Effects of different herbicides on weed dynamics and maize yield

Abstract

An experiment was carried out during the Rabi season of 2020, 2021, and 2022, the research work was carried out in the new alluvial zone at the University Agricultural Farm (AB Block), Kalyani, Bidhan Chandra Krishi Viswavidyalay, Nadia, West Bengal. To set up the experiment, a randomised block design was employed, which included nine weed management techniques and three replications. The detail of treatments used were T1: Control; T2: Free of weed; T3: 1000 g per hectare of atrazine as a pre-emergence, followed by manual weeding at 25 DAS; T4: 750 g of atrazine per hectare as a pre-emergence, followed by Topramezone 25.2 g per hectare at 25 DAS as a post-emergence; T5: 750 g per hectare of atrazine as a pre-emergence, followed by Tembotrione (120 g per hectare) at 25 DAS as a post-emergence;T6: Topramezone (25.2 g a.i ha-1) at 25 DAS as a post-emergence after atrazine (1000 g a.i ha-1) as a pre-emergence; T7:1000 g per hectare of atrazine as a pre-emergence, followed by Tembotrione (120 g a.i ha-1) at 25 DAS as post-emergence. T8: Tank mixture of Topramezone (25.2 g a.i ha-1) with Atrazine (750 g a.i ha-1) at 15 DAS; T9: Tank mixture of Tembotrione (120 g a.i ha-1) with Atrazine (750 g a.i ha-1) at 15 DAS. The weed-free plot (T2) produced the highest grain production, and it was statistically comparable to the T4 treatment (Atrazine 750 g/ha as PE, followed by Topramezone 25.2 g/ha at 25 DAS). Different weed control techniques have a substantial impact on weed number and dry weight. The lowest grassy, sedges and broadleaves weed number and weeds dry weight were observed in weed free plot (T2) at harvest. But among the herbicide treated plot, treatment T4 (750 g of atrazine per hectare as a pre-emergence, followed by Topramezone 25.2 g per hectare at 25 DAS as a post-emergence) obtained lowest weed population. The effectiveness of weed control observed with weed-free treatment (T2) was the highest at harvest crop and was significantly better than other treatments of weeds. But among the herbicide treated plot, treatment T4 (750 g of atrazine per hectare as a pre-emergence, followed by Topramezone 25.2 g per hectare at 25 DAS as a post-emergence) reported lower number of weeds. The highest weed index (46.65%) was recorded in control (T1) plot indicating that uncontrolled weed competition during the crop period caused 46.65 percent of yield loss. The weed index for the combined weed control treatments Topramezone 25.2 g/ha + Atrazine 750 g/ha at 15 DAS (T8) and Atrazine 750 g/ha (PE) & Topramezone 25.2 g/ha at 25 DAS (T4) was 17.35% and 8.50%, respectively. From the experimental results, it can be concluded that herbicides Atrazine 750 g/ha (PE) followed by Topramezone 25.2 g/ha at 25 DAS and Topramezone 25.2 g/ha + Atrazine 750 g/ha at 15 DAS were found to be most effective weed control measures in maize with higher yield during rabi season under new alluvial zone of West Bengal.