Development of a tomato/root knot nematode bioassay to screen beneficial microbes

Abstract

In common with other root knot nematodes Meloidogyne hapla is a serious plant pest. A rapid screening system for candidate microbes that benefit plant growth is a first step to developing screening bioassays in other plant-nematode systems. Cultures of M. hapla established on tomatoes were used to define the nematode damage function, and required bioassay duration for this plant-pest system, followed by scale-up to a glasshouse level. The quantities of Meloidogyne inoculum were chosen such that they would cause minor, moderate or severe plant damage; hence the degree of protection afforded by the microbes in bioassays could be readily evaluated. An inoculation rate of 3542 eggs/plant caused a significant reduction in shoot weight (30%) and an increase in root galling in excess of 50%. Percentage of root gall and root gall index were good indicators of nematode impact and provide a relatively quick method of assessment.