Effectiveness of the Application of Arbuscular Mycorrhiza Fungi and Organic Amendments to Improve Soil Quality and Plant Performance Under Stress Conditions

Abstract

Plant growth is limited in arid and/or contaminated sites due to the adverse conditions coming from heavy metal (HM) contamination and/or water stress. Moreover, soils from these areas are generally characterised by poor soil structure, low water-holding capacity, lack of organic matter and nutrient deficiency. In order to carry out a successful re-afforestation, it is necessary to improve soil quality and the ability of plants species to resist this harsh environment. The symbiosis with arbuscular mycorrhizal (AM) fungi has been proposed as one of the mechanisms of plant heavy metal tolerance and water stress avoidance. On the other hand, addition of organic amendments to the soil can reverse degradation of soil properties. Agro-waste residues such as dry olive cake (DOC) and sugar beet waste (SB) supplemented with rock phosphate (RP) can be used as organic amendments after fermentation by Aspergillus niger. The application of A. niger-treated DOC and/or SB to semi-arid soils and/or HM-contaminated soils increased aggregate stability, soil enzymatic activities, water soluble C and water soluble carbohydrates as well as nutrient availability, especially P. AM inoculation, using adapted endophytes, was more efficient with respect to increasing plant nutrition and growth as well as plant tolerance to drought or HM-stress conditions. The combined treatments involving mycorrhiza fungi inoculation and addition of the amendments into the soil can be proposed as a successful revegetation strategy for plant performance in P-deficient soils under semiarid Mediterranean conditions. The beneficial effectiveness of this symbiosis with suitable AM fungi in A. niger-treated agro-waste residue-amended soil can also be regarded as a successful biotechnological tool for reclamation of HM-contaminated soils.

Organic amendments: effects on cereals growth and cadmium remediation

“…However, increased tolerance indices by the application of organic amendments in normal and Cd stress conferred their positive effect on root growth of studied crops. Likewise, the growth promoting effects of organic amendments in metal-contaminated soil have also been reported earlier Medina and Azcón 2010).…”

Early arbuscular mycorrhiza colonization of wheat, barley and oats in Andosols of southern Chile

“…AM establishment and root colonization of cereals is known to depend on a) the AM fungi present in the soil and on the germination potential/stimulation of infective fungal propagules (Jeffries et al, 2003); b) the susceptibility of the cereal species and varieties to get infected by AM fungi (Boyetchko and Tewari, 1995) where also genetical recognition factors are involved (Gadkar et al, 2001;Balestrini and Lanfranco, 2006), and c) the soil edaphic and biotic conditions and characteristics, like nutrient status, pH, water holding capacity, aeration, organic matter content (Medina and Azcón, 2010), as well as the presence or absence of other rhizosphere and soil microorganisms (Welc et al, 2010). The interactions of these three major components, which influence the establishment of the symbiosis, are rather complex but at the final end the colonization levels within the root tissue are the result of these interactions.…”

Interactions between a Root Knot Nematode (<i>Meloidogyne exigua</i>) and Arbuscular Mycorrhizae in Coffee Plant Development (<i>Coffea arabica</i>)

“…It is known that Glomeromycota fungi are able to uptake and transport P effectively [25]. Therefore, AM plants have more P in their structure.…”