Growth enhancement of Citrus reshni after inoculation with Glomus intraradices and Trichoderma aureoviride and associated effects on microbial populations and enzyme activity in potting mixes

Abstract

There have been some scientific reports suggesting that dual inoculations with arbuscular mycorrhizal (AM) and saprophytic soil fungi may cause an additive or synergistic growth enhancement of the inoculated host plant. Some Trichoderma spp. have shown antagonistic potential against pathogenic fungi and a beneficial effect on plant growth. Joint inoculations of the mycorrhizal fungus Glomus intraradices Schenck and Smith, isolated from a citrus nursery (Tarragona, Spain) and a strain of Trichoderma aureoviride Rifai, isolated from an organic compost, were tested on a citrus rootstock, Citrus reshni Hort. ex Tan. The interactions between both microorganisms and their influence on mycorrhizal root colonization and plant growth enhancement, the changes produced in the soil microbial activity, like esterase, trehalase, phosphatase and chitinase activities, and on microbial populations were evaluated in three organic substrates : (1) sphagnum peat and autoclaved sandy soil (1/1, v/v), (2) sphagnum peat, quartz sand and perlite (1/1/1, v/v) and (3) pine bark compost (BVU, Prodeasa Product). Substrate characteristics were more important than the AM inoculation treatment in the determination of enzyme activity. In bark compost, the number of bacterial colonies obtained on soil-dilution plates was significantly higher than in peat and sand mixtures. Inoculation with T. aureoviride alone produced no significant effect on growth enhancement of C. reshni. However, dual inoculation with both, T. aureoviride and G. intraradices significantly increased plant growth in two of the substrates used and was the best treatment in pine bark amended compost. The inoculation with T. aureoviride did not affect the development of mycorrhizal root colonization. These results show a synergistic effect of G. intraradices and T. aureoviride on the growth of C. reshni in organic substrates and indicate the potential benefits of using combined inoculations.

Inoculation of cyclamen (Cyclamen persicum) and poinsettia (Euphorbia pulcherrima) with arbuscular mycorrhizal fungi and Trichoderma harzianum

“…The positive effects of combinations of the AMF and Trichoderma aureoviride were previously reported for Tagetes erecta grown in a peat-perlite mixture (Calvet et al 1993) and for Citrus reshni grown in two horticulture substrates (Camprubí et al 1995). Some studies showed that T. harzianum exhibits a negative effect on the development of AMF (Green et al 1999(Green et al ), however, rámek et al (2000 showed the same positive effects of AMF inoculation on the growth of three balcony plant species (Verbena, Torenia, Diascia) when inoculated separately or together with Trichoderma harzianum application.…”

Arbuscular mycorrhizal protein mRNA over-expression in bread wheat seedlings by Trichoderma harzianum Raifi (KRL-AG2) elicitation

“…Previous studies on T. harzianum fungi were mainly concerning in their biological role as; 1) plant biocontrol agent involved in diseases systemic acquired resistance for many plant species (Bais et al, 2005;Camprubia et al, 1995;Deshwal et al, 2003;Dhillion, 1994;Sharma and Dohroo, 1996;Siddiqui and Mahmood, 1996;Yedidia et al, 1999) and 2) plant growth stimulation and yield promotion (Fehlberg et al, 2004;Mohammed et al, 2008). Since, T. harzianum have significant effects on mycorrhizal development and symbiosis of AMF in many investigated vascular plant species, they are now Fig.…”

“…However, accurate mechanism and associated signaling pathways are largely unknown. For example, information about interaction mechanisms and mutual signals is rare (Camprubia et al, 1995;McAllister et al, 1994;Tarafdar and Marschner, 1995). Very little is known about how AMF detect the presence of their host plant and how they set up symbiotic relationships with them (Giovannetti et al, 1996).…”

Influence of an arbuscular mycorrhizal fungus on the interaction of a binucleate Rhizoctonia species with Myc+ and Myc– pea roots

“…The interaction of AM fungi with mutualistic micro-organisms usually has a synergistic effect on plant growth, as shown for Rhizobium (Asimi et al 1980), Frankia (Fraga-Beddiar andLe Tacon 1990) and Pseudomonas (Sreenivasa and Krishnaraj 1992). In addition, dual inoculation with AM fungi and soil saprophytic fungi, such as Trichoderma sp., may have a synergistic benefit for host plants (Camprubi et al 1995). Binucleate Rhizoctonia (BNR) species are common colonizers of plant roots in cultivated soils (Hurd and Grisham 1983;Juan-Abgona et al 1996;Tu et al 1996;Ceresini and Souza 1997;Elias-Medina et al 1997).…”