Nematicidal potency of silver nanoparticles and extracts from Borreria verticillata (L.) G. Mey against Meloidogyne incognita on tomato plants

Recurrent use of synthetic nematicides on a comprehensive level is accountable for the consequential negative impact on humans and the environment. An attractive panacea to reduce the impact is the use of green and eco-friendly nematicides. Here, we prepared extracts and nano based nematicide from Borreria verticillata, an abundant member of the Rubiaceae plant family that is overlooked and classified as weed. Air dried whole plant of B. verticillata was milled into powder and divided into three parts. Two parts were extracted in methanol, the third part was applied directly in powdered form as soil amendment, while the fresh aerial part was hydro-distilled for essential oil extraction and constituents of the essential oil were analysed with GCMS. Furthermore, a part of the methanol extract was utilized in the synthesis of silver nanoparticles. The AgNPs absorbed at 431 nm, FTIR spectrum depicted strong bands at 3220, 2972, 1049 and 881 cm-1 indicating phenol and glycoside as the reducing, capping and stabilizing agent, while SEM revealed that the NPs are elliptic in shape and 22–85 nm in size. Germacrene D, a-humulene, carvacrol, thymol, and p-cymene are the major primary constituents of the EO as indicated by the GCMS. The NPs and other extracts and powder from B. verticillata were applied on Meloidogyne incognita infected tomato plants in the field. Flowering was luxuriant in treated tomato plants which translated to high yield. There was a direct relationship between fruit yield and dosage of all the treatments applied. Reduction in number of eggs per root system, root gall index and number of nematodes in soil was noted. B. verticillata mediated AgNP and other extracts may perhaps function as a nematicide against M. incognita in tomato cultivation systems.