Topramezone: A selective post-emergence herbicide in chickpea for higher weed control efficiency and crop productivity

Chickpea (Cicer arietinum L.) is a dominant pulse crop in the world for its climate resilience and nutritional values. Weed infestation causes a significant yield loss in chickpea and jeopardize in realizing the potential yield across regions. Pendimethalin as pre-emergence (PRE) is the ruling herbicide, however, post-emergence (POST) herbicides are limited in this crop particularly for managing broad-leaved weeds and higher yield gain. We assessed the impact of POST herbicides available in different crops on weed phytotoxicity, crop selectivity and yield performance in chickpea on sandy-loam soil of Kanpur, India. The experiment was undertaken for two consecutive years (2016-17 and 2017-18) comprising nine herbicides, besides unweeded control (UWC) and weed-free check (WFC). Among the herbicides tested, halosulfuron-methyl 70 g a.i. ha(-1) and tembotrione 100 g a.i. ha(-1) showed the maximum phytotoxicity scale of 5-10 on chickpea. Clodinafop-propargyl + sodium-acifluorfen 122.5 g a.i. ha(-1) and imazethapyr + imazamox 70 g a.i. ha(-1) had a recoverable phytotoxicity (scale 3-5) on chickpea. Topramezone 20.6 g a.i. ha(-1) at 25 days after sowing (DAS) resulted in higher phytotoxicity on weeds (toxicity scale of 7-10) without any phytotoxicity on chickpea. It significantly controlled the dominant broad-leaved weeds: Chenopodium album L., Lepidium didymum L., Spergula arvensis L., Medicago polymorpha L. and Fumaria parviflora Lam. compared to the remaining herbicides. Topramezone reduced total weed density by 68-70% and 48-51% (P = 0.05) at 45 and 95 DAS compared with UWC, respectively. Therefore, this herbicide had higher (P = 0.05) weed control efficiency in both years (89.8% in 2016-17 and 76.5% in 2017-18) than remaining treatments. Topramezone increased 15.3-19.6% chickpea seed yield than the recommended herbicide pendimethalin 1000 g a.i. ha(-1) - quizalofop-p-ethyl 100 g a.i. ha(-1) without affecting the nodulation and fluorescein diacetate activity. The UWC resulted in 64% (mean of two years) yield loss compared to the WFC in chickpea. Importantly, topramezone gave comparable yield with WFC. Hence, topramezone can be safely used in chickpea for managing broad-leaved weeds and realizing higher productivity.