نوع مقاله : مقاله پژوهشی
نویسندگان
گروه مهندسی تولید و ژنتیک گیاهی، دانشکده کشاورزی، دانشگاه شهید چمران اهواز، اهواز، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Introduction
Among oilseeds, canola is one of the most important oilseed plants in the world. Weeds are a very important competitor and one of the main factors reducing production in canola cultivation. Early control of weeds with pre-emergence herbicides reduces weed damage in canola. A herbicide acts selectively and controls weeds without harming the crop, if applied correctly and at the right time, otherwise, it will not only fail to control the weeds but also reduce the crop yield. Every weed is sensitive herbicides use during a specific growth stage, and if the recommended time for the use of herbicides is not observed, it will cause damage to the yield of the crop. To prevent increasing weed resistance to post-emergence herbicides and diversify timing and mode of action for herbicides, this experiment aimed to investigate the effectiveness of imazathapyr, trifluralin and oxyfluorfen herbicides on rapeseed (Brassica napus L.) weed control.
Materials and Methods
In order to investigate pre-emergence herbicides and application time on weed control and canola yield, a research was conducted in the agricultural year 1402-1401 in the research farm of the Department of Production Engineering and Plant Genetics, Faculty of Agriculture, Shahid Chamran University of Ahvaz. The experiment was conducted in a factorial experiment based on a randomized complete block design with three replications. The experimental factors were the type of pre-emergence herbicide at three levels (imazethapyr, trifluralin, oxyfluorfen) and the time of herbicide application at four levels (two weeks before planting, one week before planting, at planting, and one week after planting) along with an unweeded control. The Hyola 50 canola variety was planted on the first of Aban (October 23). The number and dry weight of weeds per square meter were measured by identifying the species and separating broad-leaved and narrow-leaved weeds at five times including 30, 60, 80, 100 days after planting and harvesting time. After ripening of rapeseed plants, seed and biological yield were measured. To estimate the yield components, including the number of plants per square meter, the number of branches and siliques per plant, and the number of seeds per silique, 10 plants were randomly selected from the middle lines of each plot by removing the marginal effects. The data were checked for normality and analyzed using SAS 9.4 software through analysis of variance. The means were separated using the Duncan test at the 5% level of significance.
Results and Discussion
The results showed that seed yield of canola, under the application of trifluralin herbicide (on average of all four spraying times) and oxyfluorfen herbicide two weeks before planting, increased by 18% and 12%, respectively, compared to the unweeded control. There was a positive correlation between seed yield with the number of plants per square meter at harvest time (90%) and a negative correlation with the number and weight of weeds (between -34 and -39%). The yield components, the number of plants per square meter, the number of branches and siliques per plant, and the number of seeds per silique were also affected by the interaction of the type of herbicide × time of spraying. Among the yield components, there was no significant difference in the thousand-grain weight of canola between the levels of herbicide type, spraying time, and their interaction. The results showed that canola was very susceptible to imazethapyr herbicide at all four application times. Compared to the other two herbicides, imazethapyr caused the highest percentage of canola burn and the lowest number of plants per square meter at harvest time. Imazethapyr also resulted in the lowest seed yield and other yield components. There was no damage to canola plants in the trifluralin herbicide treatment at all four application times and the yield components were superior until harvest. All three herbicides significantly reduced the population of broadleaf and narrowleaf weeds in the canola field compared to the unweeded control at 30 and 60 days after planting. The reduction in the population of broadleaf and narrowleaf weeds continued from 80 days after planting until harvest in trifluralin and oxyfluorfen herbicides, although this effect of reducing the weed population was more pronounced in trifluralin herbicide than in oxyfluorfen herbicide. At the end of the season, the population of both narrow-leaved and broad-leaved weeds increased in plots of rapeseed that had been damaged by the application of the herbicide imazethapyr. This was due to the decrease in interspecific competition.
Conclusions
It seems that for early weed control, when rapeseed is growing slowly in the low temperatures of autumn, in addition to the herbicide trifluralin, oxyfluorfen, as a pre-emergence herbicide, can be a good option for further research to introduce it in rapeseed, especially in fields with dominant broad-leaved weeds.
کلیدواژهها [English]
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