گزینش علف‌کش‌های قابل مصرف در کینوآ (Chenopodium quinoa Willd.)

Background and objectives: Quinoa (Chenpodium quinoa Willd.) is an herbaceous flowering annual plant in the amaranth family grown as a crop primarily for its valuable seeds; the seeds are rich in protein, fibers, vitamins, and minerals in amounts greater than in many grains. Because of drought and salt tolerance, Quinoa can be cultivated in the areas affected by drought and salt stress conditions in the country. Weeds are the major obstacles in increasing the productivity of Quinoa. Since now, there has been no remarkable research and suitable herbicides available for weed control in Quinoa fields during the post-emergence stage. The aim of the present study was to screening the herbicides already registered for weed control in different crops rather than quinoa, and to test the possible tolerance of quinoa to the applied herbicides for secure and safe herbicide recommendations.
Materials and methods: A field study was conducted for screening and selection of possible herbicides to be used for chemical weed control in quinoa fields of Astan Ghods Razavi, in Anabad, located in Bardascan in Khorasan Razavi province, Iran, in 2019. Herbicides were sprayed as post emergence (foliar applied) at 4-6 leafy stage of quinoa by matabi® rechargeable sprayer calibrated to deliver 350 l ha-1 of spray solution. The layout was a completely randomized block design with three replicates. Treatments were post emergence application of atrazine (800 g a i ha-1), metribuzin (525 g a i ha-1), phenmedipham+ desmedipham+ ethofumesate (822 g a i ha-1), quizalofop tefuryl (60 g a i ha-1), clethodim (96 g a i ha-1), haloxyfop methyl (104 g a i ha-1), acetochlor (228 g a i ha-1), bensulfuron methyl (30 g a i ha-1), bentazon (1440 g a i ha-1), queen merak+ metazachlor (1040 g a i ha-1), clopyralid (225 g a i ha-1), 2, 4-D + dicamba (698 g a i ha-1), imazethapyr (100 g a i ha-1), isoxaflutole+ thiencarbazone methyl (232.5 g a i ha-1), ethofumesate (1250 g a i ha-1), oxadiazone (360 g a i ha-1), oxyfluorfen (360 g a i ha-1), pendimethalin (Prol®) (675 and 1350 g a i ha-1), sethoxydim (375 g a i ha-1), sulfosulfuron (19.95 g a i ha-1), clodinafop (192 g a i ha-1), tribenuron methyl (15 g a i ha-1), rimsulfuron+ nicosulfuron (131.25 g a i ha-1) plus hand weeding and untreated control.
Results: Two weeks after herbicide spray, no visual injury were observed on quinoa when sprayed with clethodim, quizalofop tefuryl, clodinafop, haloxyfop methyl, sethoxydim and pendimethalin (675 g a i ha-1). Severe visual damage (100% injury) however, observed on quinoa when sprayed with atrazine, metribuzin, phenmedipham+ desmedipham+ ethofumesate, oxyfluorfen, bentazon and oxadiazone. The rest of the herbicides were rated in between. Quinoa grain yield when sprayed with clethodim (3190.7 kg ha-1) and quizalofop tefuryl (2674.7 kg ha-1) were not significantly different from hand weeding (3346.7 kg ha-1). But application of atrazine, metribuzin, phenmedipham+ desmedipham+ ethofumesate, oxyfluorfen, bentazon and 2, 4-D + dicamba yielded to complete quinoa death. Quinoa grain yield when sprayed with bensulfuron methyl (1402.7 kg ha-1), imazethapyr (1184 kg ha-1), clopyralid (1402.7 kg ha-1) and pendimethalin (784 and 964 kg ha-1 at doses of 675 and 1350 g a i ha-1, respectively) were promising results while still significantly lower than that of hand weeding control.
Conclusion: Application of quizalofop-tefuryl and clotidim can be recommended to be used for weed control in quinoa. Besides application of haloxyfop methyl, sethoxydim, clodinafop, bensulfuron methyl, imazethapyr, clopyralid, pendimethalin and queen merak+ metazachlor showed promising results but still more experimentation need to be done for final recommendation.