IRANIAN JOURNAL OF WEED SCIENCE
Year:2020 | Volume:16 | Issue:1|Papers Count:12

To evaluate the soil residue of imazthapyr effects on cotton and maize, an experiment was carried out based on completely randomized design at greenhouse of Agricultural Faculty of University of Gonbad Kavous. Different doses of imazthapyr (0, 4. 5, 23, 45, 68, 91, 140, 180, 230, 340 and 450 μ g. kg-1 soil) were applied on maize and cotton and finally the dry weight of root and shoot, shoot height, root length and leaf area of crops were measured. Three and four Log-logistic curves were fitted to the data. Results indicated that almost all data fitted better to the three parameter log-logistic curve. Results of separate fitting of the data showed that the residue of imazthapyr always reduced dry weight of crops. For 50 percent reduction of shoot dry weight of cotton and maize, 13. 26 and 21. 91 g. a. i. ha-1of imazthapyr were needed respectively. To reduce 50 percent of root dry weight of cotton and maize, 72. 75 and 25. 19 g. a. i. ha-1of imazyhapyr were needed. Generally, the results of data simultaneously fitting showed that maize root and shoot sensitivity to imazthapyr were always more than cotton. Shoot height, root length and leaf area were decreased as imazthapyr residue was increased.

To determine the selective herbicides for weed control in black cumin, an experiment was conducted based on a randomized complete block design at the Research Farm of university of Zanjan. Experimental treatments consisted of POST application of foramsulforon, oxadiazinon, niclosulfuron, rimsulforone, sulfosulfuron, atlantis Ottelo and Pre-plant application of pendimethaline. Results showed that the treatments had a significant effect on the density and biomass of weeds and black cumin (P <0. 01). All herbicides except atlantis and foramsulforon decreased grasses weed biomass. Biomass of broadleaf weeds was reduced by herbicides in which the highest control was obtained from Atlantis and Ottelo. The treatments including pendimethaline, rimsulforone, Ottelo and Atlantis controlled total weeds by 60, 59, 57 and 50 %, respectively. The highest crop yield was achieved in weed free plots. Among the herbicides, oxadiazinon and foramsulforon caused the lowest injury on black cumin.

In this research, the biological potential of rhizosphere Fusarium (Fusarium spp. ) species to control some important weeds of wheat fields was studied. In the greenhouse, wild barely (Hordeum spontaneum), wild oat (Avena ludoviciana), rye (Secale cereale) wild mustard (Sinapis arvensis), and turnipweed (Rapistrum rugosum) seeds were planted on the soils sampled from wheat fileds of East Azerbayejan, Alborz, Tehran, North Khorasan, Razavi Khorasan, Khouzestan, Fars, Qazvin, Qom, Mazandaran, Kermanshah, Hamedan and Golestan provinces. Fusarium species of plants root were isolated. Effect of Fusarium isolates on seedling radicle length was considered as the criteria for successful control (inhibition of radicle length≥ 70%) in the bioassay experiments. In the first step of bioassay experiments, lettuce (Lactuca sativa) seedling was used as a test plant and the next step was carried out on mentioned weed species. Finally, wheat seedling of Sivand cultivar was used to evaluate the host specifity of selected isolates from pervious stages. Isolates with efficient inhibitory effects on weeds with least inhibitory (seedling radicle reduction≥ 10%) effect on wheat, were determined as successful selective biological control agents and identified with morphological and molecular methods. Results showed that one isolation of F. oxysporum on wild mustard and turnipweed, one isolate of F. brachygibbosum on wild barely and one isolate of F. equiseti on wild barely and wild oat, controlled the species very effectively. Knowledge about microbial agenets for biological control of weed species could be helpful in diversifying current management methods and maintenance of efficacy of available chemical herbicides.

Selection of suitable nozzle type, regarding the size of droplets and the volume of spray to apply herbicides optimally is necessary. In the spray deposition experiment, conducted using a factorial (six nozzle types × two nozzle sizes) arranged as a completely randomized block design, the moisture-sensitive papers were used and localized in four positions. In dose-response experiment, six doses of clodinafop-propargyl (0, 8, 16, 32, 48, and 64 gr. a. i. ha-1) were sprayed using six nozzle types with two nozzle sizes (11002 and 11004) at five-leaf growth stage of winter wild oat. As the nozzle number increased, more surface area of all moisture sensitive papers was wetted. Although the size of droplets increases with increasing the size of nozzles, the efficacy of clodinafop-propargyl to control winter wild oat was increased. For the nozzles size of 11004, the performance of nozzles in the efficacy of clodinafop-propargyl based on the ED90 values was as Twin Fan Standard > Standard Flat Fan > Compact Fan Air > Twin Fan Low Drift > Fan Low Drift > Twin Fan Air.

Fitness costs of herbicide resistance may be more evident and increase under stress environmental conditions. To test this hypothesis, a herbicide-resistant (R) and a herbicide-susceptible (S) phenotype with controlled and homogenized genetic background were isolated within a non– target-site resistant (NTSR) black-grass population. Accumulated maximum germination (Gmax) and time to reach the Gmax (G50) of biotypes were examined under non-stress and abiotic-stress conditions (salinity at 16 dSm-1, drought at-0. 8 Mpa). In addition, seedling pre-emergence biotypes growths were evaluated under nonstress condition. There was no difference in Gmax between the R and S biotypes, whereas the Gmax of R phenotype was 28% and 49% lower than that of the S phenotype under salinity-and drought-stress conditions, respectively. The R phenotype germinated around seven to 16 hours later than the S phenotype under all non-stress and abiotic-stress conditions, i. e. the R phenotype had higher G50 than the other phenotype. The experiments of seedling pre-emergence growth showed that the R and S biotypes had similar root and shoot length under non-stress condition. The results clearly showed that the germinability fitness costs of NTSR black-grass increase when the plants are grown under salinity and drought stress conditions.

Water hyacinth (Eichhornia crassipes (Mart. ) Solms) is the most important invasive aquatic weed in the world. This plant has expanded widely in aquatic habitats in the north of Iran in less than a decade after introduction. To introduce herbicides for chemical control of this weed, two pot experiments were conducted at the Rice Research Institute of Iran in 2017 and 2018. The purpose of the first experiment was to screen herbicides to identify effective herbicides for water hyacinth control. Results showed that among 21 studied herbicides, 15 herbicides had less than 16% and 6 herbicides had more than 30% efficacy on water hyacinth control. The second experiment was performed with the most effective herbicides in the first experiment and with the dose studied in the first experiment and double dose. The results showed that the efficacy of U46-Difloid (2, 4-D, SL 72%, 2160 g ai/ha), U46-Combifloid (2, 4-D+MCPA, SL 67. 5%, 2700 g ai/ha), Dialensuper (2, 4-D+Dicamba, SL 46. 4%, 1856 g ai/ha), Roundup (Glyphosate, SL 41%, 1640 g ai/ha), Nominee (Bispyribac sodium “ BPS” , SC 10%, 50 g ai/ha) and Cleanweed (BPS, SC 40%, 80, g ai/ha) at double dose was 75, 93, 81, 93, 91 and 100% respectively. Among the investigated herbicides, the inhibitory effect of BPS (Nominee and Cleanweed) on biomass, leaf area and propagation of water hayacinth seedlings in both investigated doses was similar or more than other herbicides. Therefore, BPS as a selective herbicide for rice and authorized for aquatic ecosystems without toxicity on fish, is recommended for chemical control of water hayacinth.

To evaluate the climatic impacts and future climatic changes on geographical distribution of the Dodartia (Dodartia orientalisas L. ), an invasive weed species in the world and Iran, a study was conducted in Ferdowsi University of Mashhad, using CLIMEX software, in 2016. The input data for the software included two group of data i. e. growth and stresses parameters through which some useful findings such as growth degree day were obtained based on the field study and other data such as base, optimum and ceiling temperatures as well as some information related to the regional climate of the study were acquired from the previous studis and the output analysis of the software. The results revealed that the distribution of the weed in Iran was observed mostly in North, Razavi, and South Khorasan, Kohkiloyeh, Chaharmahal, Fars, Lorestan, Ilam, Kermanshah, Hamedan, Markazi and Tehran provinces which will be highly expanded towards the northern west country provinces as a result of the occurrence of climatic changes. The plant species has a distribution potential in the world towards east china, most east European countries and central states of USA. So that the regions rely in the geographical position of 35 to 55 latitude, which gradually will extend towards the higher northern latitude that leads to limited continental spread of the plant to Africa, Australia and South America. Therefore, to manage this weed, while taking steps towards its quarantine, further studies on the control methods and tools to restrict its establishment, development and expansion should be conducted in vulnerable countries at risk.

To evaluate the effects of bromicide AM (bromoxynil + MCPA) alone or mixed by salicylic acid, cytogaite, and ammonium sulphate on chlorophyll a fluorescence (ChlF) of redroot pigweed (Amaranthus retroflexus L. ), a greenhouse experiment was conducted in randomized complete block design with three replications in Agricultural Faculty of University of Tabriz in 2017. Bromicide AM, 16 hours after application, increased minimum fluorescence (F0) 84%, thermal dissipation quantum yield (F0/Fm) 89% and the rate of accumulation of closed reaction centers (Δ V/Δ to) 59% and decreased maximum fluorescence (Fm) 40%, maximum quantum yield of photochemistry (Fv/Fm) 71%, electron transport yield (φ Eo) 94%, normalized area (Sm) 97% and time needed to reach Fm (Tfm) 89%. Salicylic acid as a growth regulator had not negative effect on the efficacy of bromicide AM. 64 hours after herbicide application, synergistic effect on bromicide AM ammonium sulphate and cytogaite reduced 52% and 45% Fm, 62% and 37% Fv/Fm, 25% and 11% Fv/ F0, and enhanced 6% and 3. 5% F0/Fm, 72% and 25% specific fluxes expressed per reaction centers (ABS/RC), 83% and 30% ratio – flux of dissipated energy per reaction center in t = 0, respectively. Results showed that assessment of chlorophyll a fluorescence is a rapid and non-destructive technique for detecting photosynthetic apparatus response of plant to applied herbicide alone and or mixing with adjuvants.

An experiment was conducted to evaluate the effect of different common herbicides on soybean yield and yield components. Experiment was carried out using a randomized complete block design (RCBD) with three replications at the Agricultural and Natural Resources Research Center of Moghan, Ardebil, Iran during 2017-2018. Treatments were the application of ethalfluralin, imazethapyr, trifluralin, metribuzin, bentazone, and alacolor herbicides and with and without hand weeding control. The results of variance analysis showed that the treatments had significant differences in herbicide efficiency, weed density and total dry weight. One month after herbicides spraying, trifluralin and ethalfluralin had the highest effect on the weed control; however, two months after herbicides spraying, all other treatments also showed their control effects and all herbicides were located in same statistical group. In this study, all herbicides treatments significantly reduced the density and dry weight of weeds compared to control; however, their effect was less than hand weeding. The number of pods per plant, biological and grain yield and soybean protein content percentage were significantly affected by all treatments; however, the other traits including plant height, growth period, chlorophyll index, 1000-seed weight, and grain oil percentage were not significantly different. The highest number of pods per plant (333. 92) and grain yield (2792 kg/ha) were obtained in hand weeding treatment. Among the herbicides treatments, the application of ethalfluralin had the highest seed yield (1896 kg. ha-1). Generally, based on the results of this study, application of 2 L. ha-1 ethalfluralin could be recommended for effective weed control in soybean production systems.

Dust deposited on the foliage of weeds can have an adverse effect on the efficacy of herbicides, thus, this effect should be eliminated somehow. In this greenhouse study conducting at Bu-Ali Sina University in 2018, the response of fresh/dry weight ratio of winter wild oat to the 6 doses of oxyfluorfen (0, 28. 8, 60, 120, 240, and 480 g a. i. ha-1), paraquat (0, 36, 75, 150, 300, and 600 g a. i. ha-1), and glufosinate (0, 60, 125, 250, 500, and 1000 g a. i. ha-1) sprayed at rates of 240, 480, or 240 L ha-1 plus mepiquat at 50 g ha-1 under 0 and 20 Kg dust ha-1 conditions were investigated. In the absence of dust, addition of mepiquat to oxyfluorfen and paraquat spray solutions did not have a significant effect on their efficacy but its addition to glufosinate spray solution gave a significant negative effect on its efficacy. In the presence of dust, the addition of mepiquat to oxyfluorfen spray solution did not have a significant effect on its efficacy but its addition to glufosinate spray solution has 6-time negative effect on its efficacy. While, the mepiquat addition to paraquat spray solution had a positive effect on its efficacy and increased the efficacy by 62. 07%. In the absence or presence of dust, spray volume increasing from 240 to 480 L ha-1 improved the efficacy of all herbicides in desiccating the foliage of winter wild oat.

To study the effect of herbicides in alfalfa weed control in South Kerman, an experiment was conducted in a randomized complete blocks design with three replications in the Agricultural Research and Education Center, Jiroft, Iran during 2013-2014. Treatments included application of once and twice 5 L/ha EPTC herbicide, 750 g/ha metribuzin, 3 and 3. 5 L/ha 2, 4-DB, 3 L/ha bentazon, 0. 5 L/ha imazethapyr plus 200 ml/ha Citogate and 1 L/ha imazethapyr as post-emergence, and weed infested as control. Results showed that herbicide applications had significant effects on density and dry weight of weeds and alfalfa dry weight. Herbicide applications significantly decreased density and dry weight of weeds. Once and twice spray application of imazethapyr (1 and 0. 5 L/ha) had a good efficiency in weed control. Also, once and twice spray application of 1 L/ha imazethapyr reduced weed dry weights 78 and 77% in the first, 78 and 77% in the second, and 86 and 82% in the third alfalfa harvest. Imazethapyr and EPTC herbicides had no alfalfa leaf injury and increased dry weight of alfalfa during three harvests. Although, 2, 4-DB herbicide showed good weed control, but these treatments had leaf injury in the first alfalfa harvest. Twice and once spray application of imazethapyr (1 L/ha) resulted in the highest alfalfa yield. This treatment increased alfalfa biomass 32 and 28% in the first, 30 and 28% in the second and 33 and 30% in the third harvests. Therefore, once spray application of 1 L/ha imazethapyr is recommended because of its efficiency in weed control and yield increasing.

In the recent years, the use of allelopathic potential of crop plants in weed management has attracted great attention of many specialists. Since Lepidium draba, Secale cereal and Descurainia sophia are among the most important weeds in barley fields in Kerman region, this research was conducted to evaluate the allelopathic potential of barley (Hordeum vulgare) cultivars (including Nosrat, Macuiee and Valfagr) on germination and growth characteristics of these three weed species. The study was conducted as factorial in completely randomized block design with three replications in both laboratory and greenhouse of Shahid Bahonar university of Kerman, Iran. Results showed that effects of aqueous extracts of vegetative organs of barley cultivars on germination and growth characteristics of weeds were different. Among the weeds treated with different extracts, the highest germination percentage (98. 33%) were belonged to S. cereal and D. sophia, which were treated with Nosrat and Makuiee leaves extract. Although leaf and stem extracts of Nosrat cultivar did not have significant effect on stem and root dry weight of S. cereal and L. draba, they resulted in significant decrease of stems and roots dry weight of D. sophia by 75% and 90%, compared to the control, respectively. Although, S. cereal had the highest sensivity in terms of chlorophyll a and b, which were generated by Makuiee and Nosrat cultivars, respectively, the inhibition of Makouei leaf extract was greater on carotenoids content of L. draba. In general, three barley cultivars extracts had the most negative allopathic effects on the growth of D. sophia.