Can Soil Microorganisms Reduce Broomrape (Orobanche spp.) Infestation in Cropping Systems?

Abstract

Among the parasitic plants around the world, broomrape is proposed as the most serious threat for crop production and food security. It attacks important crops belonging to different families such as Solanaceae, Fabaceae, Asteraceae, etc. which have a substantial contribution to supply people’s food in a global scale. Sometimes, destructive effects of the parasite lead to the complete loss of the crop yield. In recent years, broomrape infestation has notably extended in various parts of the world including Iran. Conventional methods to control broomrape are usually expensive and in most cases inefficient. Moreover, the chemical compounds used to suppress the parasite such as methyl bromide and chloropicrin can severely damage beneficial soil organisms and destroy atmospheric ozone layer. Recently, soil microorganisms have been proposed as effective and environmentally sound agents to control broomrape and reduce its damaging effects in agroecosystems. They can be divided into two main groups including pathogenic and nonpathogenic microorganisms which can affect the parasite directly and indirectly, respectively. Among the pathogenic microorganisms, Fusarium spp. are the most important candidates, and among the nonpathogenic ones, two famous symbionts, i.e., mycorrhiza and Rhizobium spp., are mostly proposed. However, there are no many reports on the role of soil microorganisms as biocontrol agents for broomrape. In this chapter, some important microorganisms having controlling effects on this parasitic weed and the mechanisms by which their effects can be achieved are discussed.