Trianthema portulacastrum, weed competition, weed dynamics, yield, Zea mays
This study aimed to assess a brassicaceous weed Coronopus didymus (L.) Sm. as a source of potential natural herbicides for management of an alien weed parthenium (Parthenium hysterophorus L.). Initially, the effect of aqueous leaf, stem, root and flower extracts (0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0%) of the weed was checked on germination and growth of the target weed. Leaf and stem extracts showed the best herbicidal activity and a 2.5% extract of the each plant part completely inhibited germination of parthenium seeds. The lowest extract concentration (0.5%) of leaf and stem reduced germination by 56 and 46%, shoot length by 43 and 12%, root length by 59 and 62%, and biomass of whole plant by 44 and 15%, respectively. Root and flower extracts were less herbicidal and reduced parthenium germination by 23–52% and 33–56%, respectively. In a pot experiment, soil was incorporated with 0.2, 0.4, 0.6, 0.8, 0.10, 1.2% (w/w) crushed dry biomass of C. didymus, parthenium seeds were sown after one week and the effect of amendment on germination and plant growth was recorded after 45 days of sowing. All the doses of soil amendment significantly suppressed root length by 21–48% over control. A 1.2% soil amendment significantly reduced biomass of parthenium seedlings by 23%. This study concludes that leaf and stem extracts of parthenium possess potent herbicidal potential for control of parthenium.