نوع مقاله : مقاله کامل علمی- پژوهشی
نویسندگان
1 گروه مهندسی تولید و ژنتیک گیاهی، دانشکده کشاورزی، دانشگاه علوم کشاورزی و منابع طبیعی خوزستان، باوی، ملاثانی، ایران.
2 دانشیار، گروه مهندسی تولید و ژنتیک گیاهی، دانشکده کشاورزی، دانشگاه علوم کشاورزی و منابع طبیعی خوزستان، باوی، ملاثانی، ایران.
3 محقق، موسسه تحقیقات و آموزش توسعه نیشکر و صنایع جانبی خوزستان، اهواز، ایران،
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and objectives: In Khuzestan, the species diversity of rapeseed weeds varies significantly with changes in environmental conditions at the time of sowing this plant. During the period between the second half of October and the first half of November, when a large portion of the province's rapeseed is cultivated, Malva spp. is dominant. If left uncontrolled, it not only causes a decrease in grain yield, but also greatly increases the loss of impurities and moisture in the grain delivered to shopping centers after harvest. Due to the limited herbicide variety for rapeseed and the ineffectiveness of recommended herbicides, the use of herbicides registered for other crops has become inevitable in rapeseed cultivation. Meanwhile, oxadiazon has shown good potential for controlling some damaging weeds such as mallow species. Therefore, in this study, the response of rapeseed yield to the application doses of the herbicide mixture "oxadiazon + clopyralid" at different sowing dates was investigated.
Materials and methods: Experimental treatments including different mixing ratios of "clopyralid + oxadiazon" herbicides including 250 ml ha-1 clopyralid + 50 ml ha-1 oxadiazon, 500 ml ha-1 clopyralid + 100 ml ha-1 oxadiazon, 750 ml ha-1 clopyralid + 150 ml ha-1 oxadiazon, 1 L ha-1 clopyralid + 200 ml ha-1 oxadiazon, and without the use of herbicides (weedy control). These treatments were evaluated on weed biomass and rapeseed yield on five sowing dates including 20 October, 4 November, 18 November, 2 December and 16 December 2022 growing season. Each sowing date was assumed as a location and the data were analyzed as combinedly.
Results: The results showed that the use of higher doses of "oxadiazon + clopyralid" herbicide mixture and earlier sowing dates led to a decrease in the maximum dry weight of weeds. At earlier sowing dates, lower rates of herbicide combination were effective in reducing weed biomass by 50%. Based on the output of the model, the greatest decrease in seed yield was observed in a range of conditions of lower doses and delayed sowing dates. The application of about 75% of the maximum amount consumed from the herbicide mixture "oxadiazon + clopyralid" on the sowing dates of October 20, November 4, and November 18, respectively, resulted in yield loss of only about 0.7%, 3.3%, and 8.9%, respectively. Also, the drop in rapeseed yield on the sowing dates of December 2 and December 16 with the same amount of application of "oxadiazon + clopyralid" herbicide mixture reached about 25.6% and 50.3%, respectively. Developed models were able to describe well the responses of weed biomass and rapeseed yield to sowing dates and different herbicide doses. This study showed that the combination of higher doses of "clopyralid + oxadiazon" herbicides with earlier sowing dates effectively reduced weed biomass and increased rapeseed yield.
Conclusion: The reduction of weed biomass in response to the earlier sowing date and the application of the full dose of "oxadiazon + clopyralid" herbicide mixture showed that the competitive ability of weeds in these conditions is much lower than the condition of late sowing date and the use of a reduced dose of herbicide (ratios less than 50% of full dose). In addition, weed biomass decreased at all sowing dates in response to increased herbicide dosage. In other words, weed biomass decreased with early sowing of rapeseed or increasing the dosage of herbicide application. These findings emphasize the necessity of optimizing sowing date and herbicide dose in order to promote sustainable rapeseed production.
کلیدواژه‌ها [English]
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