Growth and productivity of maize (Zea mays) as influenced by sequential and combined application of tank mix herbicides

The experiment was conducted during 2021–22 at Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand to evaluate the impact of sequential and tank mix application of pre- and post-emergence herbicide on weed dynamics and maize productivity. The study was comprised of 9 treatments viz. Weedy (T1 ); Weed free (T2 ); Pre-emergence (PE) application of Atrazine -1 kg a.i./ha fb hand weeding (T3 ); PE application of Atrazine - 0.75 kg a.i./ha fb Post Emergence (Post E) application of Topramezone - 25.2 g a.i./ha (T4 ); PE application of Atrazine - 0.75 kg a.i./ha fb Post E application of Tembotrione - 120 g a.i./ha (T5 ); PE application of Atrazine - 1.0 kg a.i./ha fb Post E application of Topramezone - 25.2 g a.i./ha (T6 ); PE application of Atrazine - 1.0 kg a.i./ha fb Post E application of Tembotrione - 120 g a.i./ha (T7 ); Early Post E application of Topramezone - 25.2 g a.i./ha + Atrazine - 0.75 kg a.i./ha (T8 ) and Early Post E application of Tembotrione - 120 g a.i./ha + Atrazine - 0.75 kg a.i./ha (T9 ). Eleusine indica, Echinochloa colona, Digitaria sanguinalis and Eragrostis japonica were dominant among grassy weeds whereas broad leaf weeds included Cucumis melo, Phyllanthus niruri, Cleome viscosa and Commelina benghalensis. Cyperus rotundus was dominant among sedges. Topramezone - 25.2 g a.i./ha + Atrazine - 0.75 kg a.i./ha Early Post E resulted significantly lower total weed density and was similar to other herbicidal treatments. The highest grain yield (7.2 t/ha) was recorded in a weed-free crop that was similar to all herbicidetreated crops and significantly higher than the weedy crop. Tank mix application of atrazine - 0.75 kg a.i./ha with tembotrione 120 g a.i./ha or topramezone 25.2 g a.i./ha at 15 DAS can be suggested owing to higher grain yield and profits for farmers while lowering the dose and expenses involved in manual weeding and spraying atrazine separately.