| Abstrakt: |
Background and objectives: Weeds are one of the most significant biological limiting factors crop production worldwide. In Iran, weed damage in wheat fields has been reported to range from 25% to 30%. Herbicide application is the primary method for weed control in cereals. However, the decline in crop rotation and indiscriminate use of herbicide have led to the spread of difficult -to-control species, such as Lolium rigidum L. in agricultural fields. Also, the application of pre-mixed herbicides is one of the most common methods to enhance the efficiency of herbicides and to broaden weed control spectrum. This experiment was conducted to evaluate the efficacy of the pre-mixed herbicide fenoxaprop-p-ethyl+ metribuzin (FenoMetri) for controlling weeds in wheat of different regions. Materials and methods: This experiment was conducted in a randomized complete block design with 10 treatments and four replications in four regions of Karaj, Shahrekord, Kermanshah and Darab during 2021-2022 growing season. The experimental treatments included the application of bromoxynil+ MCPA (Bromicid MA@, EC 40%)+ clodinafop-propargyl (Topik@, EC 80%) at a rate of 1.5+1 L ha-1, tribenuron-methyl (Granestar®, DF 75%)+ topik® at a rate of 20 g + 1 L ha-1, bromoxynil+ MCPA (bromicide MA® ) + fenoxaprop-p-ethyl+ mefenpyr -diethyl (Puma-super®, EW 7.5 %) at a rate of 1.5 + 1 L ha-1, iodosulfuron methyl sodium + mesosulfuron methyl+ mefenpyr diethyl (Atlantis®, OD 12%) at a rate of 1.5 L ha-1, diflufenican + iodosulfuron-methyl-sodium+ mesosulfuron-methyl +mefenpyr-diethyl (Othello®, OD 6%) at a rate of 1.6 L ha-1, metribuzin (Sencor®, WP 70%) at a rate of 800 g ha-1, fenoxaprop-p-ethyl + metribuzin (FenoMetri, 21.37% EC) at dose rates of 0.8, 1 and 1.2 L ha-1 and control (weed free). Each plot was divided into two subplots. One subplot was sprayed (treatment) and subplot was unsprayed (weedy check). Sencor® was applied during two stages of early post-emergence of wheat (1 to 3 leaves or Zadok's 11 to 13) and at the wheat tillering stage (Zadok's 25) in at a rate of 400+ 400 g ha-1. Other herbicide treatments were applied the at the wheat tillering stage (Zadok's 25), according to the 3 to 5 leaf stage of the weeds. The plot had dimensions of 8 × 2 m² with a plant density of 400 plants m-2 and 8 planting rows. Spraying was done using a fixed-pressure back sprayer of Matabi equipped with a fan spray nozzle (8002) at a pressure of 200 kPa and spray volume of 300 L ha-1. Measured traits included the determination of the percentage decrease of density, dry weight of weed species, grain yield and percentage of yield changes. The data were checked for normality and analyzed using SAS 9.3 software through analysis of variance. Results: The results revealed a diverse spectrum of weeds (12 species) across the experimental locations. Avena sterilis subsp. ludoviciana (Durieu) Nyman was dominant in three tested locations Karaj, Kermanshah and Shahrekord. Convolvulus arvensis was in two locations Darab and Kermanshah, while Descurainia sophia was found in two locations Karaj and Shahrekord, Lolium rigidum was present in Darab and Karaj. Other dominant weed species were Centaurea depressa M. Bieb. and Secale cereale L. were present dominantly in Shahrekord. Galium aparine L. and Lamium amplexicaule L. were present dominantly in Kermanshah. Carthamus oxyacantha M. Bieb. and Melilotus officinalis (L.) Pall. were present dominantly in Darab. Fumaria officinalis L. and Sonchus oleraceus L. were present in Karaj. The results showed that herbicides were applied significantly reduced weed density and dry weight, as well as a significant increase in grain yield. Moreover, weed control efficiency improved with an increase in the application rate of FenoMetri herbicide. FenoMetri herbicide at a rate of 1.2 L ha-1 decreased the weed density of F. officinalis and S. oleraceus by 92%, and A. ludoviciana, C. oxyacantha and M. officinalis by 45-55%. Reductions of 35-45% were observed for C. arvensis, D. sophia, L. rigidum, and L. amplexicaule, while C. depressa, G. aparine, and S. cereale showed reductions of less than 20%. Additionally, grain yield increased by 5 to 10 % in different regions. The most effective treatment for controlling L. rigidum (75 to 80%) was achieved with the application of the herbicide Sencor®. Overall, species S. cereale, L. rigidum, C. depressa, and C. arvensis were more difficult to control compared to other species, respectively. Othello® herbicide exhibited better efficacy than other herbicides in all four regions, and increased grain yield by 14 to 19%. Conclusion: Based on the experiment results in four locations, the herbicide efficacy of the pre-mix FenoMetri in controlling weed species was significantly lower than compared to commonly used herbicides, except for F. officinalis and S. oleraceus. Therefore, the FenoMetri herbicide is not recommended at the dosage rates used due to its limited spectrum of weed control and the lack of optimal efficiency in controlling most of the tested species. [ABSTRACT FROM AUTHOR] |
