Bio-efficacy of pre-and post-emergence herbicides on growth, productivity, nodulation of black gram (Vigna mungo L.) under coastal plain of Odisha

Weeds compete with plants for resources during cultivation and the control of weeds during the critical period of cropweed competition is crucial to avoid yield loss ranging from 50%-90% in black gram. The first 4-5 weeks are critical for black gram crop-weed competition. The composition of weed flora, the duration of crop-weed competition and its intensity significantly impact yield losses in black gram cultivation. Therefore, the current study aims to evaluate weed management practices in rabi black gram, with a focus on identifying herbicides that enhance weed control, increase productivity and profitability.

A field experiment was conducted during the rabi season of 2021-2022 and 2022-2023 consecutively at Odisha University of Agriculture and Technology, Bhubaneswar. The field experiment comprised of eight treatments on different herbicide applications as T₁- Fenoxaprop-p-ethyl @ 65 g a.i. ha^-1, T₂- Quizalofop-p-ethyl @ 50 g a.i. ha^-1, T₃- Cyhalofop-butyl @ 75 g a.i. ha^-1, T₄- Pendimethalin @ 750 g a.i. ha^-1, T₅- Oxyflourfen @ 50 g a.i. ha^-1, T₆- Tembotrione @ 120 g a.i. ha^-1, T₇- Weed check (control) and T₈- Weed free, which was laid under randomised block design. Collected samples were analyzed in the field and laboratory for crop-weed competition, herbicide phytotoxicity and yield attributes.

The results revealed that weed-free treatment recorded the lowest weed population (5.27-5.45), weed dry weight (1.35 g- 2.20 g) and lowest weed index (0.00%) at all growth stages followed by pendimethalin (PE) application. Among yield attributes, weed-free treatment recorded the highest plant height (cm) which was at par with pendimethalin (PE) followed by cyhalofop-butyl (PoE) application. The magnitude of seed yield was increased under weed-free (1035.46 kg ha^-1) and pendimethalin (PE) and cyhalofop-butyl (PoE) applications by 53.62% and 48.40%, respectively over the weedy check. Application of tembotrione recorded the highest herbicide phytotoxicity (5.3-7.6) over the rest of the treatments. It can be concluded that the application of pendimethalin 30 EC 750 g ha^-1 as PE at 2 DAS followed by cyhalofop-butyl 10 EC 75 g ha^-1 can be advisable for better weed control, lower herbicide phytotoxicity and higher yield.