Wild marigold (Tagetes minuta L.) biomass and essential oil composition modulated by weed management techniques

Weed management system plays an important role in reducing the yield losses brought by uncontrolled weeds in the agricultural production system. Moreover, the weed management studies on aromatic crops, particularly Tagetes minuta L. are not well documented. Thus a study was carried out at CSIR-Institute of Himalayan Bioresource Technology Palampur, India, during 2018 and 2019. Nine treatments of herbicides viz., pendimethalin at 1.50 kg a.i./ha (P), imazethapyr at 0.10 kg a.i./ha (I), carfentrazone-ethyl at 0.02 kg a.i./ha (C), P HW, I + HW, C + HW (integration of all herbicide treatments with hand weeding) and hand weeding alone (HW). Lowest weed density (16.69 and 15.61 m(-2)), weed biomass (9.10 and 10.09 g m(-2)) at 75 and 105 days after sowing (DAS), respectively, and the highest total above ground biomass (17925 kg ha(-1)), essential oil (EO) yield (103.11 kg ha(-1)) was recorded in imazethapyr + hand weeding (I + HW) amongst all weed control treatments. Herbicide integrated with hand weeding lead to the reduction of the number and dry weight of weeds, with a significant increase in T. minuta total aboveground biomass and EO yield. Essential oil analysis found Z-beta-ocimene, dihydrotagetone, tagetone, and ocimenone as the main constituents which were differently influenced by different weed control treatments. Treatment I + HW may therefore be recommended as weed control method for aromatic plant growers, especially in T. minuta production.

Automated summary

Weed management is crucial in agriculture, especially for aromatic crops like Tagetes minuta L. The study found that the combination of imazethapyr and hand weeding was the most effective treatment in reducing weed density and biomass, leading to higher total aboveground biomass and essential oil yield in T. minuta.