مطالعه کارآیی علف‌کش پیش‌آمیخته بروموکسینیل+توفوردی برای کنترل علف‌های هرز پهن‌برگ در مزارع گندم (triticum aestivum l.) کشور

به منظور ارزیابی علف‏کش بروموکسینیل+توفوردی (بوکتریل یونیورسال % 56ec) در کنترل علف های هرز پهن برگ آزمایشی در قالب طرح بلوک‏های کامل تصادفی با چهار تکرار در مناطق کرج ، شهریار، کرمانشاه و فارس طی سال زراعی 97-1396 اجرا شد. تیمارها شامل کاربرد علف‌کش‌های توفوردی+ام سی پی آ (1.5 لیتر در هکتار توفوردی کمبی فلوئید)، تری بنورون متیل (20 گرم در هکتار گرانستار 75%)، مزوسولفورون‌متیل+ یدوسولفورون متیل سدیم+ دیفلوفنیکان+ مفن‌پایر‌دی‌اتیل (1.6 لیتر اتللو 6%)، مکوپروپ پیدیکلوپروپ پی+ام سی پی آ (2.5 لیتر در هکتار دوپلسان سوپر60 %)، بروموکسینیل+ام سی پی آ (1.5 لیتر در هکتار برومایسید ام آ 40%)، توفوردی+ دایکامبا (0.8 لیتر در هکتار دیالان سوپر 34.4%)، تریاسولفورون+دایکامبا (165 گرم در هکتار لینتور %70) و علف‏کش جدید بروموکسینیل+ توفوردی (بوکتریل یونیورسال 56% در مقادیر 0.75، 1، 1.25، 1.5، 1.75 و 2 لیتر در هکتار) بود. نتایج نشان داد علف‏کش بروموکسینیل +توفوردی در مقدار 1.25 لیتر در هکتار قادر به کنترل معنی دار بیش از 80 درصد بیشتر علف های هرز پهن برگ گندم بود اما برای کنترل علف های هرز دشوارکنترل نظیر ارشته خطایی (lepyrodiclis holosteoides)، پیچک صحرایی (convolvulus arvensis) و بی تی راخ (galium tricornutum l.) مقدار 1.5 لیتر در هکتار و رسیدن به عملکرد مطلوب در این محصول زراعی قابل توصیه است. هیچ یک از علف کش های آزمایش باعث خسارت ظاهری به گندم در مناطق مختلف آزمایش نشدند.

Efficacy of Bromoxynil+ 2, 4-D (Buctril Universal 56%EC) as Broadleaf Weed Killer in the Wheat Fields of Iran

Introduction: Plant Protection Organization (PPO) has registered seventeen commercial herbicides formulations for broadleaved weed control of wheat in Iran (Nourbakhsh, 2019). Among these herbicides, five herbicides contain one active ingredient and the others have two or three active ingredients including acetolactate synthase (ALS) enzyme inhibiting groups, syntheticauxin groups, photosynthetic inhibitor of photosystem II, and pigment synthesis inhibitor groups, which are sometimes formulated with safeners (Tomlin, 2009). Previous studies show that existing weed species do not similarly respond to herbicides and therefore the percentage control of some of the weed species is lower than the other species (Ohadi, 2010). These hardtocontrol weeds are naturally resistant to herbicides. Thus, new herbicides with several active ingredients are suggested to be used to suppress such weeds. The aim of this work was to find the best chemical treatments against weeds in wheat production based on using new herbicides bromoxynil+2,4D and comparing their efficacy with the common registered herbicides in the major wheat growing areas of Iran. Material and Method: A field study was conducted in four regions of Iran, including Karaj, Shahryar, Kermanshah and Shiraz during 20172018 growing season. The statistical layout was a completely randomized block design with four replicates. Eight herbicides in 13 treatments were 2,4D+MCPA (U46Cambi fluid® 67.5%SL, 1.5 1 L ha1), Mecopropp + Dichlopropp + MCPA (Duplosan super® 60% SL , 1 L ha1), Bromoxynil + MCPA (Bromicide® 40% EC, 1.5 L ha1), Tribenuronmethyl (Granstar® 75% DF, 20 gr ha1), Mesosulfuronmethyl + Iodosulfuronmethyl sodium+ Diflufenican+Mefenpyrediethyl (Othello® 75% WG, 1.6 L ha1), 2,4D + Dicamba (Dialant super® 46.4 SL, 0.8 L ha1), Triasulfuron + Dicamba (Lintur® 70% WG, 165 gr ha1), and the new herbicide Bromoxynil + 2,4D with six recommended doses (Buctrile Univeral® 56% EC, 0.75, 1,1.25, 1.5, 1.75 and 2 L ha1).  A handweeded treatment and an unweeded treatment served as controls. Weed density and weed dry weight for each plot were measured four weeks after the last application the herbicides.  Wheat was harvested from six m2 of each plot after removing border plots. Wheat grain yield was determined after adjusting the moisture level of grain to 14 %. Data from each region were subjected to statistical analysis using SAS/STAT® statistical software and the means were separated by Duncan (α=5%). Results and Discussion: The results showed a diverse spectrum of weeds (18 species) at the experimental locations. Descuriania Sophia was dominant in three tested locations except Kermanshah. The next dominant weed species were Galium aparine L. and Centaurea depressa M.B. were present dominantly in Kermanshah and Shiraz. Lepyrodiclis holosteoides and Convolvulus arvensis as noxious weeds, respectively were dominant in Shahryar and Kermanashah. Malcolmia africana and Sinapis arvensis were present in Karaj. Across the experimental locations, Bromoxynil + 2,4D was efficient at 1.52 L ha1 concentrations for total weed control (85.7 to 91.47%). However, when applied at dosage of under 1.5 L ha1, its weed control efficiency was lower (63 to 80%). Mecopropp + Dichlopropp + MCPA and Bromoxynil + MCPA with 82% average efficiency in controlling weeds in all the locations, which was in agreement with the findings of some previous studies (Minbashi and Saeedi, 2019). 2,4D + Dicamba and Triasulfuron + Dicamba were inefficient in weed control (6872%) across all locations. Bromoxynil + 2,4D (1.5 L ha1 and upper doses), Mecopropp + Dichlopropp + MCPA, and Bromoxynil + MCPA  were the most efficient to control Lepyrodiclis holosteoides with 86.99 to 99.19% of weed density.This weed beside C. arvensis and G. aparine were identified as difficulttocontrol weeds. None of herbicides showed visual injury symptoms on wheat. Conclusion: According to these experiments, we found that the Bromoxynil + 2,4D (1.5 L ha1 and upper doses) as new candidate herbicide showed good to excellent (85%100%) weed control efficiency averaged in the all experimental locations and it could be recommended to be used in wheat field after registration process. Due to environmental concern, it should be applied at lower doses. Mecopropp + Dichlopropp + MCPA and Bromoxynil + MCPA were found to be the next two efficient herbicides. C. arvensis, was the most difficulttocontrol weed that there was not controlled by new herbicides. L. holosteoides and G. aparine were difficulttocontrol weed species.