Document Type : Research Article
Authors
1
Assistant Professor of Plant Protection Research Department, Fars Agricultural and Natural Resources Research and Education Center, AREEO, Darab, Iran
2
Research Associate an, Iranian Research Institute of Plant Protection, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran, respectively
3
Associates Professor of Department of Weed Research, Plant Pest and Disease Research Institute, AREEO, Tehran, Iran
Abstract
Introduction: Wheat (Triticum aestivum) is one of the most important crops in Iran. The area under cultivation of this crop in Fars’s province is 421,000 hectares. Weeds are one of the most significant factors limiting crop production. They primarily decrease grain yield by competing with the crop for light, nutrients, water, and root space. Weeds can cause a significant reduction in wheat yield, with an average by 23-35%. The most important weed species of wheat in Fars are including Lolium rigidum L., Bromus tectorum L., Mavla neglecta Wallr., Hirschfeldia incana L., Carthamus oxyacanthus M.B., Centaurea solstitialis L., Veronica persica L. The rigid ryegrass (Lolium rigidum) is one of the most troublesome weeds in winter wheat fields of Fars province. This weed, Lolium rigidum, has the capacity to produce 45,000 seeds m−2 in infested wheat fields. Its highly competitive nature for nutrients has been reported to cause a significant reduction in wheat yield. The application of herbicides is the most common method of weed control in wheat fields. Herbicides are registered for weed control in winter wheat fields included of Axial®, Topik®, Othello®, Atlantis®, Total®, Bromicide® MA, Geranestar® and Apiros®. There are a limited number of herbicides that is used in wheat. Therefore, it is necessary to register new herbicides in winter wheat. The objectives of this research were to optimize the dosage of FenoMetri in combination with a non-ionic surfactant, Tifis®, and to compare its efficacy with other pre-mixed herbicides (Bromicide® MA, Othello®, and Atlantis®).
Materials and Methods: In order to study the efficacy of herbicides in controlling weeds in wheat fields, an experiment was conducted at the Fars Province Agricultural and Natural Resources Research and Education Center, Darab, Iran, during 2021-2022. This experiment was carried out using a randomized complete block design with 14 treatments and 4 replications. The treatments included post emergence application of Bromicide MA® at 1.5 L ha–1 + Topik® at 1 L ha–1, Bromicide MA® at 1.5 L ha–1 +Puma-super® at 1 L ha–1, Granstar® at 20 g ha–1+Topik® at 1 L ha–1, Atlantis® at 1.5 L ha–1, Othello® at 1.6 L ha–1, Tifis® at 300 g ha–1, FenoMetri at 0.8, 1 and 1.2 L ha–1 with and without surfactant at 1 L ha–1, Sencor® 800 g ha–1 (400 g ha–1 in the 1- 3 leaf stage + 400 g ha–1 in the tillering stage of wheat and Control (hand weeding). Each plot was divided into two subplots. One subplot was treated with the herbicide applications, while the other subplot was left unsprayed to consider as a weedy check treatment for comparison purposes. Herbicide treatments were applied in tillering stage of wheat (Zadoks’ scale = 25) using a pressure backpack sprayer equipped with an 8002 flat fan nozzle tip, which delivered 350 L ha-1 at 2 bar spray pressure. Traits were recorded including weed density, weed biomass, plant height, grains per spike, number spikes, 1000 grains weigh, grain yield and biological yield. Weed density and dry weight were determined in random 0.50-m2 quadrates per plot. The grain yield and biological yield were recorded for a 3 m2 and 0.50 m2 from each plot, respectively. Weed control efficiency (WCE) representing the degree of reduction in the density or dry biomass of weeds due to herbicide treatment was determined using Equation 1.
WCE (%)= ((A-B))/( A)×100, (1)
where, A and B are the density or dry biomass of weeds in the unsprayed and sprayed subplots, respectively (Somani, 1992). The changes in each trait of yield wheat (Yi), as mentioned above, were determined using Equation 2
Y_i (%)=(Y_s )/Y_u ×100, (2)
where Ys and Yu are the amount of each trait in the sprayed and unsprayed subplots (weedy check treatment), respectively. After checking data normality, the data were subjected to analysis of variance using SAS 9.2 software. To compare the means, the Fisher's Least Significant Difference (LSD) test was used at the 5% level of significance.
Results and Discussion: Weeds infestations included Lolium rigidum L., Convolvulus arvensis L., Melilotus officinalis (L.) Lam and Carthamus oxyacanthus M.B. The highest and lowest density were observed for L. rigidum (56%) and C. oxyacanthus (5.1%), respectively. While, the highest and lowest weight were observed for L. rigidum (74%) and C. oxyacanthus (4%), respectively. The statistical analysis of the data on the weed density and biomass were revealed that applied herbicides significantly decreased both weed density and biomass. Additionally, the herbicide treatments led to a significant increase in the number of spikes per m², grains per spike, 1000 grains weight, grain yield, and biological yield. The Bromicide MA® had the best treatment for controlling the broad-leaved weed by 80 – 85%, On the other hand, Sencor had the best control for ryegrass (L. rigidum) by 80%. The application of FenoMetri at 1.2 L ha–1 with Surfactant® decreased the biomass of C. arvensis, C. oxyacanthus, M. officinalis, L. rigidum and total weed by 71, 63, 52, 48 and 73% respectively. It also increased grain and biological yields up to 20% and 22% as compared to the weedy check treatment. Additionally, the herbicides of Sencor® and Othello® showed the highest- grain yield after hand weeding, respectively.
Conclusion: The application of FenoMetri at 1.2 L ha–1 with Surfactant effectively controlled the density of weed species by 45–71% and the dry biomass of weed species by 48–72%. It also increased grain and biological yields by up to 20% and 22%, respectively, compared to the weedy check treatment. However, the efficacy of FenoMetri herbicide in controlling weeds was lower compared to commonly used herbicides such as Othello®, Bromicide MA® + Topik®, and Bromicide MA® + Puma super®. Therefore, it is recommended to evaluate the FenoMetri herbicide with higher application rates.
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