Plant-parasitic nematode management via biofumigation using brassica and non-brassica plants: Current status and future prospects

Plant-parasitic nematodes (PPNs) are considered as one of the major limiting factors in global crop production system. Due to the introduction of tighter limits in registering new biocidal molecules and a gradual phase-out of nematicides for high environmental impact, considerations for non-chemical alternatives have been realised. The biofumigation technique which involves the incorporation of mechanically chopped brassicaceous plant material into the soil to control soilborne nematodes offers an attractive alternative for PPN management. Biofumigant effect is mainly caused by the volatile and toxic isothiocynates originated from the hydrolysis of secondary metabolite glucosinolate present in the Brassica tissues. The scope of biofumigation has been expanded to other non-brassica plants which produce volatile pathogen-suppressing molecules. The graminaceous plants such as sorghum and sudangrass are known to produce nematicidal cyanides via enzymatic hydrolysis of precursor cyanogenic glycoside/dhurrin. The allelopathic plant marigold is known to produce α-terthienyl, which has shown potential biofumigation effect against PPNs. The objective of this review is to detail the tactics used to manipulate various brassica and non-brassica biofumigant crops and to present the mechanisms responsible for PPN suppression by these crops. The ecological aspects underpinning the responses of PPNs to these crops were not austerely discussed in earlier literature. Herein, we present a holistic assessment of the impact of biofumigation technique in managing PPNs in various crops and explore the employability of this technique in integrated nematode management (INM) practices. Keywords: Brassica, Sorghum, Sudangrass, Marigold, Root-knot nematode, Seed meal, Green manure, Cover cro