Growth of Argentine Mesquite Inoculated with Vesicular-Arbuscular Mycorrhizal Fungi

Abstract

Argentine mesquite (Prosopis alba) seedlings were inoculated with the vesicular-arbuscular mycorrhizal (VAM) fungi, Glomus intraradices , container-grown for five months, and transplanted into a simulated landscape in Tempe, Arizona. After transplanting, mesquite trees were either drip irrigated at regular intervals or nonirrigated for one year. Six months after transplanting, VAM fungal colonization was observed only in the roots of inoculated mesquite but by 12 months, roots of both inoculated and noninoculated mesquite were colonized by VAM fungi. Higher levels of VAM fungal colonization occurred in roots of irrigated mesquite. While irrigation promoted mesquite shoot growth, VAM inoculation inhibited shoot growth of nonirrigated trees. Trunk caliper was greater for irrigated trees than for nonirrigated trees and was not affected by VAM infection. VAM fungi promoted the growth of thinner roots for irrigated trees and thicker roots for nonirrigated trees after six months. At the conclusion of the study, root growth was enhanced by drip irrigation and was not affected by previous VAM fungal inoculation.