Interactions in the Symbiosis of Acaciasaligna with Glomusmosseae and Rhizobium in a Fumigated and Unfumigated Soil

Abstract

To increase nutrient uptake and plant growth, the effects of single and dual inoculation with Rhizobium and arbuscular mycorrhizal fungi (AMF) on Acacia saligna plants were investigated in greenhouse. The substrate was a clay-loamy soil low in plant available N and P. The soil has been fumigated by using Basamid. Plants were either inoculated with an AMF alone, with a strain of a compatible Rhizobium alone, or with both endophytes. A control was uninoculated. All treatments received a N- and P-free nutrient solution. Plant growth, nodulation, mycorrhizal infection, nutrient content (N and P) and N 2 -fixation were studied. Under the experimental conditions tested, dual inoculation significantly increased total dry weight by 56.9%, mycorrhizal infection 14-fold and N and P content of plants by 70.9% and 76.3%, respectively. Rhizobium inoculation alone significantly increased shoot dry weight, nodulation and total N content. Mycorrhizal inoculation increased root dry weight, mycorrhizal infection and total shoot P content. 15 N isotope dilution method was used to measure N 2 -fixation in the different treatments. Mycorrhizal inoculation of host plants increased fixed N 2 content by 4.4mg N plant -1 over the uninoculated controls. Rhizobium inoculation increased N 2 -fixation by 10.8mg N plant-1. Dual inoculation increased it by 22.5mg N plant -1 .