Efficacy of p-hydroxy-phenyl-pyruvate dioxygenase (HPPD) enzyme-inhibitive tembotrione and topramezone herbicides for weed-management in rainy season grain sorghum (Sorghum bicolor)

Abstract

A field experiment was conducted during the rainy season (kharif) of 2019 and 2020 at Maharana Pratap University of Agriculture and Technology, Udaipur, Rajasthan, to ascertain the weed-management efficacy of postemergence (PoE) tembotrione and topramezone at 25 days after sowing following pre-emergence (PE) atrazine in the kharif grain sorghum [Sorghum bicolor (L.) Moench]. Eight treatments (6 herbicidal along with weed-free and weedy check) were evaluated in randomized block design (RBD) with 3 replications. Results showed that, uncontrolled weeds have inflicted a grain, stover yield and net income penalty of 63.7, 55.5 and 69% over weed-free check (3.47, 12.34 t/ha and `135,216). Pre-emergence (PE) application of atrazine @ 0.5 kg a.i./ha was found to be the most promising herbicide in terms of benefit: cost ratio (5.76) despite having 12.4, 6.2, and 6.71% lower grain, stover and net income than weed-free treatment (5.03). Both PE and PoE application of atrazine did not bring any yield and profit gains over its PE application. Topramezone and tembotrione (PoE) controlled weeds as effective as weed-free treatment and their impacts persisted up to crop maturity. However, on account of crop phytotoxicity that is dependent on dose (2.83–5.17) severe yield losses (60 and 51.9% grain and stover) were recorded. Both tembotrione and topramezone at their higher dose (0.0242 and 0.0363 kg a.i./ha) resulted in at par grain yield (1.18 t/ha) as weedy check (1.26 t/ha).