جستجوی مقالات مرتبط با کلیدواژه « عملکرد » در نشریات گروه « گیاهپزشکی »

Purple nutsedge is one of the harmful weeds in onion (Allium cepa L.) fields. This project aims to investigate the effectiveness of oxyfluorfen, cetoxydim, bentazone and penoxolam herbicides along with the use of adjuvant. The use of additives is one of the most important effective ways to increase the efficiency and reduce the amount of herbicides. It was carried out in the form of a randomized complete block design with 11 treatments and three replications in industrial and cultivation fields in the year of 2021. The results of the project showed that the effect of different herbicides on the traits of Cyperus rotundus was significant and significantly reduced the number of shoots, number of tubers, above and below fresh and dry weight of shoots of Cyperus rotundus. The best treatment using bentazone + oil and cetoxydim + bentazone was obtained, yeild onion highest was obtained by hand weeding (47.272 ton. ha) and Bentazone + oil: Sethoxydim: Bentazone (43.636 ton. ha). Which was not significantly different from the control treatment (weed free). Therefore, the combination of the post-emergence application of bentazon + oil and cetoxydim + bentazone can be effective for controlling the purple nutsedge.

Chickpea (Cicer arietinum L.) is one of the most important legumes. In order to investigate the efficacy of some post-emergence herbicides on the control of chickpea weeds in the south of kerman, an experiment was conducted in a randomized complete block design with 8 treatments (6 herbicides and 2 control) and four replications in the farm of Jiroft university research center in 2020. Treatments were using herbicides application post-emergence in 2-4-leafy stage of weeds, including bentazone (Basagran M®, 3 L ha-1), bensulfuron-methyl (Londax® 3 L ha-1), bentazone (3 L ha-1 Basagran M®) + hand weeding, penoxsulam (Rezlan®,1.5 L ha-1), oxadiazon + oxyfluorfen (Ronstar®+ Goal®, 1.5 + 2 L ha-1) and imazethapyr (Pursuit®, 1.5 L ha-1), weed-infested and weed-free controls. Fresh and dry weight of weeds, the density of weeds, the total density of chickpea, as well as the visual damage to weeds and chickpea in each treatment were measured. Results showed that there was a significant difference among the herbicide treatments. The highest yield of chickpeas (2690 kg/ha) was observed in hand weeding control treatment (weed-free), oxadiazon + oxyfluorfen (2660 kg/ha) and bensulfuron-methyl (2216 kg/ha) were in the next orders. The lowest chickpea yield was observed in the weed infested treatment (540 kg/ha). Application of oxadiazon + oxyfluorfen and bensulfuron-methyl as post-emergence were the most appropriate treatments to control weeds in winter pea fields in the south of Kerman.

The dust storm has become a regional phenomenon due to occurrence of severe droughts. Dust storms, recognized as significant atmospheric phenomena and associated with climate change, exert detrimental effects on plant growth and crop yield. This study aimed to assess the impact of soil dust on the competition between mung bean and red-root pigweed.

An experiment was carried out at the research greenhouse of Faculty of Agriculture at Ilam University during spring and summer 2022. The experiment was conducted as a factorial based on a completely randomized design with four replications. The experimental treatments were included five replacement ratios of mung bean and redroot pigweed (planting patterns 75% mung bean + 25% pigweed; 50% mung bean + 50% pigweed; 25% mung bean + 75% pigweed; monoculture of mung bean and redroot pigweed) and dust were at two levels (0 and 60 gr m-3).

The results showed that the dust causes symptoms of necrosis and leaf burn in mung bean and pigweed. The highest amount of carotenoids (3.59 mg g-1 fresh weight of leaf) was observed in the planting pattern of 75% mung bean + 25% pigweed under no dust conditions. The monoculture of pigweed under dust conditions had the lowest amount of carotenoids. Dust reduced the amount of total chlorophyll, leaf relative water content, plant height and length of inflorescence in Pigweed plant by 23.4, 12, 14.7 and 12%, respectively. Dust caused a decrease in the leaf area in pigweed in different patterns of intercropping. Photosynthesis rate, transpiration rate, leaf area, plant height, number of pods per plant and number of seed per plant in mung bean were respectively decreased by 31.2, 24.9, 28.8, 17.7, 29.7 and 36.7% due to dust application. The highest photosynthesis rate in mungbean (5.28 µmol of CO2 m-2 s-1), leaf area (129.1 cm2) and the number of seeds per plant (13 seed plant-1) were obtained from monoculture of mungbean. However, they were decreased under competition with pigweed. The biological yield in mungbean and pigweed under dust condition were, respectively, 42.6 and 16.8 % lower than that of no dust condition. Under dust conditions, the grain yield of mung bean and pigweed were, respectively, 32.8% and 42.6% lower than that of no dust condition. The actual yield of mung bean under competition with pigweed was lower than the predicted yield indicating the higher competitive effects of pigweed. In all planting patterns with and without dust, the total actual yields were higher than the predicted yield indicating a negative interference effects for mung bean. The relative total yield in most of the planting patterns was greater than one, suggesting increase in the partial relative yield and reduction of intra-species competition in pigweed. The negative effects of pigweed on mungbean were more visible in high densities of pigweed, which also showed a higher positive dominance index. The competition index showed a value greater than one for the pigweed indicating the greater competitive ability of this weed compared to mung bean. Under both conditions, with and without dust, pigweed exhibited the highest relative density coefficient in all planting patterns, establishing itself as the dominant plant compared to mung bean, which had a relative density coefficient less than one. The competition index for mung bean, across all intercropping patterns, was also less than one, indicating its lower competitive ability compared to pigweed. Interspecific competition with pigweed resulted in an actual yield loss for mung bean, highlighting that interspecific competition in mung bean surpasses intraspecific competition. Conversely, pigweed showed a greater susceptibility to intraspecific competition.

The results showed that pigweed has a higher competitive ability and by increased exploitation of environmental resources, cause a decrease in mung bean yield. Despite the high competition ability of pigweed, soil dust cause reduction in its growth and biomass.

Slugs are the most important pest of lettuce fields in the north of the country, and feed on different parts of lettuce plants, including leaves, stems, roots, and seeds, and destroy them. Currently, common chemical pesticides are used to control them. Nowadays, the use of non-chemical methods, such as attracting and catching slugs by trapping, in order to reduce the consumption of pesticides is necessary. In this regard, the efficiency of one type of commercial trap and two types of homemade traps with and without bait was compared against Deroceras agreste Linnaeus. The experiment was conducted in a completely randomized block design with eight treatments and four replications in 2019 and 2020 in field conditions. According to the results of simple and combined analysis of variance, among the treatments, green commercial trap with bait and green homemade box trap with bait (with total mean number of slugs captured, 76.5 and 75.6 in two years, respectively), had the highest attraction without significant difference from each other and the colorless plastic bottle trap (with total mean number of slugs captured, 29.8 in two years) had the least attraction. Also, green commercial with non-alcoholic beer bait and homemade green box trap with non-alcoholic beer with attracting and trapping the more slugs caused less damage to leaves (7.6 and 6.8 % in two years, respectively) and more yield (with means 13.1 and 11.5 kg/m2 in two years, respectively). The traps with bait compared the traps without bait and the green homemade box traps with bait compared with the cream box traps with bait were significantly more effective in attracting of slugs. Therefore, it is possible to use an inexpensive homemade green box trap with non-alcoholic beer, which has the same efficiency as commercial trap, to reduce the population and control slugs in lettuce fields.

Rapeseed is one of the most important crops cultivated for oil extraction and has the highest annual growth rate (in terms of production) among the essential oilseeds in the world. Due to its slow growth rate, the rapeseed plant has little competitive ability against weeds in the early growing season, which causes it to be severely damaged by weed interference. Since the long-term presence of weeds in rapeseed could reduce its quality and yield, early weed control is essential to achieve economically acceptable yields.

In order to control broadleaf weeds in rapeseed fields, a factorial experiment based on a randomized complete block design with three replications was conducted in winter 2019 in Benvar Nazer region, Andimeshk county, Iran. The experimental factors included two types of rapeseed hybrids (Hayola 50 and Agamax) and clopyralid herbicide (1.5 L ha-1 recommended dose, EC30%, Aryashimi, Iran) application with a fixed dose of 1 lit ha-1 for all treatments along with oxadiazon herbicide (recommended dose of 3 L ha-1 for using in rice as pre-plant before the two leaved barnyard grass, EC12%, Shimagro company, Iran) at doses of 100, 175, and 200 ml ha-1, and oxadiargyl herbicide (recommended dose of 3-3.5 L ha-1 for using in rice as pre-emergence or at the beginning of weed emergence in transplanted rice, SC3%, Herbicide Production Company, Iran) with doses of 100, 125, and 150 ml ha-1. Weedy and weeding control (complete control by manual weeding) were considered as control treatments. Herbicides were applied by a 12 liter back sprayer equipped with a TJET 11003 nozzle, which was calibrated for spraying 200 liters per hectare, in the initial 2-leaf stage to the beginning of 4 true leaves for chemical control of weeds in the plots. The grass weeds were removed by hand. Broadleaf weeds were counted separately according to the weed species at before spraying, three and six weeks after spraying and were cut at the soil surface and dried at 70 °C in oven. Then, weed dry weight was measured with a digital scale 0.01 and the percentage reduction in density and dry weight of weeds were calculated. In addition, the amount herbicides used on rapeseed was visually assessed using the EWRS standard table. Then, yield and yield components of rapeseed including number of siliques, seed no. per silique, 1000-seed weight, seed yield, biological yield and harvest index were measured.

Results showed that the predominant weed species in the experimental plots included wild clover, queen anne᾿s lace, mallow, Anagalis spp., wild mustard, and field bindweed, which the highest frequency (31.29%) belonged to wild clover and the lowest frequency (1.03%) belonged to field bindweed. The ANOVA results showed that the reduction percentage of density and dry weight of weeds and seed yield were affected by experimental treatments; as the treatments of clopyralid + oxadiazon 100, clopyralid + oxadiazon 175, clopyralid + oxadiargyl 125 in Hyola50 hybrid and clopyralid + oxadiazon 175 in Agamax hybrid reduced the density and dry weight of weeds by 100%. While, the lowest reduction percentage of weed density and dry weight (44.74 and 55.33%, respectively) was observed in Agamax hybrid and clopyralid (1 L ha-1) treatment. Also, the highest and lowest herbicide injury on weeds were observed in clopyralid+oxadiazon 100 (9.67%) and clopyralid alone and combination of clopyralid+oxadiargyl 100 and 150 in Agamax hybrid (0%), respectively. The highest seed yield, biological yield and 1000-seed weight of rapeseed were observed in clopyralid+oxadiazon 200, oxadiargyl 125 and 150 (3377.6 kg ha-1, 11295 kg ha-1, and 3.27 g, respectively), and the lowest was observed in weedy control treatment (2064.2 Kg ha-1, 7458 Kg ha-1 and 2.87 g). 1000-seed weight is less affected by treatments and is a genetic trait. The highest and lowest number of seeds per silique under the influence of herbicide treatment were related to clopyralid+oxadiazone 175 and clopyralid+oxadiargyl 100 (23.33 and 18.17), respectively. An increase in the number of seeds per silique was observed with increasing the dose of herbicide oxadiazone in combination with clopyralid up to 175 ml ha-1. The highest number of siliques per plant was obtained in weeding treatment in Agamax hybrid with 189.33 silique per plant, which was significantly different from weedy control treatment. Also, the lowest number of weed control silique was obtained with Hayola 50 hybrid, which was not significantly different from clopyralid+oxadiazone 100 in Agamax hybrid.

According to the results, mixing herbicides is a solution to eliminate the competition of weeds with rapeseed and increase the yield so that the yield of up to 3.3 tons is obtained, which compared to clopyralide only as a control treatment. In general, the highest yield of rapeseed from plots treated with clopyralid+oxadiazon 200, oxadiargyl 125, and 150 were the best treatment in comparison with the applied treatments. The best treatment is the one in which rapeseed yield has been the highest. In addition, since clopyralid is a selective herbicide in rapeseed, it did not have sufficient efficacy due to poor control of important weeds such as wild mustard. It should also be noted that further testing of the above herbicide mixtures on rapeseed fields throughout the country is necessary in order to obtain the results that are the basis for recommending these mixtures in rapeseed.

Root-knot nematode is one of the serious diseases of kenaf which affects its growth and biomass productivity. However, the amount of crop loss in different varieties of kenaf is not equal. The aim of this study was to determine the effect of root knot nematode on biomass production of kenaf varieties. The biomass productivity of sixteen (16) kenaf varieties was examined under four different levels of nematode inoculum. Yield productivity criteria consisted of FPM, DPM, MSM and DMSM of the plants measured 120 days after their planting. Based on the results of this study, it can be concluded that the productivity of kenaf varieties differs both in the absence and in the presence of nematode infection. M. incognita race 1 showed that the yield productivity of all varieties tested here can be reduced. This reduction; however, varied between varieties. When challenged with RKN, cultivars 113 and Tainang1 were found to be quite promising cultivars with maximum FPM and DPM production, respectively. Varieties G4 (Kelantan) and G4 (AUST) were also found to be at the two extremes of MSM and DMSM when infected with nematodes. Based on our results, it can be concluded that in the presence of RKN, cultivars 113, Tainang1, G4 (Kelantan) and G4 (AUST) are very promising kenaf cultivars showing potential biomass production of FPM, DPM, MSM and DMSM, respectively. It was also found that the resistant cultivar outperformed the susceptible cultivar for all of these four parameters at harvest time.

Powdery mildew of wheat caused by Blumeria graminis f.sp. tritici, is one of the most important and common wheat disease in humid, semi-humid and semi-arid regions of the world, including Iran. At present, one of the important aspects of the management of this disease is its chemical control. In this study, the efficacy of the Pilartep (Tebuconazole +Pyraclostrobin) SC 30% was evaluated in controlling the powdery mildew of wheat in three regions of Qarakheil and Bayekola (Mazandaran) and Kohnekand (North Khorasan province) regions based on randomized complete block design with six treatments and four replications. Experimental treatments included Pilartep (SC 30%) 0.4, 0.5, 0.6 and 0.7 l/h, Tilt (EC 25%) 1 l/h, Folicur (EW 25%) 1 l/h and control. Spraying operation was performed in the growing stage of stem emergence with the emergence of flag leaves. The plots were evaluated for disease incidence and severity percentage using double digit scale and at the end of the season, wheat yields were recorded for each plot. In evaluating the effect of fungicides on incidence, disease severity percentage and crop yield, Pilartep fungicide at the rate of 0.6 and 0.7 l/h was placed in the first statistical group (the highest group). In general, according to the results obtained in order to use the fungicide optimally, Pilartep (SC 30%) at the rate of 0.6 l/h is recommended in the control of powdery mildew of wheat.

Competition for resources among plants has long been considered to generate stress for plants and to be important for determining the distribution of species, as well as their evolution. Competition can occur among the organs of a plant (intra plant competition), or negative interactions between the plants of a species (intra specific competition) or interference among different plant species (inter specific competition). Weeds have long been considered as the main competitor of crop plants. These plants can be problematic due to competition with crop plants over light, water and nutrients, decreases the quantity and quality of the product and the creation of a suitable refuge for insects and pathogens. The presence of weeds in soybean reduces seed yield and the rate of this decrease depends on weed density and stage growth stage. In agriculture areas, crop density is kept constant whereas weed density varies in accordance to local infestation degree. Therefore, variation in plant proportion of crops and weeds is established. Thus, in competition studies, it is important to measure the influence of plant density on the competitive process as well as the variation in plant proportion. There are several methodologies used to study plant competition. However, most researchers measured just the interference of weeds on crop growth and production without concerning about the competition process. Thus, it is important to use appropriate experimental designs and methods of analysis to understand the competition process not just by quantifying crop losses but in a mechanistic way. Replacement series experiments allow the control of plant density and proportion, where plant density is kept constant while plant proportion is changed for both studied species. This study aimed to investigate the response of soybeans to the interaction of three species of foxtail (Setaria glauca, S. verticillata and S. viridis) and competitions between the species of these three weeds.

These pot experiments were carried out at Sari Agricultural Sciences and Natural Resources University based on a completely randomized design in three replications. The first experimental treatments included planting ratios: 25:75, 50:50, 75:25 (soybean-weed) and pure stand of soybean and weed and in the other three experiments, each of the weeds compared in pairs with the ratios listed above. Density of soybean and weed in the sole stand was four plants per pot and in the planting ratio of 50:05 soybean-weed, two plants were considered from each plant. Also, in the planting ratio of 75:25 soybean and weed, 4 seeds were cultivated in each pot, wherein planting ratio of 75% three seeds of soybean or weed and planting ratio of 25% one seed of soybean or weed was planted. The traits studied in this experiment included seed yield, number of sub-branches, number of pods per plant, number of seeds per pod and 100- seed weight of soybeans. Weed biomass, height, number of leaves, number of spikes and number of tillers of weeds were also calculated in competition with each other. In addition, the ability of weed competition and the competition index were determined.

The results showed that the competitive ability of three species with soybean showed that the maximum soybean seed yield (15.56 g plant-1) were obtained in weed-free conditions (soybean monoculture) and increasing soybean density in interference with three species of foxtail reduce weeds biomass compare to the monoculture of weed. Although, survey competitive withstand ability of soybean to different densities of three species of foxtail showed that soybean is more tolerant to low densities (25%) of S. glauca, S. verticillata and S. viridis, but the competitive ability of soybeans compared to these three species was S. glauca > S. verticillata > S. viridis; because the increasing density of S. glauca, caused decreasing soybean yield with a gentle slope while, increasing density of S. viridis, made a decrement of soybean yield with a steep slope. The competitive ability of three species of foxtail together showed that increasing density of any species will diminished the growth index of other species when maximum height, tiller number, leaf number, spike number and biomass of all three species was observed in their monoculture.

The results of the competition of all three species of terns with each other show that inter-species competition has been more effective in reducing weed population life than the intra-species competition; Thus, S. viridis species could have a greater decreasing effect on S. verticillata and S. glauca species by creating more height, more tillers and leaves and as a result higher biomass production. So, the competitiveness between the three species was S. glauca <S. verticillata <S. viridis. According to the findings of the present study, by increasing the density of soybeans, weeds can be managed, especially in their low densities.

In order to evaluate the effect of different methods in control of weeds in pumpkin fields, an experiment was conducted based on randomized completely block design with four replications in 2019. Treatments consisted of weed free, complete weeding, mulch (clear and dark plastic), intercropping with quinoa, once weeding and three herbicides: Trifluralin (7.5 liters of commercial material per hectare) before planting and after crop growth, indaziflam (100 ml commercial material per hectare), pendimethalin (6 liters commercial material per hectare). Indaziflam and pendimethalin chemical treatments were applied after emergence on July. Results showed that the dark plastic mulch caused the maximum dry matter (141.4 g/m2) and fresh (289.8 g/m2) weight of pumpkin leaf and the maximum dry matter (78.5 g/m2) and fresh (641.6 g/m2) weight of pumpkin shoot in comparison of other treatments. In addition, dry matter of weeds got decrease up to 90 percent just through by type of dark plastic from mulch treatment and 97 percent by clear one. Furthermore, it caused 49 and 129 percent increasing respectively in fresh and dry matter weight of pumpkin. On condition of chemical control, using Trifluralin herbicide before of planting caused the fruit diameter (13.4 cm), fruit area (46 cm) and seed (35.5 g) dry matter of pumpkin so improved the yield in comparison other chemical treatments. Finally, using different mulching treatment got yield increased up to maximum, proper control of weeds and decreased the environmental pollution through decreasing of chemical materials.

In this study, the effect of Lixusincanescens on five sugar beet cultivars on five sugar beet cultivars (Shkoofa, Flores, SyRobustus, Silvetta and HilleshogMonatunno) in the year 2019-2020. Sampling was performed every 8days from early July to mid-September. At each date, the experimental sample of larval damage on the petiole, the number of eggs and larvae were counted, and at the end of the experiment, the yield and sugar titer were analyzed. The results showed, the significant difference between larval damage on the petiole, the number of eggs and larvae, yield and sugar grade result on the studied cultivars at the level of five times the probability of meaning. The lowest larval damage index on petiole was in Shokof (2.5) and Silvetta (2.5), and the highest in Monatunno (6.25) and Flores (5.5); The lowest number of eggs per plant in Shokofa (2.25) and Silvetta (3.25) and the highest in Monatunno (5.25) and Flores (5) The lowest number of larvae in Shokofa (1.75) and Silvetta (75/75) and the highest was observed in Monatunno (6.25) and Flores (5) cultivars. The highest density of eggs and larvae was observed in the sixth (August 11) and seventh (August 19) sampling. The highest yield and sugar content were observed in Shokofa and Silvetta cultivars and the lowest in Monatunno and SyRobustus cultivars. The results of this experiment can indicate that Shkoofa and Silota dances can be the best option in virus management due to the least amount of petiole damage, egg and larval density.

Abstract In order to evaluate the effect of Fusarium verticillioides on seed yield, catalase (CAT) activity on polyacrylamide gel and quantum yield of maize line, a factorial experiment based on randomized complete block design with five replications during 2017 growing season at the Payame Noor University, Mamaghan branch was performed. The experimental factors were two maize lines (B73 and MO17) and two levels of F. verticillioides (control and fusarium contamination). The results indicated that Fusarium verticillioides reduced seed yield, but enhanced CAT acivity in two maize lines. Further more, minimum fluorescence (Fo) in MO17 decreased, and increased in B73. Water splitting complex at donor side of PSII (FV/Fo) in B73 was increased, but was decreased in MO17. The level of maximum fluorescence (FM) in both line decreased. The energy necessary for closing reaction centers in PSII (Sm) and number of the QA reduction during fluorescence from Fo until FM (N) in MO17 were increased, but were decreased in B73. The results of this study revealed++ using from the chlorophyll a fluorescence can be a rapid and non-destructive method for evaluation of the maize reactions to injures caused by fusarium fungi infections.

Oilseeds such as sesame (Sesamum indicum L.) are one of the rich sources of energy and protein that form the second most important food resource of the world after cereals. The factors like suitable plant density and weeds control are important for maximum economical yield. This crop is highly adapted to the climatic conditions of Iran and is highly tolerated to the drought. Therefore, the objective of the present study was to investigate the effect of weed free periods and plant density of sesame on yield, yield components and agronomic traits of sesame in Birjand, Iran.

The present study was carried out in research farm of Islamic Azad University of Birjand (Long. 59°13' E., Lat. 32°52' N., Alt. 1491m.). This experiment was performed as factorial based on Randomized Complete Blocks Design with three replications in 2013. Treatments were including weed free periods at five levels (weed free until 20, 40, and 60 days after sesame emergence, perfect weed interference and perfect weed free) and plant density at three levels (7, 14, and 28 plant m-2). In this research morphological traits, yield and yield components of sesame and dry weight and number of weeds per m2 were measured. The texture of the soil in research farm was clay loam with the pH of 7.24, electrical conductivity of 4.14 mmhos cm-1 and total N, P and K content was 0.038%, 7.21 and 223.5 ppm at the depth of 0-30 cm, respectively. Data were analyzed by SAS statistical software and means were compared by Duncan's Multiple Range test at 5% probability level.

Analysis of variance showed that yield and yield components traits were significantly influenced by plant density and weed free period. In addition, plant height, stem diameter, branches number of main stem, length capsule were significantly influenced by weed free period, but plant density affected only on plant height and first capsule height from the soil. The interaction between weed free period and sesame plant density was not significant on all traits except biological yield. Means comparison showed that increasing of weed free period had positive effect on morphological traits, yield and yield components of sesame, so that capsule number per m2 increased 3.98, 2.45 and 1.1 times, respectively in perfect weed free treatment compared to the treatments of the perfect weed interference and weed free until 20 and 40 days after sesame emergence. In addition, seed number per capsule increased 155, 20.2, and 9.8%, respectively and 1000-seed weight increased 20.3, 13.6, and 8.9%, respectively. The highest of seed yield (913.62 kg ha-1) belonged to the perfect weed free treatment that in comparison with treatments of perfect weed interference and weed free until 20, 40 and 60 days after sesame emergence had superiority of 15.5, 4, 1.8 and 1.3 times, respectively. Moreover, results indicated that in the perfect weed interference, weeds number per m2 had superiority of 22.6, 3.7 and 2.4 times, and weeds dry weight per m2 had superiority of 40, 8 and 2.8 times, respectively as compared with treatments of weed free until 60, 40 and 20 days after sesame emergence. These findings can be attributed to the increase in competition between crop plant and weeds for growth resources with prolonged weed growth. However, increasing the weed free period caused lower weeds emergence and growth and hence greater resources uptake by sesame plants that finally increased yield component and seed yield of sesame. Means comparison showed that the increase in plant density from 7 to 28 plants m-2 increased capsule number per m2 and seed yield by 76.4 and 72.79%, respectively and decreased weeds number and dry weight by 26.4 and 45.39%, respectively. It is seems that higher plant density per unit area caused maximum usage of production parameters and on the other hand, suitable density (28 plant m-2) increased the ability of crop competition  with weeds.

The results of this study showed that both weed interference and plant density, are the affecting factors on yield and yield components of sesame. The lowest yield was achieved at the highest level of weed interference and the lowest density of plants per square meter. High plant density is effective in crop yield due to reduced weed interference. Also, since the plant is susceptible to weed growth in the early stages, increasing the free weed period causes rapid plant growth and increases performance. According to the obtained results in this study, the best treatment for high yield production was perfect weed free and density of 28 plant per square meter.

The European corn borer, Ostrinia nubilalis Hübner, is one of the most important pests of corn. In this study, the influences of corn monoculture (C), sainfoin monoculture (S) and strip-intercropping of corn with sainfoin in the four row ratios: 2C:2S, 2C:4S, 2C:6S and 2C:8S were evaluated on the population density of the European corn borer, diversity and abundance of its natural enemies and yield of both crops in an experimental field during 2016 and 2017. Our results indicated that the densities of eggs and larvae of this pest decreased significantly in the intercrops especially in 2C: 6S and 2C: 8S compared with corn monoculture. The Shannon diversity index (H´) for predators in the intercrops was significantly greater than that in the corn monoculture. Moreover, the percentage of parasitized eggs and larvae were higher in the intercrops, especially in 2C:6S and 2C:8S, compared with the corn monoculture. Furthermore, the percentage of infested plants was also lower in 2C:6S and 2C:8S compared with the other treatments. On the other hand, high values of land equivalent ratio were found in 2C:6S (1.16 in 2016 and 1.15 in 2017) and 2C:8S (1.17 in 2016 and 1.16 in 2017). Therefore, it could be concluded that 2C:6S and 2C:8S intercrops are useful in integrated management of the European corn borer in the field.

Barley is one of the world's main sources of nutrients for human and animal, and E. integriceps is one of the most important pests reducing its yield. This study was conducted on different barley genotypes to identify the genotypes that are resistant to Sunn pest. The study was a randomized complete block design with three replications that was conducted in 2016 and 2017 in Neyshabour Agricultural Research Center. The results showed that the highest number of E. integriceps was recorded in genotype 3 and the lowest number of E. integriceps was related to genotypes 2 and 6. Genotype 13, with the important indices of grain yield under non-stress condition (Yp) and genotype 10, with the important indices of grain yield under stress condition (Ys) in the region, were identified to have high yield potential and low sensitivity to E. integriceps. Yp had a positive and significant correlation with the mean of productivity (MP), geometric mean (GMP), and stress tolerance index (STI). YS had a positive and significant correlation with all indices except stress susceptibility index (SSI) and tolerance index (TOL). Therefore, the MP, GMP, and STI were the only indices that showed a positive and significant correlation with Yp and Ys. In conclusion, based on the results of this study, genotype 20 can be nominated as a E. integriceps-resistant genotype in Neishabour region. Genotype 1 can also be reported as a sensitive genotype to E. integriceps with low yield.

This study conducted to evaluate the effects of L- Tryptophan on performance and defensive behavior of honeybees (Apis mellifera meda </em>L.). For this purpose, in a completely randomized design experiment; 25 beehives with same population and same aged half sib queens of Meda breed were randomly distributed in to five treatments and five replications so that each experimental unit were consist of 20000 boxes. Five experimental groups were containing bees nourished by syrups with 0, 750, 1500, 2250 and 3000 mg/litter L-Tryptophan for 2 months. The honey production measured and defensive behavior evaluation by installing a black leather bull in front of each boxes and counting stringed points on it per minute.  The results of Duncan’s test showed that the most of honey production related to bees fed syrup containing 2250 mg/litter L-tryptophan and in this treatment defensive behavior were significantly lower (P<0/01) than bees that did’nt consume tryptophan. However, population significantly decreased (P<0/05) in bees fed syrup containing 2250 mg/litter L-tryptophan comparing with bee’s did’nt consume tryptophan.

This experiment was conducted during 2015-2016 in Karaj to evaluate the performance of some herbicides in view of broad leaf weeds control in new- seeded and established alfalfa. The efficacy of 2,4-DB (Butress( in weed control of alfalfa was compared with commonly used herbicides in alfalfa.
The experiment was performed in randomized complete-block design with 4 replications and 12 treatments. In new-seeded alfalfa, the treatments were included EPTC (Eradican) 5 L/ha, Metribuzine (Sencor) 750 g/ha, 2,4-DB (Butress) 3 and 3.5 L/ha, Bentazon (Bazagran) 3 L/ha, Imazethapyr (Persuite) 0.5 and 1 L/ha, and without herbicide control treatment. In established alfalfa, the herbicide treatments was the same, but metribuzine and EPTC were not used.
In new-seeded alfalfa, the best treatments for density decrease of Sisymbrium irio, Descurania sophia and Malcolmia africana were Metribuzine 750 g/ha, Bentazone 3 L/ha, and Imazethapyr 1 L/ha. The best treatments for biomass decrease of Sisymbrium irio were Bentazon (Bazagran) 3 L/ha and Imazethapyr (Persuite) 0.5 and 1 L/h, The best treatments for biomass decrease of Descurania sophia were Bentazon (Bazagran) 3 L/ha, Imazethapyr (Persuite) 0.5 and 1 L/h, and Metribuzine (Sencor) 750 g/h. The best treatments for biomass decrease of Malcolmia africana were Bentazon (Bazagran) 3 L/ha, Imazethapyr (Persuite) 0.5 and 1 L/h, Metribuzine (Sencor) 750 g/h, and 2,4-DB (Butress) 3 and 3.5 L/ha. The best treatments for increasing yield in new-seeded alfalfa during first harvest was Imazethapyr 1 L/ha, during second harvest were Imazethapyr 0.5 and 1 L/ha and during the third harvest were Imazethapyr 0.5 and 1 L/ha, 2,4-DB 3 and 3.5 L/ha, and Bentazon 3 L/ha. Metribuzine 750 g/ha caused phytotoxicity in new-seeded alfalfa during all of the cuttings. In established alfalfa, 2,4-DB 3.5 L/ha was the best herbicide in density reduction of Lactuca, and the best treatment for decrease in Lactuca biomass were 2,4-DB 3.5 L/ha, Imazethapyr (Persuite) 0.5, and 1 L/h. The best treatment for increase in established alfalfa yield at first harvest was Imazethapyr 0.5 and 1 L/ha, at the second harvest were Imazethapyr 1 L/ha, Bentazon 3 L/ha, and 2,4-DB 3.5 L/ha, and at the third harvest were all herbicide treatments except for Metribuzine 750 g/ha and 2,4-DB 3 L/ha.
In new-seeded alfalfa, Metribuzine (Sencor) 750 g/ha, Bentazon (Bazagran) 3 L/ha, and Imazethapyr (Persuite) 1 L/ha were the best treatments in decrease of Sisymbrium irio, Descurania sophia and Malcolmia africana density. 2,4-DB (Butress) 3 and 3.5 L/ha was successful only in decrease of density of Malcolmia africana. The efficacy of Bentazon (Bazagran) 3 L/ha and Imazethapyr (Persuite) 1 L/ha was significant in decrease of Sisymbrium irio, Descurania sophia and Malcolmia africana biomass. Alfalfa yield loss was observed in response to Metribuzine 750 g/ha during all three harvests. In established alfalfa, 2,4-DB 3.5 L/ha with the highest ability in Lactuca density decrease and Metribuzine 750 g/ha with complete control of Sonchus were the best treatments. 2,4-DB 3.5 L/ha and Imazethapyr (Persuite) 0.5 and 1 L/h with significant decrease in Lactuca biomass and Metribuzine 750 g/ha with complete control of Sonchus were better treatments. Due to phytotoxicity of Metribuzine 750 g/ha, the yield loss of alfalfa was observed in response to that herbicide during all three cuttings. Therefore, efficacy of Bentazon, 2,4-DB and Imazethapyr depends on their dose and weed species. The same herbicides are recommended to increase alfalfa yield. Metribuzine could control weeds, but it is not recommended for weed control, because alfalfa yield decreased under the effect of this herbicide. In this study, Metribuzine was used as post-emergence. If Metribuzine was used as a soil-applied herbicide, better result can be obtained. It is necessary for supplementary studies for exact results.

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.

Cabbage aphid (Brevicorynebrassicae L.) is one of the most important pests of canola in Iran. The pest attacks to the leaves, stems, flowers and pods of the host plant. Feeding and sucking the sap from the plant tissues normally cause leaf and stem deformities and reduce the quality and quantity of the seeds. It was reported that damage caused by the pest can reduce 9 to 77% of the canola yield. Several studies indicated that host plant resistance is an important method which influences population dynamics of B. brassicae and reduces damage of the pest in the field conditions.Using resistant varieties can be the simplest, practical, effective and economical method for the pest control ascomparedwith other control methods. The aim of this investigation was to study population dynamics of the cabbage aphid on different canola cultivars under the natural field infestation and evaluate thepest influence on the studied cultivars/hybrids yield and yield components in Shahre-kord.
Material and Population dynamics and damage of cabbage aphid were studied on five cultivars (including: Okapi, Licord, Talaye, Modena, Tasilo) and two hybrids (Hyola 308 and Hyola 401) of canola based on the completely randomized block design in three replicates under the field conditions. To study population dynamics of the pest, sampling was started from the beginning of the infestation (the first decade of April) and continued weekly until harvesting time. For this purpose, five plants in each replicates were selected randomly and the number of aphids (nymphs and adults) was counted on 10 cm of each stem. Moreover, at the harvesting time, 10 plants from each replicate were selected randomly and the yield and yield components includingnumber of pods, number of seed per pods, weight of 1000 seeds were measured. Statistical analysis was done using Proc ANOVA in SAS 9.1 software.
Ourstudy addressed the seasonal activity and population dynamics of the canola aphid on different canola varieties under the field conditions.The results indicated that the activity of cabbage aphidwas started from the first decade of April and reached to the highest level at the flowering stage at the third decade of May. The highest (450 aphids/plant) and lowest (200 aphids/plant) population density were observed on Talaye cultivar and Hyola 401 hybrid, respectively. Similar results were reported by KhazduziNejadJamali et al. (2012) and Sarwar et al (2002).Mean comparison of yield and yield components in different canola cultivars and hybrids under the field infestation to cabbage aphid showed the highest (83.47) and lowest (12.69) number of pods in Hyola308 hybrid and Modena cultivar, respectively. Moreover, the highest (13.27) number of seeds per pod was observed in Tasilo cultivars, whereasthe highest seed weight was identifiedin Tasilo and Hyola hybrids. Themaximum and minimumyieldwere, respectively, recorded forTasilocultivar(0.41 gr/plant) and Modenacultivar(0.01 gr/plant).Our finding was similar to the results of Monfared et al (2003) who reported that Hyola 308 and Hyola 401 hybrids and Talaye and Licord varieties were resistant to the cabbage aphid. Keyhanian et al (2008) observed the highest pest population on Licord cultivar which supports our findings. However, they reported the lowest yield in Hyola401 which is in contrast with our results. The differences between the results canbe due to the influence of environmental factors on the studied cultivars.
Our results demonstrated that Hyola 401 hybrid had the highest number of pods per plantand number of seed per pod and Tasilo cultivar had the highest yield and seed weight. In addition, the lowest yield and yield components was found for Modena cultivar. Therefore, Tasilo was the most suitable and Modena was the least suitable cultivar for growingin Shahre-kord.Sincepesticide applicationto control the pest has several disadvantages such as increasing production cost, developing resistant races, destroying natural enemies and environmental hazards,integrated pest management based on the host plant resistance is, therefore, essential for controlling the canola aphid. Usingthe resistant hybrids and cultivars can reduce insecticides hazards, protect natural enemies and help integrated management of the canola aphid.

Soil-borne fungi and root-knot nematodes are distributed all over the world and cause great economic loss to tobacco. The best managing method to these diseases is using resistant cultivars. This research was performed to determine the effect of black shank and root-knot nematode on quality and yield of tolerant air-cured tobacco cultivars in Golestan province during 2014-2015 with 4 treatments and 3 replications. Three tolerant (K17, Burley Geel3 and BCE) and a susceptible tobacco cultivar (Burley 21 as control) were planted and grown on 5 × 8 m2 plots in a randomized complete block design (RCBD) as coupled plots in a field that was naturally infested with both pathogens in Valeshabad village of Gorgan. Black shank (Phytophthora nicotianae) severity on tobacco plants was determined weekly based on 1 to 5 index. Evaluation of root-knot nematode infection was performed based on gall index (0-10 scoring system), number of egg masses, and average number of eggs per egg mass at the end of season. Important morphological, agronomical and qualitative traits were determined. Mean comparison of qualitative traits showed that in the terms of nicotine content, BCE had the highest and Burley 21 had the lowest amount. For potassium level, BCE had the highest and K17 had the lowest amount. For total nitrogen, Burley 21 had the highest and Burley Geel3 had the lowest content. Reaction of air-cured tobacco varieties to soil-borne pathogenic agents showed significant differences at P≤1% or 5%. In terms of all agronomic traits, yield and disease amount, BCE cultivar was superior and showed lowest disease incidence and infection percent. The susceptible control cultivar (Burley 21) showed the highest rate of infection to soil-borne diseases and was the poorest in agronomic traits and yield.