Iranian Plant Protection Research
Year:2020 | Volume:34 | Issue:1|Papers Count:11

Introduction: Sugar beet is adaptable to be cultivated in different weather conditions and regions. In 2015, the overall area for sugar beet cultivation was estimated about 105, 000 hectares which 19000 of this was in Khorasan Razavi province. Sugar beet is considered as a valuable agricultural crop both for economy and employment. Nevertheless, producing this crop faces many challenges including the high number of pests. One of these pathogenic factors is the nematodes. Among plant-parasitic nematodes cyst nematodes are a large group with economic importance in different countries. These nematodes cause much damage to agricultural crops. Among the different cyst nematode genera Globodera and Heterodera have species which are important due to economic damage. Materials and Methods: During the year of 2016, 22 samples of soil and roots of sugar beet in cyst nematodes contaminated field in Khorasan Razavi were gathered. Cyst nematodes were extracted by the use of a small clip and a binocular and put in petri dish with some water. White females were also taken from the root by a delicate needle and put in sterile distilled water after washing. Separating and purifying fungi were done in 3 parts: separating fungi from cysts and females, separating fungi from eggs and larvae nematode, and making single spore fungi and pure culture. The cysts and separated females were washed by distilled water for several times and antisepticised for 1, 2 or 3 minutes in 10% Sodium Hypochlorite, and 10% and 20% Ethyl alcohol. Cysts and females were washed again with sterile distilled water and sterile sifter was used. The cysts and females in petri dish containing PCA, PDA, CMA and MEA culture mediums were separately taken and cultured by a needle under laminar. Four cysts were placed at the 4 sides of each 8cm petri dish containing the above mentioned culture mediums. 16 brown cysts from each soil sample were cultured. Two petri dishes from each sample were kept and checked consistently in two hot and cold temperatures in incubator with 20-25 and incubator with 8-10. After 7-14 days the grown fungi were taken to a new culture medium of PDA for a better development and in later stages they were purified on WA culture medium by single spore or hyphal tip methods. Purified fungi were kept in test tubes containing PCA food environment and 4 temperature and also on sand for later studies. Cyst shells were destructed by cyst crusher (homogenizer) and their eggs and mash were released. Released eggs from cysts were formed into suspension in sterile water. 0. 5-1 ml of suspension of eggs and larvae were taken by sterile micropipette and diffused on petri dish containing water agar culture medium. These culture mediums were kept and checked regularly in dark in the incubator with 20-25. Grown fungi from these eggs and larvae were taken to a new culture medium and purified by single spore and hyphal tip methods. WA culture medium was used for single spurring and purifying fungi. PCR based methods: morphological and molecular identification, were used to identify the fungi isolates. Mycelium fungi growth phases, fungi DNA extraction, PCR reaction and electrophoresis were done to identify molecular fungi. Lipase and chitinase assays were performed on the isolates. Results and Discussion: For Lipase test, each fungal isolate was cultured on peptone agar media and after 7 days isolates were examined. Around the colony of the isolates produced by the lipase enzyme formed a precipitate or a colorless aura, which is due to the formation of calcium salts from free lauric acid by the lipase enzyme, which indicates the positive activity of lipase. Among the isolates, Colletotrichum gloeosporioides had the highest sediment content, indicating the activity of lipase enzyme and the highest isolate in this test. After that, Neonectria macrodidyma and Penicillium chrysogenum showed the highest activity of lipase enzyme activity. Fusarium oxysporum showed no sediment and the lowest level of lipase enzyme activity was observed in this fungus. For chitinase test, isolates were cultured on colitic kitein medium. Around the colony and also the color of the culture medium, the chitinase-producing isolates changed the violet color, which indicates the positive activity of the chitinase enzyme in these isolates. Relative analysis of chitinase activity showed that the isolate of P. chrysogenum had the largest and fastest change in color to violet, indicating the highest production of chitinase enzyme by this fungus. The lowest chitinase production was by C. gloeosporioides, which showed the slightest and slowest changes in color compared with other isolates and the weakest isolate was introduced for the production of chitinase enzyme. Conclusion: In this research, different fungi were isolated from sugar beet cysts. Most fungal isolates belonged to Torbat-e-Haidiriyah and Fariman, and the least isolates belonged to Khaf. The highest frequency of Fusarium isolates was found to be 37. 35%. Isolation of Simplicillium lanosoniveum fungi, P. chrysogenum, C. gloeosporioides was the first reported cyst nematode in sugar beet. In the relative analysis of lipase activity, it was found that P. chrysogenum and C. gloeosporioides fungi exhibited the highest amount of lipase production, which was the highest marker in this test. Relative analysis of chitinase activity showed that P. chrysogenum had the largest and fastest color change to purple, indicating the highest production of chitinase enzyme by this fungus. The lowest chitinase production was obtained by isolate C. gloeosporioides, which showed the slightest and slowest changes in color compared with other isolates. The fungus P. chrysogenum showed the best results in both tests, this fungus is, therefore, recommended for further research with the observation of the necessary points.

Introduction: The sweet potato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), is an economically important pest of a variety of agricultural crops worldwide. The control of sweet potato whitefly largely relies on the use of synthetic insecticides. However, the efficiency of chemical control is questionable with respect to the activity of adults and immatures on the abaxial surfaces of leaves. In addition, under the strong selection pressure of the chemical control, whitefly populations have become resistant to most registered insecticides. Therefore, the search for more environmentally friendly options for whitefly control is necessary. Botanical extracts are broad-spectrum materials, used in pest control and they compared to synthetic ones may be safer for the environment, are, generally, less expensive and are often decomposed to nontoxic products. They are potentially suitable for use in integrated pest management. Recently, in addition to the botanical insecticides, vermicomposting has been also proposed as a safe control method for insect pests. Vermicompost is an organic soil amendment, produced by earthworm digestion of organic waste. Studies show that plants grown in soil amended with vermicompost grow faster, are more productive and are less susceptible to a number of arthropod pests. In this research studied the mortality effect of ethanol extracts of the seeds and leave of Ricinus communis L. (Euphorbiaceae), Sophora alopecuriodes L. (Fabaceae), Aloe vera (L. ) (Liliaceae) on adults of B. tabaci that reared on a tomato that planting in vermicompost from two different sources (pistachio waste and cattle manure). This result was compared with the insecticide abamectin. Materials and Methods: The experiments were carried out in a completely randomized design and in a growth chamber at 25± 2 º C, photoperiod of 16: 8 (L: D) and with the 55± 5 % relative humidity. Seed from the tomato cultivar ‘ CH-Falat’ were sown into the pots (5×10 cm), containing different growth media. The three growth mixtures tested were: (i) 100% BAGA (sterile plant growth media); (ii) 70% BAGA with 30% pistachio waste vermicompost; (iii) 70% BAGA with 30% cattle manure vermicompost. After the bushes reached the 2-4 leaf stage the bioassay tests were done by using the leaf-dip method. After drying of leaves, 20 adults of B. tabaci (24h) were released into each pot. The mixture of ethanol and distilled water (1: 10) was as a control. After 72 h, mortality was recorded. To determine the effects of the sub-lethal dose (LC25) on the developmental durations of B. tabaci, the tomato pots that were prepared as above mentioned, dipped into LC25 concentration of each extract and abamectin, for 5s. After the drying of leaves, 15 pairs of B. tabaci adults were released in the pots and the cage was covered on the pot immediately. B. tabaci were removed from the plants after 72 hours and only the eggs less than 24 hours old were kept for the recording of the different stages of B. tabaci. Results and Discussion: Based on the results, the kind of growth media was effective in the influence of extracts and abamectin, and the least LC50 of each insecticide was recorded in growth media that was added by pistachio waste vermicompost. Among the extracts, Aloe vera and leave of R. communis extracts showed the best and lowest effect against the B. tabaci with LC 50 value of 0. 855 g/l and 22. 841 g/l respectively (in pistachio waste vermicompost media). Subletal (LC25) effects of treatments on biological parameters of B. tabaci were significant compared to the control plant (p<0. 05). Based on the results, the most mortality (%) in egg (22. 84%), nymphal (42. 11%) and pupal (11. 94%) periods of B. tabaci was recorded for abamectin, Aloe vera and S. alopecuriodes extracts respectively. The interaction between vermicompost and extract was significant, and the longest of the nymphal period (19. 83± 0. 67 days) was recorded on whiteflies that were treated by R. communis and reared on tomato plants grown in pistachio waste vermicompost. The shortest of this period (11. 14± 0. 34 days) was recorded on control plant that grown in BAGA. Taken together, the longest development time was recorded on whiteflies that treated by S. alopecuriodes and reared on tomato plants grown in pistachio waste vermicompost and the shortest of this period was on insects treated by Aloe vera extract and pistachio waste vermicompost media. Plants fertilized with pistachio waste vermicompost had significantly higher phenolic content (10 mg/mL) than control (BAGA) (6. 08 mg/mL), while those in cattle manure vermicompost group exhibited intermediary value (7. 28 mg/mL). Conclusion: These results indicated that the concomitant use of extract and vermicompost was more effective for controlling of B. tabaci. The most mortality caused by Aloe vera extract and amending of pistachio waste vermicompost into growth media increased its effectiveness. So, these extract and vermicompost can play an important role in the managing of B. tabaci in greenhouse crops.

Introduction: Bracon hebetor Say is a well-known cosmopolitan ectoparasitoid that attacks larvae of the various lepidopteran pests, in both grain storage and field conditions. This parasitoid mass-reared on Anagasta kuehniella (Zeller) larvae in many insectaries of Iran and released annually into cotton, soybean, tomato and maize fields especially to control Helicoverpa armigera (Hü bner) in augmentative biological control programs. Cold storage has been considered as an important part in augmentative biological control programs. This technique enables insectaries to store a sufficient number of biocontrol agents for a prolonged period, thus allowing the release of natural enemies concurrent with the critical stages of the pest and minimizing the cost of insect colony maintenance when they are not in demand. In an effort to improve the techniques used in the mass rearing and release of this parasitoid we assessed the storage feasibility of pupa and adult stages of this wasp at a low temperature and the effects of cold storage on its biological and reproductive parameters. Materials and Methods: B. hebetor adults were initially obtained from a commercial insectarium in Gorgan, northern Iran and reared on Anagasta kuehniella (Zeller) larvae as factitious host for about five generations. Cold storage experiments were carried out on pupal and adult stages of parasitoid separately. Five hundred 5-days old pupae and five hundred couples of both sexes (female and male) of one-day-old adult parasitoids were collected from the colony and divided into ten groups of 50 parasitoids. Each group (considered as a replication) was released into plastic vials separately, fed adults for 24 hours with a 30% honey solution and then stored in a refrigerator (5± 1˚ C, and full darkness) for 7, 14, 21, 30, 45, and 60 days. Vials of non-refrigerated control groups were kept at 26± 1˚ C, 60± 5% RH, and a photoperiod of 16L: 8D h. After each storage period, the pupa eclosion percent and adult mortality percent were subsequently assessed. To evaluate the effect of cold storage on longevity and fecundity of parasitoid, 30 female-male pairs were chosen randomly from the emerging adults (in pupae cold storage experiment) or surviving adults (in adults cold storage experiment), and each pair was placed in a plastic vial separately. Daily, the paired wasps in each container were provided 10 last instars A. kuehniella larvae on a piece of paper, as well as several drops of honey solution. The number of eggs laid was recorded on a daily basis until the female parasitoids died. To evaluate the effect of cold storage on parasitoid performance in the next (F1) generation, 50 newly laid eggs of parasitoid were removed from parasitized host larvae, placed in 10 cm diameter petri dishes individually (one egg/dish) and allowed to develop to adult stage. Developmental time (the period from egg to adult emergence) was recorded for male and female progeny separately and sex ratio (female percentage) of emerging adults was then determined. All experiments were carried out using a completely randomized design (CRD) and data were analyzed using one-way ANOVA and LSD test. Results and Discussion: Eclosion rate of cold-exposed pupae decreased significantly with increasing cold storage duration. After 7 days of cold storage, about 93 percent of pupae were emerged, whereas all pupae died and no adult wasp was emerged, after 30 days of cold storage. However, cold storage of pupae even for a short duration (e. g. 7 days), had a significant adverse effects on longevity, fecundity and sex ratio of emerged adult parasitoids and means of these parameters were reduced by 55. 8, 53. 4 and 20%, respectively, compared to unstored control pupae. In adult cold storage experiment, survival rate of both male and female parasitoids was reduced significantly, according to cold duration. Adult mortality percent increased with storage duration and reached 100 and 97. 14 % in 60 days storage of male and female parasitoids, respectively. One week storage at 5˚ C resulted in 4. 42 percent mortality in females which was not significantly different from that of the control. Cold storage duration had no adverse effect on the longevity of both male and female parasitoids. Reproductive parameters including mean of daily oviposition (eggs/day/female) and clutch size (eggs/larva) were also not significantly affected by cold storage durations. Low temperature storage of parental parasitoids had no significant effect on developmental time (the period from egg to adult emergence) and sex ratio in the F1 generation. Developmental time of progeny had a little variation among the treatments and changed from 11. 9 to12. 77 days in male and 12. 07 to 12. 8 days in female progeny. Conclusion: Cold storage of pupae even for a short period, reduced significantly their eclosion rate and longevity and fecundity of adults emerged from these cold-exposed pupae. Cold storage of adult B. hebetor, affected negatively their survival, whereas other fitness traits such as longevity, fecundity, developmental time and sex ratio were not significantly reduced after cold storage. In conclusion, B. hebetor pupae is not recommended to be stored at low temperature, even for a short period but adult parasitoids can be cold stored for up to 7 days, with negligible mortality (4. 41 %). The results of this study can be used in parasitoid mass rearing and cold storing in insectaries.

Introduction: European red mite (Panonychus ulmi (Koch)) and two-spotted spider mite (Tetranychus urticae Koch) are the two major pests of deciduous trees and most of the acaricides used in the control of them in apple orchards of Iran. The early of these two mite damages on leaf chlorophyll contents caused plant retardation, reduce fruit size and quality in apple production. Extensive mite pest damages during the middle of spring and summer months not only caused complete leaves shedding but side effects of this unusual condition imposed shortages of nutritional on vigorously of infested apple trees in next year on apple production also. Most of the new acaricides introduced and registered here in the last two decades demanded and evaluated against apple mite pests. Reduce the hazardous risk of synthetic acaricides application, so many efforts since 1995 undertaken since 1995 for sustainable mite pest’ s management and keeping environmental and natural enemies safer in apple orchards. Evaluation of organic pesticides in developed countries in control of apple pests received more attention mostly to overcome spider mite pest damages in the world. In Iran, the only sulfur powder was tested in 1954 against citrus russet mite and no other mineral as an acaricide tested on apple mite pests in Iran. In this study, for the first time, the effect of Kaolin doses investigated on active stages of European red mite in four major apple growing orchards of Iran. Concerned literature survey indicated that this the first in depended kaolin effects report from Iran. Material and Methods: Different kaolin doses (3, 4 and 5%) against Panonychus ulmi infested apple orchards during investigated 2014. Effect of this pesticide was compared with registered acaricides such as Envidor (spirodiclofen 240 SC), floramite (bifenazate 24% SC), Danitol (fenpropathrin 10% EC), Ortus (fenpyroximate 5% SC), 1. 5% detergent dishwashing along with water sprayed on apple trees as in uncontrolled treatment. Experiments conducted in different provinces of Iran (West Azerbaijan, Esfahan, Ardebil and Khorasan Razavi provinces during 2014). Treatment effectiveness was determined by random 40 apple leaves collected at the interval of one day before and 3, 7, 14 and 21 days after treatments. Active mite stages on the upper side of the apple leaf counted with the help of a stereomicroscope. Collected alive mite raw data from each treatment at different interval times, converted into morality% by Henderson-Tilton formula. Mean mortality% analysis variance done with SAS software. Grouping and ranking effects of each treatment carried out by DUNCAN methods. Results and Discussion: Mite mean density before treatments on apple leaves among treatments found varied during 2014 in different provinces. The highest mean of mite out of 40 leaves before treatments in West Azerbaijan, Esfahan, Ardebil and Khorasan Razavi provinces recorded 11. 60± 0. 28, 13. 52± 1. 29, 11. 85± 0. 32 and 4. 75± 0. 15 respectively with total apple leaves infestation of 65 to 80% in all provinces. Lower doses (3 and 4%) of kaolin pesticides in the control of mite pests in all experimental stations except in Ardebil observed very weakly and less than 50% up to 14 days after. The highest mite mortality% time up to 7 days after treatments for 5% kaolin dose recorded 75. 97% and 78. 70 up to 7 days in Oromia and Ardebil and up to 14 days after observed 66. 68%, 75. 23% in Esfahan and Khorasan Razavi provinces respectively. A sharp reduction in apple mite pest control recorded at 21 days sampling interval for kaolin 5%. All kaolin doses sprayed on apple trees found without phytotoxicity during the hot and dried period of sampling time in all places. Expected control with 5% kaolin application at the early stages of P. ulmi activity for a once during the growing season is possible. Conclusion: Application 5% kaolin at the lower incidence of Panonychus ulmi for once during the growing season in apple orchards recommended.

Introduction: Arbuscular mycorrhizal fungi are one of the most important fungi in the soil, which coexist with the roots of many plants almost from 400 million years ago. These fungi play an important role in the sustainable functioning of agricultural ecosystems. Mycorrhizal fungi are not only beneficial and can increase the growth of plants, in some cases, some mycorrhizal species also cause growth reduction in certain species of plants. Investigating the effect of mycorrhizal fungus on growth of nine important weed species in the fields showed that the growth of weeds in the presence of fungi decreases. The Piriformospora indica is a root-endophytic fungus that was isolated from the rhizosphere soil in the Thar Desert of India. This fungus same as typical AMF greatly improves the grown and overall biomass production of a broad spectrum of hosts. This fungus coexists on the root of a number of crops and weeds of monocotyledons, dicotyledons, Chenopodiaceae and Brassicaceae that do not inoculated by mycorrhizal fungi. This research was conducted to evaluate and compare the growth response of wheat and some important weeds of this crop, to Glomus mosseae and P. indica in controlled conditions, for ecological management of weeds. Materials and Methods: In order to investigate fungal root colonization of wheat and some weed species, nine separated trails were carried out as completely randomized design with five replications in 2016. Treatments were inoculation with Glomus mosseae, Piriformospora indica and non-inoculated control on nine plant species of wheat (Tritium asativum L. ) wild rye (Secale cereal L. ), wild barley (Hordeum spontaneum Koch), barley (Hordeum morinum L. ), wild oats (Avena ludoviciana Durieu), flixweed (Descurainia Sophia L. ), drooping brome )Bromus tectorum L. ), chickweed (Stellaria media L. ) and grass pea (Lathyrus sativus L. ). The soil used was (1: 1) soil and fine sand. After passing through a sieve of two mesh, for three consecutive days and for four hours per day was sterilized in oven at 120 ° C. After filling pots out with one kg of autoclaved soil, spores of G. mosseae and mycelia pieces of P. indica, were added to the pots. Ten seedlings were transferred in to each pot and were thinned to three seedlings per pot at 2-4 leaves stage. Plants were harvested 8 weeks after transplanting, the plants were removed from the crown and transferred to the laboratory. The roots of the plants were washed with distilled water to be thoroughly cleaned, and then the root of a plant from each pot was randomly cut into pieces of one centimeter and prepared to determine the percentage of colonization. Shoot and root dry matter and mycorrhizal growth responses were determined as well. Results and Discussion: The results indicated the different effects of fungi on wheat and weed species. Roots of wheat were colonized by G. mosseae and P. indica fungi by 87. 9 and 90%, respectively. The lowest amount of root colonization by P. indica and G. mossea was observed in the chickweed by 10 and 7. 5%, respectively. As a result of coexistence of both species of fungi with barley, wild barley, flixweed, drooping brome and grass pea, root and shoot dry weight were increased, and in some other plants, in the presence of either G. mosseae or P. indica, the root and shoot dry weight decreased, compared to the control. The dry weight of wild rye and chickweed in coexistence with P. indica was 0. 13 and 0. 35 g plant-1, respectively, and in coexistence with G. mosseae was 0. 14 and 0. 33 g plant-1, respectively. Compared to the control, the use of P. indica reduced shoot dry weight of wild rye and chickweed by 31. 58% and 14. 63%, respectively, and the use of G. mosseae in wild rye reduced 26. 36% of shoot dry weight. Dry weight of Elusine coracana in presence of Phizophagus intraradices mycorrhizal fungus increased by 40% and in the presence of P. indica increased by 81% compared with control. Biomass reduction in lambsquarters in the presence of mycorrhizal fungi was 26% compared with the un-inoculated plants. The weeds and wheat in the presence of P. indica and G. mosseae varied in terms of mycorrhizal growth response. Mycorrhizal growth response of weeds was varied from-32. 26 to +48. 78 percentages. Among the monocotyledon weeds, the highest growth response was observed in the presence of P. indica in the weed of barley (47. 78%) and wild barley (44. 14%). Both P. indica and G. mosseae caused a negative growth response in wild rye, so that the growth response in the presence of P. indica was-0. 66% and in the presence of G. mosseae-23. 22%, indicates that the growth reduction of wild rye was higher in the presence of P. indica. The difference in mycorrhizal growth response in weeds, in addition to plant species, depends on the type of soil and environmental conditions. Conclusion: In general, due to the different reactions of wheat and some studied weed species to P. indica and G. mosseae inoculation, it seems that the application of these fungi in wheat fields could cause reduction in grass weed damages.

Introduction: There are many factors that affect the efficacy of herbicides such as formulation, physicochemical properties of the herbicide molecule, morphology and physiology of weeds, application time, and environmental conditions at the time of herbicide application and quality of their carriers. Meanwhile, water is considered as the most important and common carrier in most herbicides in which the activity of herbicide molecules are influenced by its quality. In general, there are many factors that stimulate water quality such as water hardness, pH of water, water temperature, bicarbonate ion content, turbidity of water and organic matter, iron and other substances affect the uptake, transport and optimum performance of some herbicides. Effect of magnetic fields on water is now the subject of an increasingly large research effort because it is known to reduce water hardness. In physic science, it is well established that by passing water through a magnetic device, the water can be influenced. However, the literature review in physical science in different country indicated also that magnetized water induced a change in water physicochemical properties such as conductivity, surface tension, viscosity, vaporization rate, and pH. So this technology was used in different countries who all reported the successful use of magnets in treating water for herbicide application. Using magnetized water in sprayer`s tank for some herbicide which sensitive to hard water, with reduced does, might lead to better weed control. Material and Methods: To study the effect of passing water of sprayer`s tank through magnetic field on Nicosulfuron efficacy, yield and yield components of Corn (Zea mays L. ) two factorial experiments conducted based on randomized complete block design with three replications at the research field of Ferdowsi University of Mashhad ( Lat 36˚ 15' N, Long 59˚ 28' E; 985 m Altitude) during 2016-2017. Experimental factors included Nicosulfuron dose in 5 levels: 0, 20, 40, 60 and 80 g a. i. ha-1 (recommended dose) and water type of sprayer`s tank with 3 levels (no magnetic water, 10 and 20 times passed water through magnetic field 650 mT). Magnetized water was produced by a commercial magnet namely AQUA CORRECT (650 Gauss magnetic field). Plots were sprayed on 6-leaf stage of corn by a knapsack sprayer with a flat nozzle no. 8002 at 240 kPa and with delivery volume of 185 liters per hectare. At the end of growth season (physiological maturity of corn), crop height, yield and yield components of corn including plant height, No. of row per ear, ear length, No. of grain per row, No. of total grain per ear, 100 seed weight, grain yield, biological yield and harvest index and total weed density and total weed biomass measured in 2 m2 area of each plot. After Batrlet test and confirmation of homogeneity of error between two years of all data were analyzed by SAS ver. 9. 1 and Excel ver. 2007 and treatments were separated using LSD Test. All statements of significance were based on probability of (P ≤ 0. 05). Results and Discussion: According to the results, 10 times of passing water of sprayer`s tank through magnetic field (650 mT) combined to 60 and 80 g a. i. ha-1 Nicosulfuron significantly reduced total weed density and biomass in corn field. The maximum biological yield of crop (42510 Kg ha-1), grain number in ear`s row (45), total number of grain per ear (627. 2) and weight of 100 grain of corn (35. 5 g) observed in 10 times of passing water of sprayer`s tank through magnetic field (650 mT) with the 60 and 80 g a. i. ha-1 of Nicosulfuron, which were 57, 21, 44, and19% more than the control treatment (no herbicide and no magnetized water), respectively. Also grain yield of corn increased significantly (p ≤ 0. 05) in control treatment of water with increasing the Nicosulfuron herbicide doses in both years of this experiment. The maximum yield observed in the combination of maximum Nicosulfuron dose with 10 times passed water of sprayer`s tank through magnetic field (650 mT) in both years. The lowest grain yield observed in the control treatment and the highest ones achieved in 100 percentage of herbicide recommended dose. It was concluded that the best combination treatment was 60 and 80 g a. i. ha-1 of Nicosulfuron and 10 times passing water sprayer`s tank through magnetic field 650 mT for corn.

Introduction: Jimsonweed (Datura stramonium L. ) is considered as a serious weed in many crops such as corn, soybean, Chitti been and cotton and in waste land. Due to jimsonweed is resistant to most commonly used herbicides, its control is difficult. Contamination of wheat, rye, buckwheat and linseed with seeds of jimsonweed resulting in poisoning have been reported. A precise prediction of the phenological development of jimsonweed in crops would provide timely control for more efficient management of it in growing season. Materials and Methods: The experiment was carried out at Iranian Plant Protection Research farm in Karaj (Meshgin dasht) during 2013. The experiment was a split plot layout as randomized complete block design with three replications per planting date (March, April, May, June, July and August) and ecotypes (Karaj, Ghazvin, Shiraz, Gorgan, Esfahan, Mashhad and Oromiee) as the main plot and the subplot. Jimsonweed seeds were cultivated manually in four rows at a distance of 30 cm and a depth of 3-5 cm. The plants were noted twice a week to record the phonological stages of growth. Seven main stages were selected and studied according to the study of phonological stages of jimsonweed based on BBCH codes. The base temperature of jimsonweed was considered 8 º C. Time to main phonological stages of jimsonweed ecotypes including emergence, three-leaf, eight-leaf, flowering, fruiting, opening fruit and maturity were compared using linear regression model. Results and Discussion: One of the reasons for using linear regression to describe the phenological development of plants is that, during plant life and at the time of seedling emergence, the reaction of the rate of development of most plants is linear or near the linear temperature, which is the nature of the traditional thermal time method (GDD). This suggests that with increasing environmental temperature, there is a difference between the seeds of different ecotypes of jimsonweed during emergence of seedlings. Emergence rate was higher in Oromiee ecotype than the other ecotypes. Oromiee and Gorgan ecotypes reached to three-leaf stage sooner than the other ecotypes. Oromiee ecotype with smaller canopy reached sooner to reproductive stage that can be used as a mechanism for survival and seed production for future generations against the falling temperature during the last months of plant growth. The ecotype of Shiraz showed less reaction to temperature in this stage than other ecotypes due to higher average temperature in Shiraz city compared to Karaj city. Oromiee ecotype was more sensitive to temperature than other jimsonweed ecotypes. In other words, the rate of reaching to the phenological stages in this ecotype was higher for each unit of temperature. The rapid reaction of this ecotype to the increase of temperature could be due to the conditions of the growth of the mother plant of this ecotype compared to the other jimsonweed ecotypes. This trend was reversed in the ecotype of Shiraz, which means that this ecotype was less sensitive to temperature, and grew at a slower rate than the other jimsonweed ecotypes. The mother plants of this ecotype, in contrast to the Oromiee ecotype, were produced at a higher average temperature, which resulted in a lower reaction due to an increase in temperature per unit of temperature. Conclusion: Different ecotypes of jimsonweed have different phonological responses relative to the temperature. In addition, the rates of phonological development of ecotypes with different geographic regions were significantly different. In general, jimsonweed ecotypes showed the highest and lowest sensitivity to the increase in temperature at emergence and reproduction stages, respectively. Having knowledge of plant phenology, through the establishment of land preparation and planting date, will be effective for sustainable weed management. Additionally, the determination of the best time for spray also depends on the precise knowledge of the phonological stages. In many cases, the ineffectiveness of herbicides is due to the growth stages of the weed and the reduction of their sensitivity to them. Disturbance in the dynamics of the seed bank of weeds also requires knowledge of the germination characteristics and plant phonological stages. Recognizing these different behaviors in different ecotypes of weeds is very important and plays a very important role in recognizing patterns of weed adaptation to environmental conditions and also choosing appropriate management strategies.

Introduction: After moisture, temperature is the main driving force affecting seed germination. Population-based models are useful tools for describing and predicting germination in relation to time and temperature. These models estimate the thermal thresholds for seed germination, taking into account both the speed and final percentage of germination in different temperature regimes. The population-based approach has been widely used to model the thermal response of various plant processes such as germination and dormancy of seeds as well as seedling emergence in the field. However, the assumptions of this approach on the germination of seeds of some plant species, especially weeds, are not always correct. Therefore, in this research, the accuracy of prediction of different thermal-time approaches for modeling the germination time courses of bishop's weed (Ammi majus L. ) in response to constant temperature regimes was evaluated. Bishop's weed was selected because there are no reports regarding the germination response thresholds of this species to temperature in the scientific resources. Materials and Methods: Experiment was conducted at the Seed Technology Laboratory of Agricultural and Natural Resources University of Khuzestan in November 2017. In this study, germination response of bishop's weed was evaluated at different constant temperatures. The seeds of bishop's weed were collected from the margins of several wheat fields at the time of their natural dispersal in June 2014. The seeds of bishop's weed were incubated in the dark using incubators with controlled environments at eight constant temperatures of 8, 12, 16, 20, 24, 28, 32 and 36 º C with a range of ± 0. 2 º C. These temperature regimes cover both the sub-and supra-optimal temperature ranges. The trial was performed in a completely randomized design with four replications. The germinated seeds (criterion, radicle protrusion of > 2 mm) were counted and removed at frequent time intervals. The event-time approach (package drc in R environment software) was applied to determine the time taken for cumulative germination to reach subpopulation percentiles of 20, 50 and 80% of maximum in each temperature regimes. Experimentally obtained cumulative-germination curves were used to perform a non-linear regression procedure to assess the relative accuracy of different thermal-germination models in predicting germination response under constant incubation temperatures. Assessment of goodness-of-fit was performed by the Akaike information criterion (AIC). Results and Discussion: The values of RMSE and AIC showed that the model had better and more accurate fit to bishop's weed germination data when the Tb (base temperature) and θ Tm (thermal-time required to complete germination at temperatures greater than optimal (To)) were assumed to be constant for the whole seed population, and Normal distribution was used to describe the variation in θ T(g) (thermal-time required to complete the germination of each given seed fraction at a temperatures between the Tb and To) and Tm(g) (maximum temperature (Tm) for seed thermo-inhibition of given fraction g at temperatures between the To and Tm). Based on this approach, the Tb and θ Tm for this plant were estimated to be 1. 06 º C and 1155. 41 º C h, respectively. The values of θ T and Tm for seed fraction of 50% (θ T(50) and Tm(50)) were determined as 2708. 62 º C h and 34. 55 º C, respectively. The value of To was not constant for different germination fractions (To(g)), and for fraction 50% (To(50)) was determined to be 24. 51 º C. Thermal-time analysis is considered by many researchers to have physiologically and ecologically relevant parameters and, in its standard form, provides several useful indices of seed germination behavior in response to temperature. Despite its popularity, the generality of its assumptions has not been examined systematically. If these assumptions do not hold, at least approximately, in a particular situation, misleading interpretations can easily arise. The thermal-germination model presented here explained some of the adaptive characteristics of the germination response of bishop's weed to ambient temperature. Seed thermo-inhibition in this weed species occurred at temperatures beyond 25. 43 º C. In other words, the seeds of bishop's weed do not germinate when temperature will exceed this limit and thus remaining capable of germinating until the environmental conditions change. Conclusion: In summary, in this study, the thermal thresholds for seed germination of bishop's weed were identified. Our results showed that the Tb was constant for the whole seed population. The thermal-germination model described here gave an acceptable explanation of the observed seed germination patterns. Almost all the concepts and mathematical models described in this study can be applied to modeling seedling emergence in the field.

Introduction: When a contact herbicide is applied in the dark time of a day than in the light time, better weed control will be observed. Velvetleaf is a typical example of weeds in displaying the phenomenon of foliar Nyctinasty. This feature causes the leaf surface of velvetleaf is perpendicularly oriented to the ground during the dark time of day. As a result, when a contact herbicide is applied in the dark time of the day by a single flat fan nozzle which generates a perpendicular motion of spray droplets to the ground, the leaf surface of velvetleaf cannot be covered well. Therefore, the foliar Nyctinasty in velvetleaf reduces the efficacy of contact herbicide applied in the dark time of day. The main hypothesis leading this study was that if the motion of spray droplets is not perpendicular to the ground, it is possible to wet the leaves of velvetleaf in the dark time of day. In this study, the effects of using twin flat fan nozzles which generates a non-perpendicular motion of spray droplets to the ground in comparison with single flat fan nozzle on the efficacy of Paraquat at the different times of day were investigated. Materials and Methods: This study was conducted in outdoor conditions at Bu-Ali Sina University, Hamedan, Iran. Treatments consisted of five doses of Paraquat (0, 75, 150, 300, and 600 g a. i. ha-1) using three types of nozzles (single anti-drift flat fan, twin anti-drift flat fan 2020, and twin anti-drift flat fan 7030) in two nozzle sizes (110015 and 11002) at four times of day (before sunset at 20: 00, after sunset at 22: 00, before sunrise at 05: 00, and after sunrise at 7: 00) with four replications which were sprayed at the six-to-seven-leaf stage of velvetleaf. Two days after spraying at 7: 00, the shoots of velvetleaf were harvested nearly 1 cm above the soil surface. The individual fresh: dry weight ratio was used to analyze as nonlinear regression using a four-parametric logistic model. Results and Discussion At all four application times of the day, increasing the nozzle size of single anti-drift flat fan nozzle increased the dose of Paraquat required for the 90% desiccation of velvetleaf shoots. While, except at some application times of day (22: 00 and 07: 00 in the case of twin anti-drift flat fan nozzle 2020 and 5: 00 in the case of twin anti-drift flat fan nozzle 7030), increasing the nozzle size of twin anti-drift flat fan nozzles decreased the dose of Paraquat required for the 90% desiccation of velvetleaf shoots. Except in some cases (11002 twin anti-drift flat fan nozzle 2020 and 110015 twin anti-drift flat fan nozzle 7030), when Paraquat was sprayed with any nozzle size at 20: 00 and 07: 00, there was no significant difference in its efficacy. When Paraquat was sprayed with any nozzle size at 20: 00 and 07: 00, there was no significant difference in its efficacy. But, when it was sprayed with any nozzle size at 22: 00 and 05: 00, a significant difference in its efficacy was observed. So, the dose of Paraquat required for the 90% desiccation of velvetleaf shoots at 22: 00 was significantly lower than that at 05: 00. Our principal hypothesis in this study was confirmed. As when Paraquat was applied with twin anti-drift flat fan nozzles in the dark time of day, it more effectively improved the desiccation of velvetleaf shoots. Conclusion: The treatment of the application of Paraquat with 11002 twin anti-drift flat fan nozzle 7030 at 22: 00 required the minimum Paraquat dose to create the same desiccation intensity as other treatments. Therefore, this treatment is recommendable.

Introduction: Onion (Allium cepa L. ) is one of the most important vegetables (with 2. 305 million tons production) in Iran. Onion cultivation area of southern Kerman is 5732 hectares and this region is ranked first for onion production (307 thousand tons of production) in Iran. Onion growth and yield are significantly reduced by weed competition. Among the dominant weeds in onion fields at southern Kerman, Cyperus rotundus is one of the most important and problematic weeds. The slow growth of onion in the early stage, causes a significant yield loss due to the competition. C. rotundus is a perennial weed of the Cyperaceae family spreading quickly throughout the extensive underground system and tuber, with high ability to compete. This weed can decrease the average onions yield by 23 – 84%. Application of herbicides is the most prevalent weed control method in onion fields. Oxyfluorfen, and haloxyfop-r-methyl ester, are the commonly used herbicides for C. rotundus control in onion fields at southern Kerman. Therefore, the objective of this study was to investigate the effects of different herbicides on this weed. Materials and Methods: This experiment was conducted in Agricultural and Natural Resources research and Education Center, Jiroft, southern Kerman, during 2017-2018 and 2018-19. The experiment was carried out in randomized complete block design with three replications. The experiment treatments included: T1-Metribuzin (Sencor) 80% WP 500 gr. ha-1, T2-Oxyfluorfen(goal) EC24%, 2 lit. ha-1, T3-Oxadiazon (ronstar) EC 12% 3 lit. ha-1 + Oxyfluorfen(goal) EC24%, 2 lit. ha-1, T4-Pendimethalin (stomp) EC33%, 3 lit. ha-1, T5 Oxadiazon (ronstar) EC 12% 3 lit. ha-1, T6-Oxadiazon (ronstar) EC 12% 3 lit. ha-1 + Bentazon (bazageran) SL48% 3 lit. ha-1, T7-Oxyfluorfen(goal) EC24% at 1/5 lit. ha-1 two stages by 0. 75 lit. ha-1, (one week after transplanting and three weeks afterwards), T8-Pendimethalin (prowl) CS 45. 5% 3 lit. ha-1, T9-hand weeding and T10-control (no control). Other weeds except C. rotundus were hand-removed during the season. The herbicides were applied using a Matabi sprayer with delivering 354 L ha-1 at 2 bar spray pressure. C. rotundus shoot and underground organs dry weight, density, average of bulb weight and onion yield were measured. Statistical analysis was carried out using SAS ver. 9. 1 software and the comparison of means was undertaken based on the LSD test. Results and Discussion: The combined analysis of variance showed that the effect of treatment was significant on shoot and underground organs dry weight and density of C. rotundus, mean onion weight of bulb and yield, and reduced dry weight and density of C. rotundus and increased the onion yield. Among the chemical treatments, the combined application of Oxadiazon (Ronstar) as pre emergence followed by application of Bentazon (Bazageran) as post emergence (Treatment 6), decreased the density, underground and shoot dry weight of C. rotundus by 96. 89 and 93% relative to the control, respectively. The highest onion yield was obtained from the mentioned treatment and increased the onion yield by 87% with respect to the control. Indeed, the combined application of these two herbicides in different growth stages of weeds and onion, was able to resolve the limitations of separate application of these herbicides leading to the most effective control of C. rotundus. Conclusion: The results of this experiment show that the combination of herbicides can be an effective strategy to increase their effectiveness. The combined application of Oxadiazon (Ronstar) EC 12% at 3 lit. ha-1 as pre emergence + Bentazon (Bazageran) SL48% at 3 lit. ha-1 as post emergence was the most effective treatment after hand-weeding on purple nutsedge management and increasing the onion yield. Therefore, the mentioned treatment is recommended to control of C. rotundus in transplanting cultivation of onion in autumn farming in south of Kerman Provence.

Introduction: In recent years, food production known as a main challenge for increasing human population. Along with the development of agricultural systems, weed management practices have been developed to sustainable management. Allelopathy is the biochemical interaction of inhibition and promotion within plants or micro-organisms. Allelopathy considered as a mechanism of some plants was proposed firstly by Molish in 1937. Allelopathy has a broad application prospects in increasing crop production, plant protection, and biological control. There are many known allelochemicals: water soluble organic acid, straight-chain alcohols, aliphatic series, aldehydes, ketones, simple unsaturated lactone, long-chain fatty acids, multi-alkyne, naphthoquinone, anthraquinone acid, quinone compound, simple phenols, benzoic acid and its derivatives, cinnamic acid and its derivatives, coumarin, flavonoids, tannins, terpenoids, steroids, amino acids, peptides, alkaloids, cyanohydrin, sulfide, glucosinolates, nucleotides. While phenolic acids and the terpenoid compounds are more common types. Giradol (Chrozophora tinctoria L. ) known as an invasive annual summer plant that belongs to Ephorbiaceae family. Giradol not only can reduce the crop productivity by competition for light, water and nutrient mineral but also can decrease crop growth and productivity as it has the phenolic components such as tannins, saponins, cumarins, phenylpropanoid glycosides, and flavonoids. Thus, it may have allelopathic effects. Giradol have been reported in the wide range of fields in Khorasan Razavi province. This study was conducted for determining allelopathic effects of Giradol on tomato as the main crop being cultivated in Khorasan Razavi province. Materials and Methods: In order to evaluate allelopathic effects of Giradol on seed germination of tomato (Lycopersicon esculentum mill. ), this study was conducted in weed research lab of Ferdowsi University of Mashhad on the basis of a Completely Randomized Design (CRD) with factorial arrangement with 4 replications in 2014. The treatments consisted of Giradol organs at 4 levels (root, stem, leaf and total plant without inflorescence) and their aqueous extract concentrations at 11 level (0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10%). The plant organs were harvested from Fariman in the summer of 2014. The samples were carefully washed and then dried. The sample were ground and 10 g for each sample was added to 100 ml distilled water. The samples were shacked for 12 h, and the shaking process was done again after 72 h. The extracts were passed through the filter paper. The stoke solutions were diluted. Then, 6 ml from each extract was added to each experimental unit. The petri dishes were placed in a germinator at 25/15° C in 45/65% relative humidity with a 16/8 h day/night regime, respectively. The measuring traits were germination percent, germination rate, means of germination time, vigor, and root length, shoot length, root length to shoot length ratio, root dry weight, shoot dry weight, and seedling weight. Results and Discussion: The result of this experiment showed that concentration of aqueous extract had a significant effect on germination percent, germination rate, means of germination time, vigor, and root length, shoot length, root length to shoot length ratio, root dry weight, shoot dry weight and seedling weight at 0. 1% probability. Same results have been reported by Seyyedi et al (8) for allelopathic effect of castor bean organs on germination percent, germination rate and means of germination time of dodder. The variation response of different concentration of castor bean aqueous extract on germination of seeds dodder has been reported. The result of this experiment also showed that germination percent, germination rate, means of germination time, shoot length and root length had no significant effects by the type of plant organs whereas other trials showed significant effects. Generally, the leaf and stem water extracts had the highest negative effects on germination percent compared to the root and whole plant Giradol extracts. The same results reported by Rooffard and Omidbeigi (7) on the influence of extract concentration on the germination percent. Conclusion: The results showed that the concentration of the aqueous extract significantly affects the germination and seedling growth. Furthermore, the extract of different organs adversely influences the germination percentage, germination rate, mean of germination time, and shoot length. It seems that proper management of Giradol weeds before and during tomato growth can lead to higher germination and more uniform plant emergence and finally can be of help for enhancing crop yield.