SAS (V9.1) and Excel were used to analyze the data and draw the figures. Means were compared using the FLSD test at a 5% probability level.

Analysis of variance results showed that the simple effects of three experimental factors (salinity stress, manure, and humic acid) were significant on all studied traits (on the relative water content, Electrical conductivity and membrane stability, chlorophyll a and b contents, and proline content). With increasing salinity level, increased proline content (286.5%), membrane Electrical conductivity (4.2%) and carotenoids (88.79%) and decreased chlorophyll a (20.7 1 %) and b content (39.38%), relative water content (23.16%) and membrane stability (13.54%). The application of animal manure and humic acid increased the relative water content, membrane stability and chlorophyll content under stress conditions, which indicates the modifying effect of these fertilizers in reducing the adverse effects of salinity stress. The interaction effects were significant, too.

The results of this research showed that the use of water with high salinity, such as salinity of 8 ds.m-1, caused significant changes in the physiological traits of the plant, including relative leaf water content, membrane stability, membrane electrolyte leakage, chlorophylls, and proline. With increasing salinity levels, the amount of proline, membrane electrolyte leakage, and carotenoid increased, and the content of chlorophyll a and b, relative water content, and membrane stability decreased. The application of animal manure and humic acid increased the relative water content, membrane stability, and chlorophyll content under stress conditions, which indicates the moderating effect of these fertilizers in reducing the adverse effects of salinity stress. Considering the positive effects of using organic fertilizers in this experiment, it is recommended to test and investigate the use of humic acid during the growing season in addition to the use of animal manure before planting and the use of humic acid in bulk Thus, it is suggested to use humic acid and animal manure in cotton cultivation to adjust the salinity levels.

Purple nutsedge (Cyperus rotundus L.) is a problematic weed in tropical regions particularly in Jiroft, Kahnooj and Birjand, so that farmers annually suffer severe damage to their vegetable and cucurbit crops. Currently, very little research on the biological basis of this noxious weed has been don.This study was conducted to evaluate the effect of burial depth on tubes germination and emergence of different purple nutsedge ecotypes. Purple nutsedge tubers were collected from birjand, kahnooj and jiroft regions. A factorial experiment was conducted based on randomized complete block design in University of Birjand with three replications. To investigate the viability of tubers before being used for bioassays, their germination potentials were examined in a growth chamber set at 25/15°C. Then, ten tubers of each ecotype with almost equal weight (3.6gr) and size were planted in polyethylene tubes with 25 cm in diameter and 50 cm in height. Ten tubers of each purple nutsedge ecotype were sown at 8 different depths, including 0, 2.5, 5, 10, 20, 30, 40 and 50 cm. At the termination of experiment, number of tubers and pre tubers, underground tuber dry weight, shoot number and above ground dry weight were recorded. Results showed that purple nutsedge tubers were able to emerge from very deep burial depths (up to a depth of 50 cm), and in this regard, there were some differences among the three ecotypes. Generally, as depth increases, the number and weight of tubers, and shoots decreased; whereas the burial depth showed no effect on the shoot height and pre-tuber production. Therefore, in addition to deep plowing, other control methods such as cultural control and chemical methods should be used in an integrated management.

To investigate the effects of foliar application of Acadian seaweed extract® and Biomix poultry manure® on qualitative traits and secondary metabolites of saffron, an experiment was conducted as a factorial arrangement based on a randomized complete block design with three replications in the city of Ferdows the during growing season of 2017-2018. Experimental treatments included four levels of Acadian seaweed extract® (0, 1, 1.5, and 2 kg. l000 L-1 water) and four levels of liquid Biomix poultry manure® (0, 2, 4 and 6 L. l000 L-1 water). Measured traits included phenol, anthocyanin, crocin, picrocrocin, safranal, and fresh and dry stigma yield. Results showed the effect of treatments was significant on the studied traits. So that saffron stigma picrocrocin in treatment of 2 kg. l000 L-1 Acadian seaweed extracts® was 26% more than the control. Liquid poultry manure® also had a significant effect on secondary metabolites of saffron, so that saffron stigma picrocrocin in treatment of 6 L. l000 L-1 Biomix poultry manure® was 24% more than the control. Interaction between Acadian seaweed extract® and Biomix poultry manure® had a significant effect on anthocyanin, crocin, safranal, and phenol content. The highest increase was observed in 2 kg. l000 L-1 Acadian® and 6 L. l000 L-1 Biomix poultry manure®. Also, the use of seaweed extract® had a significant effect on stigma yield, so that the yield of fresh stigma (13%) and dry stigma (20%) in the treatment of 2 kg. l000 L-1 seaweed extracts® was higher than the control. According to the results of this study, the use of seaweed Acadian® (2 kg. l000 L-1 water) alone or in combination with Biomix poultry manure® (6 L. l000 L-1water) can play an important role in enhancing the yield and quality characteristics of saffron.

Nitrogen is a determining element in nutrition, plant growth, and its quantitative and qualitative performance. Considering the high cultivated area of dryland wheat in the country and the economical importance of this crop in dryland conditions, it is necessary to consider any solution to optimize the quantity and quality of this product.

a strip split plot design based on RCBD with three replicates was conducted under rainfed and supplemental irrigation conditions during two cropping seasons (2016-17 and 2017-18) to evaluate the effect of Nitrogen (urea) applied by different foliar application treatments and top dressing fertilizer on grain yield, grain protein content, Zeleny number, and gluten index of wheat, Experimental treatments were: A: control (without application of N), foliar application of urea during booting, booting + grain filling and grain filling stages as the main plot, B: wheat cultivars as sub-plots, C: top dressing fertilizer including application and non-application (control) in strip factor were considered.

The results of a combined analysis of variance and mean comparison showed that foliar spraying of urea fertilizer in all three growth stages significantly increased grain yield, nitrogen content, the percentage of grain protein and grain hardness, Zeleny number and grain gluten index. The application of top dressing fertilizer in both rainfed and supplementary irrigation conditions on grain yield, grain protein and gluten index was also significant. The highest gluten index in rainfed conditions (24.08%) and supplementary irrigation (16.19%) was related to foliar application of urea during the grain filling stage. The highest index of gluten, grain hardness and Zeleny number in both rainfed and supplementary irrigation conditions belonged to Rijaw variety. Rijaw variety had the highest value with 27.3 and Azar-2 variety had the lowest gluten index value with 18.6. Foliar application of urea during the grain filling stage had the most contribution to the increase of grain protein and the control treatment had the least contribution. The highest amount of grain yield in rainfed conditions was 2907 and in supplementary irrigation conditions were 3957 kg, which compared to the control treatment (no application of vinegar fertilizer), increased the grain yield by 19 and 16% in both rainfed and supplementary irrigation conditions, respectively.

The results of this research showed that foliar application treatments and top dressing fertilizer in both rainfed conditions and supplementary irrigation were effective in improving quality traits. In this study, supplementary irrigation led to a significant increase in grain yield compared to rainfed conditions.

Purple nutsedge causes severe damages to vegetable crops in Jiroft, Kahnooj and Birjand. In order to evaluate the effects of high temperature and time of exposure to high temperatures on various ecotypes of purple nutsedge tubers, a factorial experiment was conducted based on randomized complete block design with 3 replications in the Research greenhouse of Birjand University, Iran, in 2016. Experimental factors consisted of 3 ecotypes (Jiroft, Kahnooj and Birjand), different temperatures from 40 to 60°C with 5°C increments, and exposure time including 1, 2, 4, 8, 16, 32 and 64 hours. Results indicated that at all exposure times, 40°C temperature did not affect the growth characteristics of purple nutsedge, while at 45 °C, increasing the exposure time decreased the growth characteristics of purple nutsedge. Three-parameter logistic model estimation showed that  tuber viability (T50) at 45 °C in Jiroft ecotype was 14.64 hours, it decreased to 5.01 hours  at 50 °C. T50 was about 66% lower than for 45 ° C, but it was 19.76 hours in Kahnooj ecotype at 45 °C, while at 50 °C, this parameter decreased to 2.73 hours (86.2%). T50 of Birjand ecotype at 45 °C was 12.90 hours, but at 50 °C, the tubers viability reduced and T50 was 8.91 hours (31% decrease). Results of this research could have an important role in controlling purple nutsedge in vegetable fields.

To evaluate the additive effect of intercropping of potato and quinoa, and weed management on yield and quantitive traits of potato, this study was conducted in a split plot experiment based on randomized complete block design (RCBD) with four replications at Jiroft and Kahnooj regions. Weed management treatments (control, without controlling weeds), paraquat herbicide (3 liter per hectare) and manual weeding, were considered as the main plot, and additive intercropping patterns (potato: quinoa in density levels of 5:15, 5:20 and 5:30 plants.m-2) and potato sole cropping (5 plants.m-2) were assigned to sub-plots. Based on the results, intercropping cultivation had significant effects on reducing weed densities and increasing plant height, leaves number per plant, leaf area index, tuber number per plant, tuber yield and marketable tuber yield. Increased densities of quinoa in intercropping cultivation caused an enhancing trend in potato plant height (4.2-9.1 %), leaves number per plant (7.9-16.6 %) and leaf area index (5.6-12.7 %) as compared to potato sole cropping treatment (control). Manual weeding, also decreased in weed density (16.1 %), and increased leaves number per plant (3.7 %), tuber number per plant (9.4 %), tuber yield (6.3 %) and marketable tuber yield (9.8 %) in comparison to that of paraquat herbicide treatment. The highest mean tuber number (7.5 number.plant-1) was observed in the 5:20 intercroping treatment, which resulted in 7.1% increase in the tuber number as compared with the control treatment. Highest tuber yield (4.54 kg.m-2) and marketable tuber yield (4.01 kg.m-2) were also obtained with the 5:20 intercroping treatment under manual weeding at Kahnooj region, and resulted in 69.4 and 20 % increases in tuber yield and marketable tuber yield respectively, as compared with the potato sole cropping without weeding (control treatment) in this region. Generaly, the best results were obtained in potato and quinoa intercropping with density of 5:20 plants.m-2 under manual weeding at Kahnooj region

Plants in arid and semi-arid regions are constantly exposed to environmental stresses such as salinity. The sensitivity of different plants to salinity stress at different growth stages is quite different. In many plants, perhaps the most sensitive stage of the plant growth cycle to salinity, is germination and emergence stages. Germination and emergence of seeds are the first important stages in plant establishment which is affected by most environmental stresses. In South Khorasan, which has saline soil and water, conventional millet cultivation is common, and it’s most important weeds are lambsquarters, tumble pigweed and purslane. Since the irrigation of millet fields in this region of the country is performed with saline water, this experiment was conducted out to investigate the emergence response of millet and lambsquarters, tumble pigweed and purslane weeds, under sodium chloride salinity in Hoagland solution.

In order to evaluate the effect of salinity stress on quality and emergence rate of common millet, lambsquarters, tumble pigweed and purslane, four separate experiments were conducted out in a randomized complete block design with three replications in 2017 in the research greenhouse of agricultural faculty at Birjand University. Experimental treatments consisted of 10 salinity levels including Hoagland solution with 2 dS/m as control, 4, 6, 8, 10, 12, 14, 16, 18 and 20 dS/m (created sodium chloride in Hoagland solution). Hoagland formula was used for preparation of nutrient solution and sodium chloride was used for preparation of different salinity levels. After filling each pot with 1.5 liters of acid washed sand, 25 seeds from each species were placed at 1 cm depth from soil surface. Seedling emergence were counted daily. In order to investigate the response of each species to salinity stress, the emergence percentage in each species was analyzed in a randomized complete block design without considering treatments with zero emergence percentage. Data analysis was performed using SAS software. GLM procedure was used for analysis of variance and comparison of mean performed with protected LSD at 5% probability level.

The results showed that common millet, purslane, tumble pigweed and lambsquarters seeds had the ability to germinate up to 20, 16, 12 and 12 dS/m, respectively. The start of emergence for common millet seeds up to 10 dS/m and tumble pigweed up to 8 dS/m was 3 days after sowing. Meanwhile, the seeds of lambsquarters emergence up to 6 dS/m on the fourth day, and purslane in 2 dS/m on the second day after sowing. Millet plants were emergence up to 18 dS/m salinity in the first five days after sowing. The results also showed that for common millet and tumble pigweed, no significant difference were observed for single seedling dry weight at 2 and 4 dS/m. Increasing salinity from 2 to 4 dS/m led to a significant decrease in purslane seedling dry weight but with increasing salinity stress from 4 to 8 dS/m, the reduction in seedling dry weight was not significant. In this study, with increasing salinity stress from 2 to 8 dS/m, dry weight of common millet, purslane, lambsquarter and tumble pigweed decreased by 55, 73.8, 80.7 and 79.5%, respectively. In this study, after ensuring that the seeds did not emerge, to determine the viability of non-emerged seeds, the pots were irrigated with distilled water. Under this condition, non-emerged millet seeds in the pots were not able to germinate at any levels of salinity stress. Purslane had no germination under salinity stress of 18 and 20 dS/m, but there were 34% and 62% emergence percentage respectively, when the salinity were terminated. Under mild stress, the percentage of germinated purslane seeds was 18% after recovery, which decreased with increasing salinity up to 12 dS/m and then increased.

In general, the results showed that salinity stress caused a change in the emergence behavior of millet and purslane, tumble pigweed and lambsquarters weeds. Common millet had the ability to germinate at all levels of salinity stress, but tumble pigweed and lambsquarters had the potential to emerge up to 12 dS/m and for the purslane up to 16 dS/m. Also, with increasing salinity stress from 8 to 16 dS/m, dry weight of seedling of common millet, purslane, tumble pigweed and lambsquarters decreased by 66, 82, 100 and 100 percent, respectively. At the end, the results showed that occurrence of salinity stress and its removal, the purslane seeds had a greater ability to keep their viability, whereas the common millet seeds completely lost their viability.

The aim of this study is to investigate the effect of foliar application of Acadian seaweed extract and Biomix liquid poultry manure on vegetative growth, corm, and yield of saffron. The experiment was conducted in a randomized complete block design with three replications in the city of Ferdows city during the 2017-2018 growing year. Experimental treatments included four levels of Acadian seaweed extract (0, 1, 1.5, and 2 kg. l000 L-1 water) and four levels of liquid Biomix liquid poultry manure (0, 4, 5, and 6 L. l000 L-1 water). The results showed a significant effect of treatments on the studied traits, such as maximum number of flowers (99.50 N. m-2), fresh yield of flowers (33.34 g.m-2), dry weight of saffron stigma (0.341 g. m-2), dry leaf weight (0.592 g plant-1), and leaf length (63.75 cm) obtained in 2 kg. l000 L-1 seaweed extract. Besides, the results showed a significant effect of liquid poultry manure on flower number and yield (94.250 N.m-2 and 32.285 g. m-2, respectively), leaf length (60.66 cm), fresh and dry leaf weight (0.74 and 0.46 g.m-2, respectively), and total weight of replacement corm (37.02 g.m-2). Also, the least amount of the mentioned traits were observed from the control treatment. The interaction between these two fertilizers was also significant in fresh and dry leaf weight and the total and average diameter of replacement corm. Thus, fresh and dry leaf weight (210% and 273%, respectively) were highest in the treatment of 2 kg. l000 L-1 of seaweed extract and 6 L. l000 L-1 of liquid poultry manure. Moreover, total and average diameter of replacement corm (33% and 50%, respectively) were highest in the treatment of 2 kg. l000 L-1 of seaweed extract and no liquid poultry manure. According to the results of this study, the use of Acadian seaweed extract (2 kg. l000L-1 water) alone or in combination with Biomix liquid poultry manure (6 L. l000 L-1 water) can play an important role in enhancing the vegetative growth, corm, and yield of saffron.

Light is a vital component for photosynthesis and plays a significant role in the competitive ability of plants. The nitrogen response of competing plants may be affected by radiation availability and maximum potential growth rate, which determine plant N requirements. Shading reduces the light intensity, which leads to changes in the morphology, physiology, biomass, grain yield, and quality of crops. Moreover, shading stress delays flowering and decreases biomass and grain yield. Since photosynthesis results in dry matter accumulation, and reduced light is known to limit carbon accumulation and nitrogen content, understanding these processes in weeds may provide insight as to their effects on crop production, help to predict their occurrence, and ultimately provide the needed information for their management. In order to evaluate foxtail millet competition with pigweed at different levels of radiation and nitrogen, two separate experiments were conducted in split plot arranged in randomized complete block design with three replications at the Research Farm of Birjand University in 2015. Texturally the soil was loam, with 8.16 pH, 0.03% total N, 12 ppm available P and 250 ppm available K. The experiment was laid out in a split-plot design with three replications having three shade levels (0, 41 and 75% shade) in main plot and three pigweed density (0, 12 and 24 plant per square meter) in subplots in two separate experiments, one under nitrogen application and the other without nitrogen usage. In 0% shade treatment, sunlight was allowed to fall over the millet and pigweed without any barrier. In 41% and 75% treatments, however, the light levels in the form of PAR were reduced using shade nets. At the end of growth stage millet traits including days to panicule emergence, days to maturity, grain filling period, number of grain per panicule, 1000 grain weight, grain yield, forage yield, biomass and harvest index were measured. Data analyses were performed using two-way analysis of variance (ANOVA) with SAS 9.1. Means of treatments were compared between nitrogen, shade treatments and pigweed densities according to protected least significance difference (FLSD) test at the 5% level. Nitrogen had a significant effect (P < 0.01) on days to panicule emergence, days to maturity at 1% probability level and on grain filling period and grain yield at 5% probability level. Application of 150 kg nitrogen per hectare led to improvement of phenological traits and grain yield of millet. Nitrogen can extend vegetative growth stage period of plants and reduce grain filling rate (Nezamzadeh et al., 2011). Also, nitrogen fertilizer can increase grain formation and grain yield through improvement of photosynthesis ability owing to increases in leaf area index and leaf area duration (Moosavi et al., 2015). Shading had a significant (P < 0.01) influence on millet phenological traits and grain yield and had a significant effect (P < 0.05) on number of grain per panicule. Shading at level of 75% dramatically reduced number of grain per panicule and grain yield of millet while increased days to panicule emergence, days to maturity and grain filling period. Nasrollah-zadeh et al., (2011) also reported that grain filling period of faba bean increased by 3-4 days in shaded plants in comparison with control. With shading stress at its highest level, grain yield was significantly reduced by 61% from 3.70 to 1.44 ton per hectare. The effect of pigweed density on grain yield (P < 0.05) and plant height and stem diameter was significant (P < 0.01). The effect of pigweed density was also significant on forage yield (P < 0.01) and days to panicule emergence and grain yield (P < 0.05). Pigweed density of 24 plants per square meter led to 21% reduction in millet grain yield against control. The interaction between nitrogen and pigweed density on millet traits was limited, and only significantly (P < 0.05) affected grain yield. In competition of crops and weeds, the space required for crop to expand the leaf area decreases, and the competition between the species increases to absorb the active photosynthesis radiation. Under these conditions, less assimilates are transmitted to the reproductive organs, which has a profound effect on reduction in grain yield and further on harvest index (Gholamhoseini et al. 2015). The results of this study showed that the grain yield of foxtail millet reduced by 61 percent with increasing of shading intensity contrasting with no shading. This reduction was due to the negative effects of shading on the number of grain per panicule and 1000-grain weight. Harvest index also decreased with increasing shading levels. The reduction in harvest index was due to a greater reduction in grain yield contrasting dry matter production at shading treatments. Also, grain yield at the highest level of pigweed density was 21% lower. These results, considering the importance of weed control, show that proper management of weed control in the field by providing conditions to faster closing canopy in order to reduce the competition of pigweed can be effective in grain yield improvement of foxtail millet.

Introduction Potato is amongst the most important crops in the world, which is the third most consumed crop worldwide after rice and wheat and is followed by corn in this regard (Kazemi et al., 2016). Abiotic stresses like drought may cause adverse effects on growth and tuber yield of potato plants as they are very sensitive to soil moisture reduction (Deblond et al., 1999). Potassium is used as a cofactor of enzymes, osmotic activities and plant electrolyte regulation, and is an essential element for osmotic control that can reduce osmotic potential and improve plant acclimatization under drought conditions (Taiz & Zeiger, 1991). Given the importance of potato production and its high demand for water and because of scant research being conducted on the planting patterns of this crop, the present study aimed to investigate the effects of various planting patterns and different potassium levels on potato growth indices under water-limited conditions in Khorasan Razavi province. Materials and Methods This experiment was conducted in Jolge Rokh- agricultural research station over spring and summer of 2016 and 2017 cropping seasons. The experiment was set up as split split plot arrangement based on a randomized complete block design with three replications. The trial factors consisted of three planting patterns including common planting, common dense planting and zigzag planting designated as the main plots, and irrigation with three levels [control (without stress), irrigation based on 80% of the crop water requirement (as deficit irrigation treatment), and irrigation based on 60% of the crop water requirement (as stress treatment)] designated as the sub -plots, and three levels of potassium fertilizer (0 (control), 75 and 150 kg potassium sulfate per hectare) designated as sub-subplots The water needed for the plant was determined based on water requirement of the potato, which was determined using the software (OPTIWAT) and FAO Penman- Monteith method. The leaf area and leaf dry weight were measured during the growing period at two-week intervals. Results and Discussion The results showed that the greatest leaf area index (LAI), crop growth rate (CGR) and total dry matter (TDM) were observed with zigzag planting pattern at either year of the study. The maximum TDM under common, common dense and zigzag planting in the first year were 634.3, 671.9 and 870 g.m-2, respectively, while the corresponding values for the second year were 808.5, 919.2 and 1065 g.m-2, respectively. Irrigation treatments based on 80 % and 60% of the crop water requirement reduced the growth indices and yield of the tubers. The greatest tuber yield was observed with full irrigation treatment (100% of the crop water requirement (32 and 35.2 ton. ha-1 in the first and second year, respectively), while the lowest tuber yield was obtained with 60% of the crop water requirement (20.2 and 20.4 ton. ha-1 in the first and second year, respectively). The results showed that potassium sulfate increased TDM, LAI, CGR, NAR and tuber yield. The application of 150 kg of potassium sulfate produced the greatest TDM (850.2 and 1118.9 g.m-2 in the first and second year, respectively), whereas no fertilizer usage gave the lowest TDM (584.2 and 743 g.m-2 in the first and second year, respectively). In potato plants, sufficient quantities of potassium increase the number of tubers and dry matter production through strengthening potato stems, and at the same time, the plant can acclimatize to environmental stresses. Conclusion The results showed that the greatest LAI, TDM, CGR, NAR and tuber yield were observed with the zigzag planting. On the other hand, irrigation based on 60% the crop water requirement reduced the growth indices and tuber yield. It is worth noting that applying 80% of the crop water requirement also decreased the investigated the growth traits of the potato plants. Therefore, it is recommended that the exposure of potato plants to deficit irrigation conditions be avoided and the efforts should be made to provide them with adequate water. But the remarkable point was that the usage of potassium sulfate fertilizer could enhance and improve growth rates under low irrigation and water stress conditions.

The cultivation of crops in most parts of the world, in addition to competing with different weed species, is affected by a variety of environmental stresses, including salinity stress. The changes in the growth rate and production of crops under the influence of salinity stress and competition with weeds have been extensively studied. However, what is currently less investigated is the competition of several species of weeds with crops and the competition of crops with weeds under salt stress. Therefore, the aim of this experiment was to evaluate the competition between tumble pigweed, common purslaneand and common millet under soil salinity stress. This study was conducted as a factorial experiment based on a randomized complete block design with three replications. Experimental treatments consisted of two rates of soil salinity (3 and 10 dS.m-1), and different ratios of interference of the three species (tumble pigweed, common purslaneand, millet) including 0-0 -100, 0-25-75, 12.5-12.5-75, and 25-0-75, 50-0-50, 25-25-50, 0-50-50, 75-0-25, 37.5-37.5-25, 0-75-25, 0-100-0, 50-50-0 and 0-100-0. The desired density in each pot was constant and equal to 8 plants. After preparing the soil and passing through a 2 mm sieve, fertilizer and saline solutions were added to the soil and the soil was transferred to 5 kg pots. Then all three plants were planted and attained to intended density at the four leaf stage. At the end of the experiment, each plant species was separately harvested from each pot and were weighed after complete drying. Finally, for analyzing the results of the experiment, relative yield indicators, total relative yield (Land Equal Ratio), relative crowding and agressivity indices were used. The results showed that increasing soil salinity decreased the dry matter produced by common millet, tumble pigweed and common purslane by 19.5, 4.7 and 27.8 percent, respectively. Comapring the relative yield of millet with those of tumble pigweed and common purslane and also both weeds together by different ratios of planting showed that these values were more than predicted ones under either 3 or 10 dS.m-1 salinity level, which indicates the weak competitive ability of these two weeds against millet. The results of the relative crowding index of species showed that in the ratio of 75% of millet and 12.5% tumble pigweed and 12.5% of common purslane, the greatest rate of relative crowding index was achieved for millet under salinity level of 3 dS.m-1. Also, the greatest relative crowding index of tumble pigweed and common purslane under either salinity level was observed with the cultivated ratio of 75% for both weeds and 25% for millet, suggesting an increased competitive ability of these two weed species through increasing their density even under a higher level of soil salinity. By evaluating the agressivity index between tumble pigweed and purselane, it was found that this value was negative for purselane under the salinity level of 3 dS.m-1. Therefore, it seems that tumble pigweed is more competitive than the common purslane where both weed species grow together. In general, the results of this study showed that in conditions of salinity of 3 and 10 dS.m-1, common millet had more competitive ability than the two studied weeds, but with increasing salinity level, competitive ability of millet was reduced, while it increased weeds competitiveness. Therefore, in the situation of high weed densities, we may expect a greater damage to crops under salinity stress.

Salinity is one of the most important abiotic stresses that cause severe effects on crop production around the world. Estimates indicate that more than 800 million hectares of arable lands in the world are affected by salinity. Salinity impacts on various aspects of growth from germination to seed production in plants. Plants′ responses to salinity, however, are different and depend on the toxicity, osmotic potential, as well as the stress duration. Purple nutsedge (Cyperus rotundus L.) is one of the noxious weeds. This weed belongs to sedge family, and is a C4 perennial plant which reproduce by sexual (seeds) and asexual (tubers and rhizomes) means. It can cause tremendous damage on summer crop fields such as onion, potato, maize, sunflower, and so on. Evaluation of weed growth responses to saline condition came about by water and soil can provide for us very important information by which we choose appropriate weed control strategies. Since a few experiments have been evaluated growth characteristics of purple nutsedge under salinity stress, this study was conducted to evaluate the salinity effects on growth characteristics of purple nutsedge.
Material and To evaluate the effect of irrigation water and soil salinity on growth characteristics of purple nutsedge, two separate experiments were conducted in a randomized complete block design with three replications in the greenhouse of Faculty of Agriculture at University of Birjand in 2013. The first experiment contained five salinity levels of water including 0, 3, 5, 7 and 9 dS.m-1 and in the second experiment, there were five salinity levels of soil including 1, 3, 5, 7 and 9 dS.m-1. The salinity levels of water were prepared through solving a certain amount of NaCl in water based on this equation: NaCl (mg. L-1) =EC (dS.m-1)×640.. Following determination of soil electrical conductivity, soil salinity levels were prepared by adding NaCl to the soil based on saturation moisture percent and field capacity. A tuber of purple nutsedge was planted at 2.5 cm depth in each pot. Experiments were terminated at the end of the vegetative growth stage of purple nutsedge (105 days after emergence). Measured traits were plant height, stem number per pot, leaf area, and tuber number per pot, shoot and underground dry weight. After collecting the data, ANOVA was performed using Genstat Ver. 9 and mean comparisons were performed using Fisher's least significant difference test at 5% significant level. In order to evaluate purple nutsedge growth response to salinity stress, an exponential decay model was used; Y=a*exp(-b*x), thta in this model, a and b represents the maximum amount of studied traits and the slope of curve according to the model estimation, respectively.
The results of both experiments showed that the growth characteristics of purple nutsedge (plant height, stem number per pot, leaf area, tubers number per pot, shoot and underground dry weight) were significantly affected under soil (P

Weeds are important components of agricultural ecosystems that compete with agricultural crops to capture resources and caused irreparable damage to the crops. By producing herbicides, a significant change was created in the management of weeds. But now days some new problems such as resistance of weeds to herbicides, loss of useful species and environmental pollutions have forced farmers to employ non-chemical weed management methods. An important non-chemical method for seed control of weeds is soil solarization, which has been used as a way for controlling weeds, pests and diseases. South Khorasan enjoys plenty of solar radiation during the summer which can be used as a useful tool for weed control.
To evaluate the effect of soil solarization on downy brome )Bromus tectorum L.( control, an experiment was conducted at the research farm of College of Agriculture, University of Birjand during the summer of 2010. The factorial experiment was performed as a randomized complete block design with three factors including the number of clear plastic layers (uncovered as the control, one-layer and two–layer plastic sheets(, duration of coverage (15, 30 and 45 days) and seed burial depth (0, 5, 10 and 15 cm) with three replications. Seeds were buried at different soil depths in the field and experimental plots were covered with the corresponding plastic layers. The seed samples alternatively were pulled out of different depths of soil and transported to the research laboratory. The seeds which were germinated in the field were counted, and the rest of them were incubated in a germinator set at 25/15°Cfor day/night. During the germination period, some index such as; germination rate, percentage of decayed and germinated seeds were measured. Tetrazolium test was used to examine the viability of not germinated seeds.
Results showed that solarization significantly increased soil temperature (as much as 6.3 to 15.1°C) compared to the control. The percentage of germination in the field decreased by increasing the layers of plastic coverage, as well asby increasing burial depths. The maximum percentage of decayed seeds were observed at two-layer plastic, one-layer plastic and control treatments, respectively. The percentage of decayed seeds increased by increasing solarization duration and it decreased by increasing burial depth. During the whole period of solarization, the lowest decay percentage was observed in the control treatment, while the greatest corresponding values were obtained from the seeds placed under oneand two-layer plastic sheets, indicating that accumulated temperatures under these sheets caused an increased decay percentage. At the soil surface and 5 cm burial depth, none of the downy brome seeds in 1- and 2-layer plastic sheet could germinate in the laboratory. It seems that the high temperatures generated by soil solarization have destroyed downy brome seeds under plastic covered treatments. A soil solarization period of 15 days was sufficient for destroying the seeds on the soil surface and those buried at 5 cm depth, while a solarization period of 45 days was required to destroy the seeds buried at 10 and 15 cm depths. Seeds that had been exposed to high temperatures caused by solarization for a longer period, had a lower germination rate. The greatest germination rate was observed in the control treatment and on the soil surface. The results of Tetrazolium test showed that all none germinated downy brome seeds which were subjected to Tetrazolium test had lost their viability, or in other words, were decayed. After finishing the solarization experiment we found that the concentration of sodium, calcium, and magnesium and sodium uptake ratio and soil pH decreased decreased under solarized plots. Moreover, electrical conductivity (EC) increased.
Overall, the results showed that solarization reduced the downy brome seed germinability and ultimately led to an effective method to control of this weed. It appears that solarization can be used as a non-chemical method for downy brome control especially in arid regions of the country. According to the results of this study, covering the soil with two-layer plastic sheet was the most effective and the best method of solarization.

Light is a vital component for photosynthesis and plays a significant role in the competitive ability of plants. The nitrogen response of competing plants may be affected by radiation availability and maximum potential growth rate, which determine N requirements. Shading reduces the light intensity, which leads to changes in the morphology, physiology, biomass, grain yield and quality of crops. Finally, shading stress delays flowering and decreases biomass and grain yield. Because photosynthesis is associated with dry matter accumulation, and light is known to limit carbon accumulation and nitrogen content, understanding these processes in weeds may provide insight as to their effects on crop production, help to predict their occurrence, and ultimately provide the needed information for their management.
In order to evaluate foxtail millet competition with pigweed at different levels of radiation and nitrogen, two separate experiments in split plot arranged in randomized complete block design with three replications were conducted in 2015 at the Research Farm of Birjand University. Texturally, the soil was loam, with 8.16 pH, 0.03% total N, 12 ppm available P and 250 ppm available K. The experiment was laid out in a split-plot design with three replications having three shade levels (0, 41 and 75% shade) in main plot and three pigweed density (0, 12 and 24 plant per meter square) in subplots in two separate experiments, one under nitrogen application and the other without it. In 0% shade treatment, sunlight was allowed to fall over the millet and pigweed without any barrier. In 41% and 75% treatments, the light levels in the form of PAR were reduced using sheds nets. At the end of growth stage millet traits including plant height, spike length, peduncle length, stem diameter, number of leaf, lodging, grain yield and biomass and pigweed traits such as plant height, number of Lateral branches, number of seed per plant and biomass were measured. Data analyses were performed using two-way analysis of variance (ANOVA) by SAS 9.1 software. Means of treatments were compared between nitrogen, shade treatments and pigweed densities according to protected least significance differences (LSD) test at the 5% level.
Nitrogen had a significant effect on all millet traits except for peduncle length and biomass and also on pigweed height. Nitrogen led to significant increase in plant height, lodging percentage, number of leaf, spike length and grain yield of millet and also pigweed height. Shading had a significant (P This research provides information on how pigweed and foxtail millet respond to reduced radiation and low nitrogen environments. Under low-radiation environments, pigweed produced less seeds that would limit the replenishment of the next year’s seed bank. Therefore, production practices such as narrow rows that reduce radiation availability would be helpful in reducing pigweed infestations. Once a dense canopy is formed, vegetative growth and the reproductive potential of pigweed seedlings are severely restricted. A uniform dense crop canopy is of paramount importance in developing an integrated approach to control this weed because any gaps in the canopy allowing light penetration will result in a rapid weed growth and prolific seed production. Further, nitrogen deficiency seems to decrease weed competition ability and seed production leading to less infestations.

Plant species distribution, composition and diversity in deserts of arid and semi-arid areas, especially saltland; depend on soil physical and chemical gradients. The aim of this research was to investigate changes in the plant species diversity and richness along a soil salinity gradient in the margin rangelands of Petregan Playa. After vegetation zoning in relation to soil salinity, random-systematic sampling within each zone was taken. Within each zone, three stands were selected, then, within each stand, plant vegetation cover, density and species diversity indices were measured. For ordination vegetation along the soil salinity gradient, Detrended Correspondence Analysis (DCA) method was used. The results showed that there were significant differences in the plant total cover, annuals and perennials plant cover between different soil salinity zones. Also, the soil salinity gradient has a significant effect on the species richness and diversity, as the first zone (high salinity) has the lowest species richness and diversity. It can be concluded that, in general, only high salinity level has a significant effect on the plant species diversity.

In order to evaluate the effect of tumble pigweed competition on yield, yield components and seed quality of six cultivars of sunflower; an experiment was conducted with factorial layout based on a completely randomized block design at the research farm of College of Agriculture, University of Birjand in 2012. The factors were four weed densities (0, 5, 10 and 15 plants/m2) and six cultivars of sunflower (Azargol, Jame Isfahan, Syrna, Farrukh, Progress and Euroflour). The results showed that by increasing weed density, yield and yield components of sunflower were decreased. By increasing weed density from zero to 15 p.m2, grain yield of sunflower was decreased up to 40.2%. Jame Isfahan cultivar produced the highest seed yield (5.789 kg/ha), and Farrukh cultivar had the least percentage of seed yield loss in weed density of 15 p/m2. Generally, Progress, Euroflour and Jame Isfahan cultivars had the most competitiveness and Azargol cultivar showed the least competitiveness against tumble pigweed.

Despite the importance of oily crops in development of Iran, there are few studies on nutrition with micronutrient in these crops, especially for safflower. Safflower, a deep rooted oilseed crop, is grown in many areas of world because it can be used as oil crop, vegetable, birdfeed and spices. To achieve the acceptable growth and yield of safflower, it needs the sufficient micro- and macronutrient, so that recently, there has been an increased interest in evaluation of nutrient role in quality and quantity of safflower. Application of vermicompost in oil crop production systems of Iran has been increased; which it can improve soil structure by increasing aggregate stability as well as increase in water holding capacity and aeration. On the other hand, micronutrients are nutrients required by plants in small quantities to organize a range of physiological functions. The deficiency micronutrients is widespread in many parts of the country due to cultivation of high yielding varieties, intensive agriculture and increasing use of sulphur free fertilizers in large quantities with concomitant decrease in use of organic manures. There is little information on interaction of vermicompost and micronutrients combination on safflower. thus, this study was conducted to evaluate the effect of combinations of three important micronutrient consisted of sulphur, zinc and boron on yield and yield components as well as dry forage production of safflower in different vermicompost treatments.
Material and In this research, the effect of micronutrient application and vermicompost was examined on yield and yield components of safflower in Agriculture and Natural Resources Research Center of Kerman Province in two Kerman and Bardsir regions. The treatments were included vermicompost factor at two levels (0 and 6 t ha-1) and micronutrients combinations at 12 levels (no use, 100 kg ha-1 S, 200 kg ha-1 S, 3 ml L-1 Zn, 2 ml L-1 B, four twofold and two triplet combinations of the 3 micronutrients). A factorial experiment based on randomized block design (RCBD) was used. Vermicompost and S were used before planting as soil apply, while Zn and B were applied as foliar application. Dry forage at the flowering early and branch number per plant, head number per plant, grain number per head, weight of 1000 grains and grain yield at final ripening were determined. Analysis of variance, means comparisons (LSD at 5% probability level) and correlation coefficient were done in SAS software.
The results showed that application of vermicompost and micronutrient had positive and significant effect on head number per plant, grain number per head, weight of 1000 grains, dry forage and grain yield in both places. These could be attributed to improved soil porosity, water holding capacity and aeration caused by vermicompost. Vermicompost are also known as sources of plant nutrients and can improve soil physicochemical characteristics. Growth and yield of safflower plants in Kerman was significantly more than those in Bardsir, which was probably due to better conditions of soil in Kerman. Kerman had greater amount of nitrogen, potassium and phosphorous as well as higher level of soil organic matter. On average, vermicompost application at 6 t ha-1 was associated with 347 and 54 kg.ha-1 increasing in dry forage and grain yield, respectively. In the other hand, the highest dry forage and grain yield were obtained from plants treated with 200 kg ha-1 S, Zn and B as 2104 and 1433 and 1433 kg ha-1, respectively. Stimulated photosynthetic activity and synthesis of chloroplast and protein in result of micronutrient application might be reason of greater yield in these treatments. The grain number had the highest correlation with forage production and yield.
In general, the result of this study revealed that in both places, vermicompost and micronutrient application had positive interaction, so that the greatest forage and grain production were observed in vermicompost application with triple combination of S, Zn and B.

Despite the importance of oily crops in development of Iran, there are few studies on nutrition with micronutrient in these crops, especially for safflower. Safflower, a deep rooted oilseed crop, is grown in many areas of world because it can be used as oil crop, vegetable, birdfeed and spices. To achieve the acceptable growth and yield of safflower, it needs the sufficient micro- and macronutrient, so that recently, there has been an increased interest in evaluation of nutrient role in quality and quantity of safflower. Application of vermicompost in oil crop production systems of Iran has been increased; which it can improve soil structure by increasing aggregate stability as well as increase in water holding capacity and aeration. On the other hand, micronutrients are nutrients required by plants in small quantities to organize a range of physiological functions. The deficiency micronutrients is widespread in many parts of the country due to cultivation of high yielding varieties, intensive agriculture and increasing use of sulphur free fertilizers in large quantities with concomitant decrease in use of organic manures. There is little information on interaction of vermicompost and micronutrients combination on safflower. thus, this study was conducted to evaluate the effect of combinations of three important micronutrient consisted of sulphur, zinc and boron on yield and yield components as well as dry forage production of safflower in different vermicompost treatments.
Material and In this research, the effect of micronutrient application and vermicompost was examined on yield and yield components of safflower in Agriculture and Natural Resources Research Center of Kerman Province in two Kerman and Bardsir regions. The treatments were included vermicompost factor at two levels (0 and 6 t ha-1) and micronutrients combinations at 12 levels (no use, 100 kg ha-1 S, 200 kg ha-1 S, 3 ml L-1 Zn, 2 ml L-1 B, four twofold and two triplet combinations of the 3 micronutrients). A factorial experiment based on randomized block design (RCBD) was used. Vermicompost and S were used before planting as soil apply, while Zn and B were applied as foliar application. Dry forage at the flowering early and branch number per plant, head number per plant, grain number per head, weight of 1000 grains and grain yield at final ripening were determined. Analysis of variance, means comparisons (LSD at 5% probability level) and correlation coefficient were done in SAS software.
The results showed that application of vermicompost and micronutrient had positive and significant effect on head number per plant, grain number per head, weight of 1000 grains, dry forage and grain yield in both places. These could be attributed to improved soil porosity, water holding capacity and aeration caused by vermicompost. Vermicompost are also known as sources of plant nutrients and can improve soil physicochemical characteristics. Growth and yield of safflower plants in Kerman was significantly more than those in Bardsir, which was probably due to better conditions of soil in Kerman. Kerman had greater amount of nitrogen, potassium and phosphorous as well as higher level of soil organic matter. On average, vermicompost application at 6 t ha-1 was associated with 347 and 54 kg.ha-1 increasing in dry forage and grain yield, respectively. In the other hand, the highest dry forage and grain yield were obtained from plants treated with 200 kg ha-1 S, Zn and B as 2104 and 1433 and 1433 kg ha-1, respectively. Stimulated photosynthetic activity and synthesis of chloroplast and protein in result of micronutrient application might be reason of greater yield in these treatments. The grain number had the highest correlation with forage production and yield.
In general, the result of this study revealed that in both places, vermicompost and micronutrient application had positive interaction, so that the greatest forage and grain production were observed in vermicompost application with triple combination of S, Zn and B.

The ability of Hoary cress to absorb water and nutrients, due to creeping and extensive root system, indicates that this weed is importunate competitor for crop plants. To determine intra- and inter-specific competition between wheat and hoary cress by reciprocal yield model and other competition indices under different nitrogen levels, a factorial experiment based on RCBD was conducted with three replications in Research Greenhouse of Faculty of Agriculture, University of Birjand during 2013. Factors considered included pure nitrogen in three levels (0.05, 0.1 and 0.2 gr/kg soil), wheat density in four levels (0, 4, 8 and 12 plants per pot) and Hoary cress density in four levels (0, 2, 4 and6 plants per pot). The result of reciprocal yield model showed that in wheat intera- specific competition was higher than inter-specific competition, but in Hoary cress, intera- specific was higher. Relative competitiveness assessment showed that the effect of a wheat plant at three levels, 0.05, 0.1 and 0.2 grN/kg soil Was equal to 5.1, 4.45 and 4.42 Hoary cress plant respectively, and the effect of a wheat plant at the same fertilizer, Was equivalent whit 94, 84 and 88% of the wheat plant respectively.

Increasing crop competitive ability is an important part of integrated weed management (IWM). In this regard, identifying weeds reaction to soil fertility status for developing fertilizing methods, as components of IWM programs, is a necessity.
In order to evaluate the growth characteristics of purple nutsedge under the conditions of interference with onion, a factorial experiment based on randomized complete block design was conducted with three replications at the Research Greenhouse of University of Birjand in 2013. The first factor included three sowing methods of onion (seed sowing, onion set and transplanting) and the second factor included three levels of nitrogen (50, 100 and 150 kg N ha-1, equivalent to 25, 50 and 75 mg N kg-1 soil), urea fertilizer with a purity of 46% was used for this purpose.
The results of analysis of variance showed that sowing method and nitrogen levels had significant effects on plant height, leaf area, aboveground dry weight as well as tuber number and underground dry weights. Moreover, the interaction between sowing methods and nitrogen levels had a significant effect on plant height, leaf area, aboveground dry weight as well as tuber number and underground dry weights. The results of the comparisons of the mean for the interaction of planting methods and different levels of nitrogen indicated an increased weeds growth in direct seeding method and high levels of nitrogen in weed height trait, so that the greatest nutsedge height during the growing season (92.33 cm) was obtained at direct seeding method and high nitrogen levels . Moreover, the lowest weed height during the growing season was obtained at onion set planting method and 50 kg ha-1 nitrogen. The highest leaf area of purple nutsedge at ten weeks after planting (446.65 cm2), was obtained in direct seeding method and high levels of nitrogen, and the lowest value for this trait (203.38 cm2), was observed in onion set planting method. The greatest shoot dry weight of purple nutsedge during the growing season was observed in direct seeding method and high levels of nitrogen. The maximum amount of this trait at eight and ten weeks after planting was achieved in the level of 100 kg N ha-1 which was about 3.797 and 7.306 gr plant-1, respectively. Also the minimum shoot dry weight of weed was produced in onion set planting method and their amounts were about, 1.161 and 4.229 gr plant-1 at eight and ten weeks after planting, respectively. The greatest tuber number of purple nutsedge during the growing season were observed with seed planting method which were 7 and 15.33 tuber per pot at eight and ten weeks after planting, respectively. Moreover, the minimum tuber number of weed was produced in onion set planting method and were about 1.66 and 5.66 tuber per pot at eight and ten weeks after planting, respectively. The maximum underground dry weight of purple nutsedge during the growing season was obtained at direct seeding method and high levels of nitrogen. The maximum amount of this trait at eight and ten weeks after planting was obtained in the level of 100 kg N ha-1 which were about 2.472 and 5.396 gr plant-1, respectively .The minimum underground dry weight of weed was achieved in onion set planting method which were about, 0.888 and 1.873 gr plant-1 at eight and ten weeks after planting, respectively.
Overall ANOVA results showed that the sowing method and level of nitrogen as well as their interaction had a significant effect on all studied traits of purple nutsedge. Evaluation of growth characteristics of purple nutsedge under the conditions of interference with onion showed that the greatest and lowest growth of purple nutsedge were obtained where seed and onion sets planting methods were implemented, respectively. Moreover, the results indicated a positive response of purple nutsedge to high levels of nitrogen. Thus, in order to minimize the damage caused by purple nutsedge, the application of 100 kg N ha-1 nitrogen in onion set method is recommended as the most appropriate treatment for the management of purple nutsedge in infected onions farms. However, this study was conducted under greenhouse conditions and there is no doubt that repeating the test in the field is essential for verifying the results.

Field experiment was conducted to assess the efficacy of wheat residues and different densities of sunflower in weed control during 2007 growing season. The experimental design was a randomized complete block with three replications. The experiment was set up in factorial arrangement, amount of 0, 1250, 2500, 3750, 5000 Kg ha-1 of wheat residue and burning of residue (5000 kg ha-1) were the levels of factor A and three densities of sunflower consisting of 50000, 70000 and 90000 plants ha-1 were factor B. During growth season measurement of weed biomass and weed height in 3, 6 and 9 week after planting was conducted. Increasing amounts of wheat residue and sunflower density decreased weeds biomass and height. 71.8, 73.17 and 87.48 percent of weed biomass reduction occurred with increase in wheat residue at 3, 6 and 9 weeks after planting, respectively. Also increasing sunflower density from 50000 to 90000 Plants ha-1 decreased the weeds canopy height. Sunflower grain yield increased 29.86 and 31.73 percent with increasing wheat residue and sunflower density, respectively. Applying 2500 kg.ha-1 wheat residue integrated with sunflower planting at density of 90000 plants ha -1 can give an effective control of weeds and can be an alternative to cut herbicide use.

In order to evaluate the resistance of wild oat bitypes to clodinafop-propargyle, pinoxaden and their mixture (traxos), collected from Fars and Khoozestan provinces, pot and Petri dish bioassay studies were conducted on 8 suspected to resistance wild oat biotypes as well as one susceptible biotype at Iranian Research Institute of Plant Protection during 2008-2009. In pot bioassay experiments which were conducted as RCBD with four replications, wild oat plants were sprayed during 2-4 leaves stage using 0.25-16 times the recommended dose. Based on herbicide recommended rates (0.8, 0.45 and 1.5 l/ha for clodinafop-propargyle, pinoxaden and traxos, respectively), the applied doses were 0, 16, 32, 64, 128, 256, 512 and 1024 g ai ha-1 for clodinafop-propargyle, 11.25, 22.5, 45, 90, 180, 360 and 720 g ai ha-1 for pinoxaden and 16.87, 33.75, 67.5, 135, 270,540 and 1080 g ai ha-1 for traxos. In Petri dish bioassay studies, after determination of discriminating dose for each herbicide (0.05, 0.03 and 0.01 mg ai/l for clodinafop-propargyle, pinoxaden and traxos respectively), dose response experiments using 0.25-16 times of the discriminating dose were conducted on germinated seeds. The results indicated that all biotypes was resistant to clodinafop propargyl and cross resistance to clodinafop-propargyle, pinoxaden and their mixture (traxos) in Khoozestan populations were confirmed. Greater than 37% of biotypes were controlled by pinoxaden or traxos herbicides and the resistance level of all biotypes to traxos was lower than other herbicides.

In order to investigate the resistance level ofannual ryegrass (Lolium rigidum) biotypes to Pinoxaden herbicide, greenhouse and Petri dish bioassay studies based on CRD with 4 replications were conducted at Weed Research Department of Iranian Research Institute of plant Protection during 2008 and 2009. The resistance level of biotypes was determined in pot trials, while the herbicide dose required for 50% reduction of coleoptile length of the susceptible biotypes (GR50) as well as the susceptibility and resistance level of biotypes were studied in Petri dish bioassay trials. The experiments were conducted on 12 annual ryegrass biotypes collected from wheat fields of Fars province. The susceptible (FS) and 11 suspected to resistant biotypes (including ES1, ES2, ES3, ES4, ES5, M1, M2, M3, F1, FJ and FI2) were sprayed at 2- to 4-leaf stage by applying 0-32 times of recommended dose of Pinoxaden herbicide including 0. 45, 90, 180, 360, 720 and 1440 g ai ha-1 in greenhouse experiments. The germinated seeds were also exposed to 0, 0.4, 0.8, 1.6, 3.2, 6.4 and 12.8 g ai l-1 in Petri dish bioassay experiments. The percentage of dry matter and plant survival of each biotype was calculated compared to the untreated control and the resistance level was determined four weeks after herbicide application in greenhouse experiments. The percentage of coleoptile length of biotypes compared to the control was assessed 7 days after treating the germinated seeds with herbicide in Petri dish bioassays and the resistance level of biotypes were calculated. The results of greenhouse and Petri dish bioassay studies indicated that 4 biotypes including ES4, M2, F1 and FJ were resistant to Pinoxaden herbicide. As a general conclusion, most of the studied biotypes were sensitive pionoxaden.

(Rumex crispus) and cone catchfly (Silene conoidea), experiments were conducted based on RCBD with 3 replications at Research Laboratory of Faculty of Agriculture, Birjand University during autumn 2009 and winter 2010. Experimental treatments were light (Light/Dark and continuous dark), alternating day/night temperatures (10/5, 20/10, 25/15, 30/20 and 35/25 C), salinity stress (0 (Control), 10, 20, 40, 80, 160, 320 and 640 mM), drought stress (0 (Control), -0.1, -0.2, -0.4, -0.6, -0.8 and -1 MPa), pH (4 to 10) and sowing depth (0 to 4 cm). Results showed that seed germination of Curly dock was unaffected by either light/dark or continuous darkness conditions. Greater than 85% of curly duck seeds germinated over a broad range of alternating day/night tested temperatures under light/dark and continuous dark regimes and its germination completely ceased at 10/5 C. Cone catchfly seeds germinated greater than 70% at alternating temperature regimes equal to or lower than 25/15 C under light/dark and continuous dark regimes, but its germinability was remarkably reduced at temperature regimes warmer than 25/15 C, especially under light/dark conditions. Curly dock and Cone catchfly seeds germinated greater than 85% until the salinity level of 160 mM (NaCl), while their germination percentage at osmotic potential of -0.8 MPa were 60 and 90%, respectively. The average germinability of curly dock and cone catchfly seeds over a pH range of 4 to 10 was 90%. Seed burial significantly reduced curly dock and cone catchfly seedling emergence, so that no seedling emerged from a soil depth deeper than 3 cm and the greatest seedling emergence of curly dock and cone catchfly (98 and 74.7%, respectively) was occurred for seeds placed on the soil surface under 3 layers of filter paper.

The effects of environmental factors on germination and longevity of downy brome seeds were examined in laboratory and field experiments. Downy brome could germinate in a broad range of temperatures (15/6, 20/10, 25/15, 30/15, and 35/20ºC). The germinability, however, was different depending on the temperature range and the results showed that the highest germination was occurred in 20/10ºC (91%) under continuous dark regime, while the lowest germination percentage was observed in 35/20ºC (5%) under light/dark conditions. Salinity showed significant adverse effect on germination of this weed, so that the highest germinability was at 0 concentration of NaCl (89%). Increased salinity levels significantly decreased downy brome germination and its germination completely ceased at 320 mM NaCl. This study indicated that increasing pH in the range of 4 to 8 resulted in enhanced germination percentage, while further increase of pH significantly reduced germinability. Another experiment in which seeds were after-ripened at different depths in the field showed that increased burial depths from 0 to 10 cm accelerated seed after ripening and the lowest germination occurred in the seeds which were placed on the soil surface.